Multifunctional phosphine stabilized gold nanoparticles: an active catalytic system for three-component coupling reaction.

Multifunctional phosphine based ligands, 1,1,1-tris(diphenylphosphinomethyl)ethane [CH3C(CH2 PPh2)3][P3] and 1,1,1-tris(diphenylphosphinomethyl)ethane trisulphide [CH3C(CH2P(S)Ph2)3][P3S3] have been introduced to stabilize Au(o)-nanoparticles having small core diameter and narrow size distribution. The Au(o)-nanoparticles were synthesized by the reduction of HAuCl4 precursor with NaBH4 in the presence of ligand P3 or P3S3 using two phases, one pot reaction at room temperature. The Au(o)-nanoparticles exhibit face centered cubic (fcc) lattice having different crystalline shape i.e., single crystallite stabilized by P3 while P3S3 forms decahedral shapes. Surface plasmon bands at -520 nm and TEM study indicate particle size below 2 and 4 nm for Au(o)-nanoparticles stabilized by P3 and P3S3 respectively, which are attributable to the stronger interaction of Au(o) (Soft) with P (Soft) than Au(o) (Soft) with S (less Softer than P). Au(o)-nanoparticles stabilized by P3S3 shows higher thermal stability than that of P3. The synthesized Au(o)-nanoparticles serve as an efficient catalyst for one-pot, three-component (A3) coupling of an aldehyde, an amine and an alkyne via C-H alkyne-activation to synthesize propargylamines (85-96%) without any additives and precaution to exclude air.

Metal nanoparticles: in-situ stabilization, characterization and reactivities.

We report here, the technique for preparation, characterization and reactivities of different metals (Cu, Ni, Au, Ru, Pt etc.) nanoparticles. The stabilized metal nanoparticles are, in general, very active as catalysts, e.g., hydrogenation (with H2/transfer hydrogenation) of nitro to amino group, ketone to alcohol and also oxidation of alcohol to Ketone/aldehyde. Metal nanoparticles, due to their smaller size than bacteria, tissues etc. and high reactivities, must have high impact on safety, health and environment and therefore, a systematic study of the effect of metal nanoparticles in these aspects need be carried out.

Au(degrees)-nanoparticles: control size and morphology stabilized by tripodal phosphine based ligands and their antimicrobial activity.

Metal nanoparticles have attracted great attention due to their potential applications in the fields like electronics, opto-electronics, bioscience, catalysis, etc. New ligands 1,1,1-tris (diphenylphosphinomethyl) ethane [CH3C(CH2PPh2)3] 1 and 1,1,1-tris-(diphenylphosphino methyl) ethane trisulphide [CH3C(CH2P(S)Ph2)3] 2 for stabilization of Au(degrees)-nanoparticles having small core diameter were prepared. The Au(degrees)-nanoparticles are more active against Gram(+) bacteria, e.g., Staphylococcus aureus than Gram(-) bacteria. Among the two Au(degrees)-nanoparticles, the ligand 1 stabilized particles shows higher activity.

Synthesis, characterisation and thermal studies of ruthenium(II) carbonyl complexes of functionalised tripodal phosphine chalcogen donor ligands, [CH(3)C(CH(2)P(X)Ph(2))(3)], where X=Se, S, O.

The polymeric ruthenium(II) carbonyl complex, [Ru(CO)(2)Cl(2)](n) reacts with 1,1,1-tris-(diphenylphosphinomethyl)ethane trichalcogenide ligands, [CH(3)C(CH(2)P(X)Ph(2))(3)], where X=Se(a), S(b) and O(c) in 1:1 (metal:ligand) molar ratio to afford hexa-coordinated complexes of the type eta(2)-(X,X)-[Ru(CO)(2)Cl(2)P(3)X(3)] (1a-c). The complexes 1a-c exhibit two equally intense nu(CO) bands in the range 1979-2060cm(-1) indicating cis-disposition of the two terminal carbonyl groups. The values of nu(CO) frequencies containing different ligands, in general, follow the order: P(3)O(3)>P(3)S(3)>P(3)Se(3) which may be explained in terms of 'Soft-Hard' (Ru(II)-O) and 'Soft-Soft' (Ru(II)-S/Se) interactions. The complexes have been characterized by elemental analyses, mass, (1)H, (31)P, (77)Se and (13)C NMR spectroscopy. The thermal stability of the complexes has also been studied.