The State Key Laboratory of Molecular Reaction Dynamics and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China.
J Phys Chem A. 2013 Oct 10;117(40):10294-303. doi: 10.1021/jp406336q. Epub 2013 Sep 30.
It is accepted that the monolayer ligand shell in monolayer-protected gold nanoclusters (MPCs) plays an important role in stabilizing the metal core structure. Previous reports have shown that the core and shell do not interact chemically, and very few studies investigating the intramolecular charge transfer (ICT) between the core and ligand shell in clusters have been reported. The underlying excited state relaxation mechanisms about the influence of solvents, the optically excited vibration, and the roles of the core and shell in charge transfer remain unknown to a large extent. Here we report a femtosecond transient absorption study of a Au20(SR)16 (R = CH2CH2Ph) cluster in toluene and tetrahydrofuran. The ICT from the outside shell to the inside core upon excitation in Au20(SR)16 is identified. The observed solvation-dependent oscillations in different solvents further confirm the photoinduced ICT formation in Au20(SR)16. The results provide a fundamental understanding of the structure-property relationships about the solvation-dependent core-shell interaction in Au MPCs.
人们普遍认为，在单层保护金纳米簇（MPC）中的单层配体壳在稳定金属核结构方面起着重要作用。以前的报告表明，核和壳之间没有化学相互作用，并且很少有研究报道在簇中研究核和配体壳之间的分子内电荷转移（ICT）。关于溶剂、光激发振动以及核和壳在电荷转移中的作用对影响的基本激发态弛豫机制在很大程度上仍然未知。在这里，我们报告了在甲苯和四氢呋喃中 Au20(SR)16（R = CH2CH2Ph）团簇的飞秒瞬态吸收研究。在 Au20(SR)16 中激发时，从外壳到内部核的 ICT 被确定。在不同溶剂中观察到的溶剂依赖性振荡进一步证实了 Au20(SR)16 中光诱导 ICT 的形成。这些结果为了解 Au MPC 中与溶剂依赖性核壳相互作用有关的结构-性质关系提供了基础。
