ORCID Profile
0000-0001-8465-9678
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University of Western Sydney Parramatta Campus
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Publisher: Wiley
Date: 03-01-2017
Abstract: A series of 28 norcantharidin (NorC)-inspired analogues were accessed via a robust two-step Ugi intramolecular Diels-Alder (IMDA) sequence. Four analogues displayed whole-cell cytotoxicity equipotent to that of NorC and cisplatin against a number of cancer cell lines and a normal breast cell line (MCF10A). Notably, (3S,3aS,6R)-2-benzyl-7-methyl-N-(naphthalen-2-yl)-1-oxo-1,2,3,6-tetrahydro-3a,6-epoxyisoindole-3-carboxamide (trans-27) displayed superior whole-cell activity against breast (MCF-7, GI
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.
Publisher: Wiley
Date: 2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0DT00340A
Abstract: The hexaazamacrocycles [28](DBF)(2)N(6) {cyclo[bis(4,6-dimethyldibenzo[b,d]furaniminoethyleneiminoethylene]} and [32](DBF)(2)N(6) {cyclo[bis(4,6-dimethyldibenzo[b,d]furaniminopropyleneiminopropylene]} form stable dinuclear copper(ii) complexes suitable to behave as receptors for several anionic substrates. These two receptors were used to study the binding interactions with several substrates, such as imidazole (Him) and some carboxylates [benzoate (bz(-)), oxalate (ox(2-)), malonate (mal(2-)), phthalate (ph(2-)), isophthalate (iph(2-)), and terephthalate (tph(2-))] by spectrophotometric titrations and EPR spectroscopy in MeOH (or H(2)O):DMSO (1 : 1 v/v) solution. The largest association constant was found for ox(2-) with Cu(2)[32](DBF)(2)N(6)(4+), whereas for the aromatic dicarboxylate anions the binding constants follow the trend ph(2-) > iph(2-) > tph(2-), i.e. decrease with the increase of the distance of the two binding sites of the substrate. On the other hand, the large blue shift of 68 nm observed by addition of Him to Cu(2)[32](DBF)(2)N(6)(4+) points out for the formation of the bridged CuimCu cascade complex, indicating this receptor as a potential sensor for the detection and determination of imidazole in solution. The X-band EPR spectra of the Cu(2)[28](DBF)(2)N(6)(4+) and Cu(2)[32](DBF)(2)N(6)](4+) complexes and the cascade complexes with the substrates, performed in H(2)O:DMSO (1 : 1 v/v) at 5 to 15 K, showed that the CuCu distance is slightly larger than the one found in crystal state and that this distance increases when the substrate is accommodated between the two copper centres. The crystal structure of [Cu(2)[28](DBF)(2)N(6)(ph)(2)]·CH(3)OH was determined by X-ray diffraction and revealed the two copper centres bridged by two ph(2-) anions at a CuCu distance of 5.419(1) Å. Each copper centre is surrounded by three carboxylate oxygen atoms from two phthalate anions and three contiguous nitrogen atoms of the macrocycle in a pseudo octahedral coordination environment.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CE00749K
Abstract: In this study, a hydroxyl-rich Schiff base ligand, H 4 L , and its resulting complexes with ZnCl 2 , Zn(CH 3 COO) 2 and Zn(ClO 4 ) 2 were explored.
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B415718D
Abstract: Structural studies of metal complexes of five ditopic hexaazamacrocycles containing two pyridine rings ([n]py2N4 n= 18, 20, 22, 24 and 26) have been carried out. The synthesis of macrocycles [22]- to [26]-py2N4 are also reported. The protonation constants of the last three compounds and the stability constants of their complexes with Ni2+, Cu2+, Zn2+, and Pb2+ were determined at 25 degrees C in 0.10 mol dm(-3) KNO3 in aqueous solution. Our results with [22]py2N4 show significant differences from those described previously, while [24]py2N4 has not been studied before and [26]py2N4 is a new compound. Mononuclear and dinuclear complexes of the alent metal ions studied with [22]- to [26]-py2N4 were found in solution. The stability constants for the ML complexes of the three ligands follow the Irving-Williams order: NiL2+ > ZnL2+ > PbL2+, however for the dinuclear complexes the values for Pb2+ complexes are higher than the corresponding values for the Ni2+ and the Zn2+ complexes. The X-ray single crystal structures of the supramolecular aggregates [Cu2([20]py2N4)(H2O)4][Cu(H2O)6](SO4)3 x 3H2O and [Cu(2)([20]py(2)N4)(CH3CN)4][Ni([20]py2N4)]2(ClO4)8 x H2O, which are composed of homodinuclear [Cu2([20]py2N4])(H2O)4]4+ and [Cu2([20]py2N4])(CH3CN))4]4+, and mononuclear species, [Cu(H2O)6]2+ and [Ni([20]py2N4)]2+, respectively, assembled by an extensive network of hydrogen bonds, are also reported. In both homodinuclear complexes the copper centres are located at the end of the macrocycle and display distorted square pyramidal coordination environments with the basal plane defined by three consecutive nitrogen donors and one solvent molecule, water in and acetonitrile in . The macrocycle adopts a concertina-type conformation leading to the formation of macrocyclic cavities with the two copper centres separated by intramolecular distances of 5.526(1) and 5.508(7) A in 1a and 2a, respectively. The mononuclear complex [Ni([20]py2N4])]2+ displays a distorted octahedral co-ordination environment with the macrocycle wrapping the metal centre in a helical shape. EPR spectroscopy of the copper complexes indicated the presence of mono- and dinuclear species.
Publisher: Elsevier BV
Date: 03-2022
Publisher: American Chemical Society (ACS)
Date: 08-08-2016
DOI: 10.1021/ACS.ORGLETT.6B01842
Abstract: Two new twisted cucurbiturils, cucurbit[13]uril (tQ[13]) and cucurbit[15]uril (tQ[15]), have been synthesized and separated, and their structures have been confirmed by NMR spectroscopy and MALDI-TOF mass spectrometry together with the X-ray structures of two new complexes, {Dy(H2O)4Cd(H2O)4tQ[13]}·2.5[CdCl4]·65H2O and {Cd0.5(H2O)2tQ[15]}·[CdCl4]·47H2O. tQ[15] is the largest cucurbit[n]uril (Q[n]) in the Q[n] family reported to date. The X-ray diffraction studies of both complexes indicated that these large tQ[n]s effectively exhibit two different cavities-a central cavity and two side cavities. Preliminary host-guest behavior by each of the new systems was investigated by NMR studies.
Publisher: American Chemical Society (ACS)
Date: 11-06-2021
Publisher: The Royal Society of Chemistry
Date: 04-09-2013
DOI: 10.1039/9781849737821-00260
Abstract: Deoxyribonucleic acid is generally accepted as the primary biomolecular target of the first platinum-based chemotherapeutic agent, cisplatin, which was documented in 1845, characterised in 1893 and its potential discovered in 1965. Initial attempts to understand the structural significance of the compound by combinatorial means saw early conceptions of structure–activity relationships that were soon challenged. Almost 50 years and thousands of complexes later, DNA still remains the primary target in a variety of interactions ranging from differences in base-pair preference, irreversible covalent binding, and reversible minor/major groove binding and intercalation. Developmental efforts have seen active cytotoxic platinum complexes with structures derived beyond initial assumptions through a ersity of ligand substitution and multinuclear linkages. Nonetheless nephrotoxicity and neurotoxicity pose as dire inherent side-effects in clinical trials and application of platinum therapeutics. Subsequent development has called for means to avoid diminished efficacy due to inactivation by endogenous glutathione and other complex-binding or chelating proteins. Platinum(IV) derivatives may solve issues of unintended toxicity by means of intrinsic extracellular stability, degrading to their active platinum(II) forms once internalised within a cytosol and in acidic tumour environments. Selectivity may also be gained by the axial/apical coordination of ligands that typically bind to receptors that are overexpressed in certain tumours, such as modified-estrogen ligands. The development of platinum complexes has required an in-depth understanding of their DNA-binding interactions in order to facilitate further structural modification without loss of effective function for their eventual application as chemotherapeutics. Although platinum complexes are the focus of this chapter, some other metal complexes that interact with nucleic acids, such as ruthenium, iridium, osmium, iron, copper, titanium, vanadium gold and silver, are discussed.
Publisher: International Union of Crystallography (IUCr)
Date: 21-06-2006
DOI: 10.1107/S1600536806022331
Abstract: In the title compound, C 13 H 8 Cl 2 N 4 O 4 , the dinitrophenylhydrazone and benzene ring planes are nearly coplanar, making a dihedral angle of 3.39 (9)°. There is an intramolecular N—H...O interaction and weak intermolecular C—H...O hydrogen-bonding interactions which stabilize the packing.
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.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2TC04998H
Abstract: Scan rate dependent spin crossover behaviour is investigated in a new Fe( ii ) dinuclear triple helicate. Slow cooling allows relaxation to a densely packed state, while fast cooling traps the structure in a sparsely packed state.
Publisher: Informa UK Limited
Date: 2008
Publisher: Informa UK Limited
Date: 12-2006
Publisher: American Chemical Society (ACS)
Date: 09-01-2020
DOI: 10.1021/ACS.INORGCHEM.9B02995
Abstract: A trend between the degree of steric congestion of the Fe(II) coordination environment and the extent of spin transition (percentage completeness) has been observed in a series of halide salts of a dinuclear triple helicate architecture with the general form [Fe
Publisher: Springer Science and Business Media LLC
Date: 21-04-2008
Publisher: Informa UK Limited
Date: 08-2006
Publisher: American Chemical Society (ACS)
Date: 18-05-2009
DOI: 10.1021/JO9005798
Abstract: A macrobicycle formed by a tetraoxadiaza macrocycle containing a dibenzofuran (DBF) spacer and an isophthalamide head unit, named DBF-bz, was used as receptor for anion recognition. The molecular structure of DBF-bz was established in solution by NMR and ESI-MS spectroscopies and in single crystal by X-ray diffraction analysis. The X-ray structure showed a water molecule encapsulated into the macrobicyclic cavity by four hydrogen bonds, two of them involving the two N-H amide binding sites and the oxygen of the water molecule (N-H...O hydrogen bonds) and the other two (O-H...N) involving the amine groups as hydrogen bonding acceptors. (1)H NMR temperature dependence studies demonstrated that the same structure exists in solution. The ability of this ditopic receptor to recognize alkali halide salts was evaluated by extraction studies followed by (1)H NMR and ESI-MS spectroscopies. The macrobicycle showed a capacity to extract halide salts from aqueous solutions into organic phases. The binding ability of this macrobicycle for halides was also quantitatively investigated using (1)H NMR titrations in CDCl(3) (and DMSO-d(6)) solution, and in acidic D(2)O solution. The largest binding association constant was found for the chloride anion and the completely protonated receptor. The results suggest that the diammonium-diamide unit of the receptor strongly bind the anionic substrate via multiple N-H...Cl(-) hydrogen bonds and electrostatic interactions. The binding trend follows the order Cl(-) > Br(-) > I(-) approximately F(-) established from the best fit between the size of the anion and the cavity size of the protonated macrobicycle. Molecular dynamics (MD) simulations of the DBF-bz in CHCl(3) solution allowed a detailed insight into the structural and binding properties of the receptor.
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 05-2015
Publisher: MDPI AG
Date: 26-05-2022
Abstract: Polynuclear heterobimetallic coordination cages in which different metal cations are connected within a ligand scaffold are known to adopt a variety of polyhedral architectures, many of which display interesting functions. Within the extensive array of coordination cages incorporating Fe(II) centres reported so far, the majority contain low-spin (LS) Fe(II), with high-spin (HS) Fe(II) being less common. Herein, we present the synthesis and characterisation of a new tetradecanuclear heterobimetallic [Fe8Pd6L8](BF4]28 (1) cubic cage utilising the metalloligand approach. Use of the tripodal tris-imidazolimine derivative (2) permitted the formation of the tripodal HS Fe(II) metalloligand [FeL](BF4)2·CH3OH (3) that was subsequently used to form the coordination cage 1. Magnetic and structural analyses gave insight into the manner in which the HS environment of the metalloligand was transferred into the cage architecture along with the structural changes that accompanied its occupancy of the eight corners of the discrete cubic structure.
Publisher: MDPI AG
Date: 05-10-2022
DOI: 10.3390/MOLECULES27196592
Abstract: Inspired by ethnopharmacological knowledge, we conducted a bioassay-guided fractionation of the leaves of Tristaniopsis laurina which led to the discovery of a new anti-inflammatory compound, tristaenone A (1). The structure was elucidated by detailed spectroscopic data analysis, and the absolute configuration was established using X-ray crystallography analysis. Tristaenone A (1) suppressed LPS and IFN-γ-induced NO, TNF-α and IL-6 production in RAW 264.7 cells with IC50 values of 37.58 ± 2.45 μM, 80.6 ± 5.82 μM and 125.65 ± 0.34 μM, respectively. It also inhibited NF-κB nuclear translocation by 52.93 ± 14.14% at a concentration of 31.85 μM.
Publisher: American Chemical Society (ACS)
Date: 18-05-2018
DOI: 10.1021/ACS.INORGCHEM.8B00576
Abstract: This study presents a new mononuclear complex (1) of the form [FeL](BF
Publisher: Springer Science and Business Media LLC
Date: 08-05-2015
Publisher: Wiley
Date: 11-2005
Abstract: The host–guest binding interactions of the hexaazamacrocycle [26]py 2 N 4 , in its tetraprotonated form H 4 [26]py 2 N 4 4+ as well as in its dicopper( II ) complex [Cu 2 ([26]py 2 N 4 )(H 2 O) 4 ] 4+ , with dicarboxylate anions of different stereoelectronicrequirements, such as oxalate (ox 2– ), malonate (mal 2– ), succinate (suc 2– ), fumarate (fu 2– ) and maleate (ma 2– ), were evaluated. The association constants were determined using potentiometric methods in aqueous solution, at 298.0 K and 0.10 mol · dm –3 KCl. These values for the tetraprotonated ditopic receptor with the dicarboxylate anions revealed that the main species in solution corresponds to the formation of {H 4 [26]py 2 N 4 (A)} 2+ (pH ≈ 4–9), A being the substrate anion. The values determined are not especially high, but the receptor exhibits selectivity for the malonate anion. The study of the cascade complexes revealed several species in solution, involving mononuclear and dinuclear complexes, mainly protonated and hydrolysed species, as well as the expected complexes [Cu 2 ([26]py 2 N 4 )(A)(H 2 O) x ] 2+ or [Cu 2 ([26]py 2 N 4 )(A) 2 (H 2 O) y ]. Ox 2– and mal 2– form cascade complexes with only one anion, which will necessarily bridge the two copper atoms because of the symmetrical arrangement of the dinuclear complex. The two other studied anions, suc 2– and ma 2– , form species involving two substrate anions, although species with only one suc 2– anion were also found. UV/Vis and EPR spectroscopy have shown that the dicopper complex can operate as a sensor to detect and quantitatively determine oxalate spectrophotometrically because of the red shift of the maximum of the visible band observed by addition of ox 2– to an aqueous solution of the dinuclear copper complex. However the selectivity of [Cu 2 ([26]py 2 N 4 )(H 2 O) 4 ] 4+ as a receptor for ox 2– in the studied series is not sufficiently high to detect ox 2– spectrophotometrically in the presence of the other anions. Molecular dynamics simulations indicated that the H 4 [26]py 2 N 4 4+ receptor provides a large and flexible cavity to accommodate the studied anions. Molecular recognition is based in electrostatic interactions rather than in multiple hydrogen‐bonding interactions acting cooperatively. By contrast, the [Cu 2 ([26]py 2 N 4 )] 4+ receptor has a well‐shaped cavity with adequate size to uptake these anions as bridging ligands with formation of four Cu–O bonds. The ox 2– anion is encapsulated within the cascade complex while the remaining anions are located above the N 6 macrocyclic plane, suggesting a selective coordination behaviour of this receptor. In spite of our molecular simulation being carried out in gas phase, the modelling results are consistent with the solution studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
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.
Publisher: Springer Science and Business Media LLC
Date: 07-11-2018
Publisher: Elsevier BV
Date: 02-2015
Publisher: Wiley
Date: 09-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3DT51531A
Abstract: The sequential interaction of preformed [Cu2(L1)2(THF)2] (where H2L1 is 1,1-(1,3-phenylene)-bis(4,4-dimethylpentane-1,3-dione incorporating a 1,3-phenylene linker between its two β-diketone domains) and [Cu2(L4)2]·2H2O (where H2L4 is 1,1-(4,4′-oxybiphenylene)-bis(4,4-dimethylpentane-1,3-dione) incorporating a flexible oxybiphenylene linkage between the two β-diketone groups) with the potentially difunctional aliphatic non-planar co-ligands, N-methylpiperazine (mpip), N,N′-dimethylpiperazine (dmpip) and 1,4-thiomorpholine (thiomorph) is reported. A series of extended molecular assemblies exhibiting a range of di- and tetranuclear assemblies were obtained and their X-ray structures determined. Dinuclear [Cu2(L1)2(mpip)2]·2mpip incorporates two 5-coordinate, square pyramidal metal centres as does tetranuclear [{Cu2(L1)2}2(dmpip)2]·2dmpip. In contrast, dinuclear [Cu2(L1)2(dmpip)4]·dmpip and [{Cu2(L1)2}2(thiomorph)4]·3thiomorph each contain two 5-coordinate and two 6-coordinate centres. Each of [Cu2(L4)2(THF)2]·2THF and Cu2(L4)2(mpip)2]·H2O incorporate only 5-coordinate metal centres, with the latter complex forming a one-dimensional hydrogen bonded ribbon-like structure directed along the crystallographic a-axis. In keeping with the documented tendency for the smallest, least strained assembly to form in supramolecular self-assembly processes, the incorporation of the flexible “oxy” linkage between the 4,4′-linked phenylene rings of H2L3 results in generation of a dinuclear [Cu2L2] species rather than a trinuclear (triangular) [Cu3L3] species of the type formed by the more rigid bis-β-diketonato ligand analogue in which the biphenylene rings separating the β-diketone domains are directly coupled in their 4,4′ positions.
Publisher: Elsevier BV
Date: 11-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7DT02556D
Abstract: The neutral complexes of type [EuL], [GdL] and [DyL] incorporating a heptadentate tripodal ligand were synthesized and their optical and magnetic properties have been investigated.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1DT10523J
Abstract: The synthesis and characterisation of four 17-membered, dibenzo-substituted macrocyclic ligands incorporating unsymmetrical arrangements of their N(3)S(2), N(3)O(2) and N(3)OS (two ligands) donor atoms are described these rings complete the matrix of related macrocyclic systems incorporating both symmetric and unsymmetric donor sets reported previously. The X-ray structures of three of the new macrocycles are reported. In two of the Cu(II) structures only three of the possible five donor atoms present in the corresponding macrocyclic ligand bind to the Cu(II) site, whereas all five donors are coordinated in each of the remaining complexes. The interaction of Co(II), Ni(II) and Cu(II) with the unsymmetric macrocycle series has been investigated by potentiometric (pH) titration in 95% methanol X-ray structures of two nickel and three copper complexes of these ligands, each exhibiting 1:1 (M:L) ratios, have been obtained. The results are discussed in the context of previous results for these metals with the analogous 17-membered ring systems incorporating symmetrical arrangements of their donor atoms, with emphasis being given to both the influence of the donor atom set, as well as the donor atom sequence, on the nature of the resulting complexes.
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.ENVINT.2017.08.005
Abstract: The last few decades have seen the rise of alternative medical approaches including the use of herbal supplements, natural products, and traditional medicines, which are collectively known as 'Complementary medicines'. However, there are increasing concerns on the safety and health benefits of these medicines. One of the main hazards with the use of complementary medicines is the presence of heavy metal(loid)s such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). This review deals with the characteristics of complementary medicines in terms of heavy metal(loid)s sources, distribution, bioavailability, toxicity, and human risk assessment. The heavy metal(loid)s in these medicines are derived from uptake by medicinal plants, cross-contamination during processing, and therapeutic input of metal(loid)s. This paper discusses the distribution of heavy metal(loid)s in these medicines, in terms of their nature, concentration, and speciation. The importance of determining bioavailability towards human health risk assessment was emphasized by the need to estimate daily intake of heavy metal(loid)s in complementary medicines. The review ends with selected case studies of heavy metal(loid) toxicity from complementary medicines with specific reference to As, Cd, Pb, and Hg. The future research opportunities mentioned in the conclusion of review will help researchers to explore new avenues, methodologies, and approaches to the issue of heavy metal(loid)s in complementary medicines, thereby generating new regulations and proposing fresh approach towards safe use of these medicines.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA01272D
Abstract: Two uranium( vi ) complexes with isonicotinic acid, exhibiting a monomer and a 2D polymer, have been synthesized and characterized.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6DT01651K
Abstract: A unique, slightly distorted square prismatic, box-like coordination cage of type [Cu 6 Dy 8 L 8 (MeOH) 8 (H 2 O) 6 ](NO 3 ) 12 · χ solvent has been synthesized via the supramolecular assembly between a non-centrosymmetric Dy( iii ) metalloligand and Cu( ii ) nitrate.
Publisher: American Chemical Society (ACS)
Date: 13-04-2021
Publisher: Elsevier BV
Date: 12-2015
Publisher: Springer Science and Business Media LLC
Date: 03-05-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CC03708G
Abstract: The largest reported dinuclear Fe( ii ) triple helicate system to exhibit spin crossover is presented, with exploration of the two-step spin-transition.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7DT04190J
Abstract: VT-XPS shows that the spin behaviour is reversible between the HS and LS states in a new dinuclear helicate iron( ii ) complex.
Publisher: Elsevier BV
Date: 2013
Publisher: Wiley
Date: 24-02-2011
Publisher: The Chemical Society of Japan
Date: 15-01-2021
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.
Publisher: Wiley
Date: 07-08-2015
Publisher: American Chemical Society (ACS)
Date: 10-07-2017
Publisher: MDPI AG
Date: 07-11-2022
Abstract: The design of new metallocage polyhedra towards pre-determined structures can offer both practical as well as intellectual challenges. In this mini-review we discuss a selection of recent ex les in which the use of the metalloligand approach has been employed to overcome such challenges. An attractive feature of this approach is its stepwise nature that lends itself to the design and rational synthesis of heterometallic metal–organic cages, with the latter often associated with enhanced functionality.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC11167A
Abstract: A large 4,4'-biphenylene-spaced bis-β-diketone ligand is demonstrated to form a neutral tetrahedral M(4)L(6) metal-organic cage that encloses a volume of 844 Å(3) and encapsulates four tetrahydrofuran guest molecules.
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B609937H
Abstract: The binding properties of dioxadiaza- ([17](DBF)N2O2) and trioxadiaza- ([22](DBF)N2O3), macrocyclic ligands containing a rigid dibenzofuran group (DBF), to metal cations and structural studies of their metal complexes have been carried out. The protonation constants of these two ligands and the stability constants of their complexes with Ca2+, Ba2+, and Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and Cd2+, were determined at 298.2 K in methanol-water (1:1, v/v), and at ionic strength 0.10 mol dm-3 in KNO3. The values of the protonation constants of both ligands are similar, indicating that no cavity size effect is observed. Only mononuclear complexes of these ligands with the alent metal ions studied were found, and their stability constants are lower than expected, especially for the complexes of the macrocycle with smaller cavity size. However, the Cd2+ complex with [17](DBF)N2O2 exhibits the highest value of stability constant for the whole series of metal ions studied, indicating that this ligand reveals a remarkable selectivity for cadmium(II) in the presence of all the metal ions studied, except copper(II), indicating that this ligand reveals a remarkable selectivity for cadmium(II) in the presence of the mentioned metal ions. The crystal structures of H2[17](DBF)N2O3(2+) (diprotonated form of the ligand) and of its cadmium complex were determined by X-ray diffraction. The Cd2+ ion fits exactly inside the macrocyclic cavity exhibiting coordination number eight by coordination to all the donor atoms of the ligand, and additionally to two oxygen atoms from one nitrate anion and one oxygen atom from a water molecule. The nickel(II) and copper(II) complexes with the two ligands were further studied by UV-vis-NIR and the copper(II) complexes also by EPR spectroscopic techniques in solution indicating square-pyramidal structures and suggesting that only one nitrogen and oxygen donors of the ligands are bound to the metal. However an additional weak interaction of the second nitrogen cannot be ruled out.
Publisher: Elsevier BV
Date: 02-1111
Publisher: Springer Science and Business Media LLC
Date: 03-04-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5QI00200A
Abstract: Five new complexes of a julolidine–quinoline based ligand with 3d transition metals have been synthesised and structurally characterised.
Publisher: Elsevier BV
Date: 12-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9DT01947B
Abstract: The self-assembly of a mixed-spin [Fe
Publisher: Elsevier BV
Date: 09-2013
Publisher: Informa UK Limited
Date: 23-05-2012
Publisher: American Chemical Society (ACS)
Date: 07-10-2022
DOI: 10.26434/CHEMRXIV-2022-L8T6W
Abstract: The assembly of multifunctional polynuclear coordination cages exhibiting spin-crossover (SCO) proves to be a challenge to researchers. Previous investigations into the magnetic properties of a large cubic metallosupramolecular cage, [Fe8Pd6L8]28+, constructed using semi-rigid metalloligands and encompassing an internal void of 41 Å3, found that the Fe(II) centres that occupied the corners of the cubic structure did not undergo a spin-transition. In this work, substitution of the linker metal on the face of the cage resulted in the onset of spin crossover, as evidenced by magnetic susceptibility, Mӧssbauer and single crystal X-ray diffraction. Structural comparisons of these two cages were undertaken to shed light on the possible mechanism responsible for switching of the [Fe8M(II)6L8]28+ architecture from SCO inactive to active by simply changing in the identity of M(II). This led to the suggestion that a possible interplay of intra- and intermolecular interactions may permit SCO in the Ni(II) analogue, 1. The distorted octahedral coordination environment of the secondary Ni(II) centres occupying the cage faces provided conformational flexibility for the eight metalloligands of the cubic architecture relative to the square planar Pd(II) environment. Meanwhile the occupation of axial coordination sites of the Ni(II) cations by CH3CN prevented the close packing of cages observed for the Pd(II) analogue, leading to a more offset, distant packing arrangement of cages in the lattice, whereby important areas of the cage that were shown to change most dramatically with SCO experienced a lesser degree of steric hindrance to conformational changes upon SCO. Design through selectivity of secondary metal centres on the flexibility of metalloligand structures and the effect of axial donors packing arrangements may serve as new routes in the engineering of SCO or non-SCO cage systems.
Publisher: Informa UK Limited
Date: 13-06-2016
Publisher: Informa UK Limited
Date: 09-2006
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.
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B617704B
Abstract: New dioxadiaza- and trioxadiaza-macrocycles containing one rigid dibenzofuran unit (DBF) and N-(2-aminoethyl) pendant arms were synthesized, N,N'-bis(2-aminoethyl)-[17](DBF)N(2)O(2) (L(1)) and N,N'-bis(2-aminoethyl)-[22](DBF)N(2)O(3) (L(2)), respectively. The binding properties of both macrocycles to metal ions and structural studies of their metal complexes were carried out. The protonation constants of both compounds and the stability constants of their complexes with Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), and Pb(2+) were determined at 298.2 K, in aqueous solutions, and at ionic strength 0.10 mol dm(-3) in KNO(3). Mononuclear complexes with both ligands were formed, and dinuclear complexes were only found for L(2). The thermodynamic binding affinities of the metal complexes of L(2) are lower than those of L(1) as expected, but the Pb(2+) complexes of both macrocycles exhibit close stability constant values. On the other hand, the binding affinities of Cd(2+) and Pb(2+) for L(1) are very high, when compared to those of Co(2+), Ni(2+) and Zn(2+). These interesting properties were explained by the presence of the rigid DBF moiety in the backbone of the macrocycle and to the special match between the macrocyclic cavity size and the studied larger metal ions. To elucidate the adopted structures of complexes in solution, the nickel(II) and copper(II) complexes with both ligands were further studied by UV-vis-NIR spectroscopy in DMSO-H(2)O 1 : 1 (v/v) solution. The copper(II) complexes were also studied by EPR spectroscopy in the same mixture of solvents. The crystal structure of the copper complex of L(1) was also determined. The copper(II) displays an octahedral geometry, the four nitrogen atoms forming the equatorial plane and two oxygen atoms, one from the DBF unit and the other one from the ether oxygen, in axial positions. One of the ether oxygens of the macrocycle is out of the coordination sphere. Our results led us to suggest that this geometry is also adopted by the Co(2+) to Zn(2+) complexes, and only the larger Cd(2+) and Pb(2+) manage to form complexes with the involvement of all the oxygen atoms of the macrocyclic backbone.
Publisher: Springer Science and Business Media LLC
Date: 05-08-2011
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.JINORGBIO.2016.06.017
Abstract: Six platinum(II) complexes of the type [Pt(P
Publisher: Springer Science and Business Media LLC
Date: 06-05-2015
Publisher: Elsevier BV
Date: 05-2015
Publisher: Elsevier BV
Date: 09-2006
Publisher: Springer Science and Business Media LLC
Date: 08-03-2023
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/CH19279
Abstract: The use of metalloligands as building blocks for the assembly of metallo-organic cages has received increasing attention over the past two decades or so. In part, the popularity of this approach reflects its stepwise nature that lends itself to the predesigned construction of metallocages and especially heteronuclear metallocages. The focus of the present discussion is on the use of metalloligands for the construction of discrete polyhedral cages, very often incorporating heterometal ions as structural elements. The metalloligand approach uses metal-bound multifunctional ligand building blocks that display predesigned structural properties for coordination to a second metal ion such that the rational design and construction of both homo- and heteronuclear metal–organic cages are facilitated. The present review covers published literature in the area from early 2015 to early 2019.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2011
DOI: 10.1038/NCOMMS1208
Abstract: In the realm of supramolecular chemistry, a small number of intricately interwoven structures that bridge the boundaries between art and science have been reported. These motifs, which typically form on the nanometre scale, display both considerable beauty and complexity. However, the generation of new topologies of this type has remained a very significant synthetic challenge. Here, we describe the synthesis of a discrete highly intertwined metallosupramolecular assembly based on a universal 3-ravel motif-a topology as yet unprecedented in supramolecular chemistry. The exotic, 20-component, [Fe(8)L(12)] ravel entanglement may be considered as a 'branched knot', with in idual molecules displaying either left- or right-handed chirality. The formation of this cluster was demonstrated by single-crystal and powder X-ray diffraction. The arrangement is stabilized by a favourable combination of π-π interactions and Nature's tendency to minimize voids in molecular architectures.
Publisher: American Chemical Society (ACS)
Date: 11-01-2023
Publisher: Wiley
Date: 06-10-2015
Abstract: We have developed six dihydroxidoplatinum(IV) compounds with cytotoxic potential. Each derived from active platinum(II) species, these complexes consist of a heterocyclic ligand (HL) and ancillary ligand (AL) in the form [Pt(HL)(AL)(OH)2](2+), where HL is a methyl-functionalised variant of 1,10-phenanthroline and AL is the S,S or R,R isomer of 1,2-diaminocyclohexane. NMR characterisation and X-ray diffraction studies clearly confirmed the coordination geometry of the octahedral platinum(IV) complexes. The self-stacking of these complexes was determined using pulsed gradient stimulated echo nuclear magnetic resonance. The self-association behaviour of square planar platinum(II) complexes is largely dependent on concentration, whereas platinum(IV) complexes do not aggregate under the same conditions, possibly due to the presence of axial ligands. The cytotoxicity of the most active complex, exhibited in several cell lines, has been retained in the platinum(IV) form.
Publisher: Wiley
Date: 12-09-2011
Publisher: Wiley
Date: 24-02-2011
Publisher: CRC Press
Date: 09-12-2013
DOI: 10.1201/B16198
Publisher: MDPI AG
Date: 25-02-2023
DOI: 10.3390/MOLECULES28052160
Abstract: Our in-house ethnopharmacological knowledge directed our anti-inflammatory investigation into the leaves of Backhousia mytifolia. Bioassay guided isolation of the Australian indigenous plant Backhousia myrtifolia led to the isolation of six new rare peltogynoid derivatives named myrtinols A–F (1–6) along with three known compounds 4-O-methylcedrusin (7), 7-O-methylcedrusin (8) and 8-demethylsideroxylin (9). The chemical structures of all the compounds were elucidated by detailed spectroscopic data analysis, and absolute configuration was established using X-ray crystallography analysis. All compounds were evaluated for their anti-inflammatory activity by assessing the inhibition of nitric oxide (NO) production and tumor necrosis factor- α (TNF-α) in lipopolysaccharide (LPS) and interferon (IFN)-γ activated RAW 264.7 macrophages. A structure activity relationship was also established between compounds (1–6), noting promising anti-inflammatory potential by compounds 5 and 9 with an IC50 value of 8.51 ± 0.47 and 8.30 ± 0.96 µg/mL for NO inhibition and 17.21 ± 0.22 and 46.79 ± 5.87 µg/mL for TNF-α inhibition, respectively.
Publisher: MDPI AG
Date: 23-09-2018
DOI: 10.3390/CRYST8100376
Abstract: This work explores the effect of lattice solvent on the observed solid-state spin-transition of a previously reported dinuclear Fe(II) triple helicate series 1–3 of the general form [FeII2L3](BF4)4(CH3CN)n, where L is the Schiff base condensation product of imidazole-4-carbaldehyde with 4,4-diaminodiphenylmethane (L1), 4,4′-diaminodiphenyl sulfide (L2) and 4,4′-diaminodiphenyl ether (L3) respectively, and 1 is the complex when L = L1, 2 when L = L2 and 3 when L = L3 (Craze, A.R. Sciortino, N.F. Bhadbhade, M.M. Kepert, C.J. Marjo, C.E. Li, F. Investigation of the Spin Crossover Properties of Three Dinuclear Fe(II) Triple Helicates by Variation of the Steric Nature of the Ligand Type. Inorganics. 2017, 5 (4), 62). Desolvation of 1 and 2 during measurement resulted not only in a decrease in T1/2 and completeness of spin-crossover (SCO) but also a change in the number of steps in the spin-profile. Compounds 1 and 2 were observed to change from a two-step 70% complete transition when fully solvated, to a single-step half complete transition upon desolvation. The average T1/2 value of the two-steps in the solvated materials was equivalent to the single T1/2 of the desolvated s le. Upon solvent loss, the magnetic profile of 3 experienced a transformation from a gradual SCO or weak antiferromagnetic interaction to a single half-complete spin-transition. Variable temperature single-crystal structures are presented and the effects of solvent molecules are also explored crystallographically and via a Hirshfeld surface analysis. The spin-transition profiles of 1–3 may provide further insight into previous discrepancies in dinuclear triple helicate SCO research reported by the laboratories of Hannon and Gütlich on analogous systems (Tuna, F. Lees, M. R. Clarkson, G. J. Hannon, M. J. Readily Prepared Metallo-Supramolecular Triple Helicates Designed to Exhibit Spin-Crossover Behaviour. Chem. Eur. J. 2004, 10, 5737–5750 and Garcia, Y. Grunert, C. M. Reiman, S. van C enhoudt, O. Gütlich, P. The Two-Step Spin Conversion in a Supramolecular Triple Helicate Dinuclear Iron(II) Complex Studied by Mössbauer Spectroscopy. Eur. J. Inorg. Chem. 2006, 3333–3339).
Publisher: Wiley
Date: 09-2009
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TC00991J
Abstract: A large iron( ii ) tetrahedral cage displays temperature induced spin-crossover and liesst effects.
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.CHEMOSPHERE.2019.124664
Abstract: Chemosensors have already demonstrated potential for the detection and imaging of metal ions in solutions and biological systems, however, their applications to soil analysis are limited. This study explores the potential of utilizing a chemosensor for the detection of exchangeable Cu
Publisher: MDPI AG
Date: 02-2023
DOI: 10.3390/MOLECULES28031404
Abstract: We present five new dinuclear triple helicate compounds of types [Mn2L3](ClO4)4, [Co2L3](BF4)4, [Ni2L3](BF4)4, [Cu2L3](BF4)4, and [Zn2L3](BF4)4, where L is a previously reported semi-rigid ligand incorporating two α-diimine primary donor groups and two secondary 4-pyridyl donor groups. All complexes have been characterized in both solution and the solid state. Single crystal X-ray diffraction studies were used to probe the variation in the respective helical structures as the coordinated metal ion was altered, including the effect on the orientations of the secondary binding domains. The influence of the metal ion size, the spin state in the case of Fe(II), and the presence of Jahn-Teller distortions on the overall helical structure has been investigated. These results form a basis for the design and construction of new large metallosupramolecular architectures which manifest properties associated with the constituent helical metalloligand units.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1DT03446D
Abstract: X-ray Photoelectron Spectroscopy (XPS) has emerged as a complementary technique for the analysis of spin-crossover in the surface layers of a material.
Publisher: American Chemical Society (ACS)
Date: 04-09-2018
Publisher: American Chemical Society (ACS)
Date: 17-10-2022
DOI: 10.26434/CHEMRXIV-2022-4HW9H
Abstract: The achievement of targeted properties in spin crossover (SCO) materials is complicated by often unpredictable cooperative interactions in the solid state. Herein, we report a dinuclear Fe(II) triple helicate 1, which is a rare ex le of a SCO material possessing two distinct magnetic behaviors that depend upon the thermal scan rate. Desolvated 1 was seen to undergo spin transition (ST) which was complete following slow cooling (1 K min-1), but incomplete ST (corresponding to 50% conversion) on fast cooling (10 K min-1). The incomplete ST observed in the latter case was accompanied by a higher temperature onset of ST, differing from TIESST (Temperature-Induced Excited Spin-State Trapping) materials. The two SCO pathways have been shown to arise from the interconversion between two structural phases (a and b), with both phases having associated high spin (HS) and low spin (LS) states. SCXRD (Single Crystal X-ray Diffraction) experiments using controlled cooling rates and a synchrotron light source enabled short collection times (2-3 minutes per dataset) which has enabled the identification of a mechanism by which the slow-cooled material may fully relax. In contrast, fast-cooled materials exhibit disordered arrangements of multiple structural phases, which has in turn revealed that the [HS-LS] ↔ [LS-HS] equilibria are controllable in the solid by varying the scan rate. Such behavior has been previously observed in solution studies, but its control in solids has not been reported up to now. This study demonstrates how intermolecular cooperativity can allow multiple distinct magnetic behaviors, and provides some insight into how [HS-LS] ↔ [LS-HS] equilibria can be controlled in the solid state, which may assist in the design of next-generation logic and signaling devices.
Publisher: Informa UK Limited
Date: 05-2007
No related grants have been discovered for Feng Li.