Australian Journal of Chemistry

Published by CSIRO Publishing
Online ISSN: 0004-9425
Publications
Article
Six new anthraquinone-γ-pyrones, saliniquinones A-F (1-6), which are related to metabolites of the pluramycin/altromycin class, were isolated from a fermentation broth of the marine actinomycete Salinispora arenicola (strain CNS-325). Their structures were determined by analysis of one- and two-dimensional NMR spectroscopic and high-resolution mass spectrometric data. The relative and absolute configurations of compounds 1-6 were determined by analysis of NOESY NMR spectroscopic data and by comparison of circular dichroism and optical rotation data with model compounds found in the literature. Saliniquinone A (1) exhibited potent inhibition of the human colon adenocarcinoma cell line (HCT-116) with an IC50 of 9.9 × 10(-9) M. In the context of the biosynthetic diversity of S. arenicola, compounds 1-6 represent secondary metabolites that appear to be strain specific and thus occur outside of the core group of compounds commonly observed from this species.
 
Article
N-heterocyclic carbenes (NHCs) promote the addition of 1,1-bis(phenylsulfonyl)ethylene to the α-position of α,β-unsaturated aldehydes. The proposed reaction pathway for this Rauhut-Currier-type reaction includes an unusual conjugate addition of an NHC to a bis-vinyl sulfone.
 
Article
The thiazolidinedione, compound 1, has previously shown pan-inhibition of the phosphoinositide 3-kinase (PI3K) class I isoforms. We hypothesized the derivatization of the thiazolidinedione core of compound 1 could introduce isoform selectivity. We report the synthesis, characterization, and inhibitory activity of a novel series of 4-iminothiazolidin-2-ones for inhibition of the class I PI3K isoforms. Their synthesis was successfully achieved by multiple pathways described in this paper. Initial in vitro data of 28 analogues demonstrated poor inhibition of all class I PI3K isoforms. However, we identified an alternate target, the phosphodiesterases, and present preliminary screening results showing improved inhibitory activity.
 
GPC trace overlay of 2a, 2b, 3, 4.  
Article
Ionomers containing sodium 4-styrene sulfonate (4SS) and poly(ethylene glycol) methyl ether acrylate (PEGA) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymerization was mediated by 1-phenylethyl dithiobenzoate chain transfer agent in a dimethylformamide/water solvent system. Well-defined copolymers of pPEGA-co-4SS were produced with molecular weights ranging from 10 kDa to 40 kDa and polydispersity indices (PDIs) of 1.06-1.18 by gel permeation chromatography (GPC) against monodisperse poly(methyl methacrylate) (PMMA) standards. Post polymerization, the dithioester was reduced and trapped in situ with divinyl sulfone to produce a well-defined, semitelechelic pPEGA-co-4SS Michael acceptor polymer. UV-vis, infrared, and (1)H NMR spectroscopy confirmed that the integrity of the polymer backbone was maintained and that the vinyl sulfone was successfully incorporated at the chain end.
 
Article
A rhodamine based boronic acid linearly responds to increasing 5-aminoimidazole-4-carboxamide riboside (AICAr) concentrations in human urine. This method is thus an advance in detecting adenylosuccinate lyase (ADSL) deficiency as AICAr is a model riboside for the ADSL substrates succinyladenosine (S-Ado) and succinylaminoimidazolecarboxamide riboside (SAICAr). ADSL deficiency is a rare but devastating disease of de novo purine synthesis in infants. Its diagnosis is also significant as it is one of the autism spectrum disorders.
 
Article
Thin films of 1,3-diethylbenzimidazol-2-ylidene (BIEt) were fabricated from THF solution on solid gold substrates and characterised by high-resolution X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy. The surface-analytical data are in accord with the formation of self-assembled monolayers of BIEt molecules exhibiting an approximately vertical orientation on the substrate. The crystal structure of (BIEt)(2) was also determined.
 
Article
A powerful combination of chemically specific Raman excitation and deep tissue ultrasound imaging holds the promise to attain spatially resolved distribution of chemical compounds inside the scattering medium. In this report, an attempt is made to evaluate the recent achievements and possible challenges with an eye on potential clinical applications.
 
The optical image of an isolated rod photoreceptor cell is shown (A). The dotted lines denote the boundary of the nucleus & inner segment as well as the boundary of the inner and outer segment of the cell. Raman spectra averaged over the different cell regions are shown (B-D). A reference spectrum comprised of 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3phosphocholine and cholesterol is shown for comparison.
The band area ratios comparing the intensity of the 1655 cm −1 band representative of docosahexaenoyl acyl chains relative to the 715 cm −1 choline mode (red) and C − H deformations (white) are plotted for the ROIs depicted in figure 2. The lines are guides for the eye.  
An isolated rod photoreceptor is depicted as viewed under white illuminiation in the Raman microscope (A). The numbered regions indicate the location from which Raman spectra are collected and analyzed. Deconvolution of the Raman spectra (B) from the indicated regions show decreasing cholesterol contribution along the Rod cell. The Raman spectrum of cholesterol is provided to indicate the expected location of a cholesterol band. The relative cholesterol gradient is graphed against the normalized length of the cell showing decreasing cholesterol content in the ROS (C).  
Article
Raman vibrational spectroscopic imaging was performed on retinal rod cells isolated from bullfrogs (Rana catesbeiana). The Raman spectra enable determination of the lipid and protein rich rod outer segment (ROS) from the nucleus and inner segment of the cell. Peak fitting analysis of spectra obtained from individual rod photoreceptor cells show characteristic vibrational modes that can be associated with cholesterol and docosahexaenoic acid containing lipids. These results provide direct observations of biomolecular gradients in the rod photoreceptor cells, which, thus far, have been based on indirect detergent extracts and histochemical analysis with indicators such as filipin. The detected biomolecules are associated with regulation of the integral membrane protein rhodopsin, and methods capable direct observation of these biomolecules offer new routes to exploring their role in the regulation of cellular processes.
 
Article
A templated macrocyclization reaction was used to permanently encapsulate a highly fluorescent hydroxy-substituted squaraine dye inside a tetralactam macrocycle. The free squaraine dye is quite rigid due to internal hydrogen bonding and its photophysical properties hardly change upon encapsulation. A combination of X-ray and NMR data show that the surrounding tetralactam macrocycle adopts an unusually rigid chair conformation and does not undergo rapid pirouetting. Because of its large size and conformational rigidity, the macrocycle creates anisotropic NMR shielding zones that extend over the N,N-dibutylamino groups at each end of the squaraine thread. This shielding anisotropy allows hindered aryl-N rotation to be observed by NMR and provides direct experimental evidence that quinoid-like resonance structures are major contributors to the bis(N,N-dialkylaminophenyl)squaraine resonance hybrid.
 
Triplet excited-state emission spectra for [Gd(3LI-bis-LYS-1,2HOPO)] − ( __ ) and [Gd(H(2,2)-1,2-HOPO)] − (red line) in solid matrix (77 K, 1:4 (v/v) MeOH:EtOH) (λ ex = 340 nm).
Photophysical data of the investigated Eu III complexes 0.1 M aqueous TRIS buffer, pH = 7.4 77 K A Brightness B φ tot τ H2O [µs] τ D2O [µs] q τ [µs] [M −1 cm −1 ]
Triplet excited-state emission spectra for [Gd(3LI-bis-LYS-1,2- HOPO)] − ( __ ) and [Gd(H(2,2)-1,2-HOPO)] − (red line) in solid matrix (77 K, 1:4 (v/v) MeOH:EtOH) (λ ex = 340 nm). although the gain in stability still remains more important for aqueous measurements, and more specifically for biological measurements. The luminescence lifetimes were determined in 0.1 M aqueous TRIS buffer and reveal values of 712 µs for [Eu(3LI- bis-LYS-1,2-HOPO)] − that are of the same order as those for [Eu(5LI-1,2-HOPO) 2 ] − (737 µs), and much longer than that of [Eu(H(2,2)-1,2-HOPO)] − , which has a decay time of ∼480 µs. The difference between [Eu(5LI-1,2-HOPO) 2 ] − and [Eu(H(2,2)-1,2-HOPO)] − has been shown to result from the presence of a water molecule in the inner sphere of the latter, and the similarity in lifetimes suggests that [Eu(3LI-bis-LYS- 1,2-HOPO)] − does not have an aqua ligand coordinated to the Eu III cation (see below). In order to determine whether [Eu(3LI-bis-LYS-1,2- HOPO)] − also possesses an aqua ligand, the luminescence lifetime was also measured in deuterated water, yielding a value of 917 µs, which is comparable with that of [Eu(5LI-1,2- HOPO) 2 ] − (996 µs). The q number can therefore be obtained (Table 3) using the improved Horrocks equation, [21] revealing  
Normalized luminescence spectra of [Eu(3LI-bis-LYS-1,2- HOPO)] − ( __ ) and [Eu(H(2,2)-1,2-HOPO)] − (red line) in 0.1 M aqueous TRIS buffer solution at pH = 7.4 (λ ex = 340 nm).  
Brightness of [Eu(3LI-bis-LYS-1,2-HOPO)] − ( __ ) and [Eu(H(2,2)- 1,2-HOPO)] − (red line) in 0.1 M aqueous TRIS buffer at pH = 7.4.  
Article
The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV/visible and then efficiently transfer the energy to the lanthanoid center. The synthesis and the complexation of Ln(III) cations (Ln=Eu; Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two L-lysine units (3LI-bis-LYS) is described. This octadentate Eu(III) complex ([Eu(3LI-bis-LYS-1,2-HOPO)](-)) has been evaluated in terms of its thermodynamic stability, UV/visible absorption and luminescence properties. For this complex the conditional stability constant (pM) is 19.9, which is an order of magnitude higher than diethylenetriaminepentacetic acid (DTPA) at pH= 7.4. This Eu(III) complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH= 7.4) when compared to other octadentate ligands. Hence, despite a slight decrease of the molar absorption coefficient, a much higher brightness is obtained for [Eu(3LI-bis-LYS-1,2-HOPO)](-). This overall improvement was achieved by saturating the coordination sphere of the Eu(III) cation, yielding an increased metal centered efficiency by excluding solvent water molecules from the metal's inner sphere.
 
Article
Robust water oxidation catalysts using earth abundant metals are required as part of an overall scheme to convert sunlight into fuels. Here, we report the immobilization of [[Formula: see text]O(5)(terpy)(4)(H(2)O)(2)](ClO(4))(6) (terpy = 2,2';6',2″-terpyridine), [Mn(4)O(6)(tacn)(4)](ClO(4))(4) (tacn = 1,4,7-triazacyclononane), and manganese dioxide nanoparticles in Nafion on fluorine-doped tin oxide conducting glass electrodes. The electrodes are illuminated with white light in the presence of an applied potential and the resulting photocurrent is assigned to the oxidation of solvent water. Photodecomposition of the tetrameric complexes results in a material that is more active for light-driven electrooxidation of water. The reactivity, wavelength dependence, and stability of the compounds in Nafion under illumination are discussed.
 
Relative stereochemical representation of vibsanin E (1)  
Article
Vibsanin E (1), a structurally rare complex diterpene, consisting of a compact 3-oxatricyclo[6.3.2.0(5,10)] tridecane core and an unprecedented 3,3-dimethylacroyl enol ester functional group, formulate a considerable synthetic challenge. Williams and Davies failed to independently synthesize this nemesis, however, a 'two heads are better than one' approach delivered the first total synthesis of the molecule, since its diamond aniversary isolation.
 
Article
Nitrosyl chloride reagent effects on phenylalanine peptides
 
Article
Sequence preparation of protected peptide polymer bond with anion exchange resin using solid phase transesterification
 
Article
The mass spectra of some promazine sulphoxide derivatives have been examined. Specifically deuterated analogues of promazine and promazine sulphoxide were prepared and their mass spectra used to determine the specificity of the hydrogen transfer processes observed in the unlabelled compounds.
 
Article
Tryptic pentapeptide Asp-Glu-Leu-Thr-Lys synthesis showing relation to Gm/a/ antigen of human gamma g-globulin
 
Article
Dynamers may be defined as constitutional dynamic polymers, i.e. polymeric entities whose monomeric components are linked through reversible connections and have therefore the capacity to modify their constitution by exchange and reshuffling of their components. They may be either of molecular or supramolecular nature depending on whether the connections are reversible covalent bonds or non-covalent interactions. They are formed, respectively, either by polycondensation with functional recognition or by polyassociation with interactional recognition between the connecting subunits. Both types are illustrated by specific examples implementing hydrogen bonding on one hand and acylhydrazone formation on the other. The dynamic properties confer to dynamers the ability to undergo adaptation and driven evolution under the effect of external chemical or physical triggers. Dynamers thus are constitutional dynamic materials resulting from the application of the principles of constitutional dynamic chemistry to polymer science.
 
Article
Effects of nuclear dynamics on the energetics of polythiophene relevant for the performance of organic solar cells are studied for the first time. Nuclear motions change the expectation values of frontier orbital energies and the band gap by about 0.1 eV vs. values at the equilibrium geometry, which is expected to have a significant effect on light absorption, charge separation, and donor regeneration. A new molecular dynamics (MD) algorithm, which accounts for the quantum nature of vibrations, is introduced. It reproduces effects of temperature and deuteration which are lost in the standard MD. Inclusion of quantized vibrations leads to a broadening of the band gap and of energy levels by about 20% at 300K, while having little effect on their expectation values (which change by up to 0.03 eV). Increase in temperature from 300K to 400K and deuteration cause an additional broadening of the spectrum by about 26% and 21%, respectively.
 
Article
A previously described empirical model for solvent effects is applied to kinetic, thermodynamic and spectroscopic data selected to reflect variation in solute-solvent interactions of a dipole-dipole character. The three parameter fit was found to describe the solvent effect successfully in 75% of the cases considered. The choice of basicity parameters for protic solvents is discussed, and the basicity scales of Gutmann, Kagiya, Koppel and Palm, and Arnett, are compared. It is concluded that an extension of the present model should take into consideration entropic effects associated with solute-solvent interactions.
 
Article
A novel tetranuclear copper(II) complex [Cu<sub>4</sub>L<sub>2</sub>(μ<sub>1,1</sub>- N<sub>3</sub>)<sub>2</sub>]•CH<sub>3</sub>CN ( 1 ) has been synthesized using a symmetrical quinquedentate N<sub>2</sub>O<sub>3</sub>-donor Schiff-base ligand H<sub>3</sub>L ( N,N′ -(2-hydroxypropane-1,3-diyl)bis(2- hydroxyacetophenimine)) and characterized by elemental analysis, Fourier-transform (FT)-IR, UV-visible, electron paramagnetic resonance spectroscopy, and cyclic voltammetry. The X-ray single-crystal structure of 1 reveals three kinds of bridges among the four metal centres: one from the exogenous azido ligand and two from the phenoxo and alkoxo moieties of the Schiff base. The same structure highlights the remarkable versatility of copper(II) to adopt an array of stereochemistries. Four unusual eight-membered metallacycles exist in 1 . The μ<sub>1,1</sub>-azido, μ<sub>2</sub>-alkoxo, and μ<sub>2</sub>-phenoxo bridges among the four copper centres have facilitated interesting magnetic interactions that have been elucidated by variable-temperature magnetic susceptibility measurements and backed up by density functional theory calculations. Detailed analyses have shown that the antiferromagnetic effect through the alkoxo-bridged Cu<sup>II</sup> centres combined with the ferromagnetic interaction through the azido-bridged metal centres results in an S = 0 ground state.
 
Article
The thiyl radicals derived from 2-mercaptoethanol and thiophenol were found to undergo a complex series of reactions with 1,1,3,3-tetramethyl-2,3-dihydroisoindol-2-yloxyl (TMIO). Thus, treatment of 2-mercaptoethanol with di-t-butyl peroxyoxalate (DTBPO) in the presence of TMIO produced two N-S compounds-a sulfoxamide and a sufonamide-not the expected N-O-S adduct. The reaction between thiophenol and TMIO, which proceeded at a reasonable rate in the absence of DTBPO, produced 1,1,3,3-tetramethyl-2,3-dihydroisoindolin and its corresponding phenylsulfoxamide, diphenyl disulfide, phenylsulfinic acid, and 1, 1,3,3-tetramethyl-2,3-dihydroisoindol-2-ylphenylsulfonate (the adduct of TMIO and the phenylsulfonyl radical). The mechanism of formation of these products, and the use of TMIO for trapping S-centred radicals, are discussed. A new radical fragmentation process, which appears to be general for aminoxyl adducts of electron-rich systems, is described.
 
Article
1,1,3,3-Tetraalkylisoindolines are important intermediates in the preparation of stable nitroxides, such as 1,1,3,3-tetramethylisoindolin-2-oxyl, 1, and 1,1,3,3-tetraethylisoindolin-2-oxyl, 2. The limiting step in their preparation is the Grignard reaction between N-benzylphthalimide and the appropriate alkyl magnesium bromide, which typically proceeds in yields of ∼28?40%. A microwave-assisted variation of this reaction has been optimized to give improved yields and reduced reaction times (45?60% and 2 h, respectively).
 
Article
The reaction of the bis(1,2-diamine) copper(II) complexes of racemic propane-1,2-diamine (pn) and 2-methylpropane-1,2-diamine (dmen) with formaldehyde and nitroethane in methanol under basic conditions yields minor macrocyclic condensation products in addition to the major acyclic products. Where C-pendant methyl groups on the pair of coordinated diamines are in cis dispositions, the first -NH-CH2-C(CH3)(NO2)-CH2-NH- ring formation occurs at amine pairs distant from these C-methyl substituents, and further reaction to yield a macrocycle is not observed. However, where the C-methyl substituents are in trans dispositions, the chemistry proceeds to yield the macrocycle. Commencing with pn, trans-(6,13-diammonio-2,6,9,13-tetramethyl-1,4,7,10-tetraazacyclotetradecane)copper(II) perchlorate formed and crystallized in the space group P2(1)/n, with a 9.782(2), b 9.2794(6), c 17.017(4) Angstrom, beta 103.24(1)degrees. The copper ion is found in a square-planar environment, with the two methyl groups of the pn residues and the pairs of introduced pendant groups all in trans arrangements.
 
Article
Leaving group effects on the electrochemical dehalogenation of organic vicinal dihalides have been examined in acetonitrile for the 1,2-dihalo-1,2-diphenylethanes and trans-1,2-dihalo-cyclohexanes. Reduction potentials and product distributions support a stepwise addition of two electrons, as previously proposed for the isomers of 1,2-dibromo-1,2-diphenylethane. A general reduction mechanism for the vicinal dihalides is proposed. Literature data for the electrochemical reduction of the 5,6-dihalodecanes, previously thought to favour a concerted two-electron mechanism, may be explained in terms of a stepwise process.
 
Article
The 93 K X-ray crystal structure of tris(ethane-1,2-diamine)zinc(II) dinitrate is reported. As predicted by the spectroscopic studies of other workers, there is a reversible phase transition of the structure at low temperature. We have determined this temperature to be 143 K. The structure at this temperature and below resembles that of the room temperature structure, except the crystallographic D-3 symmetry of the complex cation (296 K) is lowered to C-2 ( below 144 K) by subtle changes in cation-anion hydrogen bonding. No change in the conformation of the cation or its bond lengths and angles was found.
 
Article
The title compound (5) has been synthesized and its presence sought in various eucalypt leaf oils. Aspects of the chemistry of the precursor aziridine (14) are discussed.
 
13 C n.m.r. data in CDCl 3 solution 
Article
The problems of structure in diastereomers where one chiral centre is remote from another are further investigated in the 1,2,8,9,9-pentabromo-p-menthane series.
 
ORTEP views of compound A in its monoclinic (a) and triclinic (b) forms; 30% probability ellipsoids shown. The conformations of the two molecules are indistinguishable.
Scheme 1.
Article
The non-bonding interaction between two bromine atoms sited 1,3-diaxially on a simple cyclohexane ring is explored by X-ray crystallography. The ring is distorted to allow the bromine atoms an interatomic distance of 3.54 angstrom.
 
Article
The title compound (3) has been synthesized and its presence sought in the urinary metabolites of the brushtail possum.
 
Article
The major trans (1) and minor cis (2) isomers of 1,4,8,11-tetraazacyclotetradecane-6,13-dicarboxylate have been characterized as the complexes [Co(1)](ClO4) and [Co(H-2)(OH2)]Cl(ClO4).H2O. The former crystallized in the C-2/c space group and the latter in the P2(1)/c space group, with cell parameters a 16.258(7), b 9.050(3), c 15.413(6) Angstrom, beta133.29(3)degrees, and a 9.694(4), b 16.135(1), c 12.973(5) Angstrom, beta 93.00(2)degrees, respectively. Their characterization completes identification of the respective trans and cis isomers for the series of C-pendant macrocycles also including 1,4,8,11-tetraazacyclotetradecane-6-amine-13-carboxylate ((3), (4)) and 1,4,8,11-tetraazacyclotetradecane-6,13-diamine ((5), (6)). The complexes show limited distortion from octahedral geometry with the strain in the presence of the coordinated C-pendant carboxylate significantly reduced compared with that for the C-pendant amine in analogues, a consequence mainly of six-membered as opposed to five-membered chelate rings involving the pendant donor. A comparison of the physical properties for the trans isomers of the octahedral complexes of (1), (3), and (5), which reflect progressively increasing strain, is presented.
 
Article
A number of 1 : 1 silver(1) halide/nitrogen base adducts, [ LAgX ], have been synthesized by recrystallization of the parent silver(I) halide from the neat base, and their solid state structures determined by single-crystal X-ray diffraction and rationalized in terms of the hierarchy of structural types described in the preceding papers based on steric profile of the base. In consequence of increased metal atom size (cf. Cu), a more limited array of structural types is observed.[(pyridine) AgBr,I ] ∞, [(2,4,6-trimethylpyridine) AgCI,Br,I ] ∞ and [( quinaldine ) AgCI,Br ] are 'stair' polymers; [( piperidine ) AgBr,I ]4 and [(2,2,6,6-tetramethyIpiperidine) AgI ]4 are 'cube' tetramers, while [( diethylamine ) AgCI,Br,I ] provide the first complete metal halide series of the novel 'tube' polymer. Yes Yes
 
Article
Within the class of (4-pyridinyl)vinylpyridines developed by Abbott laboratories as potent neuronal nicotinic acetylcholine receptor ligands, p-PVP-MEMA ({(R)-2-[6-chloro-5-((E)-2-pyridin-4-ylvinyl)pyridin-3-yloxy]-1-methylethyl}methylamine) is the lead compound of a novel series that do not display the traditional nicotinic-like pyrrole-ring but still possessing high subnanomolar affinity (Ki 0.077 nm—displacement of [3H](–)cytisine from whole rat brain synaptic membranes). In the present study, p-PVP-MEMA and its nor-derivative ({(R)-2-[6-chloro-5-((E)-2-pyridin-4-ylvinyl)pyridin-3-yloxy]-1-methylethyl}methylamine) as precursor for labelling with the short-lived positron-emitter carbon-11 (T1/2 20.4 min) were synthesized in 10 chemical steps from 2-hydroxy-5-nitropyridine and Boc-d-alanine. N-Alkylation of nor-p-PVP-MEMA with [11C]methyl iodide afforded [11C]p-PVP-MEMA (>98% radiochemically pure, specific activity of 86.4 GBq μmol–1) in 2% (non-decay corrected and non-optimized) radiochemical yield, in 34 min (including HPLC purification and formulation). Preliminary positron emission tomography (PET) results obtained in a Papio hamadryas baboon showed that [11C]p-PVP-MEMA is not a suitable PET-radioligand. Yes Yes
 
Article
Mixed base pyridine (py)/triphenylphosphine adducts of the silver(I) halides, AgX (X = Cl, Br, I), have been synthesized for 1 : 1 : 1 stoichiometry. The three complexes are isomorphous and isostructural, being monoclinic, P21/c, a ≈ 11.2, b ≈ 16.8, c ≈ 16.5 Å , β ≈ 122 º ; the complexes are centrosymmetric µ, µ?- dihalo -bridged dimers , [(PPh3)( py )AgX2Ag( py )(PPh3)1 (Z = 2 dimers ). Although the stoichiometry of the complex itself is as above, an additional unit of pyridine per silver atom is found as solvent in the lattice, implying the unlikelihood of the existence of an independent 1 : 2 : 1 AgX : py : PPh3 molecular series. In addition, the iodide has been isolated as a different C2/m (?) disordered polymorph. Yes Yes
 
Article
The crystal structures of the title compounds have been determined by single-crystal X-ray diffraction methods at 295 K. Crystal data for (PPh3)2CuBr2Cu(PPh3) (1) show that the crystals are iso-morphous with the previously studied chloro analogue, being monoclinic, P21/c, a 19.390(8), b 9.912(5), c 26.979(9) Ǻ, β 112,33(3)°; R 0.043 for No 3444. Cu( trigonal )- P;Br respectively are 2.191(3); 2.409(2), 2.364(2) Ǻ. Cu(tetrahedral)- P;Br respectively are 2.241(3), 2.249(3); 2.550(2), 2.571(2) Ǻ. Crystals of 'step' [PPh3CuBr]4 (2) are isomorphous with the solvated bromo and unsolvated iodo analogues, being monoclinic, C2/c, a 25.687(10), b 16.084(7), c 17.815(9) Ǻ, β 110.92(3)°; R 0.072 for No 3055. Cu( trigonal )- P;Br respectively are 2.206(5); 2.371(3), 2.427(2) Ǻ. Cu(tetrahedral)- P;Br are 2.207(4); 2.446(2), 2.676(3), 2.515(3) Ǻ. Yes Yes
 
Article
Following molecular modelling employing molecular mechanics and semi-empirical (PM3) calculations as an aid to ligand design, a new copper(I)-containing [2]-catenane has been prepared by the reaction of 6,6'-bis[(4 ''-formylphenoxy) methyl]-2,2'-bipyridyl with 1,6-hexanediamine in the presence of a copper(I) template, followed by in situ sodium borohydride reduction of the tetra-imine species generated. The corresponding [2]-catenane was obtained as a deep orange crystalline solid. The X-ray structure of this product along with that of the corresponding bis-dialdehyde precursor copper(I) complex have been determined. In the latter case, the structure is pre-organized for catenane formation. The new catenane appears to be the first example of a tetrahedral metal template product incorporating a bis-bipyridyl derivative core. Isolation of the metal-free [2]-catenane has also been achieved following treatment of the copper(I) catenane complex in dimethylsulfoxide with tetrabutylammonium cyanide.
 
Article
An exploratory chemical effort has been undertaken to develop a novel series of compounds as selective CB1 agonists. It is hoped that compounds of this type will have clinical utility in pain control and cerebral ischaemia following stroke or traumatic head injury. We report here medicinal chemistry studies directed towards the investigation of several classes of 1-benzo[b]thiophen and benzofuran derivatives as novel CB1 agonists. We have discovered a novel series of compounds, which contain a 1-benzo[b]thiophen or a benzofuran group as the central aromatic group. Our investigation of this series of compounds has enhanced our understanding of the importance of binding sites within the CB1 receptor for favourable CB1 potency. Our understanding of these factors allowed us to modify the structure of a 1-benzothiophen derivative and improve its potency at the CB1 receptor.
 
Article
The 1 : 1 proton-transfer compounds of creatinine with a series of aromatic carboxylic acids have been prepared and characterized using infrared spectroscopy and in one case with single-crystal X-ray crystallography. The acids are the mononitro-substituted benzoic acids 3,5-dinitrobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid and pyrazine-2,3-dicarboxylic acid. The crystal structure of the compound with pyrazine-2,3-dicarboxylic acid, [(C4H8N3O+)(C6H3N2O4–)], shows a chain structure based on a primary asymmetric cyclic hydrogen-bonding dimer formed through the carboxylate group and the hetero-nitrogen of the acid, and the protonated imine and the adjacent hetero-amine proton of creatinine. Peripheral extension is through the second imine proton to the second carboxylic acid group of an adjacent acid molecule. Manuscript received: 1 February 2001.
 
Article
The structures of 2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl azide and 2,3,4,6-tetra-O-acetyl-beta-D-mannopyranosyl azide were determined using X-ray crystallographic and one-dimensional NOESY techniques.
 
Article
The 1 : 1 adducts of 2,6-diaminopyridine (2,6-dap) with a series of nitro-substituted aromatic carboxylic acids have been prepared and the crystal structure of one of these, with 2-nitrobenzoic acid (2-nba), [(2,6-dap)+ (2-nba)-] has been determined by X-ray crystallography and refined to a residual R 0·034 for 655 observed reflections. Crystals are monoclinic, space group P 21/c, with four molecules in a cell of dimensions a 7·376(2), b 22·837(3), c 7·716(2) Å, β 90·01(2)°. The structure involves proton transfer with the resulting pyridinium proton and an amine proton combining with the carboxyl oxygens of the 2-nba molecule in a primary cyclic hydrogen-bonding association. Additional interactions, involving all the remaining amine protons of 2,6-dap with both carboxyl oxygens and one nitro oxygen of 2-nba, complete a chain polymer structure. All other members of this series have been confirmed by infrared spectroscopy as proton transfer adducts.
 
Article
The crystal structures of (ND4)2V(SO4)2.6D2O and (ND4)2V0.45Zn0.55(SO4)2.6D2O have been determined at 5.8 K by neutron diffraction. The 663 and 857 unique reflections measured respectively refined to give R(F2) 0.035 and 0.045. The crystals are monoclinic, P21/a, isostructural with the other members of the series of Tutton salts. The V-O bond length of 211.8 pm [210.4 pm for mean (V/Zn)-O in the solid solution with Zn] is intermediate between these for the Mn (214.9 pm) and the Ni(205.5 pm) salts. It is shorter than the value determined by X-ray diffraction at 295 K. The major departure from a regular VO6 octahedron is a shortened V-O(9) bond, such as is observed in the other Tutton salts, to give a tetragonal distortion.
 
Article
The crystal and molecular structure of the 2 : 1 triphenylphosphine copper(I) benzoate complex [(PPh3)2CuO2CC6H5] have been determined by a room-temperature single-crystal X-ray study. The complex is isomorphous with the dithiobenzoate analogue, crystallizing in the orthorhombic space group P212121 with a 20·094(5), b 16·929(9), c 10·659(8) Å, Z 4; conventional R on |F| was 0·039 for 4261 independent 'observed' (I > 3σ(I)) reflections. Comparison of structural data for this and other [(PPh3)2CuO2CR] complexes shows that the P–Cu–P angle and the anion coordination are dependent on both the donor strength of the anion and on steric interactions between the anion and the triphenylphosphine ligands. The structure of the analogous nitrate complex [(PPh3)2CuNO3] has also been redetermined. Yes Yes
 
Article
The crystal structures of the proton-transfer compounds of 3,5-dinitrosalicylic acid (dnsa) with a series of common monocyclic heteroaromatic amines (pyridine, 4-cyanopyridine, pyridine-4-carboxylic acid, 2,6-diaminopyridine, and 2-aminopyrimidine) have been determined and the hydrogen-bonding associations in each analyzed. The compounds are the adduct [(C5H6N)+(dnsa)–· (dnsa)] (1), the 1 : 1 salts [(C6H5N2)+(dnsa)–] (2), [(C6H6NO2)+(dnsa)–] (3), [(C5H8N3)+(dnsa)–] (4), and the 2 : 2 ethanol hemi-solvate [2(C4H6N3)+·2(dnsa)–· 0.5(EtOH)] (5). With all compounds, protonation of the hetero-nitrogen atom occurs with subsequent hydrogen bonding to the oxygen atoms of the functional groups of the dnsa anions, resulting in the formation of relatively simple linear or chain polymer associations. Compound (1) represents a rare example of other than a 1 : 1 association, and the first example of a 2 : 1 (dnsa/amine) type, with the unusual presence of an additional adduct molecule of dnsa in the structure. Yes Yes
 
Article
The crystal structures of the proton-transfer compounds of 3,5-dinitrosalicylic acid (dnsa) with ammonia (two polymorphs) and a series of common aliphatic amines (methylamine, triethylamine, hexamethylenetetramine and ethylenediamine) have been determined and the hydrogen-bonding associations in each analysed. The compounds are [(NH4)+(dnsa)-] (1A, 1B), [(CH3NH3)+(dnsa)-] (2), [{(C2H5)3NH}+(dnsa)-] (3), [(C6H12 N4H)+(dnsa)-] (4) and [{(CH2 NH3) 2}2+(dnsa)2-·H2O] (5). It is of interest that with hydrate (5) the phenolic proton of dnsa is also lost on reaction, giving a rare dianionic species. In all compounds, protonation of the amino group of the Lewis base occurs, with subsequent hydrogen bonding via this and other hydrogens variously to the carboxylic, nitro and phenolic oxygens of dnsa, and in the case of (5), the lattice water. The result is the formation of simple linear associations with the tertiary amines, or network polymers with the less-substituted examples. Short intramolecular hydrogen bonds between the phenolic group and the carboxylate group are found in all compounds except (5), with the proton localized on the carboxylate oxygen rather than on the phenolic oxygen, but in the case of (3), delocalized within the hydrogen bond. Yes Yes
 
Article
The crystal structures of the 1:1 proton-transfer compounds of 3,5-dinitrosalicylic acid (dnsa) with a series of common polycyclic aromatic and heteroaromatic amines (quinoline, 1-naphthylamine, 1,2,3,4-tetrahydroquinoline, quinaldic acid, benzimidazole, 1,10-phenanthroline, and 2,2′-bipyridine) have been determined and the hydrogen-bonding associations in each analyzed. The compounds are [(C9H8N)+(dnsa)–] 1, [(C10H10N)+(dnsa)–] 2, [(C9H12N)+(dnsa)–] 3, [(C10H8NO2)+(dnsa)–] 4, [(C7H7N2)+(dnsa)–] 5, [(C12H9N2)+(dnsa)–] 6, and [(C10H9N2)+(dnsa)–] 7. In all compounds, protonation of either the substituent amino group or the hetero-N of the Lewis base occurs, with subsequent hydrogen bonding via this and other hydrogen donors variously to the carboxylate, phenate, and nitro oxygen acceptors of the dnsa anions. The result is the formation of primary N+–H···O associations which with secondary peripheral interactions, which within this set of compounds includes an increased incidence of aromatic C–H···O associations, give framework polymer structures. In three of the compounds [1, 4, and 6], cation–anion π–π interactions are also found. The completion of this series of compounds has now allowed the categorization of the molecular assembly modes in the proton-transfer compounds of 3,5-dinitrosalicylic acid. Yes Yes
 
Article
Linear, two-coordinate compounds of molecular formula (PPh3) AuX have been characterized by solid-state and solution 31P n.m.r. spectroscopy, and single-crystal X-ray diffraction techniques. The solid state n.m.r. spectra reveal single, broad resonance lines for X = NO3 (chemical shift 19 ppm , ref. 85% H3PO4), CH3C02 (24 ppm), SCN (36ppm), CN (37 ppm ) and CH3 (47 ppm ) and doublets for X = Cl (27, 33 ppm ), Br (28, 36 ppm ) and I (34, 38 ppm ), the latter three spectra being recorded at 121.47 MHz and 161.96 MHz. Solution spectra show relatively sharp single resonances for each compound with 6 values generally slightly higher than in the solid state. Crystal data are reported for X = NO3, space gro )p P21/c, a 8 895(9), b 10.117(8), c 19.57(2) Å; β 97.43(8)º, Au-P,O = 2.199(5), 2.02(1) Å. Crystals of compounds with X = Br, I and SCN are isomorphous with the AuCl compound, belonging to space group 212121. For X = Br, a 12.479(5), b 13.45(1), c 10.0!2(8) Å; Au-P, Br = 2.252(6), 2.407(2) Å. For X = I, a 12.529(8), b 13.870(5), c 10.188(4) Å; Au-P, I = 2.254(5), 2.556(2) Å. For X = SCN, a 12.257(5), b 13.776(8), c 10.754(6) Å; Au-P, S = 2.252(7), 2.304(7) Å. Yes Yes
 
Article
The mixed donor 12-membered macrocyclic ligand 1-oxa-7-thia-4,10-diazacyclododecane ([12]aneN2OS) has been synthesized and the mercury(II) and lead(II) complexes, [Hg([12]aneN2OS)(NO3)2] and [Pb([12]aneN2OS)(NO3)2], have been isolated and characterized by X-ray crystallography. Crystals of the mercury complex are monoclinic, space group P 21/c, a 9·576(2), b 10·757(2), c 14·789(4) Å, β 93·58(2)°, whilst crystals of the lead complex are monoclinic, space group P 21/n, a 19·490(7), b 8·010(2), c 19·576(6) Å, β 109·90(2)°. The protonation constants and stability constants have been determined potentiometrically in aqueous solution. The protonation constants for [12]aneN2OS (log KHL 9·13; log K H2L 6·85) appear typical for secondary amines in similar trans-substituted 12-membered macrocycles. The magnitudes of the stability constants (HgII, log KHgL 10·5; PbII, log KPbL 6·6) are consistent with trends observed previously for macrocyclic ligands as secondary amine donors are replaced with oxygen and thioether donors.
 
ORTEP representation of the cationic component of complex 6b. Hydrogen atoms have been removed for clarity.
Article
Ethanol solns. of the cobalt(II) halides react with an excess of 2-(ortho-anilinyl)-4,4-dimethyl-2-oxazoline (1: i.e. 2-(2'-anilinyl)-4,4-dimethyl-4,5-dihydro-1,3-oxazole) to give isolable κ2-N,N'-bonded species of 1 in good to excellent yields. The complexes CoX2(1-κ2-N,N')·(H2O)n were isolated for X = Cl (2: n = 1/2), X = Br and I (3 and 4, resp.; n = 0); the solid-state structures (X-ray) are in accordance with those suggested by UV-visible spectroscopy and cond. measurements (i.e. non-ionic complexes with a pseudo-tetrahedral coordination motif around Co). In contrast, reaction of excess 1 with Co(NCS)2 forms octahedral (UV-visible, X-ray) bis-isothiocyanato complex Co(NCS-κ1-N')2(1-κ2-N,N')2 (5) with cis-oriented NCS groups and trans-disposed oxazolines. Calcns. at the PM3(tm) level of theory suggest that this isomer is close in energy to the four other possible (gas-phase) isomers. Treatment of ethanol solns. of hydrated cobaltous nitrate with excess 1 yields a material analyzed as [Co(NO3)(1)(H2O)2](NO3) (6a) and a small amt. (less than 1%) of a second complex (6b); the latter was characterized (X-ray) as the hydrated octahedral complex [Co(NO3-κ1-O)(1-κ2-N,N')2(OH2)](NO3). In this case, the nitrato and aqua groupings are located cis to one another and trans to the coordinated -NH2 groups. Complex 6a is surmised to have a [Co(NO3-κ2-O,O')2(1-κ2-N,N')(OH2)2]NO3 structure. Cobalt compds. 2-5 and 1 have also been screened for their antifungal properties against Aspergillus niger, Aspergillus flavus, Candida albicans, and Saccharomyces cerevisiae but were found to be inactive in this regard. [on SciFinder(R)]
 
Article
Bicyclooctanols 3 and 4 were formed with control of the stereochemistry at C8 by using an aluminium enolate of cyclohexanone in 1,2-dimethoxyethane. Bicyclooctanols 1 and 3 were stable towards aqueous hydrochloric acid for short times (< 3.5 h), and ring open to a diastereomeric mix of monoalkylated 5 under protic or aprotic conditions in the presence of base ( NaOH or lithium diisopropylamide). The rate of ring opening appears to be dependent on reaction temperature. Bicyclooctanols 1, 3, and 4 displayed remarkable stability when heated at reflux in benzene, whereas use of ethanol prompted stereoselective ring opening of 1 and 3 to give individual diastereomers of monoalkylated 5 and ring opening of 4 to give a 50 : 50 mix of diastereomers of 5. This unexpected result was attributed to the stereochemistry of the bicyclooctanol and placement of hydrogen-bonding sites.
 
Article
The 6th Heron Island Conference on Reactive Intermediates and Unusual Molecules - Synthesis and Mechanism was held at the Heron Island Resort on the Great Barrier Reef, 7- 13 July 2013, with some 80 scientists in attendance from all over the world, presenting highlights of their work in lecture and poster format ( Fig. 1). These meetings, which enjoy an excellent international reputation, present unique opportunities for interaction between Australian and overseas chemists in subject areas varying from organic synthesis to reaction mechanism, computational and theoretical chemistry, physical/ materials chemistry, inorganic chemistry, biological/ medicinal chemistry, and spectroscopy. This issue of Aust. J. Chem. presents a collection of papers authored by delegates at the meeting and comprise a wide range of topics, including amine boranes ( S.- Y. Liu et al.),[ 1] rhodium carbenoids ( A. Padwa et al.),[ 2] singlet oxygen ( T. Linker et al.),[ 3] hydrogen peroxide fuel cells ( S. Fukuzumi et al.),[ 4]
 
Article
High-field 19F n.m.r. measurements in Me4NF solutions at 278 K confirm the existence of [AlFi](3-i)+ complexes for i ≤ 5 but indicate that the widely assumed [A1F6]3- does not form at significant concentrations in aqueous solution even at very high F-/AlIII ratios.
 
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Glen B. Deacon
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