Biocatalytic deracemization of alkyl-2-hydroxy-4-arylbut-3-ynoates using whole cells of Candida parapsilosis ATCC 7330

Racemic alkyl-2-hydroxy-4-arylbut-3-ynoates were deracemized to the (S)-alkyl-2-hydroxy-4-arylbut-3-ynoates in excellent enantiomeric excesses (up to >99%) and good isolated yields (up to 81%) with the biocatalyst Candida parapsilosis ATCC 7330. The absolute configuration of the resulting enantiomer was assigned by ¹H NMR using Mosher’s method.     

A confocal laser scanning microscopic study on thermoresponsive binary microgel dispersions incorporated with CdTe quantum dots

Monodisperse poly(N-isopropylacrylamide) (PNIPAM) particles loaded with cadmium telluride (CdTe) quantum dots (QDs) of two different sizes (4.7 nm and 5.6 nm) were synthesized in aqueous medium by bonding the capping agent on the quantum dots to the amide groups of PNIPAM and incubating the samples at 45°C. A huge increase in the photoluminescence (PL) intensity (green and red regions) is observed for the PNIPAM-CdTe QDs composites compared to the parent CdTe QDs. We report here for the first time the imaging of binary dispersion of green and red luminescent PNIPAM-CdTe QDs composites using a fluorescence confocal laser scanning microscope. These composites have potential applications both in material science and biology.     

Synthesis, spectral characterization, catalytic and antibacterial studies of new Ru(III) Schiff base complexes containing chloride/bromide and triphenylphosphine/arsine as co-ligands

A new Ru(III) Schiff base complexes of the type [RuX(EPh₃)L] (X = Cl/Br; E = P/As; L = dianion of the Schiff bases were derived by the condensation of 1,4-diformylbenzene with o-aminobenzoic acid/o-aminophenol/o-aminothiophenol in the 1:2 stoichiometric ratio) have been synthesized from the reactions of [RuX₃(EPh₃)₃] with appropriate Schiff base ligands in benzene in the 2:1 stoichiometric ratio. The new complexes have been characterized by analytical, spectral (IR, electronic, ¹H, ¹³C NMR and ESR), magnetic moment and electrochemical studies. An octahedral structure has been tentatively proposed for all these new complexes. All the new complexes have been found to be better catalyst for the oxidation of alcohols using molecular oxygen as co-oxidant at ambient temperature and aryl–aryl coupling reactions. These complexes were also subjected to antibacterial activity studies against Escherichia coli, Aeromonas hydrophilla and Salmonella typhi.     

Raman spectral analysis of phenoxyacetic acid and some chloro substituted phenoxyacetic acids

Raman spectra of phenoxyacetic acid and chlorine substituted phenoxyacetic acids viz., o-chlorophenoxyacetic acid, p-chlorophenoxyacetic acid and 2,6-dichlorophenoxyacetic acid have been analysed with the aid of abinitio theoretical calculations. The effect of chlorine substituents on the Raman spectra of phenoxyacetic acid have also been analysed by considering some important vibrational modes.     

Spectral, redox and catalytic studies of triphenylphosphine/triphenylarsine complexes of Ru(III) with N, O donor ligands derived from 2-hydroxy-1-naphthaldehyde and primary amines

A series of new mixed ligand hexacoordinated ruthenium(III) Schiff base complexes of the type [RuX(2)(EPh(3))(2)(LL')] (X=Cl, E=P; X=Cl or Br, E=As and LL'=anion of the Schiff bases derived from the condensation of 2-hydroxy-1-naphthaldehyde with aniline, 4-chloroaniline, 2-methyl aniline and 4-methoxy aniline) are reported. All the complexes have been characterized by analytical and spectral (IR, electronic and EPR) data. The redox behavior of the complexes has also been studied. The complexes exhibit catalytic activity in the oxidation of benzyl alcohol to benzaldehyde in the presence of N-methyl morpholine-N-oxide (NMO). An octahedral structure has been proposed for all of the complexes.     

Asymmetric addition of trimethylsilylcyanide to N-benzylimines catalyzed by recyclable chiral dimeric V(V) salen complex

Chiral dimeric vanadium (V) salen complex (10 mol%) derived from 5,5-Methylene di-[(S,S)-{N-(3-tert-butyl salicylidine)-N′-(3′,5′-di-tert-butyl salicylidene)]-1,2-cyclohexanediamine] with vanadyl suphate followed by auto oxidation was used as efficient catalyst for enantioselective Strecker reaction of N-benzylimines with TMSCN at −30 °C. Excellent yield (92%) of α-aminonitrile and high chiral induction was achieved (ee up to 94%) in case of 2-methoxy substituted N-benzylimines in 10 h. The catalytic system worked well up to four cycles with retention of enantioselectivity.     

Open-mouthed metallic microcapsules: exploring performance improvements at agglomeration-free interiors

Although artificial capsule structures have been thoroughly investigated, functionality at the surfaces of their interiors has been surprisingly overlooked. In order to exploit this aspect of capsular structure, we here report the breakthrough fabrication of metallic (platinum) microcapsules with sufficient accessibility and electroactivity at both interior and exterior surfaces (open-mouthed platinum microcapsules), and also we demonstrate improvements in electrochemical and catalytic functions to emphasize the practical importance of our concept. The open-mouthed platinum microcapsules were prepared by template synthesis using polystyrene spheres, where surface-fused crystalline nanoparticles formed a capsule shell. Subsequent removal of the polystyrene spheres induced formation of mouth-like openings. The open-mouthed platinum microcapsules exhibit a substantial increase of their electrode capability for methanol oxidation and catalytic activities for carbon monoxide (CO) oxidation. Notably, activity loss during CO oxidation due to undesirable particle agglomeration can be drastically suppressed using the open-mouthed microcapsules.     

A cis‐stilbene derivative

The title compound, 4′‐methoxy‐α,2,3′,4‐tetra­nitro­stilbene, C₁₅H₁₀N₄O₉, crystallizes in the centrosymmetric space group P2₁/c with one mol­ecule in the asymmetric unit. The phenyl rings are inclined to one another and form a dihedral angle of 57.4 (1)°. The size of this angle is a result of intermolecular C—H⃛O interactions involving the phenyl H atoms. The torsion angle between the phenyl rings, −7.5 (3)°, indicates a cis geometry between them. The methoxy group is almost coplanar with the phenyl ring, and the nitro groups are twisted with respect to the phenyl rings because of the short H⃛O contacts. The crystal packing is stabilized by C—H⃛O hydrogen bonds, and the intermolecular hydrogen bonds form a C(12) graph‐set chain running along the [010] direction.     

Crystal Structure of 1-(4-(5,6-Dihydropyridazin-1(4H)-yl)Phenyl)-N-Methylmethanesulfonamide

Crystallography Reports - The title compound, 1-(4-(5,6-dihydropyridazin-1(4H)-yl)phenyl)-N-methylmethanesulfonamide (C12H17N3O2S), was isolated as an impurity during the preparation of sumatriptan...