ORCID Profile
0000-0002-0007-4486
Current Organisation
La Trobe University
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Analytical Chemistry | Physical Chemistry of Materials | Main Group Metal Chemistry | Optical Properties of Materials | Transition Metal Chemistry | Synthesis of Materials | Inorganic Chemistry | Solid State Chemistry | Organic Chemical Synthesis | Sensor Technology (Chemical aspects) | Bioinorganic Chemistry | Electroanalytical Chemistry | Analytical Spectrometry | Nanochemistry and Supramolecular Chemistry | F-Block Chemistry | Physical Organic Chemistry |
Expanding Knowledge in the Chemical Sciences | Chemical sciences
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/CH14057
Abstract: A series of seven thiophen-substituted diketopyrrolopyrrole derivatives were synthesised and their solution absorption spectra characterised in a range of solvents of varying polarity. The absorption spectra of these diketopyrrolopyrrole derivatives exhibited significant negative solvatochromism. The behaviour is consistent with results of time-dependent density-functional theory calculations of excitation energies. Calculated electronic structures suggest that there is significant charge transfer between the electron-donating thiophen substituents and the diketopyrrolopyrrole core but that the magnitude of this charge shift is reduced in the excited state compared with the ground state. The resulting reduction in polarity of the excited state accounts for the negative solvatochromism observed. The implications of the results for the potential application of diketopyrrolopyrrole compounds as photovoltaic materials are considered.
Publisher: Wiley
Date: 06-05-2014
Publisher: Informa UK Limited
Date: 10-03-2006
Publisher: American Chemical Society (ACS)
Date: 18-06-2013
DOI: 10.1021/IC400263R
Abstract: A series of four Ru(II) complexes of the form [Ru(bpy)2(C(^)N)](2+) (where C(^)N is a bidentate pyridine-functionalized imidazolylidene- or benzimidazolylidene-based N-heterocyclic carbene (NHC) ligand and bpy is 2,2'-bipyridine) have been synthesized using a Ag(I) transmetalation protocol from the Ru(II) precursor compound, Ru(bpy)2Cl2. The synthesized azolium salts and Ru(II) complexes were characterized by elemental analysis, (1)H and (13)C NMR spectroscopy, cyclic voltammetry, and electronic absorption and emission spectroscopy. The molecular structures for two benzimidazolium salts and three Ru(II) complexes were determined by single crystal X-ray diffraction. The complexes display photoluminescence within the range 611-629 nm, with the emission wavelength of the benzimidazolylidene containing structures, slightly blue-shifted relative to the imidazolylidene containing complexes. All complexes exhibited a reversible, one-electron oxidation, which is assigned to the Ru(2+/3+) redox couple. When compared to [Ru(bpy)3](2+), complexes of imidazolylidene containing ligands were oxidized at more negative potentials, while those of the benzimidazolylidene containing ligands were oxidized at more positive potentials. All four complexes exhibited moderately intense electrochemiluminescence (ECL) with the obtained ECL spectra closely resembling the photoluminescence spectra. The ability to predictably fine-tune the highest occupied molecular orbital (HOMO) level of the Ru(II) complexes via the flexible synthetic strategy offered by NHCs is valuable for the design of ECL-based multiplexed detection strategies.
Publisher: American Chemical Society (ACS)
Date: 25-06-2012
DOI: 10.1021/IC300686N
Abstract: A theoretical examination of the L-E-E-L class of molecules has been carried out (E = group 14, group 15 element L = N-heterocyclic carbene, phosphine), for which Si, Ge, P, and As-NHC complexes have recently been synthesized. The focus of this study is to predict whether it is possible to stabilize the elusive E(2) molecule via formation of L-E-E-L beyond the few known ex les, and if the ligand set for this class of compounds can be extended from the NHC to the phosphine class of ligands. It is predicted that thermodynamically stable L-E-E-L complexes are possible for all group 14 and 15 elements, with the exception of nitrogen. The unknown ligand-stabilized Sn(2) and Pb(2) complexes may be considered attractive synthetic targets. In all cases the NHC complexes are more stable than the phosphines, however several of the phosphine derivatives may be isolable. The root of the extra stability conferred by the NHC ligands over the phosphines is determined to be a combination of the NHCs greater donating ability, and for the group 15 complexes, superior π acceptor capability from the E-E core. This later factor is the opposite as to what is normally observed in transition metal chemistry when comparing NHC and phosphine ligands, and may be an important consideration in the ongoing "renaissance" of low-valent main group compounds supported by ligands.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8CC10022E
Abstract: The first ex les of carbodicarbene (CDC)-s-block complexes have been synthesized. Unusual C–H bond activation and cyclization discovered.
Publisher: Wiley
Date: 03-05-2017
Publisher: Wiley
Date: 23-09-2013
DOI: 10.1002/WCMS.1172
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3DT50563D
Abstract: A theoretical study of compounds containing Be in the +1 or 0 oxidation state has been carried out. The molecules considered containing Be in the +1 oxidation state are analogues of the important Mg(I)-Mg(I) dimer supported by the β-diketiminate ligand. The molecules in the 0 oxidation state are NHC supported compounds analogous to "molecular allotropes" which has recently become a topic of importance in p-block chemistry. In this case, our results demonstrate that the Be(0) complexes are far more stable than the analogous Mg(0) complexes, highlighting the opportunities afforded in Be chemistry, despite the challenges presented by the toxicity of Be compounds.
Publisher: American Chemical Society (ACS)
Date: 27-05-2014
DOI: 10.1021/OM500076W
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CC04864D
Abstract: The reaction between trimethylsilyl azide and pentaphenylborole was further investigated theoretically and experimentally to shed light on the mechanism to form the 1,2-azaborine.
Publisher: American Chemical Society (ACS)
Date: 04-08-2015
DOI: 10.1021/ACS.INORGCHEM.5B01255
Abstract: A computational study of a set of synthetically unknown beryllium-containing rings, anionic analogues of antiaromatic boroles, has been carried out to investigate their structure, stability, and potential reactivity. The results indicate that these compounds should be electronically viable (as assessed from HOMO-LUMO and singlet-triplet gaps) and therefore potential targets for synthesis. In strong contrast with boroles, these beryllium species are predicted to be not Lewis acidic but rather Lewis basic, with reactivity centered on the endocyclic Be-C bond.
Publisher: American Chemical Society (ACS)
Date: 02-12-2019
DOI: 10.1021/ACS.INORGCHEM.9B02433
Abstract: The relative σ-donating and π-accepting capacities of a range of synthetically relevant boryl anions have been evaluated by examining the geometric, thermochemical, and electronic properties of their adducts to the Li
Publisher: American Chemical Society (ACS)
Date: 19-10-2022
DOI: 10.1021/ACS.INORGCHEM.2C01945
Abstract: The impact of the exact spatial arrangement of the alkali metal on the electronic properties of 9-carbene-9-borafluorene monoanions is assessed, and a series of [K][9-CAAC-9-borafluorene] complexes (
Publisher: Wiley
Date: 06-09-2022
DOI: 10.1002/JCC.26995
Abstract: A theoretical investigation of ligand‐stabilized MX diatomics (M = group 13, X = group 15 element) with N ‐heterocyclic carbene (NHC) ligands has been carried out to assess bonding and electronic structure. Binding of two ligands in the form L‐MX‐L is generally preferred over binding of a single ligand as L‐MX or MX‐L. Binding of carbene donor ligands is predicted to be thermodynamically favorable for all the systems, and is very favorable for the lighter group 15 systems (nitrogen and phosphorus). Detailed analysis of the bonding in these complexes has been carried out with energy decomposition analysis (EDA). In all cases, the carbene to boron and carbene to nitrogen bonding is described as an electron‐sharing double bond with both σ and π bonding interactions. For the heavier elements, bonding to C (except for PC interactions) is best described as a donor‐acceptor σ single bond.
Publisher: Elsevier
Date: 2005
Publisher: Wiley
Date: 22-01-2020
Publisher: Wiley
Date: 22-09-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 1999
DOI: 10.1039/A901211G
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2OB01418A
Abstract: PhIBr 2 has been invoked as a brominating agent, however PhIBr 2 does not appear to exist but rather forms PhI and Br 2 , with Br 2 being responsible for bromination.
Publisher: Wiley
Date: 30-03-2017
Abstract: The endocyclic ring expansion of N-heterocyclic carbene (NHC) rings by transition metal (group 12) and main group (group 13-16) element hydrides has been investigated in a computational study. In addition to previously reported insertion reactivity with Si, B, Be and Zn, similar reactivity is predicted to be feasible for heavier group 13 elements (Al, Ga, In, Tl), with the reaction barriers for Al-Tl calculated to be lower than for boron. Insertion is not expected with group 15-16 element hydrides, as the initial adduct formation is thermodynamically unfavorable. The reaction pathway with group 12 hydrides is calculated to be more favorable with two NHCs rather than a single NHC (analogous to Be), however hydride ring insertion with metal dihydrides is not feasible, but rather a reduced NHC is thermodynamically favored. For group 14, ring-insertion reactivity is predicted to be feasible with the heavier dihydrides. Trends in reactivity of element hydrides may be related to the protic or hydridic character of the element hydrides.
Publisher: American Chemical Society (ACS)
Date: 16-08-2018
Abstract: Evidence and understanding of sulfur-centered hydrogen bonding, especially where the donor is a thiol, lags far behind that for conventional OH interactions. To help address this deficiency, conformer specific IR spectra of 2-phenylethanethiol (PET) and associated 1:1 solvent complexes have been measured in SH, OH, and CH stretch regions using resonant-two-photon-ionization (R2PI) and IR-UV ion dip spectroscopic techniques. The aromatic and aliphatic CH stretch regions show signature differences between anti and gauche conformers. Supported by ab initio calculations, a PET-water cluster with an OH···S arrangement and a PET-diethyl ether cluster expressing an SH···O interaction were identified. The SH stretch band of the SH···O complex is red-shifted and undergoes significant intensity enhancement compared to the bare molecule, which is characteristic of hydrogen bonding. These findings offer insight into the nature of the thiol functional group as a potential hydrogen bond donor and acceptor.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1DT02565A
Abstract: A study on the potential activating role of pyridine in the electrophilic chlorination of anisole by PhICl 2 has led to the discovery that soluble sources of chloride ions activate PhICl 2 in the reaction at catalytic loadings, greatly increasing the rate of chlorination.
Publisher: Elsevier BV
Date: 07-2007
Publisher: Wiley
Date: 24-01-2012
Publisher: Wiley
Date: 27-02-2019
Abstract: SuFEx is a new-generation click chemistry transformation that exploits the unique properties of S-F bonds and their ability to undergo near-perfect reactions with nucleophiles. We report here the first SuFEx-based procedure for the efficient synthesis of pharmaceutically important triflones and bis(trifluoromethyl)sulfur oxyimines from sulfonyl fluorides and iminosulfur oxydifluorides, respectively. The new process involves rapid S-F exchange with trifluoromethyltrimethylsilane (TMSCF
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3DT51503F
Abstract: A theoretical study focusing on the ring expansion that occurs in the reaction of N-heterocyclic carbenes with silanes has been carried out. A detailed reaction pathway was determined which indicates that formation of C-H bonds is the crucial factor in the transformation.
Publisher: American Chemical Society (ACS)
Date: 11-06-2021
Publisher: Wiley
Date: 07-05-2020
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.BMC.2016.03.048
Abstract: A series of isoquinolines have been evaluated in a homology model of Plasmodium falciparum Protein Kinase A (PfPKA) using molecular dynamics. Synthesis of these compounds was then undertaken to investigate their structure-activity relationships. One compound was found to inhibit parasite growth in an in vitro assay and provides a lead to further develop 3-methylisoquinoline-4-carbonitriles as antimalarial compounds. Development of a potent and selective PfPKA inhibitor would provide a useful tool to shed further insight into the mechanisms enabling malaria parasites to establish infection.
Publisher: Wiley
Date: 03-03-2020
Publisher: American Chemical Society (ACS)
Date: 24-05-2019
DOI: 10.1021/ACS.INORGCHEM.9B01058
Abstract: In the past two decades, the organometallic chemistry of the alkaline earth elements has experienced a renaissance due in part to developments in ligand stabilization strategies. In order to expand the scope of redox chemistry known for magnesium and beryllium, we have synthesized a set of reduced magnesium and beryllium complexes and compared their resulting structural and electronic properties. The carbene-coordinated alkaline earth-halides, (
Publisher: American Chemical Society (ACS)
Date: 12-10-2021
Publisher: Wiley
Date: 23-08-2012
DOI: 10.1002/JCC.23095
Abstract: The molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) and MM-generalized-Born surface area (MM-GBSA) approaches are commonly used in molecular modeling and drug design. Four critical aspects of these approaches have been investigated for their effect on calculated binding energies: (1) the atomic partial charge method used to parameterize the ligand force field, (2) the method used to calculate the solvation free energy, (3) inclusion of entropy estimates, and (4) the protonation state of the ligand. HIV protease has been used as a test case with six structurally different inhibitors covering a broad range of binding strength to assess the effect of these four parameters. Atomic charge methods are demonstrated to effect both the molecular dynamics (MD) simulation and MM-PB(GB)SA binding energy calculation, with a greater effect on the MD simulation. Coefficients of determination and Spearman rank coefficients were used to quantify the performance of the MM-PB(GB)SA methods relative to the experimental data. In general, better performance was achieved using (i) atomic charge models that produced smaller mean absolute atomic charges (Gasteiger, HF/STO-3G and B3LYP/cc-pVTZ), (ii) the MM-GBSA approach over MM-PBSA, while (iii) inclusion of entropy had a slightly positive effect on correlations with experiment. Accurate representation of the ligand protonation state was found to be important. It is demonstrated that these approaches can distinguish ligands according to binding strength, underlining the usefulness of these approaches in computer-aided drug design.
Publisher: Elsevier BV
Date: 03-2016
Publisher: Wiley
Date: 21-04-2017
Publisher: Wiley
Date: 27-12-2018
Abstract: The reactions of a monomeric borole and a dimeric borole with 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene were investigated. The monomeric borole reacted at ambient temperature whereas heat was required to crack the dimer to form the monomer and induce reactivity. 2,3-Dimethyl-1,3-butadiene reacts to give erse products resulting from a cycloaddition process with the B-C moiety of the boroles acting as a dienophile, followed by rearrangements to furnish bicyclic species. For 1,3-cyclohexadiene, a [4+2] process is observed in which 1,3-cyclohexadiene serves as the dienophile and the boroles as the diene partner. The experimental results are corroborated with mechanistic theoretical calculations that indicate boroles can serve as either a diene or dienophile in cycloaddition reactions with dienes.
Publisher: Wiley
Date: 07-05-2020
Publisher: American Chemical Society (ACS)
Date: 04-01-2022
DOI: 10.1021/JACS.1C11861
Publisher: Informa UK Limited
Date: 12-07-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8DT04433C
Abstract: A series of electrochemiluminescent iridium( iii ) N-heterocyclic carbene complexes have been prepared to tune electrochemical and spectroscopic behaviour.
Publisher: American Chemical Society (ACS)
Date: 29-08-2022
DOI: 10.1021/JACS.2C06845
Abstract: The first structurally characterized ex le of a trioxaborinanone (
Publisher: American Chemical Society (ACS)
Date: 23-09-2019
DOI: 10.1021/JACS.9B07370
Abstract: We report the discovery of a tandem catalytic process to reduce energy demanding substrates, using the [Ir(ppy)
Publisher: American Chemical Society (ACS)
Date: 08-12-2021
DOI: 10.1021/ACS.INORGCHEM.1C02800
Abstract: The reactions of boratabenzene and borataphenanthrene anions with group 11 Ph
Publisher: Inderscience Publishers
Date: 2015
Publisher: American Chemical Society (ACS)
Date: 16-09-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC01391A
Abstract: A new strategy to create iridium( iii )-based ECL labels reveals limitations of conventional approaches.
Publisher: Wiley
Date: 27-01-2017
Abstract: Experimental studies suggest that the compound (NHC
Publisher: Wiley
Date: 29-01-2020
Abstract: The synthesis and reactivity study of the first isolable boraphosphaketene, cyclic(alkyl)(amino) carbene (CAAC)-borafluorene-P=C=O (2), is described. Photolysis of compound 2 results in the formation of CAAC-stabilized BP-doped phenanthryne (3) through tandem decarbonylation, monoatomic phosphide insertion, and ring-expansion. Notably, while BN-doped phenanthryne was previously discussed as a reactive intermediate which could not be isolated, the heavier BP-doped analogue exhibits remarkable solution and solid-state stability. The reactivity of 2 with stable carbenes was also explored. Addition of CAAC to 2 led to migration of the original CAAC ligand from boron to phosphorus and coordination of the added CAAC to carbon, affording compound 4. Reaction of 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (NHC) with 2 resulted in N-C bond activation to give the unusual spiro-heterocyclic compound (5).
Publisher: Wiley
Date: 05-04-2022
Abstract: Borepin, a 7-membered boron-containing heterocycle, has become an emerging molecular platform for the development of new materials and optoelectronics. While electron-deficient borepins are well-established, reduced electron-rich species have remained elusive. Herein we report the first isolable, crystalline borepin radical (2 a, 2 b) and anion (3 a, 3 b) complexes, which have been synthesized by potassium graphite (KC
Publisher: American Chemical Society (ACS)
Date: 10-01-2014
DOI: 10.1021/IC402836D
Abstract: The results of the reactions of the dicationic iodine(III) family of oxidants [PhI(pyridine)2](2+) with model Pd(II) and Pt(II) complexes are described. Depending on the specific reaction pairs, a variety of outcomes are observed. For palladium, Pd(IV) complexes cannot be observed but are implicated in C-C and C-N bond formation for Pd(II) starting materials based on phenylpyridine and 2,2-bipyridine, respectively. Theoretical comparisons with similar processes for -Cl and -OAc rather than pyridine indicate that these provide greater thermodynamic stability, and our results here show that they also give greater kinetic stability (the failure of MP2 methods for these systems is quite dramatic). In contrast, oxidation and delivery of the pyridine ligands gives dicationic Pt(IV) complexes that may be isolated and structurally characterized.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2DT30375B
Abstract: The coordination preferences of the tetradentate Schiff base, N,N'-ethylenebis(acetylacetoimine), H(2)L, with a variety of group 13 precursors, led to the formation of a series of mono and binuclear products. The reaction of H(2)L with AlMe(3) and Me(2)GaCl afforded the binuclear complexes, [L{Al(Me)(2)}(2)] 1 and [H(2)L{GaCl(Me)(2)}(2)], 3, the latter an adduct of the neutral ligand. Treatment of 1 with iodine generated the cationic Al(III) complex, [LAl(thf)(2)]I, 2, while the addition of n-BuLi to H(2)L, followed by reaction with GaCl(3) and InCl(3) led to an ionic complex [{LGaCl}(2)(μLi)]GaCl(4), 4, an In(III) dimer, [LInCl](2), 5 and monomeric [LInCl(thf)], 6. In contrast, the reaction of [In{N(SiMe(3))(2)}(3)] with H(2)L yielded a homoleptic, air stable, indium complex, [L(3)In(2)], 7. All products were definitively characterized by X-ray crystallography and their structures confirmed by pertinent spectroscopic techniques.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3CP03399F
Abstract: The structure and NMR shielding of a set of N-F containing cations is reported to near-quantitative accuracy from extensive ab initio calculations. Currently, the shortest experimentally confirmed N-F bond is...
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/CH19237
Abstract: The attempted synthesis of N-heterocyclic carbene (NHC)-stabilised dicarbon (C2) fragments via nucleophilic substitution at 1,2-diiodoethane is reported. Rather than the expected SN2 pathway, clean elimination of ethene and formation of an iodoimidazolium cation was observed. The resistance towards nucleophilic substitution piqued interest, and subsequent investigation determined NHC-halogen bonding as the source. This is in contrast to reactions between NHCs and other alkyl halides, where substitution or elimination pathways are reported. A detailed theoretical study between these cases highlights the importance of iodine as a halogen bond donor compared with other halogens, and shows that NHCs are excellent halogen bond acceptors. This reactivity suggests potential for application of the halogen bonding interaction between NHCs and organic compounds.
Publisher: Wiley
Date: 03-09-2015
Abstract: Incorporating phenylpyridine- and triazolylpyridine-based ligands decorated with methylsulfonate or tetraethylene glycol (TEG) groups, a series of iridium(III) complexes has been created for green and blue electrogenerated chemiluminescence under analytically useful aqueous conditions, with tri-n-propylamine as a coreactant. The relative electrochemiluminescence (ECL) intensities of the complexes were dependent on the sensitivity of the photodetector over the wavelength range and the pulse time of the applied electrochemical potential. In terms of the integrated area of corrected ECL spectra, with a pulse time of 0.5 s, the intensities of the Ir(III) complexes were between 18 and 102 % that of [Ru(bpy)3 ](2+) (bpy=2,2'-bipyridine). However, when the intensities were measured with a typical bialkali photomultiplier tube, the signal of the most effective blue emitter, [Ir(df-ppy)2 (pt-TEG)](+) (df-ppy=2-(2,4-difluorophenyl)pyridine anion, pt-TEG=1-(2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)ethyl)-4-(2-pyridyl)-1,2,3-triazole), was over 1200 % that of the orange-red emitter [Ru(bpy)3 ](2+) . A combined experimental and theoretical investigation of the electrochemical and spectroscopic properties of the Ir(III) complexes indicated that the greater intensity from [Ir(df-ppy)2 (pt-TEG)](+) relative to those of the other Ir(III) complexes resulted from a combination of many factors, rather than being significantly favored in one area.
Publisher: American Chemical Society (ACS)
Date: 24-07-2002
DOI: 10.1021/JP0203503
Publisher: American Chemical Society (ACS)
Date: 02-09-2021
Publisher: Wiley
Date: 04-03-2019
Abstract: Although ultimately not isolable for X-ray structural characterization, the free perfluorinated trityl cation was shown to be observable in neat triflic acid, which represents milder conditions than previous reports of this cation in "magic acid" or oleum. A triflate-bound species could be generated in organic solvents using stoichiometric amounts of triflic acid and was shown to be synthetically viable for hydride abstraction from Et
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6DT00052E
Abstract: The reactions of molecules containing E–H functionalities (E = Group 15 or 16 element) and pentaphenylborole were investigated revealing erse outcomes.
Publisher: American Chemical Society (ACS)
Date: 22-09-2023
DOI: 10.1021/JACS.3C07236
Publisher: Wiley
Date: 21-04-2017
Abstract: We report the first ex le of an alkene with two carbon-bound substituents (imidazole and imidazolium rings) where the Z-isomer has a greater thermodynamic stability than the E-isomer which persists in both the gas phase and in solution. Theoretical calculations, solution fluorescence spectroscopy and gas-phase ion mobility mass spectrometry studies confirm the preference for the Z-isomer, the stability of which is traced to a non-covalent interaction between the imidazole lone pair and the imidazolium ring.
Publisher: Wiley
Date: 03-09-2019
Abstract: The first ex les of N-heterocyclic carbene (NHC) and cyclic(alkyl)(amino) carbene (CAAC) stabilized borepinium and borafluorenium heterocycles are reported herein. The optical properties of the heterocyclic borenium cations were tuned by varying the Lewis base and by changing the number of atoms in the ring. More importantly, functionalizing the cationic boron ring system in the NHC-borafluorenium cation affords a temperature-sensitive molecule with reversible colorimetric "turn off/turn on" properties in solution. Notably, this is the first report of thermochromism in these cationic species. This property, which is mediated by an intermolecular boron-oxygen bond equilibrium, was examined in detail by X-ray crystallography, variable temperature-UV/Vis absorption spectroscopy (VT-UV/Vis), and density functional theory (DFT).
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3DT52715H
Abstract: The synthesis, isolation and crystallographic characterization of the first N-heterocyclic carbene adducts of bismuth is reported, by direct reaction of the Dipp2NHC (Dipp = 2,6-diisopropylphenyl) or (i)Pr2(Me2)NHC with BiCl3. This represents the last non-radioactive element from groups 13-17 for which an NHC-element fragment remained unreported.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CP04056G
Abstract: By combining large basis and complete basis set (CBS) extrapolations of the coupled-cluster equilibrium geometry results with rovibrational and relativistic corrections, we demonstrate that it is possible to achieve near-quantitative accuracy for the NMR shielding constants in three group 15 trifluorides – NF 3 , PF 3 and AsF 3 .
Publisher: AIP Publishing
Date: 15-07-2008
DOI: 10.1063/1.2946699
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/CH19487
Abstract: Initial reports of ring expansion reactions (RER) of N-heterocyclic carbenes (NHCs) with main-group element hydrides have led to several synthetic and theoretical investigations, which include reports of insertion by Be, B, Al, Si, and Zn hydrides. The RERs generally lead to insertion of the heteroatom into the endocyclic C–N bond with formation of an expanded heterocyclic ring. Following the recent isolation of a P-heterocyclic carbene (PHC), here we report results from a computational study (RI-SCS-MP2/def2-TZVP//M06–2X/def2-TZVP) of RERs with a series of PHCs for the ring-insertion of silicon (SiH4, SiH2Ph2) and boron (BH3, BH2NMe2) hydrides. In order to explore the roles of both electronic and steric effects on PHCs and their reactivity, a series of P-substituent PHCR (R=H, Me, Ph, and bulky Ar groups) were investigated. Bulky R groups serve to maximise ring planarity and the σ-donating capability of the PHC. For RER, the PHC analogues exhibit facile initial hydride transfer from the main-group hydrides to the carbene carbon, with barriers that are substantially lower than with NHCs. However, the full ring insertion mechanisms for PHCs are, in general, kinetically unfavourable due to a large barrier associated with the ring-expansion step. While bulky P-substituents maximise heterocycle planarity towards that of NHCs, the RER reactivity with bulky PHCs does not reflect that of an NHC.
Publisher: Elsevier BV
Date: 08-2015
Publisher: Wiley
Date: 29-01-2020
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/CH13202
Abstract: A study on the bonding in bis-pyridine halonium cations has been carried out using both theoretical and synthetic techniques. The primary thrust for the study is to highlight the opportunities potentially afforded by considering iodine as a Lewis acid in a classic coordination sense. Our results suggest that the iodine dipyridine complex ([pyr-I-pyr]+) can be considered as a coordination complex of [I]+. The lighter bromine and chlorine analogues are more towards the covalent rather than the dative side of bonding, while [pyr-F-pyr]+ is best described as an ion-molecule complex with one strong covalent F-pyr bond and one weak F-pyr dispersion interaction. Finally, theoretical and synthetic studies suggest that the commercially available [pyr-F]+ cation cannot be considered as a coordination complex of ‘F+’, despite its use as a source of electrophilic fluorine.
Publisher: American Chemical Society (ACS)
Date: 03-03-2017
Publisher: American Chemical Society (ACS)
Date: 18-04-2011
DOI: 10.1021/CI2000677
Abstract: Resistance remains a major issue with regards to HIV-1 protease, despite the availability of numerous HIV-1 protease inhibitors and copious amounts of structural and binding data. In an effort to improve our understanding of how HIV-1 protease is able to "outsmart" new drugs, we have investigated the flexibility of HIV-1 protease and in particular how it adapts to different structural stresses. Our analysis has highlighted the effects of space group on the variability between structures of HIV-1 protease and suggests that consideration of multiple structures and appropriate consideration of different conformations of the Ile50 residue is necessary in any structural analysis. Calculation of the root-mean-square deviation on a per-residue basis has been used to identify 'natural variation', while mutational and ligand analyses have been carried out to identify the effect on structure as a result of specific stresses. It was observed that mutations readily cause changes to occur at sites both close to and distant from a mutation site, with changes more likely to occur at residues that are sites of other major mutations. It is also revealed that HIV-1 protease adaption is dependent on the type and the structure of any bound ligand. Identification of the specific changes that occur due to these stresses will aid in the understanding of resistance and also aid in the design of new drugs.
Publisher: Wiley
Date: 27-02-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7CP07365H
Abstract: The hydrogen bond acceptor strength of a series of halocarbons is studied by electronic and vibrational spectroscopy.
Publisher: AIP Publishing
Date: 15-06-2005
DOI: 10.1063/1.1935513
Abstract: A series of electric and magnetic properties of hexafluorobenzene have been calculated, including the electric dipole polarizability, magnetizability, electric quadrupole moment, and nonlinear mixed electric dipole-magnetic dipole-electric quadrupole hyperpolarizabilities needed to obtain estimates of the Kerr, Cotton-Mouton, Buckingham, Jones, and magnetoelectric birefringences in the vapor phase. Time-dependent density-functional theory was employed for the calculation of linear-, quadratic, and cubic response functions. A number of density functionals have been considered, along with Sadlej’s triple-ζ basis set and the augmented correlation-consistent polarized valence double zeta and augmented correlation-consistent polarized valence triple zeta basis sets. Comparisons have been made with experiment where possible. The analysis of results allows for an assessment of the capability of time-dependent density-functional theory for high-order electromagnetic properties of an electron-rich system such as hexafluorobenzene.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4DT00946K
Abstract: This frontier article summarizes the recent activity around a new mode of reactivity for N-heterocyclic carbenes: insertion of inorganic elements into the C–N bond of the carbene ring.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CP40828G
Abstract: The neurotransmitter analogue p-aminophenethylamine (APEA) illustrates many of the pitfalls and challenges associated with spectroscopic and conformational analysis of flexible molecules. The combined experimental-theoretical study presented here resolves a long-standing controversy over its conformational energetic preferences. Jet-cooled resonance enhanced two-photon ionisation (R2PI) and IR-UV ion depletion techniques enabled conformer-specific IR spectra in the NH-CH stretch region to be measured for four distinct conformers of APEA. Comparison of spectra with theoretical calculations (including MP2, M06-2X and B3LYP with aug-cc-pVTZ basis sets) allows the two most populated conformers to be unambiguously identified as those having a gauche arrangement of the side chain, which facilitates an NH···π type hydrogen bond. The other two observed conformers are assigned to structures with an anti-side chain. A fifth gauche conformer, predicted to be least stable, is not observed. Comparison with published conformer specific IR spectra of tyramine (Makara et al., J. Phys. Chem. A, 2008, 112, 13463-13469) and Raman spectra of phenylethylamine (Golan et al., J. Chem. Phys., 2009, 131, 024305) reveals an entirely consistent pattern of spectral signatures associated with the four specific conformations of the ethylamine side chain evident in APEA, and aids assignment of the associated CH and NH stretch fundamentals, some of which have very weak IR intensities. Extensive calculations of the relative energetic trends of the five conformers have been carried out. In comparison to the highest level of theory considered, CCSD(T)-F12b/cc-pVDZ-F12, MP2 overestimate the energy difference, whereas DFT significantly underestimates the energetic preference for NH···π stabilised gauche conformers, although inclusion of dispersion (M06-2X, B3LYP-D3) improves the DFT results.
Publisher: Informa UK Limited
Date: 20-02-2005
Publisher: American Chemical Society (ACS)
Date: 25-03-2016
Publisher: American Chemical Society (ACS)
Date: 03-2016
DOI: 10.1021/ACS.INORGCHEM.5B02667
Abstract: In this paper we report on the use of [NO][BF4] to access tricationic tetrakis(pyridine)gold(III) from Au powder, a species inaccessible using the more traditional (tetrahydrothiophene)AuCl route. It is then demonstrated that this family of compounds can be used to access new terminal Au(III) hydroxides, a challenging class of compounds, and the first crystallographically characterized ex les employing bidentate ligands. Finally, preliminary biological studies indicate good activity for derivatives featuring polydentate ligands against the HeLa and PC3 cell lines but also strong inhibition of primary HUVEC cells.
Publisher: American Chemical Society (ACS)
Date: 13-06-2022
DOI: 10.1021/ACS.INORGCHEM.2C00930
Abstract: Borole-doped polycyclic aromatic hydrocarbons (PAHs) have garnered attention in recent years due to their attractive photophysical properties and potential utility in electronic devices. In this work, a borole-doped PAH, 12-boradibenzofluorene, is synthesized and formal intermolecular nitrene and oxygen atom insertion reactions were employed to access 1,2-azaborine- and 1,2-oxaborine-containing analogues of the carbonaceous PAH pentaphene. Iodosobenzene is established as a versatile reagent for oxygen atom insertion reactions into a variety of borole species to access 1,2-oxaborine systems.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0SC06851A
Abstract: The direct chemical reduction of CAACCO2 adducts by alkali metals to yield multinuclear clusters is reported. The mono- and dianions of CO 2 have been studied for decades and are fundamentally important oxycarbanions and critical species in CO 2 fixation chemistry.
Publisher: American Chemical Society (ACS)
Date: 28-06-2018
DOI: 10.1021/ACS.ORGLETT.8B01673
Abstract: A convenient method for the synthesis of 1,2,4-triazol-3-imines through a selective, formal, 1,3-dipolar cycloaddition of organo-cyanamide ions with nitrile imine dipoles is reported. Hydrolysis of the 1,2,4-triazol-3-imines yields the corresponding 1,2,4-triazol-5-ones. A stepwise mechanism, supported by DFT calculations, is invoked to explain the reaction selectivity.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7DT01370A
Abstract: A theoretical evaluation of the unknown addition of diorganoberyllium to model alkenes and alkynes (carboberyllation) shows the reaction with alkynes should be feasible. In contrast with carboboration a 1,2-regioselectivity is predicted.
Publisher: American Chemical Society (ACS)
Date: 10-10-2013
DOI: 10.1021/OM400800D
Publisher: Wiley
Date: 13-09-2013
Abstract: The study of ligand stabilised mono- and diatomic zero oxidation state complexes is a young and fascinating topic. This area merges the fields of low-oxidation-state main-group chemistry, homoatomic multiple bonding and fundamental coordination chemistry. As with a great deal of recent coordination chemistry within the d-block, carbene ligands are clearly the star of the show, highlighting their importance within the p-block as well. This Minireview focuses on the significant developments of the past two years.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4DT03549F
Abstract: A straightforward synthesis of a new type of iodine( iii ) complex is presented – an N ′ N chelated [ICl 2 ] + cation.
Publisher: Elsevier BV
Date: 09-2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7DT03046K
Abstract: Reaction of phenylsilane with the ring expanded carbene 6-Mes results in facile Si-H oxidative addition to the carbenic carbon at room temperature. Heating the resultant diorganosilane product induces ring expansion through silicon to carbon migration of either the Si-H or Si-Ph bonds.
Publisher: American Chemical Society (ACS)
Date: 30-04-2015
DOI: 10.1021/ACS.INORGCHEM.5B00537
Abstract: We report a novel C-H to C-N bond metathesis at the 3-position of 1,2-diphenyltellurophene via oxidation of the Te(II) center to Te(IV) using the I(III) oxidant [PhI(4-DMAP)2](2+). Spontaneous reduction of a transient Te(IV) coordination compound to Te(II) generates an electrophilic equivalent of 4-DMAP that substitutes at a C-H bond at the 3-position of the tellurophene. Theoretical and synthetic reaction pathway studies confirm that a Te(IV) coordination complex with 4-DMAP is an intermediate. In the course of these pathway studies, it was also found that the identity of the I(III) oxidant generated from PhI(OAc)2 and 2 TMS-OTf is PhI(OAc)(OTf) and not PhI(OTf)2, as had been previously thought.
Publisher: Wiley
Date: 27-12-2023
Abstract: The addition of non‐benzenoid quinones, acenapthenequinone or aceanthrenequinone, to the 9‐carbene‐9‐borafluorene monoanion ( 1 ) affords the first ex les of dianionic 10‐membered bora‐crown ethers ( 2 – 5 ), which are characterized by multi‐nuclear NMR spectroscopy ( 1 H, 13 C, 11 B), X‐ray crystallography, elemental analysis, and UV/Vis spectroscopy. These tetraoxadiborecines have distinct absorption profiles based on the positioning of the alkali metal cations. When compound 4 , which has a vacant C 4 B 2 O 4 cavity, is reacted with sodium tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate, a color change from purple to orange serves as a visual indicator of metal binding to the central ring, whereby the Na + ion coordinates to four oxygen atoms. A detailed theoretical analysis of the calculated reaction energetics is provided to gain insight into the reaction mechanism for the formation of 2 – 5 . These data, and the electronic structures of proposed intermediates, indicate that the reaction proceeds via a boron enolate intermediate.
Publisher: Wiley
Date: 05-04-2022
Abstract: Borepin, a 7‐membered boron‐containing heterocycle, has become an emerging molecular platform for the development of new materials and optoelectronics. While electron‐deficient borepins are well‐established, reduced electron‐rich species have remained elusive. Herein we report the first isolable, crystalline borepin radical ( 2 a , 2 b ) and anion ( 3 a , 3 b ) complexes, which have been synthesized by potassium graphite (KC 8 ) reduction of cyclic(alkyl)(amino) carbene‐dibenzo[b,d]borepin precursors. Borepin radicals and anions have been characterized by EPR or NMR, elemental analysis, X‐ray crystallography, and cyclic voltammetry. In addition, the bonding features have been investigated computationally using density functional theory.
Publisher: American Chemical Society (ACS)
Date: 08-03-2013
DOI: 10.1021/OM4000133
Publisher: Wiley
Date: 16-08-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CC04725F
Abstract: I( iii ) reagent [PhI(Pyr) 2 ] 2+ (Weiss’ reagent) can be activated with borane Lewis acids in which a pyridine ligand is abstracted giving a more reactive derivative of the reagents.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8DT02020E
Abstract: We have carried out a theoretical investigation of benzene substituted with BeO to assess stability and aromatic properties (with 1–3 BeO units in a six-membered ring) C 4 H 4 BeO, C 2 H 2 Be 2 O 2 , and Be 3 O 3 .
Publisher: American Chemical Society (ACS)
Date: 02-10-2018
Abstract: A new class of redox metallopolymer based on cyclometalated iridium(III) centers is described, with unusually intense luminescence properties in aqueous media. We report the facile synthesis, photophysical and electrochemical characterization, supported by DFT calculations and their electrochemiluminescence (ECL) properties which, under some circumstances, are significantly greater than the analogous ruthenium-based materials. The photoluminescence (PL) and ECL of these materials are further dramatically enhanced when dispersed or immobilized as polymeric nanoparticles (PNPs). This aggregation-induced emission (AIE and AIECL) operates by providing important protection for the cyclometalated iridium(III) centers against the types of quenching processes which commonly afflict iridium-based luminophores in aqueous media. The results suggest interesting new avenues of research for the application of such materials in and PL and ECL-based detection and imaging as well as light-emitting devices.
Publisher: Wiley
Date: 07-06-2013
DOI: 10.1002/AOC.3003
Publisher: American Chemical Society (ACS)
Date: 16-08-2005
DOI: 10.1021/CT050101T
Abstract: The rotational g factor for a large number of organic compounds has been investigated with density-functional theory. Rapid convergence toward the basis-set limit is ensured by the use of London atomic orbitals. A statistical analysis of the results has been carried out in comparison with accurate experimental data. It is shown that gradient-corrected and hybrid functionals reproduce experimental results most closely, with the Keal-Tozer KT2 functional being the most accurate.
Publisher: Wiley
Date: 10-09-2014
Abstract: A computational study has been carried out to examine the feasibility of generating a simple monocyclic cyclopentadienyl cation that may be sufficiently stable to isolate and handle at ambient temperatures. Using judicious placement of electron-withdrawing groups (CF3) about the ring we have identified a derivative that may approach the stability of isolobal (and isolatable) borole rings, as evaluated by HOMO-LUMO and singlet-triplet gaps. These Cp(+) derivatives may therefore be an attractive target for synthetic isolation.
Publisher: Elsevier BV
Date: 11-2002
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6DT01129B
Abstract: Ag( i ) complexes with diNHC ligands are efficient transmetalating agents towards transition metals.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CP00498G
Abstract: The ground state potential energy surfaces (PESs) of MH(2)(n+) (M = Li, Be, Na, Mg, K, Ca n = 1, 2) have been investigated using relativistically corrected, coupled-cluster (CC) and multi-reference configuration interaction (MRCI) methods. The PESs for MH(2)(+) (M = Li, Na, K) and MH(2)(n+) (M = Be, Mg, Ca n = 1, 2) exhibit global minima corresponding to C(2v) symmetry equilibrium structures, with local minima for D(∞h) and C(∞v) symmetry states. Conversely, the ground state PESs of LiH(2)(2+), NaH(2)(2+) and KH(2)(2+) are repulsive. In all cases, the D(∞h) states resulting from the insertion of M(n+) into the H(2) moiety were significantly higher in energy than the co-linear C(2v) states. It is generally assumed a priori that these species are the result of the interaction between the metal ion charge state and the quadrupole moment of the H(2) moiety. However, analysis of the functional ΔΘ(αα)(R(M(n+)-H(2))) = Θ(αα)(MH(2)(n+)) - Θ(αα)(M(n+)) (which is effectively the difference between traceless quadrupole moments (Θ(αα)) of MH(2)(n+) and the isolated M(n+) ion computed using MRCI) as a function of M(n+)-H(2) distance demonstrates that a local maximum in ΔΘ(αα) along the molecular C(2) axis is necessary for the formation of a thermodynamically stable complex. It is concluded that the topology of ΔΘ(αα) provides a convenient indicator of the stability of such molecular ion-quadrupole complexes.
Publisher: American Chemical Society (ACS)
Date: 09-2015
DOI: 10.1021/ACS.INORGCHEM.5B01040
Abstract: The reactions of pentaphenylborole with imines, isocyanides, and acetonitrile were investigated experimentally and theoretically. On the basis of literature precedent, we envisioned that the dipolar substrates would undergo facile ring expansion reactions to yield new BNC5 heterocycles. For acetonitrile and one particular imine, this ring expansion process was observed. However, in many cases, unexpected reactivity occurred. This included hydride migration of an imine ring expanded product and the ortho C-H bond activation of an aryl group of an imine if two phenyl groups were present on the α-carbon. A bulky group on the nitrogen atom of an imine prevented coordination to the boron center, and no reaction was observed, indicating that coordination to the borole is a critical step for any type of reaction to occur. Isocyanides made coordination complexes, but heating to induce further reactivity resulted in mixtures. The mechanisms were elucidated via DFT calculations, which complement the experimental findings.
Publisher: American Chemical Society (ACS)
Date: 16-05-2018
Publisher: Elsevier BV
Date: 09-2006
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5AN01462J
Abstract: A simple graphical approach to characterise the energetically feasible electrogenerated chemiluminescence (ECL) reaction pathways with tri- n -propylamine is discussed.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4DT03566F
Abstract: The effect of varying the N-heterocyclic carbene (NHC) ligand on the ring expansion and endocyclic C–N activation of NHCs by silanes and boranes has been investigated with theoretical methods.
Publisher: Springer Science and Business Media LLC
Date: 13-11-2013
DOI: 10.1007/S00894-012-1660-4
Abstract: X-ray crystallography studies have identified that most cyclic inhibitors of HIV protease (including cyclic ureas) bind in a symmetric manner, however some cyclic inhibitors, such as cyclic sulfamides, bind in a non-symmetric manner. This raises the question as to whether it is possible for cyclic sulfamides to bind symmetrically and conversely for cyclic ureas to bind non-symmetrically. Herein we report an analysis of the conformational preference of cyclic ureas and sulfamides both free in solution and bound to HIV protease, including an investigation of the effect of branching. Quantum chemical calculations (B3LYP, M06-2X, MP2, CCSD(T)) predict the cyclic urea to prefer a symmetric conformation in solution, with a large activation barrier towards inter-conversion to the non-symmetric conformation. This differs from the cyclic sulfamides, which marginally prefer a non-symmetric conformation with a much smaller barrier to inter-conversion making it more likely for a non-preferred conformation to be observed. It is predicted that the cyclic scaffold itself favours a symmetric form, while branching induces a preference for a non-symmetric form. MD simulations on the free inhibitors identified inter-conversion with the cyclic sulfamides but not the cyclic ureas, in support of the quantum chemical results. MM-PB(GB)SA calculations on the cyclic inhibitors bound to HIV protease corroborate the X-ray crystallography studies, identifying the cyclic ureas to bind symmetrically and the cyclic sulfamides in a non-symmetrical manner. While the non-preferred form of the sulfamide may well be present as a free molecule in solution, our results suggest that it is unlikely to bind to HIV protease in a symmetric manner.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0AN00952K
Abstract: Using a combination of electrochemical, spectroscopic and computational techniques, we have explored the fundamental properties of a series of ruthenium diimine complexes designed for coupling with other molecules or surfaces for electrochemiluminescence (ECL) sensing applications. With appropriate choice of ligand functionality, it is possible to manipulate emission wavelengths while keeping the redox ability of the complex relatively constant. DFT calculations show that in the case of electron withdrawing substituents such as ester or amide, the excited state is located on the substituted bipyridine ligand whereas in the case of alkyl functionality it is localised on a bipyridine. The factors that dictate annihilation ECL efficiency are interrelated. For ex le, the same factors that determine ΔG for the annihilation reaction (i.e. the relative energies of the HOMO and LUMO) have a corresponding effect on the energy of the excited state product. As a result, most of the complexes populate the excited state with an efficiency (Φ(ex)) of close to 80% despite the relatively wide range of emission maxima. The quantum yield of emission (Φ(p)) and the possibility of competing side reactions are found to be the main determinants of ECL intensity.
Publisher: Wiley
Date: 27-12-2023
Abstract: The addition of non‐benzenoid quinones, acenapthenequinone or aceanthrenequinone, to the 9‐carbene‐9‐borafluorene monoanion ( 1 ) affords the first ex les of dianionic 10‐membered bora‐crown ethers ( 2 – 5 ), which are characterized by multi‐nuclear NMR spectroscopy ( 1 H, 13 C, 11 B), X‐ray crystallography, elemental analysis, and UV/Vis spectroscopy. These tetraoxadiborecines have distinct absorption profiles based on the positioning of the alkali metal cations. When compound 4 , which has a vacant C 4 B 2 O 4 cavity, is reacted with sodium tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate, a color change from purple to orange serves as a visual indicator of metal binding to the central ring, whereby the Na + ion coordinates to four oxygen atoms. A detailed theoretical analysis of the calculated reaction energetics is provided to gain insight into the reaction mechanism for the formation of 2 – 5 . These data, and the electronic structures of proposed intermediates, indicate that the reaction proceeds via a boron enolate intermediate.
Publisher: American Chemical Society (ACS)
Date: 05-08-2019
DOI: 10.1021/ACS.INORGCHEM.9B01643
Abstract: Recent synthetic efforts have uncovered several bond activation pathways mediated by beryllium. Having the highest charge density and electronegativity, the chemistry of beryllium often erges from that of its heavier alkaline earth metal congeners. Herein, we report the synthesis of a new carbodicarbene beryllacycle (
Publisher: American Chemical Society (ACS)
Date: 17-08-2023
Publisher: Wiley
Date: 24-10-2018
Abstract: The endocyclic ring expansion of N-heterocyclic carbene (NHC) rings containing one N atom and one P, N, C, O or S heteroatom has been investigated in a computational study. Ring expansion was determined to follow a common pathway, leading to a final expanded six-membered ring that was predicted to be thermodynamically stable for all heterocycles. However, reactivity is driven by kinetics with ring-expansion reactivity not expected for the P/NHC and C/NHC (cAAC) containing heterocycles due to large barriers for ring-expansion. In contrast, ring expansion is predicted to be feasible for N-heterocyclic carbenes containing an O (O/NHC) or S (S/NHC) heteroatom, with insertion into the O-C and S-C bond favoured over insertion into the N-C bond, respectively.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CC01567B
Abstract: PhICl 2 reacts with pyridine to form a simple coordination complex via halogen bonding and does not result in an activated [PhI(Pyr)(Cl)] + cation as previously proposed.
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B208640A
Publisher: Wiley
Date: 14-01-2015
Abstract: The attempted synthesis of NHC-stabilized dicarbon (NHC=C=C=NHC) through deprotonation of a doubly protonated precursor ([NHC-CH=CH-NHC](2+) ) is reported. Rather than deprotonation, a clean reduction to NHC=CH-CH=NHC is observed with a variety of bases. The apparent resistance towards deprotonation to the target compound led to a reinvestigation of the electronic structure of NHC→CC←NHC, which showed that the highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO/LUMO) gap is likely too small to allow for isolation of this species. This is in contrast to the recent isolation of the cyclic alkylaminocarbene analogue (cAAC=C=C=cAAC), which has a large HOMO-LUMO gap. A detailed theoretical study illuminates the differences in electronic structures between these molecules, highlighting another case of the potential advantages of using cAAC rather than NHC as a ligand. The bonding analysis suggests that the dicarbon compounds are well represented in terms of donor-acceptor interactions L→C2 ←L (L=NHC, cAAC).
Publisher: American Chemical Society (ACS)
Date: 21-08-2014
DOI: 10.1021/JA506365M
Abstract: We report the first ex les of Au(III) tricationic complexes bound only by neutral monodentate ligands, which are a new class of gold reagents. Oxidative addition to the bis-pyridine Au(I) cation, [Au(4-DMAP)2](+), using a series of dicationic I(III) oxidants of the general form [PhI(L)2](2+) (L = pyridine, 4-DMAP, 4-cyanopyridine) allows ready access to homoleptic and pseudo-homoleptic Au(III) complexes [Au(4-DMAP)2(L)2](3+). The facile oxidative addition of Au(I) species additionally demonstrates the efficacy of PhI(L)2](2+) reagents as halide-free oxidants for Au(I). Comparisons are made via attempts to oxidize NHC-Au(I)Cl, where introduction of the chloride anion results in complex mixtures via ligand and chloride exchange, demonstrating the advantage of using the pyridine-based homoleptic compounds. The new Au(III) trications show intriguing reactivity with water, yielding dinuclear oxo-bridged and rare terminal Au(III)-OH complexes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0DT02177F
Abstract: A family of four Ir( iii ) complexes with either pyridyl-1,2,4-triazole or pyridyl-1,3,4-oxadiazole ligands bearing boronic acid groups have been prepared as potential luminescent sensors for carbohydrates.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CC03400A
Abstract: 1,2-Dibromoethane-1-sulfonyl fluoride ( DESF ): a bench stable and readily accessible precursor to BESF for the synthesis of β-sultams, sulfonyl fluoride substituted isoxazoles, triazoles and Michael adducts with SuFEx-able pendant sulfonyl fluoride handles.
Publisher: Wiley
Date: 07-05-2015
Publisher: Wiley
Date: 02-10-2013
Abstract: The photophysical and related properties of platinum(II) Schiff base complexes can be finely and predictably tuned over a wide range of wavelengths by small and easily implemented changes to ligand structure. A series of such complexes, differing only in the number and positioning of methoxy substituents on the phenoxy ring, were synthesised and their photophysical, electrochemical and electrochemiluminescent (ECL) properties investigated. Theoretical calculations were performed in order to gain further insight into the relationship between structure and properties in these materials. By positioning methoxy groups para and/or ortho to either the imine or the oxygen group on the ligand, electron density could be directed selectively toward the LUMO or HOMO as required. This allowed the emission colour (both photoluminescent and electrochemiluminescent) to be tuned over a wide range between 587 and 739 nm. The variation in orbital energies was also manifested in the positions of the absorption bands and the redox properties of the complexes, as well as in the NMR shifts for the uncoordinated ligands. All reported complexes displayed intense electrochemiluminescence (ECL), which could be initiated either by annihilation or co-reactant pathways. The relationship between the electrochemical and photophysical properties and the efficiency of the ECL is discussed. For two of the complexes solid-state ECL could be generated from electrodeposited layers of the complex.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4DT03378G
Abstract: Theoretical and experimental studies of a series of iridium N-heterocyclic carbene complexes.
Publisher: Wiley
Date: 03-03-2014
Abstract: Compared to tris(2-phenylpyridine)iridium(III) ([Ir(ppy)3 ]), iridium(III) complexes containing difluorophenylpyridine (df-ppy) and/or an ancillary triazolylpyridine ligand [3-phenyl-1,2,4-triazol-5-ylpyridinato (ptp) or 1-benzyl-1,2,3-triazol-4-ylpyridine (ptb)] exhibit considerable hypsochromic shifts (ca. 25-60 nm), due to the significant stabilising effect of these ligands on the HOMO energy, whilst having relatively little effect on the LUMO. Despite their lower photoluminescence quantum yields compared with [Ir(ppy)3 ] and [Ir(df-ppy)3 ], the iridium(III) complexes containing triazolylpyridine ligands gave greater electrogenerated chemiluminescence (ECL) intensities (using tri-n-propylamine (TPA) as a co-reactant), which can in part be ascribed to the more energetically favourable reactions of the oxidised complex (M(+) ) with both TPA and its neutral radical oxidation product. The calculated iridium(III) complex LUMO energies were shown to be a good predictor of the corresponding M(+) LUMO energies, and both HOMO and LUMO levels are related to ECL efficiency. The theoretical and experimental data together show that the best strategy for the design of efficient new blue-shifted electrochemiluminophores is to aim to stabilise the HOMO, while only moderately stabilising the LUMO, thereby increasing the energy gap but ensuring favourable thermodynamics and kinetics for the ECL reaction. Of the iridium(III) complexes examined, [Ir(df-ppy)2 (ptb)](+) was most attractive as a blue-emitter for ECL detection, featuring a large hypsochromic shift (λmax =454 and 484 nm), superior co-reactant ECL intensity than the archetypal homoleptic green and blue emitters: [Ir(ppy)3 ] and [Ir(df-ppy)3 ] (by over 16-fold and threefold, respectively), and greater solubility in polar solvents.
Publisher: Wiley
Date: 03-02-2020
Publisher: IOP Publishing
Date: 24-02-2016
DOI: 10.1088/0957-4484/27/13/135606
Abstract: β(3)-amino acid based polypeptides offer a unique starting material for the design of self-assembled nanostructures such as fibres and hierarchical dendritic assemblies, due to their well-defined helical geometry in which the peptide side chains align at 120° due to the 3.0-3.1 residue pitch of the helix. In a previous work we have described the head-to-tail self-assembly of N-terminal acetylated β(3)-peptides into infinite helical nanorods that was achieved by designing a bioinspired supramolecular self-assembly motif. Here we describe the effect of consecutively more polar side chains on the self-assembly characteristics of β(3)-tetrapeptides Ac-β (3)Ala-β(3)Leu-β(3)Ile-β(3)Ala (Ac-β(3)[ALIA]), Ac-β(3)Ser-β(3)Leu-β(3)Ile-β(3)Ala (Ac-β(3)[SLIA]) and Ac-β (3)Lys-β (3)Leu-β(3)Ile-β (3)Glu (Ac-β(3)[KLIE]). β(3)-tetrapeptides complete 1 1/3 turns of the helix: thus in the oligomeric form the side chain positions shift 120° with each added monomer, forming a regular periodic pattern along the nanorod. Dynamic light scattering (DLS) measurements confirmed that these peptides self-assemble even in highly polar solvents such as water and DMSO, while diffusion-ordered NMR spectroscopy revealed the presence of a substantial monomeric population. Temperature dependence of the size distribution in DLS measurements suggests a dynamic equilibrium between monomers and oligomers. Solution casting produced distinct fibrillar deposits after evaporating the solvent. In the case of the apolar Ac-β(3)[ALIA] the longitudinal helix morphology gives rise to geometrically defined (∼70°) junctions between fibres, forming a mesh that opens up possibilities for applications e.g. in tissue scaffolding. The deposits of polar Ac-β(3)[SLIA] and Ac-β(3)[KLIE] exhibit fibres in regular parallel alignment over surface areas in the order of 10 μm.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CP01737A
Abstract: The annihilation electrogenerated chemiluminescence of mixtures of Ir( iii ) complexes is eliminated by manipulating reduction potentials through subtle changes in ligand structure.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CP02730H
Abstract: NMR shielding and spin–spin coupling constants of cis and trans isomers of FNNF have been determined to near-quantitative accuracy from ab initio calculations.
Publisher: American Chemical Society (ACS)
Date: 26-03-2016
DOI: 10.1021/ACS.INORGCHEM.6B00222
Abstract: A new synthetic methodology has been developed for the preparation of heterobimetallic group 11 and group 12 complexes of a symmetrical bis-NHC "pincer" ligand. The synthetic route involved the initial preparation of a mononuclear [Au(NHC)2](+) complex with pendent imidazole moieties on the NHC ligands. Subsequent alkylation of the imidazole groups with Et3OBF4 and metalation with a second metal ion (Ag(I) or Hg(II)) provided two heterobimetallic complexes. Four homobimetallic (Cu(I)2, Ag(I)2, Au(I)2, and Hg(II)2) complexes of the same bis-NHC "pincer" ligand were also prepared. The homobimetallic Cu(I)2, Au(I)2, and Hg(II)2 complexes and heterobimetallic Au(I)-Ag(I) and Au(I)-Hg(II) complexes and the synthetic intermediates for the heterobimetallic complexes were characterized by X-ray crystallography. These X-ray structures show that the bimetallic complexes adopt "twisted" conformations in the solid state, supporting short M···M interactions. Crystalline s les of the homobimetallic Ag(I)2 and Au(I)2 and heterobimetallic Au(I)-Ag(I) and Au(I)-Hg(II) complexes were emissive at room temperature and at 77 K. The geometries of the synthesized complexes were optimized at the M06-L/def2-SVP level of theory, and the electronic nature of the M···M interactions for all synthesized complexes was investigated using natural bond orbital (NBO) calculations.
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B606467A
Abstract: Multi-reference configuration interaction (MRCI) calculations have been employed to characterize the low-lying states of first-row transition metal dihelide dications, He(2)TM(2+) (TM = Sc-Cu). The most important state-ordering principles were determined to be the occupation of the 4s orbital and orientation of the occupied 3d orbital. The ground states of all species are predicted to be of D(infinityh) symmetry arising from a 3d(n+1) electronic configuration. For excited states with singly occupied 4s or doubly occupied 3d(sigma) orbitals, bending to C(2v) symmetry typically lowers the energy and shortens the He-TM bond length. Coupled cluster singles and doubles with a perturbative treatment of triple excitations (CCSD(T)) results for ground state spectroscopic properties are in agreement with the MRCI predicted trends.
Publisher: Wiley
Date: 03-01-2012
Start Date: 10-2010
End Date: 12-2010
Amount: $530,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 03-2016
End Date: 12-2019
Amount: $433,819.00
Funder: Australian Research Council
View Funded Activity