title: New cyclotetrasiloxanes bearing sila-alkyl substituted side chains and their applications as templates for gold nanowires.
abstract: New sila-alkyl substituted cyclotetrasiloxanes, [RMe2SiCH2CH2(Me)SiO]4 [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, (D4(Vi)) 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 HAuCl4·3H2O with triethylsilane (CHCl3, RT). On the other hand, the use of linear polysiloxane, [2-ThMe2SiCH2CH2(Me)SiO]n (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.
authors.affiliation: Department of Chemistry, Indian Institute of Technology, IIT-Delhi 110016, India. Shankar@chemistry.iitd.ac.in
authors.forename: Ravi
authors.initials: R
authors.lastname: Shankar
authors.forename: Manchal
authors.initials: M
authors.lastname: Chaudhary
authors.forename: Kieran C
authors.initials: KC
authors.lastname: Molloy
authors.forename: Gabriele
authors.initials: G
authors.lastname: Kociok-Köhn