Showing papers in "Canadian Journal of Chemistry in 2009"
TL;DR: The substitution of isoelectronic B-N units for C-C units in aromatic hydrocarbons produces novel heterocycles with structural similarities to the all-carbon frameworks, but with fundamentally different properties.
Abstract: The substitution of isoelectronic B–N units for C–C units in aromatic hydrocarbons produces novel heterocycles with structural similarities to the all-carbon frameworks, but with fundamentally alte...
441 citations
TL;DR: The conductor-like screening model for real solvents (COSMO-RS) has been implemented in the Amsterdam density functional program as discussed by the authors and the surface building routines now allow for finer discretization of surfaces.
Abstract: The conductor-like screening model for real solvents (COSMO-RS) has been implemented in the Amsterdam density functional program. The surface building routines now allow for finer discretization of...
170 citations
TL;DR: The B88 exchange energy density functional (created by Becke in 1988) is a crucial part of the most popular density functional in use today, B3LYP.
Abstract: The B88 exchange energy density functional (created by Becke in 1988) is a crucial part of the most popular density functional in use today, B3LYP. B88 contains one empirical parameter which was fi...
94 citations
TL;DR: Environmentally friendly conditions, large substrate scope, and ease of synthesis enhance the utility of this method over other electrophilic bromination conditions.
Abstract: Regioselective and chemoselective electrophilic bromination of a wide series of activated arenes using N-bromosuccinimide (NBS) in acetonitrile occurs readily. Environmentally friendly conditions, large substrate scope, and ease of synthesis enhance the utility of this method over other electrophilic bromination conditions.
67 citations
TL;DR: In this paper, potential energy and free energy data for three enzymatic reactions: carbon-halogen bond formation in fluorinase, hydrogen abstraction from camphor in cytochrome P450cam, and chorismate-t...
Abstract: We report potential-energy and free-energy data for three enzymatic reactions: carbon–halogen bond formation in fluorinase, hydrogen abstraction from camphor in cytochrome P450cam, and chorismate-t...
62 citations
TL;DR: Indoles are efficiently condensed with aromatic and aliphatic aldehydes in the absence of any catalyst in ionic liquid 1-butyl-3methylimidazolium bromide {bmim]Br} under microwave irradiation to a...
Abstract: Indoles are efficiently condensed with aromatic and aliphatic aldehydes in the absence of any catalyst in ionic liquid 1-butyl-3-methylimidazolium bromide {bmim]Br} under microwave irradiation to a...
60 citations
TL;DR: Several pyridine-like ligands were found to improve Pd(OAc)2-catalyzed allylic oxidation of allylbenzene to cinnamyl acetate by p-benzoquinone in acetic acid as discussed by the authors.
Abstract: Several pyridine-like ligands were found to improve Pd(OAc)2-catalyzed allylic oxidation of allylbenzene to cinnamyl acetate by p-benzoquinone in acetic acid. The best ligand examined, bipyrimidine...
58 citations
TL;DR: In this paper, pressure-induced structural transformations of the ammonia borane complex (NH3·BH3) were investigated in diamond anvil cells by Raman spectroscopy and synchrotron IR spectrograms up to 14 GPa.
Abstract: Pressure-induced structural transformations of the ammonia borane complex (NH3·BH3) were investigated in diamond anvil cells by Raman spectroscopy and synchrotron IR spectroscopy up to 14 GPa at ro...
57 citations
TL;DR: In this paper, a neutral and efficient one-pot three-component aqueous phase synthesis was developed for various spirooxindole derivatives from isatin, malononitrile, and 1,3-dicarbonyl compounds.
Abstract: A neutral and efficient one-pot three-component aqueous-phase synthesis is developed for various spirooxindole derivatives from isatin, malononitrile, and 1,3-dicarbonyl compounds in high yields by...
56 citations
TL;DR: In this paper, the authors studied the catalytic ethene trimerization at a chromium(I) indolate-AlR2Cl center using density functional theory (DFT) methods.
Abstract: Catalytic ethene trimerization at a chromium(I) indolate-AlR2Cl centre has been studied by density functional theory (DFT) methods. The reaction is found to follow the standard metallacycle mechani...
49 citations
TL;DR: An improved, simple, and facile synthesis of amidoalkyl naphthols by employing three-component one-pot condensation reaction of β-naphthol, aromatic aldehydes, and amides in ionic liquids using ytt...
Abstract: An improved, simple, and facile synthesis of amidoalkyl naphthols by employing three-component one-pot condensation reaction of β-naphthol, aromatic aldehydes, and amides in ionic liquids using ytt...
TL;DR: A new tetraoxygenated xanthone, cowaxanthone F (1), as well as four known compounds, morelloflavone (2), volkensiflavone(3), morelloftlavone-7″-O-glucoside (fukugiside, 4), and 1,6-dihydroxyxanthon...
Abstract: A new tetraoxygenated xanthone, cowaxanthone F (1), as well as four known compounds, morelloflavone (2), volkensiflavone (3), morelloflavone-7″-O-glucoside (fukugiside, 4), and 1,6-dihydroxyxanthon...
TL;DR: In this paper, the localized-orbital locator (LOL) was used to characterize the chemical bond in transition-metal hydride and dihydrogen complements.
Abstract: A bond descriptor based on the kinetic-energy density, the localized-orbital locator (LOL), is used to characterize the nature of the chemical bond in transition-metal hydride and dihydrogen comple...
TL;DR: In this paper, the influence of the exchange correlation functional on the agreement with experiment has been evaluated systematically for g tensors; 55Mn, 14N, and 1H hyperfine coupling tensors, and Heisenberg exchange couplings.
Abstract: . The EPR parameters of a series of dinuclear manganese(III,IV) complexes with mono(μ-oxo), bis(μ-oxo), (μ-oxo)(μ-carboxylato), bis(μ-oxo)(μ-carboxylato), and (μ-oxo)bis(μ-carboxylato) bridges were studied by broken-symmetry density functional (DFT) methods. The influence of the exchange-correlation functional on the agreement with experiment has been evaluated systematically for g tensors; 55Mn, 14N, and 1H hyperfine coupling tensors; and Heisenberg exchange couplings. 14N and 1H hyperfine couplings, 55Mn hyperfine anisotropies, g tensors, and exchange couplings are well described by hybrid functionals with moderate exact-exchange admixtures such as B3LYP. The isotropic 55Mn hyperfine couplings require larger exact-exchange admixtures. However, the errors of the B3LYP calculations are systematic and may be corrected by a constant scaling factor, providing good predictive power for a wide range of EPR parameters with broken-symmetry DFT and standard functionals. The influence of terminal and bridging liga...
TL;DR: In this paper, the preparation and characterization of a kaolinite-methacrylamide intercalation compound was achieved by a guest-displacement method, the direct treatment of a dimethylsulfoxide (DMSO) pre-intercalate with an aqueous solution of methacrylamide under mild conditions.
Abstract: The preparation and characterization of a kaolinite–methacrylamide intercalation compound was achieved by a guest-displacement method, the direct treatment of a dimethylsulfoxide (DMSO) pre-intercalate with an aqueous solution of methacrylamide under mild conditions, giving intercalation ratios up to 92% and an expansion of 0.53 nm of the interlayer space. The DMSO molecules were fully displaced from the interlayer space by methacrylamide. Only partial intercalation could be obtained with N-methylformamide (NMF) pre-intercalate. After intercalation, the monomer was thermally polymerized at 100 or 150 °C with various heating times. XRD, FTIR, 13C CP/MAS NMR, and thermogravimetric analysis confirmed that polymerization was partially achieved in the interlayer spaces, while the layered structure of kaolinite was maintained, constraining the polymer in an interlayer space of 0.57 nm in the c-direction. In good agreement with the TG data, elemental analysis gave a stoichiometry of Al2Si2O5(OH)4·(C4H7NO)0.52 fo...
TL;DR: In this article, a method for the discovery of novel synthetic methodology and for the design of bioactive molecules with potential therapeutic applications was proposed for organosulfur and selenium chemistry.
Abstract: Organosulfur and selenium chemistry has provided fertile ground for the discovery of novel synthetic methodology and for the design of bioactive molecules with potential therapeutic applications. T...
TL;DR: A neural network (NN) based algorithm for calculating vibrational energies and wave functions and apply it to problems in 2-, 4-, and 6-dimensions is proposed, able to compute three states of a 6-D Hamiltonian using only 50 basis functions.
Abstract: We propose a neural network (NN) based algorithm for calculating vibrational energies and wave functions and apply it to problems in 2-, 4-, and 6-dimensions. By using neurons as basis functions an...
TL;DR: Polyyne glycosides are a class of natural products that have been found in terrestrial plants, fungi, and marine algae as discussed by the authors, which display interesting and potentially useful biological activities.
Abstract: Polyyne glycosides are a class of natural products that have been found in terrestrial plants, fungi, and marine algae. Many display interesting and potentially useful biological activities, which ...
TL;DR: In this article, the first chemical application of the recent, general theory of the nuclear magnetic resonance shielding and chemical shift in paramagnetic compounds, to a set of nonaxial high-spin meta...
Abstract: We present the first chemical application of the recent, general theory of the nuclear magnetic resonance shielding and chemical shift in paramagnetic compounds, to a set of nonaxial high-spin meta...
TL;DR: In this article, the authors presented a method for the Oxidation of phenyl PtII complexes with O 2 in aqueous or methanol solutions under a given set of conditions.
Abstract: Oxidation of phenyl PtII complexes K[(dpms)PtIIPh2], 1, (dpms)PtIIPh(MeOH), 2, (dpms)PtIIPh(OH2), 3, and methyl PtII complex (dpms)PtIIMe(NH2Ph), 6, with O2 in aqueous or methanol solutions under a...
TL;DR: In this article, direct bromination and iodination of various aromatic compounds with NaBr and NaI using oxone (2KHSO5·kHSO4·K2SO4) in water was accomplished successfully in high-to-excellent yields.
Abstract: Direct bromination and iodination of various aromatic compounds with NaBr and NaI using oxone (2KHSO5·KHSO4·K2SO4) in water was accomplished successfully in high-to-excellent yields. The main benef...
TL;DR: The characterization of the stability of the fused aromatic region (FAR) in oil asphaltenes in terms of kinetic and thermodynamic stability is studied in this paper, where the authors consider the case of a single asphalte.
Abstract: The characterization of the stability of the fused aromatic region (FAR) in oil asphaltenes in terms of kinetic and thermodynamic stability is primary. Such an understanding is important if we are ...
TL;DR: In this article, an analog of Koopmans' theorem is formulated for the energies, ea, of virtual Kohn-Sham (KS) molecular orbitals from the requirement that the KS theory provides, in principle, not only the ex...
Abstract: An analog of Koopmans’ theorem is formulated for the energies, ea, of virtual Kohn–Sham (KS) molecular orbitals (MOs) from the requirement that the KS theory provides, in principle, not only the ex...
TL;DR: In this paper, simple analytical methods were developed for the extraction and determination of four pharmaceuticals and per- sonal care products (PPCPs) from water, sediments, and biota.
Abstract: Simple analytical methods were developed for the extraction and determination of four pharmaceuticals and per- sonal care products (PPCPs) from water, sediments, and biota. PPCPs were determined using tandem LC-MS in electro- spray ionization mode, and interactions with matrix co-eluents were investigated. Extractions of water samples were performed using solid-phase extraction (SPE), sediments were extracted by pressurized liquid extraction (PLE), and biota was extracted by liquid extraction. The selected analytical methods yielded recoveries ‡ 61% in all matrixes. Matrix inter- actions were investigated throughout the linear range of quantification of each compound, revealing that dissolved salts had relatively minor effects on ionization (between 14% suppression to 12% enhancement), but that sediment and biota ex- tracts caused significant matrix effects (ranging from 56% suppression to 25% enhancement). The direction and magnitude of matrix interactions reflected the physico-chemical properties of each analyte, particularly their pKa. Among the com- pounds analyzed in electrospray positive mode, carbamazepine was insensitive to matrix interactions, because it is a strong proton acceptor (pKa = 14.0). In contrast, atorvastatin (pKa = 4.5), a weaker proton acceptor, was particularly sensitive to matrix effects. For those compounds analyzed in negative-ion mode, sample alkalinity was found to be important. With a pKa of 10.4, 17a-ethinylestradiol generally exhibited matrix enhancement with increased sample alkalinity. However, the presence of acidic co-eluents contributed to matrix suppression. Lastly, TCS was particularly sensitive to matrix suppres- sion, as its circumneutral pKa (7.9) caused even slight changes in sample pH to considerably impact ionization. We con- clude that while different matrixes have clear impacts on ionization of these PPCPs, matrix effects can be quantified and overcome.
TL;DR: In this article, the rate-determining step of the addition of dihydrogen to methyl acetylaminoacrylate catalyzed by a rhodium catalyst containing a bidentate phospore was investigated.
Abstract: DFT and DFT/MM calculations are carried out on the rate-determining step of the addition of dihydrogen to methyl-(N)-acetylaminoacrylate catalyzed by a rhodium catalyst containing a bidentate phosp...
TL;DR: In this article, structural studies have been carried out for O,O-dimethylphosphorothioate anion (PA) interacting with Ag+, Hg2+, and Na+ cations.
Abstract: 31P NMR and ESI-MS structural studies have been carried out for O,O-dimethylphosphorothioate anion (PA–) interacting with Ag+, Hg2+, and Na+ cations. Evidence is presented for the formation of PA–·...
TL;DR: In this article, the chemical bonding and aromaticity patterns in metalloporphyrins were obtained with density functional theory (DFT) calculations at the OPBE/TZP level.
Abstract: We report here the chemical bonding and aromaticity patterns in metalloporphyrins, which were obtained with density functional theory (DFT) calculations at the OPBE/TZP level. This level of theory ...
TL;DR: In this article, the single-crystal X-ray structure of a microporous alkaline-earth phosphonate incorporating a new triphosphonate ligand is presented.
Abstract: The single-crystal X-ray structure of a microporous alkaline-earth phosphonate incorporating a new triphosphonate ligand is presented. Sr2(H2L)(CH3OH)(H2O)4, where L = 1,3,5-tris(4-phosphonophenyl)benzene, crystallizes in triclinic space group P-1 (a = 6.9230(4) A, b = 15.3370(9) A, c = 16.1930(11) A, α = 62.201(3)°, β = 85.288(4)°, γ = 86.665(4)°). The solid is sustained by cooperative interactions between both one-dimensional inorganic and organic columns and forms a two-fold interpenetrated microporous structure. Gas and vapour sorption experiments confirm the microporosity. Based upon the sustaining interactions, this compound can serve as a model for more porous structures as extension of its structure disfavours further interpenetration.Key words: metal–organic framework, coordination polymer, phosphonate, microporous, alkaline earth.
TL;DR: In this paper, a variety of adducts of silver salts with ethylenethiourea (etu) were described for X-ray structural and spectroscopic characterizations.
Abstract: Syntheses, single crystal X-ray structural and spectroscopic characterizations are described for a variety of adducts of silver salts with ethylenethiourea (etu). Ag2SO4/etu (1:6) is isomorphous wi...
TL;DR: In this article, density functional theory was used to study the glycosidic bond cleavage in deoxynucleotides with the main goal to determine the effects of the nucleobase, hydrogen bonding with the nucleus, and the hydrogen binding with nucleobases.
Abstract: Density functional theory was used to study the glycosidic bond cleavage in deoxynucleotides with the main goal to determine the effects of the nucleobase, hydrogen bonding with the nucleobase, and...