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.

Controllable Synthesis of Gold Nanoparticles in Aqueous Solution by Microwave Assisted Flow Chemistry

“…22 respectively (Figure 3 a and b). Consistent with the literature, 35,43 as-synthesized Au-nanowires using…”

Calcium Mediated C−H Silylation of Aromatic Heterocycles with Hydrosilanes

“…The δ-bond metathesis reaction between the Ca-thiophenyl bond (Ca1À C1, Figure 1A) in complex 2' and a SiÀ H bond in diphenylsilane and n-hexylsilane would afford the silylation products 7 a and 8 a, respectively, and regenerate the mononuclear calcium hydride complex 1'. Presumably, 7 a would be used as the silylation reagent to give bis(5-methylthiophenyl)hexylsilane (7) after the consumption of n-hexylsilane.…”

“…Silicon‐containing aromatic heterocycles are of great interest and importance in various fields, such as materials science, [7] pharmaceuticals [8] and intricate molecule synthesis [9] . The traditional route to the synthesis of silylated aromatic heterocycles involved the usage of organo‐lithium or Grignard reagents and silicon electrophiles [10] .…”

“…Molecular calcium hydride complexes [3] have been involved as key intermediates in various catalytic cycles, including hydrogenation, [4] hydro-functionalization, [5] and dehydrogenative coupling. [6] Silicon-containing aromatic heterocycles are of great interest and importance in various fields, such as materials science, [7] pharmaceuticals [8] and intricate molecule synthesis. [9] The traditional route to the synthesis of silylated aromatic heterocycles involved the usage of organo-lithium or Grignard reagents and silicon electrophiles.…”

Vinyl-Functionalized Janus Ring Siloxane: Potential Precursors to Hybrid Functional Materials

“…Among them, all-cis-cyclotetrasiloxanes can be recognized as Janus molecules [29] because they have two different faces [30,31]. These Janus compounds have been used in the synthesis of welldefined nano-precursors [32][33][34][35], cubic silsesquioxanes T 8 [30,[36][37][38], copolymers [39,40], cyclic polymers [41][42][43], highly porous materials [4,11,12,44], semiconducting materials [45], protective coating molecules [46], and catalysts [47][48][49].…”