ORCID Profile
0000-0002-3046-2017
Current Organisation
Macquarie University
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Nanomanufacturing | Nanomaterials | Analytical Chemistry | Nanotechnology | Organic Chemical Synthesis | Photodetectors, Optical Sensors and Solar Cells | Analytical Spectrometry | Materials Engineering | Microtechnology | Biologically Active Molecules | Organic Semiconductors | Structural Chemistry and Spectroscopy |
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in the Chemical Sciences | Scientific Instruments | Expanding Knowledge in Engineering | Expanding Knowledge in the Biological Sciences | Environmentally Sustainable Manufacturing not elsewhere classified | Expanding Knowledge in Technology
Publisher: Elsevier BV
Date: 11-2021
Publisher: American Chemical Society (ACS)
Date: 15-11-2010
DOI: 10.1021/OM100702X
Publisher: American Chemical Society (ACS)
Date: 22-06-2018
DOI: 10.1021/ACS.INORGCHEM.8B00564
Abstract: C^C cyclometalated platinum(II) triplet emitters bearing electronically different N-heterocyclic carbenes-(1,3-diisopropyl-4-(trifluoromethyl)-imidazol-2-ylidene (d), 1,3-diisopropyl-benzimidazol-2-ylidene (e), and 1,3-diisopropyl-imidazol-2-ylidene (f))-as neutral ligands and biphenyl (bph) as well as its fluorinated derivative octafluorobiphenyl (oFbph) as dianionic cyclometalating ancillary ligand were synthesized and structurally characterized by
Publisher: American Chemical Society (ACS)
Date: 21-07-2021
Publisher: American Chemical Society (ACS)
Date: 14-01-2015
DOI: 10.1021/OM500602M
Publisher: OSA
Date: 2016
Publisher: American Chemical Society (ACS)
Date: 18-01-2011
DOI: 10.1021/IC101632V
Abstract: A series of luminescent N-heterocyclic carbene platinum(II) complexes, [(pmim)Pt(C≡C-R)(2)] (R = C(6)H(5) (2), C(6)H(4)OMe (3), C(6)H(2)(OMe)(3) (4), C(6)H(4)NMe(2) (5), C(4)H(3)S (6), C(6)H(4)C≡CC(6)H(5) (7), 1-pyrenyl (8), and C(6)H(4)F (9)), were successfully synthesized using the precursor (pmim)PtI(2), 1 (pmim = 1,1'-dipentyl-3,3'-methylene-diimidazoline-2,2'-diylidene). The X-ray crystal structures of 1, 4, 5, and 7 have been determined. These complexes showed long-lived emission in solution at room temperature. The emission origin of the complexes is tentatively assigned to be from triplet states of predominantly intraligand (IL) character with some mixing of metal-to-ligand charge-transfer (MLCT) character. TD-DFT and DFT calculations have been performed on most of the complexes to ascertain the nature of the excited state. Changes in the alkynyl ligands lead to a change in the absorption and emission maxima seen for these complexes in a potentially predictable way.
Publisher: American Chemical Society (ACS)
Date: 10-02-2010
DOI: 10.1021/JA909764X
Abstract: The dinuclear tungsten carbyne [X(CO)(2)(dppe)WC(4)W(dppe)(CO)(2)X] (dppe = 1,2-bis(diphenylphosphino)ethane X = I (3), Cl (7)) complexes were prepared from the bisacetylide precursor Li(2)[(CO)(3)(dppe)WC(4)W(CO)(3)(dppe)] (2) via oxidative replacement of one CO group at each tungsten center with a halide substituent. The iodide ligand in 3 could be substituted with isothiocyanate or triflate resulting in [X(CO)(2)(dppe)WC(4)W(dppe)(CO)(2)X] complexes (X = NCS (8), OTf (9)). Substitution of two and all four CO ligands in 3 was achieved via subsequent photolytic or thermal activation with dppe. The "half-substituted" complex [I(CO)(2)(dppe)WC(4)W(dppe)(2)I] (11) allows reversible one-electron oxidation which results in the monocationic species [I(CO)(2)(dppe)WC(4)W(dppe)(2)I][PF(6)] (11[PF(6)]). The "all-dppe substituted" complex [I(dppe)(2)WC(4)W(dppe)(2)I] (10) possesses two reversible redox states leading to the stable monocationic [I(dppe)(2)WC(4)W(dppe)(2)I][PF(6)] (10[PF(6)]) and the dicationic [I(dppe)(2)WC(4)W(dppe)(2)I][PF(6)](2) (10[PF(6)](2)) compounds. The complexes 2, 3, [W(CO)(3)(dppe)(C[triple bond]CPh)(I)] (4), [X(CO)(2)(dppe)W[triple bond]C-C(Me)=C(Me)-C[triple bond]W(dppe)(CO)(2)X] (X = I (5), Cl (6)), 7, 8, 10, 11 and 11[PF(6)] were characterized by single crystal X-ray diffraction. The electronic properties of complexes 10, 10[PF(6)], 10[PF(6)](2), as well as of compounds 11 and 11[PF(6)], were investigated using cyclic voltammetry (CV), EPR, IR, near-IR spectroscopy, and magnetization measurements. These studies showed that the [W][triple bond]C-C[triple bond]C-C[triple bond][W] canonical form of the bridged system with strong tungsten-carbon interaction contributes significantly to the electronic coupling in the mixed-valent species 10[PF(6)] (comproportionation constant K(c) = 7.5 x 10(4)) and to the strong antiferromagnetic coupling in the dicationic complex 10[PF(6)](2) (exchange integral J = -167 cm(-1)). In addition, the rate for electron transfer between the tungsten centers in 10[PF(6)] was evaluated by near-IR and IR studies.
Publisher: Royal Society of Chemistry (RSC)
Date: 26-06-2014
DOI: 10.1039/C4DT01187B
Abstract: Stable, luminescent, and cationic monocyclometalated gold(iii) monoaryl complexes of the type [(ppy)Au(FMes)(L)](+)[OTf](-) [L = 4-phenylpyridine (), quinoline (), 4-fluoroaniline (), P(OMe)3 (), PPh3 ()], bearing different ancillary ligands, synthesized starting from the precursor complex [(ppy)Au(FMes)(OH2)](+)[OTf](-) () are reported. The preliminary assignment of the structure of the complexes by various nuclear magnetic resonance spectroscopy techniques and elemental analysis has been further corroborated by single-crystal X-ray diffraction studies. The complexes exhibit room temperature phosphorescence in solution, in neat solids and in doped PMMA films. Detailed photophysical investigations of the complexes in solution, in neat solids and in PMMA films revealed the successful tuning of the emission quantum yield (ϕp) based on the electronic properties of the ancillary ligands. The catalytic photo-oxidation of benzylic amines to their corresponding imines using molecular oxygen as the oxidant was successfully achieved in the presence of the luminescent Au(iii) complexes. It is also established that the photocatalytic performance was strongly governed by the electronic properties of the ancillary ligands on the photosensitizer as well as by the steric bulk of the substrates.
Publisher: Wiley
Date: 29-02-2012
Publisher: Wiley
Date: 05-2022
Abstract: Despite significant strides achieved in organic light emitting diode (OLED) based display technologies during the last decade, the search for highly stable and efficient true blue/deep blue emitters continues to remain elusive. During the past decade, emitters with the basic molecular scaffold consisting of Pt(II) acetylides and N‐heterocyclic carbene (NHC) ligands have opened interesting opportunities to tune the emission properties with desired chromaticity in the blue and deep blue region. With an aim to achieve the desired CIE coordinates along with low device roll‐off efficiencies and satisfactory color purity, a number of variations on the basic molecular fragment have been made. A number of NHC Pt(II) alkyne complexes bearing monodentate, bidentate and tridentate ligands have been synthesized and their photophysical investigations have been reported. Although NHC Pt(II) alkyne complexes have been explored in other areas of applications, much of the investigations have been primarily focused for their interesting emission properties appearing particularly in the shorter wavelength (450–495 nm) part of the electromagnetic spectrum for organic light emitting diode (OLED) devices. In this review, we provide an overview of the investigated NHC Pt(II) acetylide complexes by detailing their synthesis, luminescence properties, performance in devices and future perspectives.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B714291A
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC02703K
Abstract: A series of tethered dual catalysts were developed, with catalytic investigations demonstrating that tethering enhances photocatalysis and thermally activated Ir catalysis. In addition, sequential and switchable catalytic reactivity was achieved.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5DT04768D
Abstract: Dinuclear rhenium complexes with C 4 H 2 - or C 4 - bridges can show open or closed shell structures.
Publisher: American Chemical Society (ACS)
Date: 13-05-2010
DOI: 10.1021/JA102570F
Abstract: The organometallic conjugated complex H(C[triple bond]C)(2)[W][triple bond]CC[triple bond]CC[triple bond][W](C[triple bond]C)(2)H {[W] = W(dppe)(2) dppe = 1,2-bis(diphenylphosphino)ethane} containing a ditungstenatetradecaheptayne unit was synthesized by utilizing a new and efficient coupling method. The stannylated derivative was converted to the tetranuclear complex, which exhibits efficient long-range electron transfer.
Publisher: Wiley
Date: 23-08-2004
Publisher: Wiley
Date: 12-05-2014
Publisher: Wiley
Date: 03-2005
Publisher: American Chemical Society (ACS)
Date: 28-09-2023
Publisher: Wiley
Date: 07-2009
Abstract: The symmetric d 5 trans ‐bis‐alkynyl complexes {Mn[(Me) 2 P(CH 2 ) n P(Me) 2 ] 2 (C≡CC 6 H 4 R) 2 } ( n = 2, R = ‐C≡CTIPS ( 2a ) n = 3, R = ‐C≡CTIPS ( 2b ) n = 2, R = F ( 4 ) n = 3 ‐C≡CTIPS) were prepared by the reaction of [Mn(dmpe) 2 Br 2 ] with two equivalents of the corresponding acetylide LiC≡CC 6 H 4 R (R = F, ‐C≡CTIPS). The reaction of compounds 2a , 2b and 4 with [Cp 2 Fe][PF 6 ] yielded the corresponding d 4 complexes {Mn[(Me) 2 P(CH 2 ) n P(Me) 2 ] 2 (C≡CC 6 H 4 R) 2 }[PF 6 ] ( n = 2, R = ‐C≡CTIPS, [ 2a ] + n = 3, R = ‐C≡CTIPS, [ 2b ] + n = 2, R = F, [ 4 ] + n = 3 ‐C≡CTIPS). The unsymmetrically substituted trans ‐iodo‐alkynyl complex [IMn(dmpe) 2 (C≡CC 6 H 4 ‐C≡CTIPS)] ( 5 ) was obtained by treating MeCpMn(dmpe)I with one equivalent of H‐C≡CC 6 H 4 ‐C≡CTIPS in the presenceof dmpe. Deprotection of the TIPS group with TBAF gavecomplex [IMn(dmpe) 2 (C≡CC 6 H 4 C≡CH)] ( 6 ) in 94 % yield. The neutral dinuclear complexes Mn II /Mn II compounds {[Mn((Me) 2 P(CH 2 CH 2 )P(Me) 2 ) 2 (C≡CC 6 H 4 R)] 2 (μ‐C 4 )} (R = H, Me, n ‐pentyl, F) were prepared by the direct reaction of {[Mn((Me) 2 P(CH 2 CH 2 )P(Me) 2 ) 2 I] 2 (μ‐C 4 )} with the corresponding LiC≡CC 6 H 4 R (R = H, n ‐pentyl, F). These Mn II /Mn II dinuclear compounds were further oxidized to the mixed‐valent complexes and the dicationic complexes using [Cp 2 Fe][PF 6 ]. All complexes have been characterized by NMR, IR, and Raman spectroscopy. X‐ray diffraction studies were carried out on complexes 1c , 2a , 4 , [ 4 ] + , and 6 .
Publisher: American Chemical Society (ACS)
Date: 29-09-2014
DOI: 10.1021/NL5029045
Abstract: Besides active, functional molecular building blocks such as diodes or switches, passive components, for ex le, molecular wires, are required to realize molecular-scale electronics. Incorporating metal centers in the molecular backbone enables the molecular energy levels to be tuned in respect to the Fermi energy of the electrodes. Furthermore, by using more than one metal center and sp-bridging ligands, a strongly delocalized electron system is formed between these metallic "dopants", facilitating transport along the molecular backbone. Here, we study the influence of molecule-metal coupling on charge transport of dinuclear X(PP)2FeC4Fe(PP)2X molecular wires (PP = Et2PCH2CH2PEt2) X = CN (1), NCS (2), NCSe (3), C4SnMe3 (4), and C2SnMe3 (5) under ultrahigh vacuum and variable temperature conditions. In contrast to 1, which showed unstable junctions at very low conductance (8.1 × 10(-7) G0), 4 formed a Au-C4FeC4FeC4-Au junction 4' after SnMe3 extrusion, which revealed a conductance of 8.9 × 10(-3) G0, 3 orders of magnitude higher than for 2 (7.9 × 10(-6) G0) and 2 orders of magnitude higher than for 3 (3.8 × 10(-4) G0). Density functional theory (DFT) confirmed the experimental trend in the conductance for the various anchoring motifs. The strong hybridization of molecular and metal states found in the C-Au coupling case enables the delocalized electronic system of the organometallic Fe2 backbone to be extended over the molecule-metal interfaces to the metal electrodes to establish high-conductive molecular wires.
Publisher: American Chemical Society (ACS)
Date: 30-09-2006
DOI: 10.1021/OM060364L
Publisher: Wiley
Date: 24-03-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B304882A
Abstract: The theoretically characterized (DFT) C4 cumulenic species Mn(C5H4R)(dmpe) [=C=C=C=C(SnPh3)2] was obtained by photolysis of the C(sp2)-Sn bond in the vinylidene complex Mn(C5H4R)(dmpe)[=C=C(SnPh3)-C[triple bond]CSnPh3], which in turn was prepared by a thermal reaction from MnC5H4R(dmpe)(C7H8) and Ph3Sn-C4-SnPh3.
Publisher: Wiley
Date: 30-01-2014
Abstract: Highly tunable and rich phosphorescent emission properties based on the stable monocyclometalated gold(III) monoaryl structural motif are reported. Monochloro complexes of the type cis-[(N^C)Au(C6 H2 (CF3)3)(Cl)] N^C=2-phenylpyridine (ppy)] (1), [N^C=benzo[h]quinoline (bzq)] (2), [N^C=2-(5-Methyl-2-thienyl)pyridine (5m-thpy)] (3) were successfully prepared in modest to good yields by reacting an excess of 2, 4, 6-tris(trifluoromethyl)phenyl lithium (LiFmes) with the corresponding dichloride complexes cis-[(N^C)AuCl2]. Subsequent replacement of the chloride ligand in 1 with strong ligand field strength such as cyanide and terminal alkynes resulted in complexes of the type cis-[(ppy)Au(Fmes)(R)] R=CN (4), I (5), C≡C-C6 H5 (6) and C≡C-C6 H4 N(C6 H5)-p (7). Single crystal X-ray diffraction studies of all the complexes except 7 were performed to further corroborate their chemical identity. Thermogravimetric analysis (TGA) studies of the uncommon cis configured aryl alkyne complex 7 confirmed the high stability of this complex. Detailed photophysical investigations carried out in solution at room temperature, at 77 K (2-MeTHF) in rigidified media, solid state and 5 wt % PMMA revealed the phosphorescent nature of emission in these complexes. Additionally, their behavior was found to be governed based on both the nature of the cyclometalated ligand and the electronic properties of the ancillary ligands. Highly efficient interligand charge transfer in complex 7 provides access to a wide range of emission colors (solvent-dependent) from deep blue to red with phosphorescence emission quantum yield of 30 % (441 nm) and 39 % (622 nm) in solution and solid state, respectively, and is the highest reported for any Au(III) complexes. DFT and TDDFT calculations carried out further validated the observations and assignments based on the photophysical experimental findings.
Publisher: American Chemical Society (ACS)
Date: 17-02-2004
DOI: 10.1021/OM034237Q
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TC31610F
Publisher: Wiley
Date: 24-03-2021
Publisher: Wiley
Date: 18-07-2017
Publisher: Wiley
Date: 07-02-2019
Abstract: Phosphorescent mono-cyclometalated gold(III) complexes and their possible applications in organic light emitting diodes (OLEDs) can be significantly enhanced with their improved thermal stability by suppressing the reductive elimination of the respective ancillary ligands. A rational tuning of the π-conjugation of the cyclometalating ligand in conjunction with the non-conjugated 5,5'-(1-methylethylidene)bis(3-trifluoromethyl)-1H-pyrazole were used as a strategy to achieve room-temperature phosphorescence emission in a new series of gold(III) complexes. Photophysical studies of the newly synthesised and characterised complexes revealed phosphorescent emission of the complexes at room temperature in solution, thin films when doped in poly(methyl methacrylate) (PMMA) as well as in 2-Me-THF at 77 K. The complexes exhibit highly tuneable emission behaviour with photoluminescent quantum efficiencies up to 22 % and excited state lifetimes in the range of 63-300 μs. Detailed photophysical investigations in combination with DFT and TD-DFT calculations support the conclusion that the emission properties are strongly dictated by both the cyclometalating ligand and the ancillary chelating ligand. Thermogravimetric studies further show that the thermal stability of the Au
Publisher: Wiley
Date: 28-06-2007
Publisher: Wiley
Date: 25-09-2013
Publisher: Elsevier BV
Date: 12-2021
Publisher: American Chemical Society (ACS)
Date: 12-11-2010
DOI: 10.1021/IC101437H
Abstract: A series of novel luminescent cyclometalated Au(III) neutral complexes of the type cis-[(N(∧)C)AuL] [N(∧)C = 2-phenylpyridine (ppy), L = 1,1'-biphenyl (1)] and cis-[(N(∧)C)AuL(2)] [N(∧)C = 2-phenylpyridine (ppy), L = C(6)H(5) (2), C(6)F(5) (3), C(6)H(4)-CF(3)-p (4), 2-C(4)H(3)S (5)] [N(∧)C = 2-(2-thienyl)pyridine (thpy), L = C(6)H(5) (6), C(6)F(5) (7)] [N(∧)C = 2-(5-methyl-2-thienyl)pyridine (5 m-thpy), L = C(6)F(5) (8)] were successfully synthesized. The X-ray crystal structures of all compounds except 3 have been determined. These complexes were found to show long-lived emission in solution at room temperature. The emission origins of the complexes have been tentatively assigned to be derived from triplet states predominantly bearing intraligand (IL) character with some perturbation from the metal center. Density functional theory (DFT) calculations were performed to evaluate the stability associated with the complexes and TD-DFT calculations to ascertain the nature of the excited state. Variation of the cyclometalated ligands in the complexes readily leads to the tuning of the nature of the lower energy emissive states.
Publisher: American Chemical Society (ACS)
Date: 06-01-2014
DOI: 10.1021/IC401841N
Abstract: This Article reports the synthesis, structural characterization, electrochemistry, and photophysical investigations of five groups of luminescent Pt(II) alkynyl complexes bearing N-heterocyclic carbene (NHC) ligands with varying electronic properties. Complexes of the type [Pt(pmdb)(C≡CR)2] 1a-c, [Pt(pm2tz)(C≡CR)2] 2a-d, [Pt(pm3tz)(C≡CR)2] 3a-c, [Pt(ppim)(C≡CR)2] 4(a, b, e), and [Pt(ppbim)(C≡CR)2] 5(a, b, e), where pmdb =1,1'-dipentyl-3,3'-methylene-dibenzimidazoline-2,2'-diylidene, pm2tz = 1,1'-dipentyl-3,3'-methylene-di-1,2,4-triazoline-5,5'-diylidene, pm3tz = 1,1'-dipentyl-3,3'-methylene-di-1,3,4-triazoline-5,5'-diylidene, ppim = 3-pentyl-1-picolylimidazoline-2-ylidene, and ppbim = 3-pentyl-1-picolylbenzimidazoline-2-ylidene, and R = 4-C6H4F, C6H5, 4-C6H4OMe, SiMe3, and 4-C6H4N(C6H5)2, were prepared, and the consequences of the electronic properties of the NHC ligands on the phosphorescent emission efficiencies were studied. Moreover, the emission quantum efficiencies of the previously reported complexes [Pt(pmim)(C≡CR)2] where pmim = 1,1'-dipentyl-3,3'-methylene-diimidazoline-2,2'-diylidene and R = 4-C6H4F 6a, C6H5 6b, and 4-C6H4OMe 6c were also recorded in neat solid and in 10 wt % PMMA film. The square planar coordination geometry with the alkynyl ligands in cis configuration was corroborated for selected complexes by single crystal X-ray diffraction studies. The observed moderate difference in emission efficiencies of the bis-carbene complexes 6a-c, 1a-c, 2a-c, and 3a-c in conjunction with the decreasing electron-donating nature of the NHC ligands, pmim > pmdb > pm2tz ≈ pm3tz, can be attributed to the slight modification of the triplet emission parentage among the different complexes. The quantum efficiencies of complexes 4(a, b) and 5(a, b) bearing pyridyl-NHC ligand were significantly low in comparison to the bis-carbene complexes owing to the significant change in the charge transfer character of the triplet manifold. Complexes 4e and 5e bearing diarylamine phenylacetylenes display high ϕem of 27% and 33% in 10 wt % PMMA film, respectively.
Publisher: American Chemical Society (ACS)
Date: 20-05-2004
DOI: 10.1021/OM034196Y
Publisher: IEEE
Date: 07-2015
Publisher: Wiley
Date: 22-09-2004
Abstract: The dinuclear mixed-valent complex [(MeC5H4)(dmpe)MnC(2)Mn(dmpe)(C5H4Me)](+)[(eta2-MeC5H4)3Mn](-)[1](+)[2]- (dmpe=1,2-bis(dimethylphosphanyl)ethane) was prepared by the reaction of [Mn(MeC5H4)2] with dmpe and Me(3)SnC[triple chemical bond]CSnMe3. The reactions of [1](+)[2]- with K[PF6] and Na[BPh4] yielded the corresponding anion metathesis products [(MeC5H4)(dmpe)MnC2Mn(dmpe)(C5H4Me)][PF6] ([1][PF6]) and [(MeC5H4)(dmpe)MnC2Mn(dmpe)(C5H4Me)][BPh4] ([1][BPh4]). These mixed-valent species can be reduced to the neutral form by reaction with Na/Hg. The obtained complex [(MeC5H4)(dmpe)MnC2Mn(dmpe)(C5H4Me)] (1) displays a triplet/singlet spin equilibrium in solution and in the solid state, which was additionally studied by DFT calculations. The diamagnetic dicationic species [(MeC5H4)(dmpe)MnC2Mn(dmpe)(C5H4Me)][PF6]2 ([1][PF6]2) was obtained by oxidizing the mixed-valent complex [1][PF6] with one equivalent of [Fe(C5H5)2][PF6]. Both redox processes are fully reversible. The dinuclear compounds were characterized by NMR, IR, UV-visible, and Raman spectroscopy, cyclic voltammetry, and magnetic susceptibility measurements. X-ray diffraction studies were performed on [1][2], [1][PF6], [1][BPh4], and [1][PF6]2.
Publisher: American Chemical Society (ACS)
Date: 28-10-2021
DOI: 10.1021/ACSSENSORS.1C01665
Abstract: The outbreak of the COVID-19 pandemic has had a major impact on the health and well-being of people with its long-term effect on lung function and oxygen uptake. In this work, we present a unique approach to augment the phosphorescence signal from phosphorescent gold(III) complexes based on a surface plasmon-coupled emission platform and use it for designing a ratiometric sensor with high sensitivity and ultrafast response time for monitoring oxygen uptake in SARS-CoV-2-recovered patients. Two monocyclometalated Au(III) complexes, one having exclusively phosphorescence emission (λ
Publisher: American Chemical Society (ACS)
Date: 08-03-2012
DOI: 10.1021/OL300327B
Abstract: Various substituted 2-azulenes have been synthesized via Sonogashira coupling. Doping with superacids allows tunable emission from 443 to 750 nm depending on the substitution. The proton doped compounds are the first azulene alkyne based systems that show emission originating only from the S(1) excited state.
Publisher: Wiley
Date: 12-05-2014
Abstract: Design of highly efficient phosphorescent emitters based on metal- and heavy atom-free boron compounds has been demonstrated by taking advantage of the singlet fission process. The combination of a suitable molecular scaffold and appropriate electronic nature of the substituents has been utilized to tailor the phosphorescence emission properties in solution, neat solid, and in doped PMMA thin films.
Publisher: American Chemical Society (ACS)
Date: 04-05-2005
DOI: 10.1021/OM049252P
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CC02589E
Abstract: Two Zn MOFs, MOF-645 and MOF-646, comprised of polarized 1,3-azulenedicarboxylate were synthesized. The guest free MOF-646 showed strong MOF-H(2) interactions (7.8-6.8 kJ mol(-1)), which revealed the significant impact of internally polarized azulene backbone to stabilized H(2) molecules in the framework.
Publisher: Wiley
Date: 04-09-2012
Abstract: The synthesis, photophysical, and electrochemical attributes of a novel class of boron difluorides containing an aromatic‐fused alicyclic/hetero‐alicyclic ring built on a β‐iminoenamine chromophoric backbone are reported. The compounds displayed large Stokes shifts (86–121 nm), and were emissive in the solid state. The quantum yields obtained in solution at room temperature were unusually lower by an order of magnitude compared to those in the solid state. Some of the tested compounds displayed aggregation‐induced emission (AIE). Single crystal XRD analyses revealed a lack of interplanar π–π interactions, which are presumed to be absent owing to non‐planarity of the alicyclic component in the molecule. For most of the studied compounds, time‐dependent DFT (TD‐DFT) calculations invariably reveal intramolecular charge transfer (π–π*) characteristics with the frontier orbitals concentrated on the boron–nitrogen heterocycle. The participation of boron and fluorine atoms was found to be negligible.
Publisher: Wiley
Date: 05-11-2014
Abstract: Six phosphorescent (2-phenyl)pyridine (ppy) gold(III) 2,4,6-tris(trifluoromethyl)phenyl (FMes) complexes were synthesized and investigated for their anticancer potential. The compounds demonstrated strong antiproliferative activity, with EC50 values in the low micromolar range, along with significant accumulation in HeLa cancer cells after treatment for only 6 h (up to 119 ng gold per milligram of protein as measured by high-resolution continuum source atomic spectroscopy). Enzyme inhibition studies showed interaction of the gold(III) complexes with thioredoxin reductase (TrxR), a key homeostasis-regulation flavoprotein. TrxR was inhibited with IC50 values in the micromolar range. Furthermore, five of the complexes displayed selectivity toward TrxR against glutathione reductase (GR, a disulfide reductase structurally related to TrxR) by up to >49-fold. Because no major differences in bioactivity were observed across the series, [(ppy)Au(FMes)(PPh3 )OTf] (complex 4) was chosen for further in-depth biological characterization. Complex 4 was also found to interact with guanosine monophosphate in (1) H NMR studies under long incubation times. Interestingly, 4 induced a significant increase in intracellular levels of reactive oxygen species, which led to late apoptotic events and cytocidal effects.
Publisher: American Chemical Society (ACS)
Date: 02-10-2014
DOI: 10.1021/JA507672G
Abstract: A series of X(depe)2FeC≡C-C≡CFe(depe)2X complexes (depe =1,2-bis(diethylphosphino)ethane X = I 1, NCMe 2, N2 3, C2H 4, C2SnMe3 5, C4SnMe3 6, NCSe 7, NCS 8, CN 9, SH 10, and NO2 11) was designed to study the influence of the anchor group on organometallic molecular transport junctions to achieve high-conductive molecular wires. The FeC4Fe core is electronically functional due to the redox-active Fe centers and sp-bridging ligands allowing a strong electronic delocalization. 1-11 were characterized by elemental analyses, X-ray diffraction, cyclic voltammetry, NMR, IR, and Raman spectroscopy. DFT calculations on model compounds gave the HOMO/LUMO energies. 5-9 were investigated in mechanically controllable break-junctions. For 9, unincisive features at 8.1 × 10(-7) G0 indicate that sterical reasons prevent stable junctions to form or that the coordinative binding motif prohibits electron injection. 7 and 8 with the hitherto unexploited coordinatively binding end groups NCSe and NCS yielded currents of 1.3 × 10(-9) A (7) and 1.8 × 10(-10) A (8) at ±1.0 V. The SnMe3 in 5 and 6 splits off, yielding junctions with covalent C-Au bonds and currents of 6.5 × 10(-7) A (Au-5'-Au) or 2.1 × 10(-7) A (Au-6'-Au). Despite of a length of almost 2 nm, the Au-5'-Au junction reaches 1% of the maximum current assuming one conductance channel in quantum point contacts. Additionally, the current noise in the transport data is considerably reduced for the covalent C-Au coupling compared to the coordinative anchoring of 7-9, endorsing C-Au coupled organometallic complexes as excellent candidates for low-ohmic molecular wires.
Publisher: Wiley
Date: 30-09-2021
Abstract: Invited for the cover of this issue are Koushik Venkatesan and co‐workers at Macquarie University and the University of Zurich. The image depicts the conversion of 3 O 2 to 1 O 2 upon photoexcitation by new monocyclometalated gold(III) metallacycles. Read the full text of the article at 10.1002/chem.202102331 .
Publisher: Springer Science and Business Media LLC
Date: 16-11-2015
Abstract: Charge transport through single molecules can be influenced by the charge and spin states of redox-active metal centres placed in the transport pathway. These intrinsic properties are usually manipulated by varying the molecule's electrochemical and magnetic environment, a procedure that requires complex setups with multiple terminals. Here we show that oxidation and reduction of organometallic compounds containing either Fe, Ru or Mo centres can solely be triggered by the electric field applied to a two-terminal molecular junction. Whereas all compounds exhibit bias-dependent hysteresis, the Mo-containing compound additionally shows an abrupt voltage-induced conductance switching, yielding high-to-low current ratios exceeding 1,000 at bias voltages of less than 1.0 V. Density functional theory calculations identify a localized, redox-active molecular orbital that is weakly coupled to the electrodes and closely aligned with the Fermi energy of the leads because of the spin-polarized ground state unique to the Mo centre. This situation provides an additional slow and incoherent hopping channel for transport, triggering a transient charging effect in the entire molecule with a strong hysteresis and large high-to-low current ratios.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5DT00405E
Abstract: Room temperature phosphorescence based on non-cyclometalated gold( iii ) complexes with readily tunable emission properties is demonstrated.
Publisher: Elsevier BV
Date: 03-2012
Publisher: American Chemical Society (ACS)
Date: 12-2006
DOI: 10.1021/JA065645Z
Abstract: Heavy metal complexes that are phosphorescent at room temperature are becoming increasingly important in materials chemistry, principally due to their use in phosphorescent organic light-emitting devices (OLEDs). Their use in optical sensory schemes, however, has not been heavily explored. Homoleptic bis-cyclometalated Pt(II) complexes are known to undergo oxidative addition with appropriate electrophiles (principally alkyl halides) by either thermal or photochemical activation. We have applied this general reaction scheme to the development of a phosphorescence-based sensing system for cyanogen halides. To carry out structure-property relationship studies, a series of previously unreported Pt(II) complexes was prepared. Most of the complexes (excluding those that incorporated substituents on the ligands that forced steric crowding in the square plane) were strongly orange-red phosphorescent (Phi = 0.2-0.3) in a room-temperature oxygen-free solution. These sterically demanding ligands also accelerated the addition of cyanogen bromide to these complexes but slowed the addition of methyl iodide, indicating that the oxidative addition mechanisms for these two electrophiles is different. The lack of solvent-polarity effect on the addition of BrCN suggests a radical mechanism. Oxidative addition of BrCN to the metal complexes in solution or dispersed in poly(methyl methacrylate) gave blue-shifted emissive Pt(IV) complexes. The blue-shifted products give a dark-field sensing scheme that is in sharp contrast to energy transfer-based sensing schemes, which have limited signal-to-noise because of the presence of lower-energy vibronic bands of the energy donor that can overlap with the emission of the acceptor.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC14387E
Abstract: Two novel 3D MOFs, namely MOF-647A and MOF-648 (previously unknown trinodal 4-connected net), comprised of Cu ions and pyrazole-3,5-dicarboxylate were synthesized and characterized. A strategy for incorporating open metal sites in MOFs was investigated by utilizing an in situ generated metal-linker complex as a precursor to construct MOF-648.
Publisher: American Chemical Society (ACS)
Date: 09-2004
DOI: 10.1021/OM049551E
Publisher: American Chemical Society (ACS)
Date: 02-2005
DOI: 10.1021/OM049284C
Publisher: Wiley
Date: 17-03-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8DT05034A
Abstract: The electronic properties of cyclometalating ligands and ancillary ligands were successfully tailored to achieve blue emission in monocyclometalated gold( iii ) complexes.
Publisher: Wiley
Date: 25-06-2009
Publisher: Wiley
Date: 02-12-2011
Publisher: Wiley
Date: 24-08-2016
Abstract: Azulene (Az) is a non‐alternating, aromatic hydrocarbon composed of a five‐membered, electron‐rich and a seven‐membered, electron‐poor ring an electron distribution that provides intrinsic redox activity. By varying the attachment points of the two electrode‐bridging substituents to the Az center, the influence of the redox functionality on charge transport is evaluated. The conductance of the 1,3 Az derivative is at least one order of magnitude lower than those of the 2,6 Az and 4,7 Az derivatives, in agreement with density functional theory (DFT) calculations. In addition, only 1,3 Az exhibits pronounced nonlinear current–voltage characteristics with hysteresis, indicating a bias‐dependent conductance switching. DFT identifies the LUMO to be nearest to the Fermi energy of the electrodes, but to be an active transport channel only in the case of the 2,6 and the 4,7 Az derivatives, whereas the 1,3 Az derivative uses the HOMO at low and the LUMO+1 at high bias. In return, the localized, weakly coupled LUMO of 1,3 Az creates a slow electron‐hopping channel responsible for the voltage‐induced switching due to the occupation of a single molecular orbital (MO).
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC34430K
Abstract: We report a novel luminescent Al-based metal-organic gel G1 comprising 1,4,5,8-triptycenetetracarboxylic acid, which exhibits highly sensitive detection towards nitro aromatic compounds particularly picric acid. Furthermore, under identical reaction conditions, using a Co(II) salt instead, a novel 3D framework material, trip-MOF-1, was isolated and its sensitivity towards picric acid was also evaluated.
Publisher: Informa UK Limited
Date: 27-06-2016
Publisher: Wiley
Date: 25-06-2009
Abstract: Tungsten tryst: A 4-H-butatrienylidene complex of tungsten was successfully isolated and structurally characterized. It undergoes a unique self-coupling, which leads to a dimer (see picture P pink, O red) with a cross-conjugated pi system and with electrochemically and magnetically active metal centers.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8QO00820E
Abstract: 4,4′-bichromenes and 4,4′-bithiochromenes have been synthesized by a Ni catalyzed homocoupling method and their Atropisomeric behavior has been studied.
Publisher: Springer Science and Business Media LLC
Date: 07-2018
DOI: 10.1038/S41586-018-0275-Z
Abstract: Accessing the intrinsic functionality of molecules for electronic applications
Publisher: Wiley
Date: 13-11-2020
DOI: 10.1002/JRS.6020
Publisher: Wiley
Date: 08-09-2021
Abstract: The synthesis, characterization and photoluminescent properties of four cyclometalated (C N)‐type gold(III) complexes bearing a bidentate diacetylide ligand, tolan‐2,2’‐diacetylide (tda), are reported. The complexes exhibit highly tunable excited state properties and show photoluminescence (PL) across the entire visible spectrum from sky‐blue (λ PL =493 nm) to red (λ PL =675 nm) with absolute PL quantum yields (PLQY) of up to 75 % in solution, the highest PLQY found for any monocyclometalated Au(III) complex in solution. As a consequence of the use of the strongly rigidifying diacetylide bidentate ligand, a significant increase in the excited state lifetimes (τ 0 =16–258 μs) was found in solution and in thin films. The complexes showed remarkable singlet oxygen generation in aerated solution with absolute singlet oxygen quantum yield (ϕ 1Δ ) values reaching up to 7.5×10 −5 and singlet oxygen lifetimes (τ 0 1Δ ) in the range of 66–95 μs. Furthermore, the radiative and non‐radiative rates of singlet oxygen were determined using the ϕ 1Δ and τ 0 1Δ values and correlations are drawn between the formation of singlet oxygen and its interaction with cyclometalated (C N) gold(III) complexes.
Publisher: Wiley
Date: 05-11-2021
Abstract: Highly efficient deep‐blue and blue emitting complexes remain one of the most back‐breaking challenges to overcome for organic light emitting diode (OLED) devices applications. Apart from the well‐investigated emitter systems involving iridium(III) and platinum(II) metal centres, gold(I) and gold(III) systems are gaining increasing attention as emitter systems with remarkable photoluminescence and electroluminescence properties. While most of the investigated Au(I) and Au(III) complexes emit in the green to yellow region, only a handful of ex les show blue to deep‐blue emission. One of the main challenges to overcome are to develop ligand frameworks that lead to large triplet energies ( E T .7 eV), while maintaining high thermal and photostability of the complexes. A number of solutions involving the introduction of strong σ‐donors, sterically demanding ligands as well as bidentate and tridentate ligand frameworks were found in order to stabilise the gold(I) and gold(III) centres, respectively. This minireview summarises the recent advances of deep‐blue and blue‐emitting Au(I) and Au(III) complexes by highlighting the important milestones and the challenges yet to overcome.
Publisher: American Chemical Society (ACS)
Date: 23-05-2011
DOI: 10.1021/IC102216V
Abstract: A series of novel luminescent neutral cyclometalated gold(III) complexes of the type cis-[(N^C)Au(C≡CR)(2)] (R = aryl, silyl groups) having different cyclometalating cores (N^C) have been synthesized by CuI promoted halide to alkynyl metathesis with NEt(3) as in situ deprotonating agent. Along with spectroscopic characterizations (nuclear magnetic resonance and infrared spectroscopies and electrospray ionization mass spectrometry) and elemental analysis, the molecular structures of some of the complexes have been established by single-crystal X-ray diffraction studies. Photophysical studies reveal that the complexes exhibit room-temperature phosphorescence (RTP). Experimental observations and density functional theory calculations qualitatively suggest limited participation of the metal and alkynyl ligands in the lowest energy emitting state. The nature of the emission is mainly governed by metal-perturbed (3)IL(π-π*) transitions originating from the cyclometalate part of the molecule, and its variation readily leads to the tuning of the emission wavelengths. Cyclic voltammetry measurements of selected complexes showed irreversible redox behavior with near-equivalent cathodic peak potential (E(p,c)) assigned to the C^N core.
Publisher: American Chemical Society (ACS)
Date: 05-03-2013
DOI: 10.1021/JA400078C
Abstract: trans-Fe(depe)2I2 (depe =1,2-bis(diethylphosphino)ethane) was employed to stepwise incorporate Fe(II) centers into a rigid-rod butadiyne based 5,10,15,20-tetraferratetracosa-1,3,6,8,11,13,16,18,21,23-decayne. The iterative synthesis first connects two Fe(II) centers via a central butadiynediyl ligand to provide I-Fe(depe)2-C4-Fe(depe)2-I (2), then extends the system by substituting the terminal halides of 2 to yield Me3SiC4-Fe(depe)2-C4-Fe(depe)2-C4SiMe3 (3). Further modification of the termini gives the deprotected and stannylated compounds RC4-Fe(depe)2-C4-Fe(depe)2-C4R (4 and 5 R = H, Sn(CH3)3, respectively). Transmetalation with two more mononuclear units furnishes the homometallic tetranuclear compound I-Fe(depe)2-C4-Fe(depe)2-C4-Fe(depe)2-C4-Fe(depe)2-I (6), to which two more butadiynyl units were attached to give Me3SiC4-Fe(depe)2-C4-Fe(depe)2-C4-Fe(depe)2-C4-Fe(depe)2-C4SiMe3 (7). All compounds were characterized by NMR, IR, and Raman spectroscopies and by elemental analyses. X-ray diffraction studies were carried out on the dinuclear complexes revealing highly symmetrical rigid-rod structures. Cyclic voltammetric studies showed that compounds 2-7 undergo reversible and well-defined oxidations with high Kc values indicating thermodynamically stable mixed valence species. While the number of the oxidation waves of compounds 2, 6, and 7 are equivalent to the number of metal centers, the dinuclear complexes 3, 4, and 5 exhibit three reversible oxidation waves, one at significantly more positive potential. Two redox waves were attributed to the oxidation of the metal centers, while the remaining one is due to the oxidation of the butadiynediyl ligand. The electronic properties of complexes 2, 3, and 7 were investigated by spectroelectrochemical measurements.
Publisher: Wiley
Date: 11-12-2003
Abstract: The symmetric d(5) trans-bis-alkynyl complexes [Mn(dmpe)(2)(C triple bond CSiR(3))(2)] (R = Me, 1 a Et, 1 b Ph, 1 c) (dmpe = 1,2-bis(dimethylphosphino)ethane) have been prepared by the reaction of [Mn(dmpe)(2)Br(2)] with two equivalents of the corresponding acetylide LiC triple bond CSiR(3). The reactions of species 1 with [Cp(2)Fe][PF(6)] yield the corresponding d(4) complexes [Mn(dmpe)(2)(C triple bond CSiR(3))(2)][PF(6)] (R = Me, 2 a Et, 2 b Ph, 2 c). These complexes react with NBu(4)F (TBAF) at -10 degrees C to give the desilylated parent acetylide compound [Mn(dmpe)(2)(C triple bond CH)(2)][PF(6)] (6), which is stable only in solution at below 0 degrees C. The asymmetrically substituted trans-bis-alkynyl complexes [Mn(dmpe)(2)(C triple bond CSiR(3))(C triple bond CH)][PF(6)] (R = Me, 7 a Et, 7 b) related to 6 have been prepared by the reaction of the vinylidene compounds [Mn(dmpe)(2)(C triple bond CSiR(3))(C=CH(2))] (R = Me, 5 a Et, 5 b) with two equivalents of [Cp(2)Fe][PF(6)] and one equivalent of quinuclidine. The conversion of [Mn(C(5)H(4)Me)(dmpe)I] with Me(3)SiC triple bond CSnMe(3) and dmpe afforded the trans-iodide-alkynyl d(5) complex [Mn(dmpe)(2)(C triple bond CSiMe(3))I] (9). Complex 9 proved to be unstable with regard to ligand disproportionation reactions and could therefore not be oxidized to a unique Mn(III) product, which prevented its further use in acetylide coupling reactions. Compounds 2 react at room temperature with one equivalent of TBAF to form the mixed-valent species [[Mn(dmpe)(2)(C triple bond CH)](2)(micro-C(4))][PF(6)] (11) by C-C coupling of [Mn(dmpe)(2)(C triple bond CH)(C triple bond C*)] radicals generated by deprotonation of 6. In a similar way, the mixed-valent complex [[Mn(dmpe)(2)(C triple bond CSiMe(3))](2)(micro-C(4))][PF(6)] [12](+) is obtained by the reaction of 7 a with one equivalent of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). The relatively long-lived radical intermediate [Mn(dmpe)(2)(C triple bond CH)(C triple bond C*)] could be trapped as the Mn(I) complex [Mn(dmpe)(2)(C triple bond CH)(triple bond C-CO(2))] (14) by addition of an excess of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) to the reaction mixtures of species 2 and TBAF. The neutral dinuclear Mn(II)/Mn(II) compounds [[Mn(dmpe)(2)(C triple bond CR(3))](2)(micro-C(4))] (R = H, 11 R = SiMe(3), 12) are produced by the reduction of [11](+) and [12](+), respectively, with [FeCp(C(6)Me(6))]. [11](+) and [12](+) can also be oxidized with [Cp(2)Fe][PF(6)] to produce the dicationic Mn(III)/Mn(III) species [[Mn(dmpe)(2)(C triple bond CR(3))](2)(micro-C(4))][PF(6)](2) (R = H, [11](2+) R = SiMe(3), [12](2+)). Both redox processes are fully reversible. The dinuclear compounds have been characterized by NMR, IR, UV/Vis, and Raman spectroscopies, CV, and magnetic susceptibilities, as well as elemental analyses. X-ray diffraction studies have been performed on complexes 4 b, 7 b, 9, [12](+), [12](2+), and 14.
Publisher: Wiley
Date: 14-02-2017
Abstract: A series of blue-emitting phosphorescent mono-cyclometalated Au
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B615578B
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6TC05551F
Abstract: Blue and blue-green phosphorescent Au( iii ) compounds based on a novel C^C chelate ligand framework are reported.
Publisher: Wiley
Date: 05-07-2017
Abstract: White light emitting gold(III) complexes were synthesized by tuning the percentage of metal dπ contribution in the charge transfer. This was achieved through specific tailoring of the ligand scaffold, which led to increase in the HOMO π-energy properties, resulting in a decrease of efficiency on the intersystem crossing (ISC). As a consequence, monomolecular based singlet- and triplet-derived emission covering the entire visible spectrum with quantum yield up to 28 % and CIE-1931 chromaticity coordinates of (0.29, 0.33) to (0.32, 0.40) could be obtained. Furthermore, two complexes displayed excitation-dependent emission property due to hyper-ISC allowing the regulation of the ratio between fluorescence versus phosphorescence intensity and accomplish precise tuning of white light emission.
Publisher: Springer Science and Business Media LLC
Date: 03-12-2009
Publisher: Wiley
Date: 17-01-2007
Publisher: American Chemical Society (ACS)
Date: 19-11-2018
Publisher: American Chemical Society (ACS)
Date: 30-10-2015
DOI: 10.1021/ACS.INORGCHEM.5B01762
Abstract: The synthesis, structural, photophysical, and electrochemical investigations of a series of gold(III) monocyclometalated complexes bearing ancillary ligands with π-accepting properties is reported. Complexes of the type [(C(∧)N)Au(C≡N)2] [C(∧)N = 2-phenylpyridine (ppy) (1), 2-(p-tolyl)pyridine (tpy) (2), 2-(2-thienyl)-pyridine (thpy) (3), 2-(5-methyl-2-thienyl)pyridine (5m-thpy) (4), 1-phenylisoquinoline (piq) (5)], and [(N(∧)N)Au(C≡N)2] [N(∧)N = 3,5-bis(phenyl)-2-(2'-pyridyl)pyrrole (pyrpy) (6)] were prepared, and the influence of both the cyanide as an ancillary ligand as well as the different electronic properties of the cyclometalating ligands (1-5) and the chelating bidentate (6) on the triplet emission properties were studied. The physicochemical properties were evaluated by a variety of physical methods, and the structure of selected complexes was further confirmed by X-ray diffraction studies. Complexes 1-5 display long-lived emission in solution, neat solid, spin coated PMMA films, and at 77 K in 2-MeTHF. The emission energies were strongly dictated by the cyclometalating ligands independent of the cyanide ligand, which is in quite a contrast to the previously reported dicyano complexes of iridium(III) and the isoelectronic platinum(II) complexes. The nonemissive behavior of complex 6 in any medium further highlights the importance that the good σ-donating properties of the cyclometalating ligand alone is not decisive in rendering the gold complexes emissive, but also the appropriate placement of the energy level of the ligand orbitals is also important. Detailed photophysical studies in conjunction with density functional theory and time-dependent density functional theory calculations support the origin of the emission to be a metal perturbed intra ligand (3)IL (π-π*) delocalized over the cyclometalating ligand. The stability of the complexes combined with good emission quantum yields and tunability of the emission energies makes these complexes suitable alternatives to the relatively less stable monocyclometalated gold(III) diaryl or dialkyne complexes for organic light emitting device applications.
Publisher: Wiley
Date: 24-08-2016
Abstract: Azulen (Az) ist ein nicht‐alternierender aromatischer Kohlenwasserstoff, der aus einem elektronenreichen Ring mit fünf und einem elektronenarmen Ring mit sieben Gliedern besteht. Diese Elektronenverteilung führt zu einer intrinsischen Redoxaktivitiät. Durch Variieren der Befestigungspunkte der beiden elektrodenverbindenden Substituenten am Az‐Zentrum wird der Einfluss der Redoxfunktionalität auf den Ladungstransport untersucht. Die Leitfähigkeit des 1,3‐Az‐Derivats ist dabei mindestens eine Größenordnung geringer als die der 2,6‐Az‐ und 4,7‐Az‐Derivate, in Übereinstimmung mit Resultaten der Dichtefunktionaltheorie (DFT). Außerdem weist nur 1,3‐Az eine ausgeprägt nichtlineare Strom‐Spannungs‐Kennlinie mit Hysterese auf, was durch einen spannungsabhängigen Schaltvorgang ausgelöst wird. Die DFT‐Ergebnisse zeigen weiter, dass das LUMO einerseits am nächsten bei der Fermi‐Energie der Elektroden liegt, andererseits aber nur bei den 2,6‐ und 4,7‐Az‐Derivaten den aktiven Ladungskanal darstellt, während das 1,3‐Az‐Derivat bei niedriger Spannung das HOMO und bei hoher Spannung das LUMO+1 verwendet. Im Gegenzug schafft das lokalisierte, nur schwach gekoppelte LUMO des 1,3‐Az einen zusätzlichen, langsamen Transportkanal für Elektronenhopping, das für den spannungsinduzierte Schaltvorgang aufgrund der Besetzung eines einzelnen Molekülorbitals (MO) verantwortlich ist.
Location: United States of America
Start Date: 05-2018
End Date: 05-2022
Amount: $372,716.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 12-2023
Amount: $480,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2018
End Date: 04-2019
Amount: $744,100.00
Funder: Australian Research Council
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