Cameron Kepert

Truchet-tile structure of a topologically aperiodic metal–organic framework

Publisher: American Association for the Advancement of Science (AAAS)

Date: 27-01-2023

DOI: 10.1126/SCIENCE.ADE5239

Abstract: When tiles decorated to lower their symmetry are joined together, they can form aperiodic and labyrinthine patterns. Such Truchet tilings offer an efficient mechanism of visual data storage related to that used in barcodes and QR codes. We show that the crystalline metal–organic framework [OZn 4 ][1,3-benzenedicarboxylate] 3 (TRUMOF-1) is an atomic-scale realization of a complex three-dimensional Truchet tiling. Its crystal structure consists of a periodically arranged assembly of identical zinc-containing clusters connected uniformly in a well-defined but disordered fashion to give a topologically aperiodic microporous network. We suggest that this unusual structure emerges as a consequence of geometric frustration in the chemical building units from which it is assembled.

Guest-Adaptable Spin Crossover Properties in a Dinuclear Species Underpinned by Supramolecular Interactions

Publisher: American Chemical Society (ACS)

Date: 20-11-2018

DOI: 10.1021/ACS.INORGCHEM.8B02625

Abstract: Molecular crystals with guest-adaptable crystalline structures and properties are comparatively rare owing to their inherent reduced structural stability and malleability to support molecular variation. To overcome this intrinsic challenge, here we introduce structural stabilizing supramolecular interactions into a dinuclear material and henceforth demonstrate a dynamic structural and spin crossover property interchange between solvated (A·3MeOH) and desolvated (A·Ø) products (A = [Fe

Guest programmable multlstep spin crossover in a porous 2-D Hofmann-type material

Publisher: American Chemical Society (ACS)

Date: 13-01-2017

DOI: 10.1021/JACS.6B12465

Abstract: The spin crossover (SCO) phenomenon defines an elegant class of switchable materials that can show cooperative transitions when long-range elastic interactions are present. Such materials can show multistepped transitions, targeted both fundamentally and for expanded data storage applications, when antagonistic interactions (i.e., competing ferro- and antiferro-elastic interactions) drive concerted lattice distortions. To this end, a new SCO framework scaffold, [Fe

Thermal‐ and Light‐Induced Spin Crossover in a Guest‐Dependent Dinuclear Iron(II) System

Publisher: Wiley

Date: 28-01-2010

DOI: 10.1002/CHEM.200901809

Abstract: We previously reported the dinuclear material [Fe(II) (2)(ddpp)(2)(NCS)(4)] x 4 CH(2)Cl(2) (1 x 4 CH(2)Cl(2) ddpp = 2,5-di(2',2''-dipyridylamino)pyridine) and its partially desolvated analogue (1 x CH(2)Cl(2)), which undergo two- and one-step spin-crossover (SCO) transitions, respectively. Here, we manipulate the type and degree of solvation in this system and find that either a one- or two-step spin transition can be specifically targeted. The chloroform clathrate 1 x 4 CHCl(3) undergoes a relatively abrupt one-step SCO, in which the two equivalent Fe(II) sites within the dinuclear molecule crossover simultaneously. Partial desolvation of 1 x 4 CHCl(3) to form 1 x 3 CHCl(3) and 1 x CHCl(3) occurs through single-crystal-to-single-crystal processes (monoclinic C2/c to P2(1)/n to P2(1)/n) in which the two equivalent Fe(II) sites become inequivalent sites within the dinuclear molecule of each phase. Both 1 x 3 CHCl(3) and 1 x CHCl(3) undergo one-step spin transitions, with the former having a significantly higher SCO temperature than 1 x 4 CHCl(3) and the latter, and each has a broader SCO transition than 1 x 4 CHCl(3), attributable to the overlap of two SCO steps in each case. Further magnetic manipulation can be carried out on these materials through reversibly resolvating the partially desolvated material with chloroform to produce the original one-step SCO, or with dichloromethane to produce a two-step SCO reminiscent of that seen for 1 x 4 CH(2)Cl(2). Furthermore, we investigate the light-induced excited spin state trapping (LIESST) effect on 1 x 4 CH(2)Cl(2) and 1 x CH(2)Cl(2) and observe partial LIESST activity for the former and no activity for the latter.

Compositional Dependence of Negative Thermal Expansion in the Prussian Blue Analogues M^IIPt^IV(CN)₆ (M = Mn, Fe, Co, Ni, Cu, Zn, Cd)

Publisher: American Chemical Society (ACS)

Date: 05-2006

DOI: 10.1021/JA060916R

Abstract: The effect of M(II) substitution on the magnitude of the negative thermal expansion (NTE) behavior within a series of Prussian Blue analogues, M(II)Pt(IV)(CN)(6) for M(II) = Mn, Fe, Co, Ni, Cu, Zn, Cd, has been investigated using variable-temperature powder X-ray diffraction (100-400 K). The NTE behavior varies widely with M(II) substitution, from near zero thermal expansion in NiPt(CN)(6) (alpha = dl/l dT = -1.02(11) x 10(-)(6) K(-)(1)) up to a maximum in CdPt(CN)(6) (alpha = -10.02(11) x 10(-)(6) K(-)(1)). The trend in the magnitude of the NTE behavior, with increasing atomic number (Z) of the M(II) ion, follows the order Mn(II) > Fe(II) > Co(II) > Ni(II) < Cu(II) < Zn(II) < Cd(II), which correlates with the trends for M(II) cation size, the lattice parameter, and structural flexibility as indicated by the temperature-dependent structural refinements and Raman spectroscopy. Analysis of the temperature dependence of the average structures suggests that the differences in the thermal expansion are due principally to the different strengths of the metal-cyanide binding interaction and, accordingly, the different energies of transverse vibration of the cyanide bridge, with enhanced NTE behavior for more flexible lattices.

Mixed-Component Sulfone-Sulfoxide Tagged Zinc IRMOFs: In Situ Ligand Oxidation, Carbon Dioxide, and Water Sorption Studies

Publisher: American Chemical Society (ACS)

Date: 24-02-2017

DOI: 10.1021/ACS.CGD.7B00007

Quantification of the mixed-valence and intervalence charge transfer properties of a cofacial metal–organic framework via single crystal electronic absorption spectroscopy

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0SC01521K

Abstract: Gaining a fundamental understanding of charge transfer mechanisms in three-dimensional Metal–Organic Frameworks (MOFs) is crucial to the development of electroactive and conductive porous materials.

Local vibrational mechanism for negative thermal expansion: A combined neutron scattering and first-principles study

Publisher: Wiley

Date: 07-01-2010

DOI: 10.1002/ANIE.200903366

Adsorption Dynamics of Gases and Vapors on the Nanoporous Metal Organic Framework Material Ni₂(4,4‘-Bipyridine)₃(NO₃)₄:  Guest Modification of Host Sorption

Publisher: American Chemical Society (ACS)

Date: 21-09-2001

DOI: 10.1021/JA0109895

Abstract: This study combines measurements of the thermodynamics and kinetics of guest sorption with powder X-ray diffraction measurements of the nanoporous metal organic framework adsorbent (host) at different adsorptive (guest) loadings. The adsorption characteristics of nitrogen, argon, carbon dioxide, nitrous oxide and ethanol and methanol vapors on Ni2(4,4'-bipyridine)3(NO3)4 were studied over a range of temperatures as a function of pressure. Isotherm steps were observed for both carbon dioxide and nitrous oxide adsorption at approximately 10-20% of the total pore volume and at approximately 70% of total pore volume for methanol adsorption. The adsorption kinetics obey a linear driving force (LDF) mass transfer model for adsorption at low surface coverage. At high surface coverage, both methanol and ethanol adsorption follow a combined barrier resistance/diffusion model. The rates of adsorption in the region of both the carbon dioxide and methanol isotherm steps were significantly slower than those observed either before or after the step. X-ray diffraction studies at various methanol loadings showed that the host structure disordered initially but underwent a structural change in the region of the isotherm step. These isotherm steps are ascribed to discrete structural changes in the host adsorbent that are induced by adsorption on different sites. Isotherm steps were not observed for ethanol adsorption, which followed a Langmuir isotherm. Previous X-ray crystallography studies have shown that all the sites are equivalent for ethanol adsorption on Ni2(4,4'-bipyridine)3(NO3)4, with the host structure undergoing a scissoring motion and the space group remaining unchanged during adsorption. The activation energies and preexponential factors for methanol and ethanol adsorption were calculated for each pressure increment at which the linear driving force model was obeyed. There was a good correlation between activation energy and ln(preexponential factor), indicating a compensation effect. The results are discussed in terms of reversible adsorbate/adsorbent (guest/host) structural changes and interactions and the adsorption mechanism. The paper contains the first evidence of specific interactions between guests and functional groups leading to structural change in flexible porous coordination polymer frameworks.

Binary metal(II)–pyromellitate coordination polymers, M 2 (pm) (M=Co, Fe, Mn): synthesis, structures and magnetic properties

Publisher: Elsevier BV

Date: 07-2003

DOI: 10.1016/S0277-5387(03)00177-3

Commensurate CO2 Capture, and Shape Selectivity for HCCH over H2CCH2, in Zigzag Channels of a Robust Cu^I(CN)(L) Metal-Organic Framework

Publisher: American Chemical Society (ACS)

Date: 03-06-2016

DOI: 10.1021/ACS.INORGCHEM.6B00813

Abstract: A novel copper(I) metal-organic framework (MOF), {[Cu(I)2(py-pzpypz)2(μ-CN)2]·MeCN}n (1·MeCN), with an unusual topology is shown to be robust, retaining crystallinity during desolvation to give 1, which has also been structurally characterized [py-pzpypz is 4-(4-pyridyl)-2,5-dipyrazylpyridine)]. Zigzag-shaped channels, which in 1·MeCN were occupied by disordered MeCN molecules, run along the c axis of 1, resulting in a significant solvent-accessible void space (9.6% of the unit cell volume). These tight zigzags, bordered by (Cu(I)CN)n chains, make 1 an ideal candidate for investigations into shape-based selectivity. MOF 1 shows a moderate enthalpy of adsorption for binding CO2 (-32 kJ mol(-1) at moderate loadings), which results in a good selectivity for CO2 over N2 of 4.8:1 under real-world operating conditions of a 15:85 CO2/N2 mixture at 1 bar. Furthermore, 1 was investigated for shape-based selectivity of small hydrocarbons, revealing preferential uptake of linear acetylene gas over ethylene and methane, partially due to kinetic trapping of the guests with larger kinetic diameters.

Structural Systematics of Rare Earth Complexes. XII Solvated 1 : 1 Adducts of Some Lanthanoid(III) Carboxylates with 1,10-Phenanthroline and 2,2′:6′,2&Prime;-Terpyridine

Publisher: CSIRO Publishing

Date: 1999

DOI: 10.1071/CH98043

Abstract: A room-temperature single-crystal X-ray structure determination of the 1 : 1 adduct of 1,10-phenanthroline (`phen") with lutetium(III) acetate (as its dihydrate) is recorded. Crystals are triclinic, P 1, a 12·430(8), b 10·681(4), c 8·134(8) Å, α 74·76(6), β 84·81(7), γ 74·29(4)°, Z = 2 f.u. conventional R on |F| was 0·031 for No 3939 independent ‘observed’ (I 3σ(I)) diffractometer reflections. The complex [(N,N′-phen)(O,O′-ac)Lu(O-ac-O′)4Lu(O,O′-ac)(N,N′-phen)].2H2O is binuclear, the lutetium being eight-coordinated by bidentate phen and ac (acetate) ligands and four oxygen atoms from the bridging acetate ligands. Also recorded is the structural characterization of 1 : 1 Lu(ac)2Cl/tpy (tpy = 2,2′:6′,2″-terpyridine) as its pentahydrate this complex is triclinic, P 1, a 12·410(3), b 11·559(4), c 9·976(4) Å, α 85·19(3), β 70·30(3), γ 65·70(2)°, Z = 2, R 0·049 for No 4717. The complex is shown to be [(tpy)(H2O)2Lu(O2CCH3)2]Cl.3H2O, with the lutetium nine-coordinated by tridentate tpy, a pair of bidentate acetates and two unidentate water molecules, with the chloride uncoordinated. Structural characterizations of a number of 1 : 1 adducts of variously solvated lanthanoid(III) trichloroacetates, Ln(tca)3, with tpy are also recorded. Yb(tca)3/tpy/MeOH (1 : 1 : 1) is triclinic, P 1, a 14·016(4), b 12·951(5), c 9·604(3) Å, α 73·89(3), β 76·56(3), γ 69·20(3)°, Z = 2 f.u., R 0·057 for No 4465. The complex is mononuclear, the eight-coordinate N3YbO5 array containing tridentate tpy, unidentate methanol, and two unidentate and one bidentate chelating anions. 1 : 1 : 1 Ln(tca)3/tpy/OH2 adducts for Ln = La(-)Nd are triclinic, P 1, a ≈ 13·4, b ≈ 12·47, c ≈ 11·5 Å, α ≈ 114·5, β ≈ 89·9, γ ≈ 115·6°, Z = 1 binuclear array, R 0·061, 0·071 for No 3240, 2394. The two Ln atoms are O,O′-bridged by a pair of anions, the N3LnO6 nine-coordinate lanthanoid environment being completed by a tridentate tpy, one water, one unidentate and one bidentate anion. A 1 : 1 : 1 Lu(tca)3/tpy/OH2 array, by contrast, is triclinic, P 1, a 16·569(8), b 14·815(5), c 14·375(6) Å, α 62·05(3), β 81·35(4), γ 77·97(3)°, Z = 4 ‘mononuclear’ f.u., R 0·067 for No 6710. The array, remarkably, contains species of both of the above types in a 1 : 2 binuclear-to-mononuclear ratio, but with water replacing methanol in the mononuclear array.

Structural Systematics of Rare Earth Complexes. X (‘Maximally’) Hydrated Rare Earth Acetates

Publisher: CSIRO Publishing

Date: 1999

DOI: 10.1071/CH98041

Abstract: Extension/augmentation of preexisting work carried out in respect of room-temperature single-crystal X-ray structural characterization of trivalent rare earth acetates, crystallized as ‘maximal’ hydrates, Ln(ac)3.x H2O, from aqueous solution under local ambience, suggests the following array to be prevalent: For Ln = La(-)Pr: triclinic P 1 sesquihydrate, i.e. x = 1½, a ≈ 13·4, b ≈ 10·1, c ≈ 8·6 Å, α ≈ 75·6, β ≈ 103·8, γ ≈ 92·8°, Z = 4 mononuclear f.u., conventional R on |F| for Ln = La, Ce, here, being 0·043, 0·058 for No 3199, 4442 independent ‘observed’ (I 3σ(I)) diffractometer reflections respectively the complexes have the form of a two-dimensional polymer, in the ac plane, the dominant motif being a chain of lanthanoid atoms of two types linked by acetate bridges along a ... Ln(1)Ln(2)Ln(2)Ln(1)Ln(1)Ln(2) ... with further acetates cross-linking the Ln(1) in the c dimension. For Ln = (Ce(-))Nd: monoclinic P 21/c monohydrate, a ≈ 8·4, b ≈ 8·0, c ≈ 15·0 Å, β ≈ 94°, Z = 4 mononuclear f.u., for the present determinations R were 0·024, 0·044 for No 2019, 2600, the structure being a one-dimensional polymeric form with acetate bridges. For Ln = Sm(-)Lu, (i.e. implicitly with intermediate Ln): triclinic P1 tetrahydrate, a ≈ 10·4, b ≈ 9·2, c ≈ 8·8 Å, α ≈ 118, β ≈ 114, γ ≈ 92°, Z = 2 mononuclear f.u., R were 0·035, 0·030 for No 4583, 4678, the complexes being acetate-bridged dimers. It is of interest that, through the three series, the variation in the degree of hydration is not monotonic. Determinations are also recorded for a pair of crystalline compounds obtained during the attempted crystallization of europium(III) acetate hydrate from aqueous solution acidified with acetic acid (Hac), supporting their formulation as entailing the formation of mixed water/acetic acid solvates Eu(ac)3.2H2O.Hac and Eu(ac)3.H2O.2½Hac, i.e. [Eu2(ac)6(OH2)4].2Hac and [Eu2(ac)6(OH2)2(Hac)2].3Hac with common binuclear cores in which a pair of unidentate water molecule ligands in the former is replaced by a pair of unidentate acetic acid ligands in the latter with relatively minor geometrical change. The former array is rhombohedral R3, a 26·865(7), c 10·328(3) Å (hexagonal setting), Z = 9 binuclear units, isomorphous with the previously reported samarium analogue, and the latter triclinic P1, a 14·131(5), b 8·919(4), c 8·582(3) Å, α 65·41(3), β 84·72(3), γ 84·27(3)°, Z = 1 binuclear unit, R 0·046, 0·051 for No 1700, 2553. An interesting double salt, trisodium hexakis(acetato)ytterbate(III) tetrahydrate, Na3[Yb(ac)6].4H2O, is monoclinic, C2/c, a 13·139(3), b 13·936(2), c 26·030(2) Å , β 91·10(1)°, Z = 8, R 0·053 for No 3467. The eight-coordinate (YbO8) environment is comprised of oxygen atoms from a pair of O,O′-chelating and four unidentate acetate moieties.

Synthesis and Characterization of Subcell−Supercell Related Ethylenediamine-Pillared Zinc Hydroxysulfates

Publisher: American Chemical Society (ACS)

Date: 21-09-2004

DOI: 10.1021/CG034242X

Self-Assembly of a Metallomacrocycle Templated by Iron(II)

Publisher: American Chemical Society (ACS)

Date: 27-12-2011

DOI: 10.1021/IC102350T

Abstract: An unusual discrete heteronuclear metallomacrocycle was designed and synthesized via metal-ion-directed self-assembly by an iron(II) template. The formation of this metallomacrocycle was demonstrated by X-ray crystallography, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, and NMR spectroscopy.

Structural Systematics of Rare Earth Complexes. XI (‘Maximally’) Hydrated Rare Earth(III) Trifluoro- and Trichloro-acetates

Publisher: CSIRO Publishing

Date: 1999

DOI: 10.1071/CH98042

Abstract: Room-temperature single-crystal X-ray structure determinations carried out on ‘maximally’ hydrated rare earth(III) trifluoroacetates, Ln(tfa)3.x H2O, crystallized at room temperature, show the Ln = La, Ce adducts to be isomorphous and monoclinic, P 21/c, a ≈ 11·9, b ≈ 12·8, c ≈ 9·8 8 Å, β ≈ 103·7°, Z = 4 they are trihydrates. The Ln = Pr, Lu (and, implicitly, intermediate Ln) adducts are also monoclinic, P 21/c, Z = 4, and trihydrates, but of a different polymorph, with a ≈ 9·2, b 18·8, c ≈ 9·8 Å, β ≈ 114°. For the four determinations, conventional R values on |F| were 0·038, 0·032, 0·036, and 0·034 for No 2952, 4821, 4544, and 4092 independent ‘observed’ (I 3σ(I)) diffractometer reflections respectively. The Ln = La, Ce adducts are two-dimensional polymers, the sheets parallel to the bc plane the other systems are binuclear, the two metal atoms being linked by four bridging carboxylate O-tfa-O′ ligands. In both structural types, the metal atoms are eight-coordinate, but differ in the number of water molecules (2 cf. 3) in the O8 array. Extension of previous studies by single-crystal X-ray methods on the structural characterization of trivalent rare earth trichloroacetates, ‘maximally’ hydrated at local ambience, Ln(tca)3.x H2O, suggests the following arrays to be prevalent. The Ln = La adduct is a pentahydrate, monoclinic, P21/c, a 5·636(7), b 22·454(4), c 16·58(1) Å, β 90·52(8)°, Z = 4 f.u., R 0·035 for No 4154. The compound is a linear polymer along a, successive nine-coordinate La (separated by a) being linked by three O-tca-O′ bridging ligands at the opposite faces of a tricapped trigonal prismatic array, the equatorial sites being filled by water molecules. The Ln = Ce adduct is a trihydrate, monoclinic, P 21/c, a 10·071(2), b 22·973(2), c 20·222(5) Å, b 119·48(2)°, Z= 8 f.u., R 0·050 for No 5019. The array is also linear polymeric, but with successive Ce being linked alternately now by sets of two and then four O-tca-O′ bridging carboxylates along b, the Ln = Ce coordination number being diminished (relative to La) to eight with the coordination of two water molecules to each metal. Ln = Pr, Lu (and, presumptively, intermediate Ln) are dihydrates, triclinic, P 1, a ≈ 11·70, b ≈ 12·8, c ≈ 15·3 Å, α ≈ 71, β ≈ 77·85, γ ≈ 65·5°, Z = 4 f.u., R 0·056, 0·059 for No 5650, 5398. The array is a linear polymer, similar to that of the Ln = Ce adduct but alongside the bridging acetate pair one of the water molecules now bridges, resulting in a stepped Ln 1 array (along c) rather than a quasi-straight one as is found for the Ln = Ce (and La) adduct. Structure determinations are also recorded for rare earth(III) trichloroacetate ethanol trisolvates, Ln(tca)3.3EtOH. Adducts of Ln = La, Yb (and, implicitly, intermediate Ln) are isomorphous, triclinic, P 1, a ≈ 12, b ≈ 11·8, c ≈ 11·4 Å, α ≈ 114, β ≈ 100, γ ≈ 104°, Z = 2 f.u., R 0·056, 0·050 for No 3843, 4171. The complexes are centrosymmetric dimers [(EtOH)3(tca-O)Ln(O-tca-O′)4Ln(O-tca)(HOEt)3], the two metal atoms being linked by four O-tca-O′ bridging carboxylate groups the metal atoms are eight-coordinate, the other four sites being occupied by four oxygen atoms from unidentate ethanol and carboxylate moieties. Bis(bis(2-pyridyl)aminium) bis(diaquatetrakis(trichloroacetato)lanthanate(III)), 2(dpaH+) [(H2O)2-(tca-O)(tca-O,O′)2La(O-tca-O′)2La(O,O′-tca)2(O-tca)(OH2)2]2-, is triclinic, P 1, a, 13·901(2), b 13·764(3), c 10·073(2) Å, α 104·04(2), β 108·93(2), γ 101·50(2)°, Z = 1 binuclear f.u., R 0·045 for No 4999. The anion is binuclear, the two nine-coordinate lanthanum atoms being linked by a pair of bridging O-carboxylate-O′ groups. The other seven sites of the LaO9 array are occupied by a pair of O,O′ -chelating and one O-unidentate carboxylate groups and a pair of water molecules.

Two new porous UiO-66-type zirconium frameworks; open aromatic N-donor sites and their post-synthetic methylation and metallation

Publisher: Royal Society of Chemistry (RSC)

Date: 2017

DOI: 10.1039/C6TA11005C

Abstract: Free pyridyl functionality is incorporated into two new MOFs through an unusual high acidity route, and exploited through post-synthetic modification.

Low energy phonons in the NTE compounds and

Publisher: Elsevier BV

Date: 11-2006

DOI: 10.1016/J.PHYSB.2006.05.102

Reversible Guest Exchange and Ferrimagnetism (T_C = 60.5 K) in a Porous Cobalt(II)−Hydroxide Layer Structure Pillared with trans-1,4-Cyclohexanedicarboxylate

Publisher: American Chemical Society (ACS)

Date: 25-09-2015

DOI: 10.1021/IC034787G

Abstract: The synthesis, characterization, and reversible guest-exchange chemistry of a new porous magnetic material that orders ferrimagnetically at 60.5 K are described. The material, Co(5)(OH)(8)(chdc).4H(2)O (chdc = trans-1,4-cyclohexanedicarboxylate), contains tetrahedral-octahedral-tetrahedral Co(II)-hydroxide layers of composition Co((oct))(3)Co((tet))(2)(OH)(8) that are linked together by bis(unidentate) chdc pillars. Noncoordinated water molecules occupy 1-D channels situated between the chdc pillars. The material remains monocrystalline during dehydration from Co(5)(OH)(8)(chdc).4H(2)O (CDCC.4H(2)O) to Co(5)(OH)(8)(chdc) (CDCC) via an intermediate Co(5)(OH)(8)(chdc).2H(2)O (CDCC.2H(2)O) upon heating or evacuation. In-situ single crystal and powder X-ray diffraction analyses indicate that the interlayer spacing decreases in two steps, each corresponding to the loss of two water molecules per formula unit as determined by thermogravimetry. The single crystal structure of the fully dehydrated material, CDCC, has no void volume due to a tilting of the pillars and 9% decrease of the interlayer spacing with water removal. Exposure of CDCC to air causes rapid rehydration of this material to CDCC.4H(2)O, as determined by single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetry, and vibrational spectroscopy. Both the hydrated and dehydrated forms order magnetically below 60.5 K. The susceptibility data are consistent with ferrimagnetic behavior, and the value of the saturation magnetization at 2 K (ca. 2 micro(B)) is explained by a model of two sublattices, one comprising three octahedral cobalt atoms and another comprising two tetrahedral cobalt atoms. There is an enhanced 2-D correlation within the layer at temperatures just above the Curie temperature, as seen by nonlinearity in the ac susceptibility data and remanence in the isothermal magnetization. The crossover from 2-D to 3-D ordering occurs at T(C). The large anisotropy in the magnetization data on a single crystal suggests either a 2-D Ising or an XY magnet while the critical exponent of 0.25 is in favor of the latter. Both magnetization data in a small field in the ac and dc mode and isothermal magnetization data provide evidence of a further change in behavior at 23 K, which may originate from a reorientation of the moments within the layer. Variation of the pillar and of the guest-exchange chemistry, including the exchange of magnetic guests such as O(2), offers the possibility of tailoring the magnetic properties of this material.

A Family of Discrete Magnetically Switchable Nanoballs

Publisher: Wiley

Date: 30-07-2012

DOI: 10.1002/CPLU.201200123

Structural Systematics of Rare Earth Complexes. V. The Hydrated 1 : 1 Adducts of 2,2′:6′,2″-Terpyridine With the Lanthanoid(III) Chlorides

Publisher: CSIRO Publishing

Date: 1994

DOI: 10.1071/CH9940365

Abstract: Detailed examination of the strucures of the title salts, (tpy)LnCl3.xH2O, across the totality of the rare earth series shows a remarkable interplay of structural type and detail. The predominant phase is the previously studied monoclinic Cm array, a ≈ 7.5, b ≈ 16.6, c ≈ 9.8 Ǻ, β = 90.2°, V ≈ 2200 Ǻ3, Z = 2 formula units. For the initial members of the series (La → Nd ), x is 8 for Dy → Er and Lu, x = 7 is accommodated within the same lattice, as are intermediate degrees of hydration for Sm → Gd . A second monoclinic phase, P 21/c, a ≈ 11.6, b ≈ 13.9, c ≈ 13.8 Ǻ, β ≈ 92.3°, V ≈ 2200 Ǻ3, Z = 4 formula units, is found for Yb and Lu (x = 7) the same phase but with β acute (a ≈ 11.3, b ≈ 14.5, c ≈ 13.3 Ǻ, β ≈ 82.2°, V ≈ 2140 Ǻ3, Z = 4 formula units) is found for Tm (and Y) (x = 6). A less hydrated binuclear phase, x=1, has also been observed for Sm , a 10.179(3), b 9.928(4), c 9.748(4) Ǻα 112.61(3), β 109.85(3), γ 94.72(3)°, V 829.3 Ǻ3, Z = 1 dimer.

Crystal structures and physical properties of BEDT-TTF charge transfer salts with (Mo ₆ Cl ₈ )X ^2-

Publisher: The Royal Society

Date: 08-02-1998

DOI: 10.1098/RSPA.1998.0172

Elucidating Negative Thermal Expansion in MOF-5

Publisher: American Chemical Society (ACS)

Date: 09-09-2010

DOI: 10.1021/JP103212Z

Enhancing selective CO2 adsorption via chemical reduction of a redox-active metal–organic framework

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3DT00083D

Abstract: A new microporous framework, Zn(NDC)(DPMBI) (where NDC = 2,7-naphthalene dicarboxylate and DPMBI = N,N'-di-(4-pyridylmethyl)-1,2,4,5-benzenetetracarboxydiimide), containing the redox-active benzenetetracarboxydiimide (also known as pyromellitic diimide) ligand core has been crystallographically characterised and exhibits a BET surface area of 608.2 ± 0.7 m(2) g(-1). The crystallinity of the material is retained upon chemical reduction with sodium naphthalenide (NaNp), which generates the monoradical anion of the pyromellitic diimide ligand in the framework Zn(NDC)(DPMBI)·Na(x) (where x represents the molar Na(+)/Zn(2+) ratio of 0.109, 0.233, 0.367 and 0.378 from ICP-AES), as determined by EPR, solid state Vis-NIR spectroelectrochemistry and UV-Vis-NIR spectroscopy. The CO2 uptake in the reduced materials relative to the neutral framework is enhanced up to a Na(+)/Zn(2+) molar ratio of 0.367 however, beyond this concentration the surface area and CO2 uptake decrease due to pore obstruction. The CO2 isosteric heat of adsorption (|Q(st)|) and CO2/N2 selectivity (S), obtained from pure gas adsorption isotherms and Ideal Adsorbed Solution Theory (IAST) calculations, are also maximised relative to the neutral framework at this concentration of the alkali metal counter-ion. The observed enhancement in the CO2 uptake, selectivity and isoteric heat of adsorption has been attributed to stronger interactions between CO2 and both the radical DPMBI ligand backbone and the occluded Na(+) ions.

Structural and Magnetic Resolution of a Two‐Step Full Spin‐Crossover Transition in a Dinuclear Iron(II) Pyridyl‐Bridged Compound

Publisher: Wiley

Date: 27-10-2006

DOI: 10.1002/CHEM.200601069

Abstract: A dinuclear iron(II) complex containing the new pyridyl bridging ligand, 2,5-di(2',2''-dipyridylamino)pyridine (ddpp) has been synthesised and characterised by single-crystal X-ray diffraction, magnetic susceptibility and Mössbauer spectral methods. This compound, [Fe(2)(ddpp)(2)(NCS)(4)]4 CH(2)Cl(2), undergoes a two-step full spin crossover. Structural analysis at each of the three plateau temperatures has revealed a dinuclear molecule with spin states HS-HS, HS-LS and LS-LS (HS: high spin, LS: low spin) for the two iron(II) centres. This is the first time that resolution of the metal centres in a HS-LS ordered state has been achieved in a two-step dinuclear iron(II) spin-crossover compound. Thermogravimetric data show that the dichloromethane solvate molecules can be removed in two distinct steps at 120 degrees C and 200 degrees C. The partially de-solvated clathrate, [Fe(2)(ddpp)(2)(NCS)(4)]CH(2)Cl(2), undergoes a one-step transition with an increased transition temperature with respect to the as synthesised material. Structural characterisation of this material reveals subtle changes to the coordination geometries at each of the iron(II) centres and striking changes to the local environment of the dinuclear complex. The fully de-solvated material remains high spin over all temperatures. Interestingly, the solvent can be re-introduced into the monosolvated solid to achieve complete conversion back to the original two-step crossover material, [Fe(2)(ddpp)(2)(NCS)(4)]4 CH(2)Cl(2).

Metal‐Organic Framework Materials

Publisher: Wiley

Date: 19-10-2010

DOI: 10.1002/9780470711385.CH1

A cofacial metal–organic framework based photocathode for carbon dioxide reduction

Publisher: Royal Society of Chemistry (RSC)

Date: 2021

DOI: 10.1039/D0SC04691D

Abstract: The photocathode functionality of a Metal–Organic Framework (MOF) featuring cofacial photo- and electro-active ligands provides a new approach to CO 2 reduction via charge transfer with a rhenium electrocatalyst.

Magnetoresistance studies on (BEDT-TTF)4(Mo6Cl8)Cl6.xCH2Cl2 under pressure

Publisher: Elsevier BV

Date: 02-1997

DOI: 10.1016/S0379-6779(97)80998-8

Strong interplay between the electron spin lifetime in chemically synthesized graphene multilayers and surface-bound oxygen

Publisher: Wiley

Date: 13-11-2015

DOI: 10.1002/CHEM.201404309

Abstract: The electron spin lifetime in an assembly of chemically synthesized graphene sheets was found to be extremely sensitive to oxygen. Introducing small concentrations of physisorbed O2 onto the graphene surface reduced the exceptionally long 140 ns electron spin lifetime by an order of magnitude. This effect was completely reversible: Removing the O2 by using a dynamic vacuum restored the spin lifetime. The presence of covalently bound oxygen also decreased the electron spin lifetime in graphene, although to a far lesser extent compared to physisorbed O2 . The conduction electrons in graphene were found to play a significant role by counter-balancing the spin depolarization caused by oxygen molecules. Our results highlight the importance of chemical environment control and device packing in practical graphene-based spintronic applications.

A porous Mn(v) coordination framework with PtS topology: assessment of the influence of a terminal nitride on CO2 sorption

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3DT51721G

Abstract: A new coordination framework material, [Zn{MnN(CN)4(H2O)}]·2H2O·MeOH, has been characterised crystallographically and the effect of a terminal nitride on the N2, H2 and CO2 sorption capacities of the material assessed through porosimetery measurements and DRIFTS.

The Structural Systematics of Protonation of Some Important Nitrogen‐base Ligands. I Some Univalent Anion Salts of Doubly Protonated 2, 2′:6′, 2″‐Terpyridyl

Publisher: Wiley

Date: 29-05-2006

DOI: 10.1002/ZAAC.200500495

Selective gas adsorption in a pair of robust isostructural MOFs differing in framework charge and anion loading

Publisher: American Chemical Society (ACS)

Date: 02-10-2014

DOI: 10.1021/IC501876M

Abstract: Activation of the secondary assembly instructions in the mononuclear pyrazine imide complexes [Co(III)(dpzca)2](BF4) or [Co(II)(dpzca)2] and [Ni(II)(dpzca)2] has facilitated the construction of two robust nanoporous three-dimensional coordination polymers, [Co(III)(dpzca)2Ag](BF4)2·2(H2O) [1·2(H2O)] and [Ni(II)(dpzca)2Ag]BF4·0.5(acetone) [2·0.5(acetone)]. Despite the difference in charge distribution and anion loading, the framework structures of 1·2(H2O) and 2·0.5(acetone) are isostructural. One dimensional channels along the b-axis permeate the structures and contain the tetrafluoroborate counterions (the Co(III)-based MOF has twice as many BF4(-) anions as the Ni(II)-based MOF) and guest solvent molecules. These anions are not readily exchanged whereas the solvent molecules can be reversibly removed and replaced. The H2, N2, CO2, CH4, H2O, CH3OH, and CH3CN sorption behaviors of the evacuated frameworks 1 and 2 at 298 K have been studied, and modeled, and both show very high selectivity for CO2 over N2. The increased anion loading in the channels of Co(III)-based MOF 1 relative to Ni(II)-based MOF 2 results in increased selectivity for CO2 over N2 but a decrease in the sorption kinetics and storage capacity of the framework.

Structure and Magnetic Studies on a Series of Two-Dimensional Iron(II) Framework Materials with Varying Ligand Characteristics

Publisher: CSIRO Publishing

Date: 2017

DOI: 10.1071/CH16586

Abstract: Targeting the general (4,4)-grid structural motif, we have prepared seven new coordination polymers in the general family [Fe(NCX)2(L)2]·(guest) (L = bis-pyridyl-type bridging ligands X = S, Se) as an extension of the well-established spin crossover framework (SCOF) family. In all cases, the (4,4)-grid topology is formed by the bridging of octahedral iron(ii) sites in the equatorial plane by bis-pyridyl ligands of varying length, flexibility, and intermolecular interaction capacity. In particular, the six ligands n-(4-pyridyl)-isonicotinamide (pin), trans-1,2-bis(4′-pyridyl)ethane (tvp), 1,2-dibromo-1,2-bis(4′-pyridyl)ethane (dbbpe), bis(4-pyridyl)-1,2,4,5-tetrazine (bptz), 4,4′-bis(pyridyl)acetylene (bpac), and 1,4-bis(4-pyridylethynyl)benzene (bpeben) have been utilised. The seven new materials [Fe(NCS)2(pin)2]·2(MeCN) (pin-S), [Fe(tvp)2(NCS)2]·1/2(tvp)·(CH3CH2OH) (tvp-S), [Fe(dbbpe)2(NCS)2]·6(CH3CN) (dbbpe-S), [Fe(NCS)2(bptz)2]·2(CHCl3)·6(EtOH) (bptz-S), [Fe(NCSe)2(bptz)2]·4(CHCl3)·(EtOH)·(H2O) (bptz-Se), [Fe(NCS)2(bpac)2]·2(PrOH) (bpac-S), and [Fe(NCS)2(bpeben)2]·2(CHCl3) (bpeben-S) all form (4,4)-grids of varying size that are arranged in a parallel stacked topology. Despite being in the [FeN6] coordination environment known to be conducive to spin crossover, these materials all remain high-spin with thermal variation. These results are discussed in context with the large family of SCOFs that show varied spin crossover behaviours.

Dynamic photo-switching in metal-organic frameworks as a route to low-energy carbon dioxide capture and release

Publisher: Wiley

Date: 10-02-2013

DOI: 10.1002/ANIE.201206359

Supramolecular Magnetic Materials

Publisher: CSIRO Publishing

Date: 2009

DOI: 10.1071/CH09399

High Spin to Low Spin Relaxation Regime Change in a Multistep 3D Spin‐Crossover Material

Publisher: Wiley

Date: 05-01-2018

DOI: 10.1002/EJIC.201701127

Zero Thermal Expansion in a Flexible, Stable Framework: Tetramethylammonium Copper(I) Zinc(II) Cyanide

Publisher: American Chemical Society (ACS)

Date: 16-12-2009

DOI: 10.1021/JA906895J

Abstract: Tetramethylammonium copper(I) zinc(II) cyanide, which consists of N(CH(3))(4)(+) ions trapped within a cristobalite-like metal cyanide framework, has been studied by variable-temperature powder and single-crystal X-ray diffraction. Its coefficient of thermal expansion is approximately zero over the temperature range 200-400 K and comparable with the best commercial zero thermal expansion materials. The atomic displacement parameters, apparent bond lengths, and structure of a low-temperature, low-symmetry phase reveal that the low-energy vibrational modes responsible for this behavior maintain approximately rigid Zn coordination tetrahedra but involve significant distortion of their Cu counterparts.

Structure, magnetism and photomagnetism of mixed-ligand tris(pyrazolyl)methane iron(ii) spin crossover compounds

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B708773J

Abstract: A range of bis-facial tridentate chelate complexes of type [Fe((R-pz)(3)CH)((3,5-Me(2)pz)(3)CH)](BF(4))(2) has been characterised that contain two different tris-pyrazolylmethane ligands, with variations in R being H (complex crystallised as polymorphs and ) and 4-Me (), as well as R = H with a CH(2)OH arm off the methane carbon (). A tris(pyridyl)methane analogue is also described (). The tris(3,5-dimethylpyrazolyl)methane co-ligand (3,5-Me(2)pz), and the BF(4)(-) counterion, are constant throughout. The spin-crossover properties of these Fe(ii) d(6) compounds have been probed in detail by variable temperature magnetic, Mössbauer spectral and crystallographic methods. The effects of distortions from octahedral symmetry around the Fe(ii) centres, of crystal solvate molecules (1.5 MeCN in and 2 MeCN in ) and of supramolecular/crystal packing, are discussed. In the case of , subtle twisting of pyrazole rings occurs, as a function of temperature, that has a greater effect upon the relative positions of the Fe(ii) chelate molecules in polymorph than in polymorph this is thought to drive the cooperativity differences observed in the magnetism of the polymorphs. Comparisons are also made between to and their homoleptic, parent [Fe(L)(2)] (2+) materials. The complexes were screened for the LIESST (light induced excited spin state trapping) effect by measurements of diffuse absorption spectra on the surface of powder s les, at different temperatures. One ex le, , showed a 2-step thermal spin crossover transition and it was probed in detail for its photomagnetic features. The T(LIESST) and T(1/2) values for did not obey an empirical relationship, T(LIESST) = 150 - 0.3T(1/2) followed by many Fe(ii)(N-donor)(6) crossover compounds of the bis-tridentate (meridional) type, and possible reasons for this are discussed.

A study of the magnetoresistance of the charge-transfer salt at hydrostatic pressures of up to 20 kbar: evidence for a charge-density-wave ground state and the observation of pressure-induced supercon

Publisher: IOP Publishing

Date: 12-08-1996

DOI: 10.1088/0953-8984/8/33/009

Guest-Dependent Spin Crossover in a Nanoporous Molecular Framework Material

Publisher: American Association for the Advancement of Science (AAAS)

Date: 29-11-2002

DOI: 10.1126/SCIENCE.1075948

Abstract: The nanoporous metal-organic framework Fe 2 (azpy) 4 (NCS) 4 ·(guest) (azpy is trans -4,4′-azopyridine) displays reversible uptake and release of guest molecules and contains electronic switching centers that are sensitive to the nature of the sorbed guests. The switching of this material arises from the presence of iron(II) spin crossover centers within the framework lattice, the sorbed phases undergoing “half-spin” crossovers, and the desorbed phase showing no switching property. The interpenetrated framework structure displays a considerable flexibility with guest uptake and release, causing substantial changes in the local geometry of the iron(II) centers. The generation of a host lattice that interacts with exchangeable guest species in a switchable fashion has implications for the generation of previously undeveloped advanced materials with applications in areas such as molecular sensing.

3-Methyl-1-(3-methylpyridinium-4-yl)pyridinium dichloride monohydrate

Publisher: International Union of Crystallography (IUCr)

Date: 10-02-2006

DOI: 10.1107/S1600536806004533

Construction of Hydrogen-Bonded and Coordination-Bonded Networks of Cobalt(II) with Pyromellitate:  Synthesis, Structures, and Magnetic Properties

Publisher: American Chemical Society (ACS)

Date: 30-05-2002

DOI: 10.1021/IC020065Y

Abstract: Synthesis (hydrothermal and metathesis), characterization (UV-vis, IR, TG/DTA), single-crystal X-ray structures, and magnetic properties of three cobalt(II)-pyromellitate complexes, purple [Co(2)(pm)](n) (1), red [Co(2)(pm)(H(2)O)(4)](n) x 2nH(2)O (2), and pink [Co(H(2)O)(6)](H(2)pm) (3) (H(4)pm = pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid)), are described. 1 consists of one-dimensional chains of edge-sharing CoO(6) octahedra that are connected into layers via O-C-O bridges. The layers are held together by the pyromellitate (pm(4-)) backbone to give a three-dimensional structure, each ligand participating in an unprecedented 12 coordination bonds (Co-O) to 10 cobalt atoms. 2 consists of a three-dimensional coordination network possessing cavities in which unbound water molecules reside. This highly symmetric network comprises eight coordinate bonds (Co-O) between oxygen atoms of pm(4-) to six trans-Co(H(2)O)(2). 3 possesses a hydrogen-bonded sandwich structure associating layers of [Co(H(2)O)(6)](2+) and planar H(2)pm(2-). The IR spectra, reflecting the different coordination modes and charges of the pyromellitate, are presented and discussed. The magnetic properties of 1 indicate complex behavior with three ground states (collinear and canted antiferromagnetism and field-induced ferromagnetism). Above the Néel temperature (T(N)) of 16 K it displays paramagnetism with short-range ferromagnetic interactions (Theta = +16.4 K, mu(eff) = 4.90 mu(B) per Co). Below T(N) a weak spontaneous magnetization is observed at 12.8 K in low applied fields (H 1000 Oe) metamagnetic behavior is observed. Two types of hysteresis loops are observed one centered about zero field and the second about the metamagnetic critical field. The critical field and the hysteresis width increase as the temperature is lowered. The heat capacity data suggest that 1 has a 2D or 3D magnetic lattice, and the derived magnetic entropy data confirm an anisotropic s(eff) = 1/2 for the cobalt(II) ion. Magnetic susceptibility data indicate that 2 and 3 are paramagnets.

Guest-Dependent Negative Thermal Expansion in Nanoporous Prussian Blue Analogues M^IIPt^IV(CN)₆·x{H₂O} (0 ≤ x ≤ 2; M = Zn, Cd)

Publisher: American Chemical Society (ACS)

Date: 12-2005

DOI: 10.1021/JA056460F

Abstract: The guest-dependent thermal expansion behavior of the nanoporous Prussian Blue analogues MIIPtIV(CN)6.x{H2O} (0 </= x </= 2 M = Zn, Cd) has been investigated using variable temperature single-crystal X-ray diffraction. The dehydrated phases MIIPtIV(CN)6 were found to exhibit negative thermal expansion, attributed to thermal population of low energy transverse vibrations of the bridging cyanide ligands. The presence of guest molecules within the framework pore system was found capable of d ening the effect of these transverse vibrational modes. The guest-loaded ZnII phase, in which the available pore volume is commensurate with the volume occupied by in idual water molecules, possesses a considerably higher coefficient of thermal expansion, with the material switching from positive to negative thermal expansion behavior upon guest removal.

Zeolite-like crystal structure of an empty microporous molecular framework

Publisher: Royal Society of Chemistry (RSC)

Date: 1999

DOI: 10.1039/A809746A

Structural Systematics of Rare Earth Complexes. XX (Maximally) Hydrated Rare Earth Sulfates and the Double Sulfates (NH4)Ln(SO4)2.4H2O (Ln = La, Tb)

Publisher: CSIRO Publishing

Date: 1999

DOI: 10.1071/CH98050

Abstract: Room-temperature single-crystal X-ray studies carried out on trivalent rare earth sulfate hydrates, Ln2(SO4)3.xH2O, crystallized at local ambience suggest the following arrays to be prevalent. For Ln = La, the nonahydrate is found, hexagonal P 63/m, with conventional R on |F| 0·023 for No 1159 ‘observed’ (I σ(I)) diffractometer reflections (redetermination). Although for Ln = Ce a similar structure has been previously recorded, we have obtained that adduct as the monoclinic C 2/c, Z = 4, octahydrate, a phase also found for Ln = Lu and erse representative intermediate lanthanoids: a ≈ 13·6, b ≈ 6·6, c ≈ 18·2 Å, β ≈ 102° for Ln = Ce (redetermination), Dy, Yb (redetermination), Lu, R was 0·022, 0·035, 0·031, 0·024 for No 3279, 2127, 3008, 3325 respectively. The structures of two lower hydrates adventitiously obtained are also recorded: the pentahydrate for Ln = Ce, monoclinic C 2/c, a 15·741(3), b 9·632(3), c 10·358(3) Å, β 119·72(2)°, Z = 4, R 0·030 for No 3372 (a redetermination), and the trihydrate for Ln = Lu, orthorhombic Cmc21, a 13·527(5), b 18·415(5), c 9·242(7) Å, Z = 8, R 0·040 for No 1743. All structures are infinite polymeric arrays, the lanthanoid atoms being bridged by sulfate ions. Studies are also recorded for the ammonium/trivalent rare earth double sulfate tetrahydrate salts, (NH4)Ln(SO4)2.4H2O, for the (hitherto) extremal members Ln = La, Tb, which are isomorphous with the previously studied Ln = Sm monoclinic P 21/c, Z = 4 array, a ≈ 6·6, b ≈ 19, c ≈ 8·8 Å, β 97° R 0·035, 0·037 for No 3631, 3337. The array is a two-dimensional polymer, parallel to the ac plane.

Bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) Charge Transfer Salts of Re₂(NCS)₁₀^n- (n = 2, 3)

Publisher: American Chemical Society (ACS)

Date: 03-1997

DOI: 10.1021/IC960884G

Abstract: Electrolytic oxidation of BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) in the presence of anionic rhenium thiocyanato complexes has led to the crystallization of two phases containing Re(2)(NCS)(10)(n)()(-) (n = 2, 3), while Re(NCS)(6)(2)(-) and Re(2)(NCS)(8)(2)(-) gave no characterizable products. (BEDT-TTF)(3)[Re(2)(NCS)(10)].2CH(2)Cl(2) (1) and (BEDT-TTF)(2)[Re(2)(NCS)(10)].C(6)H(5)CN (2) are both triclinic (P&onemacr ) with unit cell parameters a = 12.185(3) Å, b = 13.251(3) Å, c = 14.772(2) Å, alpha = 63.69(1) degrees, beta = 86.56(2) degrees, gamma = 64.50(2) degrees (Z = 1) and a = 13.730(4) Å, b = 14.882(4) Å, c = 16.588(4) Å, alpha = 75.98(2) degrees, beta = 85.63(2) degrees, gamma = 66.95(2) degrees (Z = 2), respectively. Both salts present packing arrangements of BEDT-TTF not found before. In compound 1 mixed layers of anions and cations contain no stacks of BEDT-TTF. In 2 there are layers of segregated anions and cations, the latter having their long axes nearly parallel to the layers. This compound is the first in which Re(2)(NCS)(10)(2)(-) has been structurally characterized. In both compounds there are numerous close S-S contacts between the NCS ligands and the BEDT-TTF. The compounds are semiconductors, the conductivity being attributed to low-dimensional hopping rather than coherent transport. The magnetic properties of 1 are modeled by a superposition of a Curie-Weiss contribution for the anion and a dimer contribution from the cation.

Structural Systematics of Rare Earth Complexes. XXI Polymeric Sodium Bis(thiodiglycolato)neodymiate(III)

Publisher: CSIRO Publishing

Date: 1999

DOI: 10.1071/CH98051

Abstract: A single-crystal, room-temperature, X-ray structure determination is recorded for the title compound, NaNd(tdga)2 (‘tdga2-’ ≡ −OCOCH2SCH2COO-). Crystals are monoclinic, space group Pc, a 9·5058(4), b 7·323(1), c 9·402(4) Å, β 97·71(2)°, Z = 2 f.u., conventional R on |F| being 0·028 for No 1054 independent ‘observed’ (I 3σ(I)) diffractometer reflections. The compound is a novel polymeric array the neodymium atom is eight-coordinated by ligand oxygen atoms at distances ranging from 2·43(2) to 2·54(1) Å. A redetermination of the parent thiodiglycolic acid is also recorded (orthorhombic Pnam, a 5·0444(8), b 6·690(1), c 17·73(1) Å, Z = 4, R 0·038 for No 866).

Guest adsorption in the nanoporous metal-organic framework Cu ₃(1,3,5-benzenetricarboxylate)₂: Combined in situ X-ray diffraction and vapor sorption

Publisher: American Chemical Society (ACS)

Date: 05-08-2014

DOI: 10.1021/CM501138G

Expanding the 4,4′-bipyridine ligand: Structural variation in {M(pytpy)2}²⁺ complexes (pytpy = 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine, M = Fe, Ni, Ru) and assembly of the hydrogen-bonded, one-dimensional polymer {[Ru (pytpy) (Hpytpy)]}n^{3 n+}

Publisher: Elsevier BV

Date: 06-2008

DOI: 10.1016/J.ICA.2007.10.040

Solvent-modified dynamic porosity in chiral 3D kagome frameworks

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3DT00096F

Abstract: Dynamically porous metal-organic frameworks (MOFs) with a chiral quartz-based structure have been synthesized from the multidentate ligand 2,2'-dihydroxybiphenyl-4,4'-dicarboxylate (H2diol). Compounds [Ni(II)(H2diol)(S)2]·xS (where S = DMF or DEF) show marked changes in 77 K N2 uptake between partially desolvated [Ni(II)(H2diol)(S)2] (only the pore solvent is removed) and fully desolvated [Ni(II)(H2diol)] forms. Furthermore, [Ni(II)(H2diol)(DMF)2] displays additional solvent-dependent porosity through the rotation of DMF molecules attached to the axial coordination sites of the Ni(II) centre. A unique feature of the four coordinate Ni(II) centre in [Ni(II)(H2diol)] is the dynamic response to its chemical environment. Exposure of [Ni(II)(H2diol)] to H2O and MeOH vapour leads to coordination of both axial sites of the Ni centres and to the generation of a solvated framework, whereas exposure to EtOH, DMF, acetone, and MeCN does not lead to any change in metal coordination or structure metrics. MeOH vapour adsorption was able to be tracked by time-dependent magnetometry as the solvated and desolvated structures have different magnetic moments. Solvated and desolvated forms of the MOF show remarkable differences in their thermal expansivities [Ni(II)(H2diol)(DMF)2]·DMF displays marked positive thermal expansion (PTE) in the c-axis, yet near to zero thermal expansion, between 90 and 450 K, is observed for [Ni(II)(H2diol)]. These new MOF architectures demonstrate a dynamic structural and colourimetric response to selected adsorbates via a unique mechanism that involves a reversible change in the coordination environment of the metal centre. These coordination changes are mediated throughout the MOF by rotational mobility about the biaryl bond of the ligand.

Structures, Electrochemical and Spectral Properties of a Series of [MnN(CN)₃(diimine)]^– Complexes

Publisher: Wiley

Date: 15-05-2015

DOI: 10.1002/EJIC.201500012

Advanced functional properties in nanoporous coordination framework materials

Publisher: Royal Society of Chemistry (RSC)

Date: 2006

DOI: 10.1039/B515713G

Abstract: Coordination framework materials display a rich array of host-guest properties and are notable amongst porous media for their extreme chemical versatility. This article highlights a number of areas where specific function has been incorporated into these framework host lattices.

Perturbation of Spin Crossover Behavior by Covalent Post‐Synthetic Modification of a Porous Metal–Organic Framework

Publisher: Wiley

Date: 24-07-2014

DOI: 10.1002/ANIE.201402951

Abstract: Covalent post-synthetic modification is a versatile method for gaining high-level synthetic control over functionality within porous metal-organic frameworks and for generating new materials not accessible through one-step framework syntheses. Here we apply this topotactic synthetic approach to a porous spin crossover framework and show through detailed comparison of the structures and properties of the as-synthesised and covalently modified phases that the modification reaction proceeds quantitatively by a thermally activated single-crystal-to-single-crystal transformation to yield a material with lowered spin-switching temperature, decreased lattice cooperativity, and altered color. Structure-function relationships to emerge from this comparison show that the approach provides a new route for tuning spin crossover through control over both outer-sphere and steric interactions.

A Mixed-Spin Molecular Square with a Hybrid [2 x 2]Grid/Metallocyclic Architecture

Publisher: Wiley

Date: 24-02-2011

DOI: 10.1002/ANGE.201007409

Self-Assembly of an Imidazolate-Bridged Fe^III/Cu^II Heterometallic Cage

Publisher: American Chemical Society (ACS)

Date: 07-01-2014

DOI: 10.1021/IC402686S

Abstract: A rare, discrete, mixed-valent, heterometallic Fe(III)/Cu(II) cage, [Cu6Fe8L8](ClO4)12·χsolvent (H3L = tris{[2-{(imidazole-4-yl)methylidene}amino]ethyl}amine), was designed and synthesized via metal-ion-directed self-assembly with neutral tripodal metalloligands. The formation of this coordination cage was demonstrated by X-ray crystallography, ESI mass spectrometry, FT-IR, and UV-vis-NIR spectroscopy.

Structure and Magnetic Properties of the Spin Crossover Linear Trinuclear Complex [Fe3(furtrz)6(ptol)2(MeOH)4]·4(ptol)·4(MeOH) (furtrz: furanylidene-4H-1,2,4-triazol-4-amine ptol: p-tolylsulfonate)

Publisher: MDPI AG

Date: 16-02-2016

DOI: 10.3390/MAGNETOCHEMISTRY2010007

Systematic Metal Variation and Solvent and Hydrogen‐Gas Storage in Supramolecular Nanoballs

Publisher: Wiley

Date: 04-11-2009

DOI: 10.1002/ANIE.200903863

Anion−Solvent Dependence of Bistability in a Family of Meridional N-Donor-Ligand-Containing Iron(II) Spin Crossover Complexes

Publisher: American Chemical Society (ACS)

Date: 14-09-2007

DOI: 10.1021/IC7010919

Abstract: Five mononuclear spin crossover iron(II) bis-meridional ligand complexes of the general formula [Fe(L)(2)](X)(2).solvent, have been synthesized, where X = BF(4)- or ClO(4)- L = 2-(1-pyridin-2-ylmethyl-1H-pyrazol-3-yl)-pyrazine (picpzpz) or 2-(3-(2-pyridyl)pyrazol-1-ylmethyl)pyridine) (picpypz) solvent = MeOH or EtOH. The magnetic and structural consequences of systematic variation of meridional ligand, solvent, and anion, including a desolvated species, have been investigated. The complex [Fe(picpzpz)(2)](BF(4))(2).MeOH, 1.MeOH, displays several unique properties including a two-step spin transition with a gradual higher-temperature step ((1)T(1/2) = 197 K) and an abrupt low-temperature step with hysteresis ((2)T(1/2) = 91/98 K) and a metastable intermediate spin state below 70 K with quench-cooling. Removal of the solvent methanol results in the loss of the abrupt step and associated hysteresis (T(1/2) = 150 K). The complexes [Fe(picpzpz)(2)](BF(4))(2).EtOH (1.EtOH), [Fe(picpzpz)(2)](ClO(4))(2).MeOH (2.MeOH), [Fe(picpzpz)(2)](ClO(4))(2).EtOH (2.EtOH), and [Fe(picpypz)(2)](BF(4))(2).MeOH (3.MeOH) all show gradual one-step spin transitions with T(1/2) values in the range 210-250 K. Photomagnetic LIESST measurements on 1.MeOH reveal a near-quantitative excitation of high-spin sites and a unique two-step relaxation process related to the two-step thermal spin transition ((1)T(LIESST) = 49 K and (2)T(LIESST) = 70 K). The structural consequences of the unusual spin transition displayed by 1.MeOH have been investigated by single-crystal X-ray diffraction structural analyses between 25 and 293 K. Detailed characterization of the unit cell parameter evolution vs temperature reflects both the gradual high-temperature step and abrupt low-temperature step, including the thermal hysteresis, observed magnetically.

4-(4-Pyridylamino)pyridinium isophthalate

Publisher: International Union of Crystallography (IUCr)

Date: 31-10-2005

DOI: 10.1107/S160053680503463X

Heteroatom substitution effects in spin crossover dinuclear complexes

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C8DT05010D

Abstract: Through examining a range of heteroatom substituted dinuclear species a variety of spin crossover properties emerge, including a rare two-step spin-state transition.

Spin crossover intermediate plateau stabilization in a flexible 2-D Hofmann-type coordination polymer

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4CC01079E

Abstract: The abrupt and hysteretic two-step spin crossover in a new triazole-based 2-D Hofmann-type complex shows a record breaking 120 K intermediate plateau (IP) region stabilized by negative cooperative interactions.

Single Crystal to Single Crystal Structural Transformations in Molecular Framework Materials

Publisher: CSIRO Publishing

Date: 2006

DOI: 10.1071/CH06322

Abstract: The rapid advance in the synthesis and characterization of molecular frameworks over the past decade has opened an entirely new approach for the generation of nanoporous materials. With this advance has come an increasingly pressing need for the development of new techniques to characterize the guest-dependent structures of these novel and highly complex materials. In this review we highlight some of the relatively rare cases where single crystal diffraction has been used to characterize the flexible structures of molecular frameworks through the investigation of single crystal to single crystal (SC-SC) transformations.

MEM(TCNQ)₂at room temperature and 10 K, and the absence of a spin-Peierls transition

Publisher: International Union of Crystallography (IUCr)

Date: 09-08-2001

DOI: 10.1107/S0108270101008794

Abstract: Precise X-ray determinations of the crystal structure of the 1:2 complex of N-ethyl-N-methylmorpholinium and 7,7,8,8-tetracyano-p-quinodimethanide, abbreviated as MEM-TCNQ or MEM(TCNQ)(2) (C(7)H(16)NO(+).2C(12)H(4)N(4)(0.5-)), have been performed at 293 and at 10 K. Evidence for the expected spin-Peierls transition at 19 K is not found, and this may follow from radiation damage to the crystal or from insufficient equipment sensitivity.

Extreme compressibility in LnFe(CN)6 coordination framework materials via molecular gears and torsion springs

Publisher: Springer Science and Business Media LLC

Date: 11-01-2016

DOI: 10.1038/NCHEM.2431

Abstract: The mechanical flexibility of coordination frameworks can lead to a range of highly anomalous structural behaviours. Here, we demonstrate the extreme compressibility of the LnFe(CN)6 frameworks (Ln = Ho, Lu or Y), which reversibly compress by 20% in volume under the relatively low pressure of 1 GPa, one of the largest known pressure responses for any crystalline material. We delineate in detail the mechanism for this high compressibility, where the LnN6 units act like torsion springs synchronized by rigid Fe(CN)6 units performing the role of gears. The materials also show significant negative linear compressibility via a cam-like effect. The torsional mechanism is fundamentally distinct from the deformation mechanisms prevalent in other flexible solids and relies on competition between locally unstable metal coordination geometries and the constraints of the framework connectivity, a discovery that has implications for the strategic design of new materials with exceptional mechanical properties.

Reversible Guest Binding in a Non‐Porous Fe^II Coordination Polymer Host Toggles Spin Crossover

Publisher: Wiley

Date: 23-09-2015

DOI: 10.1002/CHEM.201502547

Abstract: Formation of either a dimetallic compound or a 1 D coordination polymer of adiponitrile adducts of [Fe(bpte)] 2+ (bpte=[1,2‐bis(pyridin‐2‐ylmethyl)thio]ethane) can be controlled by the choice of counteranion. The iron(II) atoms of the bis(adiponitrile)‐bridged dimeric complex [Fe 2 (bpte) 2 (μ 2 ‐(NC(CH 2 ) 4 CN) 2 ](SbF 6 ) 4 ( 2 ) are low spin at room temperature, as are those in the polymeric adiponitrile‐linked acetone solvate polymer {[Fe(bpte)(μ 2 ‐NC(CH 2 ) 4 CN)](BPh 4 ) 2 ⋅ Me 2 CO} ( 3⋅ Me 2 CO). On heating 3⋅ Me 2 CO to 80 °C, the acetone is abruptly removed with an accompanying purple to dull lavender colour change corresponding to a conversion to a high‐spin compound. Cooling reveals that the desolvate 3 shows hysteretic and abrupt spin crossover (SCO) S =0↔ S =2 behaviour centred at 205 K. Non‐porous 3 can reversibly absorb one equivalent of acetone per iron centre to regenerate the same crystalline phase of 3⋅ Me 2 CO concurrently reinstating a low‐spin state.

Gas and vapor adsorption in octacyanometallate-based frameworks Mn 2[M(CN)8] (M = W, Mo) with exposed Mn²⁺ sites

Publisher: Elsevier BV

Date: 2014

DOI: 10.1016/J.IJHYDENE.2013.10.143

New cobalt(ii) and zinc(ii) coordination frameworks incorporating a pyridyl–pyrazole ditopic ligand

Publisher: Royal Society of Chemistry (RSC)

Date: 2005

DOI: 10.1039/B418879A

Abstract: The metal-directed assembly of new molecular frameworks incorporating 4-(4-pyridyl)pyrazole (L), containing non-linear coordination vectors, is presented. Three metallo-arrays of types [Co(LH)2(NO3)4], [Co(LH)2(H2O)4][NO3]4.H2O and [Zn2(L-H)2Cl2].2EtOH are reported. The cobalt(II) in [Co(LH)2(NO3)4] displays distorted octahedral geometry, with the two protonated pyridyl-pyrazole ligands coordinated through their pyrazole nitrogen atoms in a trans-orientation the remaining four coordination sites are occupied by nitrate anions. Two internal hydrogen bonds occur between each pyrazole NH and the oxygens of adjacent coordinated nitrato ligands. Short intermolecular hydrogen bonds also occur between the two pyridinium hydrogens and bound nitrate ligands on different molecules to yield a two-dimensional hydrogen-bonded array. Two of these arrays interpenetrate to form an extended two dimensional layer such layers stack throughout the crystal structure. A second product of type [Co(LH)2(H2O)4][NO3]4.H2O exists as two crystallographically independent, but chemically similar, forms. In each form, the two protonated pyridyl-pyrazole ligands occupy trans positions about the cobalt, with the remaining four coordination sites being filled by water molecules to yield a distorted octahedral coordination geometry. Intramolecular hydrogen-bonding is observed between the two non-coordinated pyrazoyl nitrogen atoms and bound water oxygen atoms. The third complex, [Zn2(L-H)2Cl2].2EtOH, contains dimer units consisting of two zinc(II) ions bridged by two pyrazoylate groups in which the coordination geometry of each zinc approximates a tetrahedron. Each zinc is bound to two deprotonated pyridine-pyrazole ligands (L-H), one pyridyl group (from a different dimeric unit) and one chloro ligand. Each pyridyl nitrogen thus connects each of these zinc dimers to an adjacent dimer unit, forming a three-dimensional network containing small voids. The latter are occupied by ethanol molecules which form hydrogen bonds to the chloro ligands.

Structural diversity in coordination polymers constructed from a naphthalene-spaced dipyridyl ligand and iron(II) thiocyanate

Publisher: Springer Science and Business Media LLC

Date: 05-08-2011

DOI: 10.1007/S10847-011-0016-5

Multifunctional MOFs through CO2 fixation: A metamagnetic kagome lattice with uniaxial zero thermal expansion and reversible guest sorption

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4DT02205J

Abstract: The properties of atmospheric CO 2 fixation, metamagnetism, reversible guest adsorption and zero thermal expansion have been combined in a single robust MOF, [Cu 3 (bpac) 3 (CO 3 ) 2 ](ClO 4 ) 2 ·H 2 O ( 1 ·H 2 O).

Photoactive and physical properties of an azobenzene-containing coordination framework

Publisher: CSIRO Publishing

Date: 2017

DOI: 10.1071/CH17215

Abstract: A new three-dimensional coordination framework, [Zn4(tbazip)3(bpe)2(OH)2]·bpe·{solvent} (where bpe = 1,2-di(4-pyridyl)ethene) containing the novel photoactive ligand tbazip (tbazip = 5-((4-tert-butyl)phenylazo)isophthalic acid) has been synthesised and crystallographically characterised. The photoactivity of discrete tbazip was investigated and compared with its photoactivity while incorporated within the framework. The effect of isomerisation of the incorporated azobenzene on the chemical and physical properties of the framework were investigated using UV-vis and Raman spectroscopies. The framework is porous only to hydrogen gas at 77 K, but displayed an appreciable uptake for CO2 at 195 K.

Thermal Spin Crossover Behaviour of Two-Dimensional Hofmann-Type Coordination Polymers Incorporating Photoactive Ligands

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/CH14188

Abstract: Two spin crossover (SCO)-active 2D Hofmann-type framework materials, [Fe(3-PAP)2Pd(CN)4] (A) and [Fe(4-PAP)2Pd(CN)4] (B) containing the photoactive azo-benzene-type ligands 3-phenylazo-pyridine (3-PAP) and 4-phenylazo-pyridine (4-PAP) were prepared. These materials form non-porous Hofmann-type structures whereby 2D [FeIIPd(CN)4] grids are separated by 3- or 4-PAP ligands. The iron(ii) sites of both materials (A and B) undergo abrupt and hysteretic spin transitions with characteristic transition temperatures T1/2↓,↑: 178, 190 K (ΔT: 12 K) and T1/2↓,↑: 233, 250 K (ΔT: 17 K), respectively. Photo-magnetic characterisations reveal light-induced excited spin state trapping (LIESST) activity in both A and B with characteristic T(LIESST) values of 45 and 40 K. Although both free ligands show trans- to-cis isomerisation in solution under UV-irradiation, as evidenced via absorption spectroscopy, such photo-activity was not observed in the ligands or complexes A and B in the solid state. Structural analysis of a further non-SCO active isomer to B, [Fe(4-PAP)2Pd(CN)4]·1/2(4-PAP) (B·(4-PAP)), which contains free ligand in the pore space is reported.

Oxygen Chemisorption/Desorption in a Reversible Single-Crystal-To-Single-Crystal Transformation

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4SC01636J

Abstract: A compound that can reversibly chemisorb O 2 in the solid phase undergoes several consecutive single-crystal-to-single-crystal transformations involving the cleavage of four bonds and the creation of four new bonds , in one single molecule.

Continuous negative-to-positive tuning of thermal expansion achieved by controlled gas sorption in porous coordination frameworks

Publisher: Springer Science and Business Media LLC

Date: 19-11-2018

DOI: 10.1038/S41467-018-06850-6

Abstract: Control of the thermomechanical properties of functional materials is of great fundamental and technological significance, with the achievement of zero or negative thermal expansion behavior being a key goal for various applications. A dynamic, reversible mode of control is demonstrated for the first time in two Prussian blue derivative frameworks whose coefficients of thermal expansion are tuned continuously from negative to positive values by varying the concentration of adsorbed CO 2 . A simple empirical model that captures site-specific guest contributions to the framework expansion is derived, and displays excellent agreement with the observed lattice behaviour.

The first example of a coordination polymer from the expanded 4,4′-bipyridine ligand Ru(pytpy)<inf>2</inf>²⁺ (pytpy = 4′-(4-pyridyl)-2,2′6′,2″-terpyridine)

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B703622A

A Family of Three-Dimensional Molecular Framework Materials Containing the Three-Connecting Ligands 2,4,6-Tris(n'-pyridyl)-1,3,5-triazine: 3-tpt and 4-tpt

Publisher: CSIRO Publishing

Date: 2013

DOI: 10.1071/CH12444

Abstract: Three-dimensional (3D) framework materials containing the ligands 2,4,6-tris(4′-pyridyl)-1,3,5-triazine (4-tpt) and 2,4,6-tris(3′-pyridyl)-1,3,5-triazine (3-tpt) have been prepared and their structure and magnetic properties investigated. The [MII(NCS)2(py)4] (MII = Fe, Co, py = 3-tpt, and 4-tpt) coordination environments in these materials have been targeted in an effort to prepare high-dimensional coordination polymers which contain spin crossover (SCO) centres. Using FeII, two isotopological cubic 3D materials [Fe(NCS)2(4-tpt)4/3]·n(BzOH,ac) (1a(Bz,ac)) and [Fe(NCS)2(3-tpt)4/3]·n(BzOH,ac) (1b(Bz,ac)) were formed. However, with CoII a different 3D framework topology results, [Co(NCS)2(3-tpt)4/3]·(BzOH,ac) (2(Bz,ac)). Further synthetic variation leads to the isostructural 3D materials trans-[MII(NCS)2(4-tpt)4/3]cis-[MII(NCS)2(4-tpt)2]·n(tce, EtOH) (Fe: 3a(Tce,Et) and Co: 3b(Tce,Et)) which form 3D networks outside Wellsian classification – and for which uniquely both two- and three-connecting modes of 4-tpt are present in the one complex. Despite having the metal coordination environments for which SCO has previously been observed, magnetic susceptibilities of this family of materials reveal a high spin nature.

A highly distorted (10,3)-a coordination framework constructed from alternating T-shaped and trigonal nodes

Publisher: Royal Society of Chemistry (RSC)

Date: 2005

DOI: 10.1039/B503352G

A three-dimensional hydrogen-bonded coordination framework:catena-poly[[[tetraaquairon(II)]-μ-4,4′-bipyridine] benzene-1,4-dicarboxylate]

Publisher: International Union of Crystallography (IUCr)

Date: 11-12-2004

DOI: 10.1107/S1600536804032192

Negative Thermal Expansion in LnCo(CN)₆ (Ln=La, Pr, Sm, Ho, Lu, Y): Mechanisms and Compositional Trends

Publisher: Wiley

Date: 09-04-2013

DOI: 10.1002/ANIE.201300619

Interpenetration as a Mechanism for Negative Thermal Expansion in the Metal–Organic Framework Cu₃(btb)₂ (MOF‐14)

Publisher: Wiley

Date: 04-2014

DOI: 10.1002/ANIE.201311055

Abstract: Metal–organic framework materials (MOFs) have recently been shown in some cases to exhibit strong negative thermal expansion (NTE) behavior, while framework interpenetration has been found to reduce NTE in many materials. Using powder and single‐crystal diffraction methods we investigate the thermal expansion behavior of interpenetrated Cu 3 (btb) 2 (MOF‐14) and find that it exhibits an anomalously large NTE effect. Temperature‐dependent structural analysis shows that, contrary to other interpenetrated materials, in MOF‐14 the large positive thermal expansion of weak interactions that hold the interpenetrating networks together results in a low‐energy contractive distortion of the overall framework structure, demonstrating a new mechanism for NTE.

Inelastic neutron scattering of H2 adsorbed in HKUST-1

Publisher: Elsevier BV

Date: 10-2007

DOI: 10.1016/J.JALLCOM.2006.12.106

Curly-curly, loop-loop: Homoleptic metal(ii) complexes of pyridinecarbaldehyde 4′-(2,2′:6′,2″-terpyridyl) hydrazones and their coordination polymers

Publisher: Royal Society of Chemistry (RSC)

Date: 2008

DOI: 10.1039/B810906K

Abstract: The ligands 4-, 3- and 2-pyridinecarbaldehyde 4'-(2,2':6',2''-terpyridyl)hydrazone (, and ) have been prepared and characterized. In the homoleptic iron(ii) and ruthenium(ii) complexes, the nitrogen donor atoms of the pendant pyridine rings subtend an obtuse angle ( approximately 155 degrees ) at the metal centre, thus providing an expanded ligand, which can be used for the assembly one-dimensional coordination polymers with an undulating backbone. Protonation of the pendant pyridine rings in [FeL(2)](2+) (L = , , ) or [RuL(2)](2+) (L = , ) leads to a colour change from purple to blue, or red to pink, respectively, as the MLCT band shifts to a lower energy. The structural data for [Fe(H)()][PF(6)](3).3.5MeCN.2.5H(2)O (where [H](+) is the monoprotonated ligand) show that the [Fe(H)()](3+) cations form one-dimensional chains supported by N(py)HN(py) hydrogen bonds and that the undulating chains pack to give a porous material, with channels that accommodate the anions and solvent molecules. A single-crystal X-ray diffraction determination of {[Fe(NCS)(2)(Ru()(2))(2)][Fe(2)(NCS)(6)(OEt)(2)(EtOH)(2)][NCS](2).4EtOH.H(2)O}(n) reveals that pairs of [Ru()(2)](2+) cations connect {Fe(NCS)(2)} units to give a one-dimensional polymer comprising of linked metallamacrocycles.

Quasi-one-dimensional bis(ethylenedithio)tetrathiafulvalene charge- transfer salts with paramagnetic Group 6 anions

Publisher: Royal Society of Chemistry (RSC)

Date: 1997

DOI: 10.1039/A606025K

Hard magnets based on transition metal complexes with the dicyanamide anion, {N(CN)2}-,

Publisher: Royal Society of Chemistry (RSC)

Date: 1998

DOI: 10.1039/A803165G

2,4,6-Tris(2-pyridylsulfanylmethyl)-1,3,5-triazine

Publisher: International Union of Crystallography (IUCr)

Date: 10-01-2007

DOI: 10.1107/S1600536806054456

Synthesis, crystal structure and magnetic properties of a three-dimensional cyano-bridged heterometallic complex {NiII(Me6-[14]ane-N4)}2[WIV(CN)8]·6H2O

Publisher: Elsevier BV

Date: 08-2007

DOI: 10.1016/J.INOCHE.2007.04.031

Hydrogen adsorption in HKUST-1: a combined inelastic neutron scattering and first-principles study

Publisher: IOP Publishing

Date: 24-04-2009

DOI: 10.1088/0957-4484/20/20/204025

Abstract: Hydrogen adsorption in high surface area nanoporous coordination polymers has attracted a great deal of interest in recent years due to the potential applications in energy storage. Here we present combined inelastic neutron scattering measurements and detailed first-principles calculations aimed at unraveling the nature of hydrogen adsorption in HKUST-1 (Cu3(1,3,5-benzenetricarboxylate)2), a metal-organic framework (MOF) with unsaturated metal centers. We reveal that, in this system, the major contribution to the overall binding comes from the classical Coulomb interaction which is not screened due to the open metal site this explains the relatively high binding energies and short H2-metal distances observed in MOFs with exposed metal sites as compared to traditional ones. Despite the short distances, there is no indication of an elongation of the H-H bond for the bound H2 molecule at the metal site. We find that both the phonon and rotational energy levels of the hydrogen molecule are closely similar, making the interpretation of the inelastic neutron scattering data difficult. Finally, we show that the orientation of H2 has a surprisingly large effect on the binding potential, reducing the classical binding energy by almost 30%. The implication of these results for the development of MOF materials for better hydrogen storage is discussed.

Guest Tunable Structure and Spin Crossover Properties in a Nanoporous Coordination Framework Material

Publisher: American Chemical Society (ACS)

Date: 11-08-2009

DOI: 10.1021/JA905360G

Abstract: The electronic switching properties of the nanoporous spin crossover framework [Fe(NCS)(2)(bpbd)(2)] x x(guest), SCOF-2, can be rationally manipulated via sorption of a range of molecular guests (acetone, ethanol, methanol, propanol, 1-acetonitrile) into the 1-D channels of this material. Pronounced changes to the spin crossover properties are related directly to the steric and electronic influence of the in idual guests: the degree of lattice cooperativity, as reflected in the abruptness of the transition and presence of hysteresis, is strongly influenced by the presence of cooperative host-guest interactions, and the temperature of the transition varies with guest polarity through a proposed electrostatic interaction.

Magnetic and Electronic Properties of Three New Hetero-Bimetallic Coordination Frameworks [Ru2(O2CR)4][Au(CN)2] (R = Benzoic Acid, Furan-2-carboxylate, or Thiophen-2-carboxylate)

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/CH14196

Abstract: The crystal structures and magnetic and electronic properties of three new hetero-bimetallic coordination frameworks, [Ru2(O2CR)4][Au(CN)2] (R = phenyl (1(Ph)), 2-furan (1(Furan)), and 2-thiophene (1(Thio)), have been characterised. Through variation of the functionalised carboxylate group, both the one-dimensional chain structure and properties of the frameworks have been systematically modulated. The magnetic behaviour for each framework has been modelled with a zero-field splitting model and the presence of weak inter-dimer coupling was assessed.

A Thermal Spin Transition in a Nanoporous Iron(II) Coordination Framework Material

Publisher: Wiley

Date: 02-03-2007

DOI: 10.1002/ANIE.200603977

Four-step iron(ii) spin state cascade driven by antagonistic solid state interactions

Publisher: Royal Society of Chemistry (RSC)

Date: 2017

DOI: 10.1039/C6SC03114E

Abstract: A rare four-step spin crossover transition has been attained in a two-dimensional Hofmann-type material through the presence of an array of antagonistic host–host and host–guest interactions.

Magnetic Materials Containing the Dicyanamide Anion, {N(Cn)₂}⁻

Publisher: Informa UK Limited

Date: 09-1999

DOI: 10.1080/10587259908023362

Flexible Sorption and Transformation Behavior in a Microporous Metal-Organic Framework

Publisher: American Chemical Society (ACS)

Date: 19-07-2002

DOI: 10.1021/JA0262737

Abstract: Crystals of the metal-organic framework material Ni(2)(4,4'-bipyridine)(3)(NO(3))(4) (A) have been grown by reaction of Ni(NO(3))(2).6H(2)O and 4,4'-bipyridine in methanol solution. Single-crystal X-ray diffraction experiments show that the ladder structure of the framework is maintained after desolvation of the material, resulting in the production of a porous solid stable to 215(4) degrees C. Powder X-ray diffraction has been employed to confirm the bulk purity and temperature stability of this material. The crystal structure indicates that the pore window has an area of 12.3 A(2). However, sorption experiments show these windows will admit toluene, which has a minimum cross-sectional area of 26.6 A(2), with no significant change in the structure. Monte Carlo docking calculations show that toluene can be accommodated within the large pores of the structure. Exposure of the related microporous material Ni(2)(4,4'-bipyridine)(3)(NO(3))(4).2C(2)H(5)OH (B) to methanol vapor causes a guest-driven solid-state transformation to A which is observed using powder X-ray diffraction. This structural rearrangement proceeds directly from crystalline B to crystalline A and is complete in less than 1 day. Mechanisms for the transformation are proposed which require breaking of at least one in six of the covalent bonds that confer rigidity on the framework.

Self-assembled Co(ii) molecular squares incorporating the bridging ligand 4,7-phenanthrolino-5,6:5[prime or minute],6[prime or minute]-pyrazine

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1DT11254F

Abstract: Three high-spin tetranuclear cobalt(II) complexes have been prepared with the bridging ligand 4,7-phenanthrolino-5,6:5',6'-pyrazine (ppz) through metal-ion directed self-assembly. The complexes differ by the incorporation of three different coordinating anions: chloride, thiocyanide and selenocyanide. The physical properties of these complexes have been investigated in detail.

Crystal structures of (BEDT-TTF)3CuBr4 at 10 K and 10 kbar

Publisher: Elsevier BV

Date: 02-1997

DOI: 10.1016/S0379-6779(97)81019-3

Syntheses, structures and magnetism of α-Mn(dca)2, [Mn(dca)2(H2O)2]·H2O, [Mn(dca)2(C2H5OH)2]·(CH3)2CO, [Fe(dca)2(CH3OH)2] and [Mn(dca)2(L)2], where L = pyridine, CH3OH or DMF and dca− = dicyanamide, N

Publisher: Royal Society of Chemistry (RSC)

Date: 1999

DOI: 10.1039/A903487K

Reversible and Selective O(2) Chemisorption in a Porous Metal-Organic host material

Publisher: American Chemical Society (ACS)

Date: 28-06-2011

DOI: 10.1021/JA202228V

Abstract: The metal-organic host material [{Co(III)(2)(bpbp)(O(2))}(2)bdc](PF(6))(4) (1·2O(2) bpbp(-) = 2,6-bis(N,N-bis(2-pyridylmethyl)aminomethyl)-4-tert-butylphenolato bdc(2-) = 1,4-benzenedicarboxylato) displays reversible chemisorptive desorption and resorption of dioxygen through conversion to the deoxygenated Co(II) form [{Co(II)(2)(bpbp)}(2)bdc](PF(6))(4) (1). Single crystal X-ray diffraction analysis indicates that the host lattice 1·2O(2), achieved through desorption of included water guests from the as-synthesized phase 1·2O(2)·3H(2)O, consists of an ionic lattice containing discrete tetranuclear complexes, between which lie void regions that allow the migration of dioxygen and other guests. Powder X-ray diffraction analyses indicate that the host material retains crystallinity through the dioxygen desorption/chemisorption processes. Dioxygen chemisorption measurements on 1 show near-stoichiometric uptake of dioxygen at 5 mbar and 25 °C, and this capacity is largely retained at temperatures above 100 °C. Gas adsorption isotherms of major atmospheric gases on both 1 and 1·2O(2) indicate the potential suitability of this material for air separation, with a O(2)/N(2) selectivity factor of 38 at 1 atm. Comparison of oxygen binding in solution and in the solid state indicates a dramatic increase in binding affinity to the complex when it is incorporated in a porous solid.

Hysteretic Three‐Step Spin Crossover in a Thermo‐ and Photochromic 3D Pillared Hofmann‐type Metal–Organic Framework

Publisher: Wiley

Date: 11-09-2012

DOI: 10.1002/ANIE.201204387

Scrutinizing negative thermal expansion in MOF-5 by scattering techniques and ab initio calculations

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C2DT31491F

Abstract: Complementary experimental techniques and ab initio calculations were used to determine the origin and nature of negative thermal expansion (NTE) in the archetype metal-organic framework MOF-5 (Zn(4)O(1,4-benzenedicarboxylate)(3)). The organic linker was probed by inelastic neutron scattering under vacuum and at a gas pressure of 175 bar to distinguish between the pressure and temperature responses of the framework motions, and the local structure of the metal centers was studied by X-ray absorption spectroscopy. Multi-temperature powder- and single-crystal X-ray and neutron diffraction was used to characterize the polymeric nature of the s le and to quantify NTE over the large temperature range 4-400 K. Ab initio calculations complement the experimental data with detailed information on vibrational motions in the framework and their correlations. A uniform and comprehensive picture of NTE in MOF-5 has been drawn, and we provide direct evidence that the main contributor to NTE is translational transverse motion of the aromatic ring, which can be d ened by applying a gas pressure to the s le. The linker motion is highly correlated rather than local in nature. The relative energies of different framework vibrations populated in MOF-5 are suggested by analysis of neutron diffraction data. We note that the lowest-energy motion is a librational motion of the aromatic ring which does not contribute to NTE. The libration is followed by transverse motion of the linker and the carboxylate group. These motions result in unit-cell contraction with increasing temperature.

Iron(II) Molecular Framework Materials with 4,4'-Azopyridine

Publisher: CSIRO Publishing

Date: 2005

DOI: 10.1071/CH04290

Abstract: Three new iron(ii) molecular-framework materials incorporating the bridging ligand 4,4′-azopyridine (azpy) have been synthesized and structurally characterized: Fe2(azpy)4(NCS)4·(azpy) (A), Fe(azpy)(NCSe)2(EtOH)2·(azpy) (B), and Fe(azpy)2(NCSe)2·2(MeCN) (C). A and C consist of non-interpenetrating (4,4) grids of iron(ii) centres bridged by azpy ligands with non-coordinating azpy ligands or acetonitrile molecules occupying the spaces within and between the layers. For B, hydrogen-bonding interactions between coordinated ethanol molecules and non-coordinated azpy ligands link linear Fe–azpy chains to give a two-dimensional framework.

Tuning the carrier concentration in organic conductors: Synthesis and physical properties of BEDT-TTF salts with H2PO4− and HPO42−

Publisher: Elsevier BV

Date: 03-1995

DOI: 10.1016/0379-6779(94)02655-I

Influence of structure–activity relationships on through-space intervalence charge transfer in metal–organic frameworks with cofacial redox-active units

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C8SC01128A

Abstract: Metal–organic frameworks incorporating cofacially-aligned redox-active ligands exhibit through-space intervalence charge transfer phenomena.

Elucidating the Mechanism of a Two-Step Spin Transition in a Nanoporous Metal−Organic Framework

Publisher: American Chemical Society (ACS)

Date: 24-12-2008

DOI: 10.1021/JA8068038

Abstract: The nanoporous metal-organic framework, Fe(bpe)2(NCS)2 x 3(acetone), SCOF-4(Ac) (where bpe is 1,2-bis(4'-pyridyl)ethane), displays a two-step spin crossover (SCO) transition (65-155 K) that is sensitive to the presence of acetone guest molecules. Structural analyses have revealed a structural phase transition, from tetragonal (P42(1)c) to orthorhombic (P2(1)2(1)2), associated with the spin transition that defines a checkerboard-like ordering of spin sites at the high-spin:low-spin plateau. The reversible desorption of the acetone guest species is accompanied by a complex series of structural phase transitions that describe a dramatic flexing of the structure. The thermal trapping of a metastable state with approximately 20-25% high-spin character was observed both magnetically and structurally upon rapid quenching of SCOF-4(Ac) to 10 and 25 K, respectively. The light-induced excited spin state trapping (LIESST) effects for SCOF-4(Ac) show a 55% excitation of a metastable HS state at 10 K and a characteristic T(LIESST) value of 52 K.

The organo-pillared porous magnetic framework Co4(SO4)(OH)6(H2NC2H4NH2)0.5·3H2O

Publisher: Royal Society of Chemistry (RSC)

Date: 1999

DOI: 10.1039/A907315I

Through-Space Intervalence Charge Transfer as a Mechanism for Charge Delocalization in Metal–Organic Frameworks

Publisher: American Chemical Society (ACS)

Date: 04-05-2018

DOI: 10.1021/JACS.8B02638

Abstract: Understanding the nature of charge transfer mechanisms in 3-dimensional metal-organic frameworks (MOFs) is an important goal owing to the possibility of harnessing this knowledge to design electroactive and conductive frameworks. These materials have been proposed as the basis for the next generation of technological devices for applications in energy storage and conversion, including electrochromic devices, electrocatalysts, and battery materials. After nearly two decades of intense research into MOFs, the mechanisms of charge transfer remain relatively poorly understood, and new strategies to achieve charge mobility remain elusive and challenging to experimentally explore, validate, and model. We now demonstrate that aromatic stacking interactions in Zn(II) frameworks containing cofacial thiazolo[5,4- d]thiazole (TzTz) units lead to a mixed-valence state upon electrochemical or chemical reduction. This through-space intervalence charge transfer (IVCT) phenomenon represents a new mechanism for charge transfer in MOFs. Computational modeling of the optical data combined with application of Marcus-Hush theory to the IVCT bands for the mixed-valence framework has enabled quantification of the degree of charge transfer using both in situ and ex situ electro- and spectro-electrochemical methods. A distance dependence for the through-space electron transfer has also been identified on the basis of experimental studies and computational calculations. This work provides a new window into electron transfer phenomena in 3-dimensional coordination space, of relevance to electroactive MOFs where new mechanisms for charge transfer are highly sought after, and to understanding biological light-harvesting systems where through-space mixed-valence interactions are operative.

Carbon dioxide adsorption by physisorption and chemisorption interactions in piperazine-grafted Ni₂(dobdc) (dobdc = 1,4-dioxido-2,5- benzenedicarboxylate)

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2DT31112G

Abstract: The metal-organic framework Ni(2)(dobdc) (CPO-27-Ni, where dobdc = 1,4-dioxido-2,5-benzenedicarboxylate) has been post-synthetically modified with piperazine (pip) - a known 'accelerator' to improve the kinetics of CO(2) uptake in alkanolamine solvents for chemical absorption - and the impact of the modification on the CO(2) uptake and selectivity over N(2) has been probed. While the modified framework, Ni(2)(dobdc)(pip)(0.5) (pip-CPO-27-Ni), exhibits a lower uptake of CO(2) compared with the non-grafted material, the selectivity for CO(2) over N(2) at 25 °C and at pressures pertinent to post-combustion flue gas capture (0.1-0.15 bar) is enhanced. Mechanistically, the interaction between the CO(2) molecules and the free amine sites in pip-CPO-27-Ni occurs via physisorption and chemisorption interactions, in which CO(2) binds to the framework with an isosteric heat of adsorption (-Q(st)) of 40.5 kJ mol(-1) at very low coverage (P = 0.033 mbar), followed by binding at a higher heat of adsorption (-Q(st) = 46.2 kJ mol(-1) at P = 3.55 mbar). Pure water adsorption isotherms revealed a two-step mechanism for uptake in CPO-27-Ni, consistent with adsorption into the first and second hydration spheres of Ni(2+) followed by subsequent uptake via physisorption into the pores. Additional steric hindrance in pip-CPO-27-Ni results in a single step only. The working capacity over multiple cycles was also investigated using a temperature swing adsorption process which revealed reversible CO(2) adsorption and desorption of 10 wt% over 10 cycles.

A porous chiral framework of coordinated 1,3,5-benzenetricarboxylate: quadruple interpenetration of the (10,3)-a network

Publisher: Royal Society of Chemistry (RSC)

Date: 1998

DOI: 10.1039/A705336C

Hysteretic Four‐Step Spin Crossover within a Three‐Dimensional Porous Hofmann‐like Material

Publisher: Wiley

Date: 21-10-2016

DOI: 10.1002/ANIE.201605418

Abstract: Materials that display multiple stepped spin crossover (SCO) transitions with accompanying hysteresis present the opportunity for ternary, quaternary, and quinary electronic switching and data storage but are rare in existence. Herein, we present the first report of a four-step hysteretic SCO framework. Single-crystal structure analysis of a porous 3D Hofmann-like material showed long-range ordering of spin states: HS, HS

Direct Observation of a Transverse Vibrational Mechanism for Negative Thermal Expansion in Zn(CN)₂:  An Atomic Pair Distribution Function Analysis

Publisher: American Chemical Society (ACS)

Date: 18-10-2005

DOI: 10.1021/JA055197F

Abstract: The instantaneous structure of the cyanide-bridged negative thermal expansion (NTE) material Zn(CN)(2) has been probed using atomic pair distribution function (PDF) analysis of high energy X-ray scattering data (100-400 K). The temperature dependence of the atomic separations extracted from the PDFs indicates an increase of the average transverse displacement of the cyanide bridge from the line connecting the Zn(II) centers with increasing temperature. This allows the contraction of non-nearest-neighbor Zn...Zn' and Zn...C/N distances despite the observed expansion of the in idual direct Zn-C/N and C-N bonds. Thus, this analysis provides definitive structural confirmation that an increase in the average displacement of bridging atoms is the origin of the NTE behavior. The lattice parameters reveal a slight reduction in the NTE behavior at high temperature from a minimum coefficient of thermal expansion (alpha = dl/ldT) of -19.8 x 10(-6) K(-1) below 180 K, which is attributed to interaction between the doubly interpenetrated frameworks that comprise the structure.

Effect of gas pressure on negative thermal expansion in MOF-5

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C2CC37415C

Abstract: Powder diffraction is used to study thermal expansion properties of MOF-5 at moderate helium gas pressures: 1.7 bar (100-500 K) and 5-150 bar (150-300 K). The framework shows negative thermal expansion (NTE) at all pressures, but vibrational motions causing NTE are d ed with increasing pressures, leading to decreased NTE.

A Nanoscale Molecular Switch Triggered by Thermal, Light, and Guest Perturbation

Publisher: Wiley

Date: 17-03-2009

DOI: 10.1002/ANIE.200805178

Abstract: Bottoms up! A discrete metallo-supramolecular nanoball (see picture), synthesized by using "bottom-up" methodologies, uniquely undergoes a solvent-sensitive, physically addressable electronic spin switching. The switching occurs by thermal, light, or solvent perturbation, where importantly it can be switched "on" or "off" by green or red laser irradiation, respectively.

Synthesis, Crystal Structures, and Properties of Molecular Squares Displaying Hydrogen and π−π Bonded Networks

Publisher: American Chemical Society (ACS)

Date: 07-04-2009

DOI: 10.1021/CG801369U

Low temperature crystal structure of the organic metal ([2H8]BEDT–TTF)4Cl2·6D2O [BEDT–TTF=bis(ethylenedithio)tetrathiafulvalene]

Publisher: Royal Society of Chemistry (RSC)

Date: 1998

DOI: 10.1039/A704818A

Charge-density study of deuterated ammonium ferrous Tutton salt at 85 K and comparison with Cr^II and Cu^II salts

Publisher: International Union of Crystallography (IUCr)

Date: 12-1992

DOI: 10.1107/S0108768192004786

2,4,6-Tris(4-pyridylmethylsulfanyl)-1,3,5-triazine monohydrate

Publisher: International Union of Crystallography (IUCr)

Date: 28-05-2005

DOI: 10.1107/S1600536805016132

Increasing spin crossover cooperativity in 2D Hofmann-type materials with guest molecule removal

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C8SC01040D

Abstract: Ambient temperature spin crossover with wide hysteresis has been achieved in 2D Hofmann-type materials, where removal of guest molecules optimises ligand–ligand interactions, resulting in increased cooperativity.

Exploiting Pressure to Induce a guest-Blocked Spin Transition in a Framework Material

Publisher: American Chemical Society (ACS)

Date: 06-10-2016

DOI: 10.1021/ACS.INORGCHEM.6B01686

Abstract: A new functionalized 1,2,4-triazole ligand, 4-[(E)-2-(5-methyl-2-thienyl)vinyl]-1,2,4-triazole (thiome), was prepared to assess the broad applicability of strategically producing multistep spin transitions in two-dimensional Hofmann-type materials of the type [Fe

Layered Cobalt Hydroxysulfates with Both Rigid and Flexible Organic Pillars:  Synthesis, Structure, Porosity, and Cooperative Magnetism

Publisher: American Chemical Society (ACS)

Date: 05-02-2023

DOI: 10.1021/JA0109848

Abstract: The synthesis and characterization of two members of a family of porous magnetic materials is described. The structures of Co4(SO4)(OH)6(C2N2H8)0.5*3H2O and Co4(SO4)(OH)6(C6N2H12)0.5*H2O and their thermal stability can be tailored via the choice of organic pillar. The interactions between the pillaring agent and the compositionally complex inorganic layer are discussed. The influences of two pillaring agents i.e., the flexible ethylenediamine and the relatively rigid 1,4-diazabicyclo[2,2,2]octane, on thermal stability, rigidity upon guest loss, and magnetic behavior of the pillared solids are compared. The magnetism of the pillared layered cobalt hydroxides is complex due to the influences of multiple metal sites, inter- and intralayer exchange, spin-orbit coupling, and geometrical frustration. The wide variety of potential pillars, oxyanions, and possible metal substitutions at the octahedral and tetrahedral sites offers the possibility of tailoring the magnetic and porous properties of these materials.

Self-Assembly of an Octanuclear High-Spin FeII Molecular Cage

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/CH14404

Abstract: A discrete octanuclear high-spin FeII cage [Fe8L12](BF4)16·n(solvent) was synthesised via metal ion-directed self-assembly. The cage formation is facilitated by incorporating a relatively flexible ditopic ligand with chelating pyrazolyl–pyridine functional units. The synthesis, structure, and magnetic properties of this metallo-cage are presented.

Vectorial property dependence in bis{4′-(n-pyridyl)-2,2′: 6′,2″-terpyridine}iron(ii) and ruthenium(ii) complexes with n = 2, 3 and 4

Publisher: Royal Society of Chemistry (RSC)

Date: 2008

DOI: 10.1039/B714970K

Abstract: A comparative structural and spectroscopic investigation of the complexes [M(1)2]2+, [M(2)2]2+ and [M(3)2]2+ in which M = Fe or Ru, and ligands 1, 2 and 3 are 4'-(2-pyridyl)-, 4'-(3-pyridyl)- and 4'-(4-pyridyl)-2,2':6',2"-terpyridine, respectively, is reported. The complexes [Ru(1)2]2+, [Ru(2)2]2+ and [Ru(3)2]2+ undergo mono- and bis-N-methylation. The consequences of methylation on the absorption spectra and electrochemical properties are discussed the solid-state structure of the bis(N-methylated) derivative of [Ru(2)2][PF6]2 is presented.

Understanding the Two‐Step Spin‐Transition Phenomenon in Iron(II) 1D Chain Materials

Publisher: Wiley

Date: 30-10-2008

DOI: 10.1002/CHEM.200800886

Abstract: Three analogous one dimensional (1D) polymeric iron(II) spin crossover (SCO) materials containing the new ligand 4,6-bis(2',2''-pyridyl)pyrazine (bdpp) have been comprehensively characterised magnetically (thermal and light-induced) and structurally. Within this series are two polymorphs of the formula [Fe(NCS)(2)(bdpp)], 1 and 2 a, which differ magnetically in that phase 1 undergoes a full two-step SCO (T(1/2(1))=135 K and T(1/2(2))=90 K) whereas phase 2 a remains high spin (HS) over all temperatures. The central distinction between these two materials lies in the presence of intermolecular pi-pi interactions generated by the crystal packing in 1, which are absent in 2 a. The isostructural selenocyanate analogue of 2 a, [Fe(NCSe)(2)(bdpp)], 2 b, undergoes a full two-step SCO (T(1/2(1))=200 K and T(1/2(2))=125 K). Structural analyses of 1 and 2 b at a range of temperatures provide deep insight into their two-step SCO nature. Structural analysis of 1 at 25 K (1(LS-LS)), 123 K (1(LS-HS)) and 250 K (1(HS-HS)) reveals two distinct iron(II) centres at each temperature, with ordered, alternating HS and LS (low spin) sites at the intermediate plateau (IP) temperatures. In contrast, structural analysis of 2 b at 90 K (2 b(LS)), 150 K (2 b(LS/HS)) and 250 K (2 b(HS)) reveals one unique iron(II) centre at each temperature with an "averaged" LS/HS character at the IP temperature. Weak planes of diffuse scattering in the single-crystal X-ray diffraction patterns were observed for this phase at 90 and 150 K, indicating that 1D long range ordering of alternating HS/LS iron(II) centres occurs along the 1D coordination chains, but that there is no correlation between chains. The lack of observable diffuse scattering at 250 K suggests that the onset of the 1D structural ordering in the chain direction corresponds to the first step of the SCO and that this structural transition is electronically driven. The photomagnetic properties of both 1 and 2 b have been investigated and show approximately 62 and 53 % photo-excitation of a HS metastable state at low temperatures and T(LIESST) values of 55 and 49 K, respectively. Relaxation studies on the HS fraction in 2 b fitted well to a stretched exponential model with kinetic parameters indicative of weak cooperativity.

Phase diagram, chemical stability and physical properties of the solid-solution Ba4Nb2−xTaxO9

Publisher: Elsevier BV

Date: 10-2011

DOI: 10.1016/J.JSSC.2011.07.036

Structural Systematics of Rare Earth Complexes. VII. Crystal Structure of Bis(2,2'/6',2␛-Terpyridinium) Octaaquaterbium(III) Heptachloride Hydrate

Publisher: CSIRO Publishing

Date: 1994

DOI: 10.1071/CH9940391

Abstract: The room-temperature single-crystal X-ray structural characterization of the title compound (tpyH2)2[Tb(OH2)8]Cl7.~2⅓H2O is recorded. Crystals are triclinic, Pī , a 17.063(5), b 16.243(3), c 7.878(3) Ǻ, α 84.78(2), β 84.39(3), γ 87.81(2)°, Z = 2 formula units 3167 'observed' diffractometer reflections were refined by full-matrix least-squares procedures to a residual of 0.057. Notable features of interest of the compound are the 'chelation' of chloride ions by the terpyridinium cations , and the existence of a free [Tb(OH2)8]2+ cation in the presence of an abundance of chloride ions.

Nanoporosity of an interpenetrated NbO-type molecular framework studied by single crystal X-ray diffraction

Publisher: Royal Society of Chemistry (RSC)

Date: 2004

DOI: 10.1039/B409543J

Abstract: The molecular framework [Fe(NCS)(2)(tmbpz)(2)](tmbpz = 3,3',5,5'-tetramethyl-4,4'-bipyrazolyl) consists of a robust doubly interpenetrated NbO-type network that remains stable on the removal of solvent guest molecules.

Thermal- and Light-Induced Spin-Crossover Bistability in a Disrupted Hofmann-Type 3D Framework

Publisher: American Chemical Society (ACS)

Date: 21-07-2014

DOI: 10.1021/IC500323R

Abstract: The expected 3D and 2D topologies resulting from combining approximately linear bis- or monopyridyl ligands with [Fe(II)M(II)(CN)4] (M(II) = Pt, Pd, Ni) 4,4-grid sheets are well established. We show here the magnetic and structural consequences of incorporating a bent bispyridyl linker ligand in combination with [Fe(II)Pt(II)(CN)4] to form the material [Fe(H2O)2Fe(DPSe)2(Pt(CN)4)2]·3EtOH (DPSe = 4,4'-dipyridylselenide). Structural investigations reveal an unusual connectivity loosely resembling a 3D Hofmann topology where (1) there are two distinct local iron(II) environments, [Fe(II)N6] (Fe1) and [Fe(II)N4O2] (Fe2), (2) as a consequence of axial water coordination to Fe2, there are "holes" in the [Fe(II)Pt(II)(CN)4] 4,4 sheets because of some of the cyanido ligands being terminal rather than bridging, and (3) bridging of adjacent sheets occurs only through one in two DPSe ligands, with the other acting as a terminal ligand binding through only one pyridyl group. The magnetic properties are defined by this unusual topology such that only Fe1 is in the appropriate environment for a high-spin to low-spin transition to occur. Magnetic susceptibility data reveal a complete and abrupt hysteretic spin transition (T(1/2)↓ = 120 K and T(1/2)↑ = 130 K) of this iron(II) site Fe2 remains high-spin. This material additionally exhibits a photomagnetic response (uncommon for Hofmann-related materials), showing light-induced excited spin-state trapping [LIESST T(LIESST) = 61 K] with associated bistability evidenced in a hysteresis loop (T(1/2)↓ = 60 K and T(1/2)↑ = 66 K).

3D Long-Range Magnetic Ordering in Layered Metal–Hydroxide Triangular Lattices 25 Å Apart

Publisher: Elsevier BV

Date: 07-1999

DOI: 10.1006/JSSC.1999.8147

Novel BEDT-TTF salts with magnetic anions [MoOCl4(H2O)]− and [Re2(NCS)10]3−

Publisher: Elsevier BV

Date: 03-1995

DOI: 10.1016/0379-6779(94)02648-I

Topotactic structural conversion and hydration-dependent thermal expansion in robust LnM^III(CN)6·nH2O and flexible ALnFe^II(CN)6·nH2O frameworks (A = Li, Na, K; Ln = La-Lu, Y; M = Co, Fe; 0 ≤ n ≤ 5)

Publisher: Royal Society of Chemistry (RSC)

Date: 04-06-2014

DOI: 10.1039/C4SC00809J

New BEDT-TTF salts with transition-metal containing anions

Publisher: Elsevier BV

Date: 03-1995

DOI: 10.1016/0379-6779(94)02644-E

Tunable Porous Coordination Polymers for the Capture, Recovery and Storage of Inhalation Anesthetics

Publisher: Wiley

Date: 19-05-2017

DOI: 10.1002/CHEM.201700389

Abstract: The uptake of inhalation anesthetics by three topologically identical frameworks is described. The 3D network materials, which possess square channels of different dimensions, are formed from the relatively simple combination of Zn

A new spin crossover FeII coordination environment in a two-fold interpenetrated 3-D Hofmann-type framework material

Publisher: Royal Society of Chemistry (RSC)

Date: 2021

DOI: 10.1039/D0CC07326A

Abstract: Spin-crossover is observed for the first time in a Fe II (py) 3 (NC⋯) 3 coordination environment which arises in a two-fold interpenetrated 3-D Hofmann-like framework.

New Cadmium(II) and Iron(II) Coordination Frameworks Incorporating a Di(4‐pyridyl)isoindoline Ligand

Publisher: Wiley

Date: 06-2005

DOI: 10.1002/EJIC.200500108

Spontaneous resolution of two chiral metal–organic frameworks through local geometric and lattice frustration effects

Publisher: Royal Society of Chemistry (RSC)

Date: 2023

DOI: 10.1039/D3CE00784G

Application of the piperazine-grafted CuBTTri metal-organic framework in postcombustion carbon dioxide capture

Publisher: Elsevier BV

Date: 07-2013

DOI: 10.1016/J.MICROMESO.2013.02.036

INCOMMENSURATELY MODULATED ZRO2-XF2X-0.698-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.714

Publisher: Elsevier BV

Date: 11-1991

DOI: 10.1016/0022-4596(91)90381-Q

Negative thermal expansion and low-frequency modes in cyanide-bridged framework materials

Publisher: American Physical Society (APS)

Date: 21-04-2005

DOI: 10.1103/PHYSREVB.71.140301

Dehydration of the nanoporous coordination framework Erⁱⁱⁱ[Coⁱⁱⁱ(CN)₆]·4(H₂O): single crystal to single crystal transformation and negative thermal expansio

Publisher: Royal Society of Chemistry (RSC)

Date: 2006

DOI: 10.1039/B601344A

Abstract: Desorption of bound and unbound water molecules from the nanoporous coordination framework ErIII[CoIII(CN)6].4(H2O) to form the apohost, ErIII[CoIII(CN)6], proceeds via a single crystal to single crystal transformation in which the Er(III) cations change from 8- to 6-coordinate dehydration results in a striking change in the thermal expansion properties.

Magnetic, electrochemical and optical properties of a sulfate-bridged Co(ii) imidazole dimer

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4NJ01401D

Abstract: The electrochemical, optical and magnetic properties of a sulfate-bridged high spin Co( ii ) dimer, [Co 2 (DMIM) 4 (μ 2 -O 2 ,O,O′-SO 4 ) 2 ]·2MeCN are reported. Antiferromagnetic coupling across the μ 2 -(O 2 -sulfato) bridging mode has been identified with J = −28 cm −1 .

Structural Study of D₂ within the Trimodal Pore System of a Metal Organic Framework

Publisher: American Chemical Society (ACS)

Date: 12-04-2011

DOI: 10.1021/JP2010937

Highly unusual interpenetration isomers of electroactive nickel bis(dithiolene) coordination frameworks

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4CC05438E

Abstract: Two highly unusual isomeric coordination frameworks incorporating the nickel bis(dithiolate) metalloligand exhibit cyclable electroactive properties.

Laboratory-based separation techniques for insoluble compound mixtures: methods for the purification of metal–organic framework materials

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1DT10251F

Abstract: In this article, techniques for separating mixtures of insoluble compounds are discussed with respect to the small quantities found in laboratory preparations, as opposed to industrial quantities. The techniques include separations based on density, surface area and differences in particle size. Also discussed are simple apparatus, readily available in the laboratory or from commercial suppliers, for achieving these techniques.

Hydrogen Bond-Directed Hexagonal Frameworks Based on Coordinated 1,3,5-Benzenetricarboxylate

Publisher: Elsevier BV

Date: 06-2000

DOI: 10.1006/JSSC.2000.8691

Semiconducting charge-transfer salts of BEDT-TTF [bis(ethylenedithio)tetrathiafulvalene] with hexachlorometallate(IV) anions

Publisher: Royal Society of Chemistry (RSC)

Date: 1997

DOI: 10.1039/A605878G

Two-step spin crossover by guest-disorder induced local symmetry breaking within a 3D Hofmann-like framework

Publisher: Royal Society of Chemistry (RSC)

Date: 2022

DOI: 10.1039/D2CC03780G

Abstract: A chrysene-loaded spin crossover material exhibits a two-step thermally-activated spin transition driven by guest-induced local symmetry breaking.

Identification of bridged CO₂ binding in a Prussian blue analogue using neutron powder diffraction

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3CC46019C

Abstract: Neutron powder diffraction measurements were carried out on the evacuated and CO2-loaded Prussian blue analogue, Fe3[Co(CN)6]2, identifying two distinct CO2 adsorption sites: site A, in which CO2 uniquely bridges between two bare-metal sites, and site B, in which it interacts in a face capping motif. The saturation of site A at low loadings of CO2 demonstrates the favourable nature of the interaction of CO2 with bare-metal sites within the material.

In Situ Single-Crystal X-ray Diffraction Studies of Desorption and Sorption in a Flexible Nanoporous Molecular Framework Material

Publisher: American Chemical Society (ACS)

Date: 05-05-2005

DOI: 10.1021/JA042420K

Abstract: The subtle flexibility of the framework material Co(bpy)1.5(NO3)2.(guest) (bpy = 4,4'-bipyridine) (1.(guest)) is demonstrated quantitatively through in situ single-crystal X-ray diffraction measurements of guest desorption and sorption processes. Variable temperature unit cell determinations were employed to monitor the uptake and release of guest species, and full structural determinations have been carried out for the as-grown ethanol-loaded framework (1.(EtOH)), for the empty host framework, and for each of the five introduced guests (methanol: 1.(MeOH), acetone: 1.(ACN), acetonitrile: 1.(MeCN), tetrahydrofuran:1.(THF), dichloromethane: 1.(DCM)). The framework consists of interdigitated two-dimensional bilayers of cobalt(II) centers bridged by bpy ligands, with one-dimensional pores that account for approximately 20% of the total volume. The sorption of guest species of varying size and shape has revealed the framework's ability to adapt to different guests through a range of different framework flexibilities.

Reversible ferromagnetic–antiferromagnetic transformation upon dehydration–hydration of the nanoporous coordination framework, [Co3(OH)2(C4O4)2]·3H2O

Publisher: Royal Society of Chemistry (RSC)

Date: 2005

DOI: 10.1039/B500614G

Abstract: Reversible crystal-to-crystal transformation accompanied by change from ferromagnetic to antiferromagnetic ground states at 8 K upon dehydration-rehydration of the nanoporous coordination framework [CoII3(OH)2(C4O4)2].3H2O.

A new modification of an old framework: Hofmann layers with unusual tetracyanidometallate groups

Publisher: Royal Society of Chemistry (RSC)

Date: 2995

DOI: 10.1039/C1DT11183C

Abstract: Cyanidometallate complexes are highly versatile building units for the generation of functional porous materials. Here we report five new pillared Hofmann layer compounds incorporating the tetracyanidometallates [MoO(CN)(4)](2-) and [MnN(CN)(4)](2-). These metalloligands, which are new to this class of materials, have been combined with alent 1st-row transition metals to produce Hofmann layers that are linked into three-dimensional frameworks by ditopic bridging dipyridyls. We report the structures and anomalous thermal expansion properties of five new materials: [Mn(H(2)O)(bpy)(½){MoO(CN)(4)(bpy)(½)}]·2H(2)O (1), [Mn(H(2)O)(bpy)(½){MnN(CN)(4)(bpy)(½)}]·2H(2)O (2), [Fe(H(2)O)(bpy)(½){MnN(CN)(4)(bpy)(½)}]·2H(2)O (3), [Co(H(2)O)(bpy)(½){MnN(CN)(4)(bpy)(½)}]·2H(2)O (4) and [{Mn(H(2)O)(2)}(½){Mn(bpa)(2)}(½){MoO(CN)(4)(bpa)(½)}]·MeOH (5), (where bpy = 4,4'-bipyridine and bpa = 4,4'-bipyridylacetylene).

Structural Systematics of Rare Earth Complexes. VI. The Higher Hydrates of the Rare Earth Trichlorides

Publisher: CSIRO Publishing

Date: 1994

DOI: 10.1071/CH9940385

Abstract: Single-crystal room-temperature X-ray structure determinations of improved precision are reported for certain higher hydrates of the rare earth trichlorides (LnCl3.7H2O, Ln = La, Pr LnCl3.6H2O, Ln = Nd, Lu) (triclinic, Pī, and monoclinic, P 2/n, forms respectively) in order to define hydrogen-bonding arrays within the two lattices.

Structural Properties of the Superconducting Salt (BEDT-TTF)3Cl2·(H2O)2 at Low Temperatures

Publisher: Elsevier BV

Date: 07-1999

DOI: 10.1006/JSSC.1999.8194

Experimental and Computational Studies of a Multi‐Electron Donor–Acceptor Ligand Containing the Thiazolo[5,4‐d]thiazole Core and its Incorporation into a Metal–Organic Framework

Publisher: Wiley

Date: 24-10-2014

DOI: 10.1002/CHEM.201405089

Abstract: A ligand containing the thiazolo[5,4-d]thiazole (TzTz) core (acceptor) with terminal triarylamine moieties (donors), N,N'-(thiazolo[5,4-d]thiazole-2,5-diylbis(4,1-phenylene))bis(N-(pyridine-4-yl)pyridin-4-amine (1), was designed as a donor-acceptor system for incorporation into electronically active metal-organic frameworks (MOFs). The capacity for the ligand to undergo multiple sequential oxidation and reduction processes was examined using UV/Vis-near-infrared spectroelectrochemistry (UV/Vis-NIR SEC) in combination with DFT calculations. The delocalized nature of the highest occupied molecular orbital (HOMO) was found to inhibit charge-transfer interactions between the terminal triarylamine moieties upon oxidation, whereas radical species localized on the TzTz core were formed upon reduction. Conversion of 1 to diamagnetic 2+ and 4+ species resulted in marked changes in the emission spectra. Incorporation of this highly delocalized multi-electron donor-acceptor ligand into a new two-dimensional MOF, [Zn(NO3 )2 (1)] (2), resulted in an inhibition of the oxidation processes, but retention of the reduction capability of 1. Changes in the electrochemistry of 1 upon integration into 2 are broadly consistent with the geometric and electronic constraints enforced by ligation.

Determining the charge distribution in BEDT-TTF salts

Publisher: Elsevier BV

Date: 02-1997

DOI: 10.1016/S0379-6779(97)80983-6

Thermal Expansion Matching via Framework Flexibility in Zinc Dicyanometallates

Publisher: American Chemical Society (ACS)

Date: 22-04-2009

DOI: 10.1021/JA901355B

Abstract: The thermal expansion properties of two isostructural zinc dicyanometallates that crystallize with and without the inclusion of a weakly interacting secondary crystalline phase have been investigated using variable temperature single-crystal and powder X-ray diffraction. The guest-free Zn[Au(CN)(2)](2) framework was found to show very strong anisotropic positive and negative thermal expansion. In contrast, its cocrystal analogue Zn[Ag(CN)(2)](2) x xAgCN exhibited much more moderate behavior, such that the coefficient of thermal expansion for the host Zn[M(CN)(2)](2) framework now matched that of crystalline AgCN. It was proposed that this correlation points to a more general ability of highly flexible framework materials to "match" the thermal expansivity of adhered phases (e.g., substrates, sorbates, or cocrystallized species), suggesting a methodology of eliminating thermal strain in multicomponent assemblies.

Synthesis and analysis of the anticancer activity of platinum(ii) complexes incorporating dipyridoquinoxaline variants

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4DT02133A

Abstract: Platinum complexes incorporating variants of dpq were synthesised. Their DNA affinity and cytotoxicity were compared to complexes containing phen variants, revealing unexpected trends in biological activity.

The conjugate acid of bis{4′-(4-pyridyl)-2,2′:6′, 2″-terpyridine}iron(ii) as a self-complementary hydrogen-bonded building block

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B710332H

An Investigation of Photo‐ and Pressure‐Induced Effects in a Pair of Isostructural Two‐Dimensional Spin‐Crossover Framework Materials

Publisher: Wiley

Date: 07-05-2014

DOI: 10.1002/CHEM.201400367

Abstract: Two new isostructural iron(II) spin-crossover (SCO) framework (SCOF) materials of the type [Fe(dpms)2(NCX)2] (dpms = 4,4'-dipyridylmethyl sulfide X = S (SCOF-6(S)), X = Se (SCOF-6(Se))) have been synthesized. The 2D framework materials consist of undulating and interpenetrated rhomboid (4,4) nets. SCOF-6(S) displays an incomplete SCO transition with only approximately 30 % conversion of high-spin (HS) to low-spin iron(II) sites over the temperature range 300-4 K (T1/2 = 75 K). In contrast, the NCSe(-) analogue, SCOF-6(Se), displays a complete SCO transition (T1/2 = 135 K). Photomagnetic characterizations reveal quantitative light- induced excited spin-state trapping (LIESST) of metastable HS iron(II) sites at 10 K. The temperature at which the photoinduced stored information is erased is 58 and 50 K for SCOF-6(S) and SCOF-6(Se), respectively. Variable-pressure magnetic measurements were performed on SCOF-6(S), revealing that with increasing pressure both the T1/2 value and the extent of spin conversion are increased with pressures exceeding 5.2 kbar a complete thermal transition is achieved. This study confirms that kinetic trapping effects are responsible for hindering a complete thermally induced spin transition in SCOF-6(S) at ambient pressure due to an interplay between close T1/2 and T(LIESST) values.

[V₁₆O₃₈(CN)]^9–: A Soluble Mixed-Valence Redox-Active Building Block with Strong Antiferromagnetic Coupling

Publisher: American Chemical Society (ACS)

Date: 23-04-2012

DOI: 10.1021/IC3001834

Abstract: A new discrete [V(16)O(38)(CN)](9-) cluster, which displays the hitherto unknown 8- charge on the cluster shell and is the first to encapsulate the cyanide anion, has been synthesized and characterized by IR and UV/vis/near-IR spectroscopy, electrochemistry, and magnetic susceptibility measurements. Bond valence sum calculations conducted on the basis of the crystal structure analysis of K(9)[V(16)O(38)(CN)]·13H(2)O confirm that this new member of the polyoxovanadate series is a mixed-valence complex. The intervalence charge transfer bands arising from intrametal interactions reveal that a localized (class II) assignment is appropriate for the cluster however, a small degree of electronic delocalization is present. Interesting possibilities exist for the incorporation of this unit into higher dimensionality framework structures, where the redox, optical, and magnetic properties can be exploited and tuned.

The electronic, optical and magnetic consequences of delocalization in multifunctional donor–acceptor organic polymers

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C5CP00081E

Abstract: Redox reactions on electroactive donor–acceptor polymers can be used to tune their response to external magnetic and electrical stimuli.

Mono- and Di-nuclear gold(I) complexes containing 1,12-dicarba-closo- dodecaborane(12)

Publisher: CSIRO Publishing

Date: 2007

DOI: 10.1071/CH07232

Abstract: The first ex les of gold(i) complexes containing monodentate diphenylphosphine-1,12-carborane and bidentate 1,12-bis(diphenylphosphine)-1,12-carborane ligands are reported.

Muon-spin-rotation and magnetization study of metal-organic magnets based on the dicyanamide anion

Publisher: IOP Publishing

Date: 22-02-2001

DOI: 10.1088/0953-8984/13/10/318

Phase Control of Ferromagnetic Copper(II) Carbonate Coordination Polymers through Reagent Concentration

Publisher: Wiley

Date: 17-12-2018

DOI: 10.1002/EJIC.201801041

Selective Recovery of Dynamic Guest Structure in a Nanoporous Prussian Blue through in Situ X-ray Diffraction:  A Differential Pair Distribution Function Analysis

Publisher: American Chemical Society (ACS)

Date: 20-07-2005

DOI: 10.1021/JA053266K

Abstract: We use in situ X-ray diffraction to obtain data suitable for differential PDF analysis, providing unique insight into the structure of weakly bound, dynamic N2 molecules in the Prussian blue system Mn3[Co(CN)6]2.x{N2}. The differential PDF shows a distributed orientation of N2 molecules constrained to sites centered about the (1/4,1/4,1/4) positions within the pores. The results show a subtle response of the framework to guest loading which corresponds principally to the perturbation of the Mn ion coordination.

Spectroscopic, electronic and computational properties of a mixed tetrachalcogenafulvalene and its charge transfer complex

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C7TC03853D

Abstract: The unexplored electron donor molecule triselenathiafulvalene (TSTF) and its corresponding charge transfer complex with the well-known electron acceptor TCNQ exhibit rich electronic, optical and semiconducting properties.

A Versatile Family of Interconvertible Microporous Chiral Molecular Frameworks:  The First Example of Ligand Control of Network Chirality

Publisher: American Chemical Society (ACS)

Date: 05-2000

DOI: 10.1021/JA993814S

New metal organic frameworks incorporating the ditopic macrocyclic ligand dipyridyldibenzotetraaza[14]annulene

Publisher: Springer Science and Business Media LLC

Date: 19-07-2011

DOI: 10.1007/S10847-011-0007-6

Spin crossover-induced colossal positive and negative thermal expansion in a nanoporous coordination framework material

Publisher: Springer Science and Business Media LLC

Date: 20-10-2017

DOI: 10.1038/S41467-017-00776-1

Abstract: External control over the mechanical function of materials is paramount in the development of nanoscale machines. Yet, exploiting changes in atomic behaviour to produce controlled scalable motion is a formidable challenge. Here, we present an ultra-flexible coordination framework material in which a cooperative electronic transition induces an extreme abrupt change in the crystal lattice conformation. This arises due to a change in the preferred coordination character of Fe(II) sites at different spin states, generating scissor-type flexing of the crystal lattice. Diluting the framework with transition-inactive Ni(II) sites disrupts long-range communication of spin state through the lattice, producing a more gradual transition and continuous lattice movement, thus generating colossal positive and negative linear thermal expansion behaviour, with coefficients of thermal expansion an order of magnitude greater than previously reported. This study has wider implications in the development of advanced responsive structures, demonstrating electronic control over mechanical motion.

Royal Institution Of Great Britain / University Of London

Location: United Kingdom of Great Britain and Northern Ireland

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University Of Western Australia

Location: Australia

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University Of Oxford

Location: United Kingdom of Great Britain and Northern Ireland

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University Of Sydney

Location: Australia

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Linkage Projects - Grant ID: LP210100435

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