Photomodulated Self-Assembly of Hydrophobic Thiol Monolayer-Protected Gold Nanorods and Their Alignment in Thermotropic Liquid Crystal

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• 作者：Chenming Xue ; Karla Gutierrez-Cuevas ; Min Gao ; Augustine Urbas ; Quan Li
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：October 17, 2013
• 年：2013
• 卷：117
• 期：41
• 页码：21603-21608
• 全文大小：403K
• 年卷期：v.117,no.41(October 17, 2013)
• ISSN：1932-7455

文摘

Three terminal thiols possessing azobenzene and perylene diimide (PDI) segments covalently linked by alkylene spacers of different lengths (P_nSH, n = 4, 6, and 8) were synthesized to stabilize and functionalize gold nanorods (GNRs) via strong covalent Au鈥揝 bonds onto the gold surface. The resulting hydrophobic thiol monolayer-protected GNRs (P_nGNRs) were stable in both organic solvent and the solid state and exhibited fascinating photoresponsive self-assembly behavior. The PDI moieties provided 蟺鈥撓€ interactions to promote GNR self-assemblies while the photoresponsive azobenzene moieties offered a way to phototune the assemblies in a reversible manner. Interestingly, when P_nGNRs were mixed with a structurally similar room-temperature thermotropic liquid-crystal perylene diimide (LCP), the UV-irradiated P_nGNRs showed more compatibility with the LCP host than their corresponding unirradiated ones. Furthermore, the P_nGNRs with varied alkylene chain lengths showed different dispersion abilities in LCP. The UV-irradiated P₄GNRs did not disperse well in LCP, whereas the UV-irradiated P₆GNRs and P₈GNRs dispersed well in LCP and were further aligned upon mechanical shearing. In addition, preliminary molecular simulation was performed to explain this interesting photomodulated self-assembly of the GNRs.