New cyclotetrasiloxanes bearing sila-alkyl substituted side chains and their applications as templates for gold nanowires
作者:Ravi Shankar、Manchal Chaudhary、Kieran C. Molloy、Gabriele Kociok-Köhn
DOI:10.1039/c3dt50284h
日期:——
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, (D4Vi) 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.
通过 2,4,6,8-四甲基-2,4,6,8-四乙烯基环四硅氧烷 (D4Vi) 和二甲基苯基硅烷/二甲基-2-噻吩基硅烷之间的氢硅化反应,合成了新的硅烷基取代环四硅氧烷 [RMe2SiCH2CH2(Me)SiO]4 [R = Ph(1),2-噻吩基(2),2-呋喃基(3)]、6,8-四甲基-2,4,6,8-四乙烯基环四硅氧烷 (D4Vi) 和二甲基苯基硅烷/二甲基-2-噻吩基硅烷/二甲基-2-呋喃基硅烷在卡氏催化剂存在下发生氢化硅烷化反应而合成的。对 1 和 2 的 X 射线晶体学研究表明,甲基全反式构象与皱褶硅氧烷核心结合,并通过分子间 C-H⋯π 相互作用形成三维超分子组装体。这些硅氧烷可作为潜在的模板,通过用三乙基硅烷(CHCl3,RT)还原 HAuCl4-3H2O 来快速合成不同长宽比的金纳米线。另一方面,使用线性聚硅氧烷[2-ThMe2SiCH2CH2(Me)SiO]n (4)代替环硅氧烷 2 主要形成了多分散的 AuNPs 以及一些扩展结构。这些结果表明,环硅氧烷 1-3 上附加基团的构象限制对金纳米线组装的形态控制起着重要作用。