Search

A green and cost-effective biosynthetic approach for the preparation of icosahedral gold nanoparticles (AuNPs) using an aqueous leaf extract ofPolygonum minusas reducing and stabilising factor is described. The reduction of Au3+ions to elemental Au rapidly occurred and is completed within 20 minutes at room temperature. The size of the nanoparticles is highly sensitive to the AuCl4−/leaf extract concentration ratio and pH. Transmission electron microscopy and X-ray diffraction data indicated that the nanoparticles were in a crystalline shape (face-centred cubic), mostly icosahedral and nearly monodispersed with an average size of 23 nm. Cyclic voltammetric studies suggested that flavonoids, such as quercetin and myricetin present in the leaf extract had a tendency to donate electrons to Au3+ions and the formation of elemental Au was possible due to the transfer of electrons from these flavonoids to Au3+ions. Infrared absorption of the AuNPs and the leaf extract revealed that the oxidised (quinone) form of quercetin and myricetin were presumably the main stabilising agents in the formation of stable nanoparticles. The present biosynthesis of AuNPs was simple, rapid, cost-effective and environmentally friendly. The newly prepared biostabilised icosahedral AuNPs show good catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). [ABSTRACT FROM AUTHOR]

Four air and moisture-stable palladium(II)-Schiff base complexes, N,N'-bis(-methylsalicylidene)propane-1,3-diamine palladium(II) (2a), N,N'-bis(4-methyl--methylsalicylidene)propane-1,3-diamine palladium(II) (2b), N,N'-bis(3,5-di-tert-butylsalicylidene)propane-1,3-diamine palladium(II) (2c), and N,N'-bis(4-methoxy-salicylidene)propane-1,3-diamine palladium(II) (2d), have been successfully synthesised and characterised by CHN elemental analyses and conventional spectroscopic methods. These complexes were investigated as catalysts in the phosphine-free Mizoroki-Heck cross-coupling reactions of aryl bromides with methyl acrylate. [ABSTRACT FROM AUTHOR]

Abstract: A series of Cu-doped Cd0.1Zn0.9S solid solution with various amounts of Cu dopant was successfully prepared by hydrothermal method. The properties and the photocatalytic activity of the prepared samples for hydrogen production under visible light irradiation were compared to those prepared by co-precipitation method. The Cu-doped Cd0.1Zn0.9S samples prepared by hydrothermal method showed both improved crystallinity and photoabsorption ability as compared to the undoped sample. On the other hand, even though Cu-doped Cd0.1Zn0.9S prepared by co-precipitation method also showed improved photoabsorption ability in the visible light region, the samples showed poor crystallinity compared to the undoped one. With the same amount of Cu dopant, all samples prepared by hydrothermal method were found to exhibit higher photocatalytic activity for hydrogen production than the samples prepared by co-precipitation method. It was revealed that the amount of Cu dopant, crystallinity and narrow band gap energy are important factors to obtain highly active and stable photocatalysts. [Copyright &y& Elsevier]

Abstract: A new trinuclear di-n-butyltin(IV) complex with pyruvic acid-N(4)-cyclohexylthiosemicarbazone (H2PACT) ligand was synthesized and characterized by elemental analyses, molar conductivity, UV–Vis, FT-IR, 1H, 119Sn NMR spectroscopy and single crystal X-ray study. Single crystal X-ray diffraction data revealed that this complex was trinuclear cyclic fashion with the pyruvic acid-N(4)-cyclohexylthiosemicarbazone ligand. In the trinuclear di-n-butyltin(IV) complex, the ligand (H2PACT) is coordinated to the central tin(IV) atoms via the carboxylato-O, the azomethine-N and the thiolato-S atoms. The trinuclear tin system is formed by the bridges through the carbonyl oxygen atom of the carboxylate moieties and making the tin atom of seven coordinated in distorted pentagonal bipyramidal geometry. Single crystal X-ray data indicates that the complex (1) crystallized in cubic system with space group I-43d, a = b = c = 30.3273(17) Å, α = β = γ = 90°, Z = 16, μ(MoKα) = 1.209 mm−1, F(000) = 12,144, and final R 1 = 0.0390, wR 2 = 0.0843 for observed reflections 4582(I > 2σ(I)). [Copyright &y& Elsevier]

In the asymmetric unit of the title complex, [Ni(C16H14N3OS)2], the nickel ion is tetra-coordinated in a distorted square-planar geometry by two independent mol-ecules of the ligand which act as mononegative bidentate N,S-donors and form two five-membered chelate rings. The ligands are in trans (E) conformations with respect to the C=N bonds. The close approach of hydrogen atoms to the Ni(2+) atom suggests anagostic inter-actions (Ni⋯H-C) are present. The crystal structure is built up by a network of two C-H⋯O inter-actions. One of the inter-actions forms inversion dimers and the other links the mol-ecules into infinite chains parallel to [100]. In addition, a weak C-H⋯π inter-action is also present.

In the title compound, [PdBr(C(27)H(23)N(3)OPS)]·C(3)H(6)O, the coordination geometry about the Pd(II) atom is distorted square-planar, arising from the attached Br, S, P and N atoms (N and Br are trans), the maximum deviation from the plane being 0.2053 (4) Å for the N atom. The three benzene rings attached to the P atom make dihedral angles of 69.78 (7), 87.05 (7) and 77.50 (7)° with each other. An intra-molecular C-H⋯N hydrogen bond forms an S(6) ring motif. In the crystal, the complex mol-ecules form infinite chains along the a-axis direction through C-H⋯Br inter-actions, and a C-H⋯O inter-action links the main mol-ecule with the acetone solvent mol-ecule.

In the title compound, [Pd(C(21)H(24)N(2)O(4))], the complete mol-ecule is generated by crystallographic mirror symmetry with the Pd and three C atoms lying on the mirror plane. The Pd-O and Pd-N distances are 1.9932 (6) and 2.0029 (7) Å, respectively. The dihedral angle between two benzene rings of the ligand is 79.21 (4)°. In the crystal, C-H⋯O hydrogen bonds link the mol-ecules into layers parallel to the ab plane. These planes are further connected by C-H⋯O inter-actions, forming a three-dimensional network.

The monodeprotonated Schiff base ligand in the title compound, [Sn(CH(3))(C(14)H(19)N(4)S)Cl(2)], N,N',S-chelates to the Sn atom, which is six-coordinated in an octa-hedral environment. The three coordinating atoms along with the methyl C atom comprise a square plane, above and below which are positioned the Cl atoms. The amino group is a hydrogen-bond donor to a Cl atom of an adjacent mol-ecule, the hydrogen bond giving rise to a helical chain extending parallel to [100].

The asymmetric unit of the title complex, [Pd(C(19)H(20)N(2)O(2))]·0.5C(2)H(5)OH, contains two mol-ecules of a Pd(II) complex of a Schiff base ligand with an N(2)O(2) donor set and one ethanol mol-ecule. The Pd(II) centers are in distorted square-planar geometries with the N(2)O(2) donor atoms of the tetra-dentate Schiff base dianions. The ethanol mol-ecule takes part in an O-H⋯O hydrogen bond. In the crystal structure, mol-ecules are stacked approximately along the b-axis direction. The O atom and three H atoms of the solvent molecule are disordered over two positions; the site occupancy factors are ca 0.8 and 0.2.