New cyclotetrasiloxanes bearing sila-alkyl substituted side chains and their applications as templates for gold nanowires

New sila-alkyl substituted cyclotetrasiloxanes, [RMeSiCH CH(Me)SiO] [R = Ph(1), 2-thienyl(2), 2-furyl(3)] have been synthesized by a hydrosilylation reaction between 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, (D ) and dimethylphenylsilane/dimethyl-2-thienylsilane/dimethyl-2- furylsilane in the presence of Karstedt's catalyst. X-ray crystallographic studies of 1 and 2 reveal all-trans conformation of the methyl groups bonded to puckered siloxane core and formation of 3D supramolecular assemblies by virtue of intermolecular C-H⋯π interactions. These siloxanes act as potential templates for expeditious one pot synthesis of gold nanowires of varying aspect ratios which are obtained by reduction of HAuCl·3H O with triethylsilane (CHCl, RT). On the other hand, the use of linear polysiloxane, [2-ThMeSiCHCH (Me)SiO] (4) in lieu of the cyclosiloxane 2 affords predominant formation of polydispersed AuNPs along with a few extended structures. These results suggest that conformational confinement of the appended groups on the cyclosiloxanes, 1-3 plays an important role to impart morphological control of the gold nanowire assemblies.