title: Surface modification of adamantane-terminated gold nanoclusters using cyclodextrins.
abstract: The surface functionality of Au38S2(SAdm)20 nanoclusters (-SAdm = adamantanethiolate) in the presence of α-, β-, and γ-cyclodextrins (CDs) is studied. The supramolecular chemistry and host-guest interactions of CDs and the protecting ligands of nanoclusters are investigated using UV-vis and NMR spectroscopies, MALDI mass spectrometry, and molecular dynamics simulations. In contrast to α- and γ-CDs, the results show that β-CDs are capable of efficiently chemisorbing onto the Au38S2(SAdm)20 nanoclusters to yield Au38S2(SAdm)20-(β-CD)2 conjugates. MD simulations revealed that two -SAdm ligands of the nanoparticle with the least steric hindrance are capable to selectively be accommodated into hydrophobic cavity of β-CDs, as furthermore confirmed by NMR spectroscopy. The conjugates largely improve the stability of the nanoclusters in the presence of strong oxidants (e.g., TBHP). Further, the electrochemical properties of Au38S2(SAdm)20 nanoclusters and Au38S2(SAdm)20-(β-CD)2 conjugates are compared. The charge transfer to the redox probe molecules (e.g., K3Fe(CN)6) in solution was monitored by cyclic voltammetry. It is found that β-CDs act as an umbrella to cover the fragile metal cores of the nanoclusters, thereby blocking direct interaction with destabilizing agents and hence quenching the charge transfer process.
authors: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410000, China. renhuaqiu@hnu.edu.cn and Gold Catalysis Research Centre, State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China. chaoliu@dicp.ac.cn gaoli@dicp.ac.cn.
authors: Chunyang
authors: C
authors: Yan
authors: Gold Catalysis Research Centre, State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China. chaoliu@dicp.ac.cn gaoli@dicp.ac.cn.
authors: Chao
authors: C
authors: Liu
authors: Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
authors: Hadi
authors: H
authors: Abroshan
authors: Gold Catalysis Research Centre, State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China. chaoliu@dicp.ac.cn gaoli@dicp.ac.cn and University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Zhimin
authors: Z
authors: Li
authors: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410000, China. renhuaqiu@hnu.edu.cn.
authors: Renhua
authors: R
authors: Qiu
authors: Gold Catalysis Research Centre, State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China. chaoliu@dicp.ac.cn gaoli@dicp.ac.cn.
authors: Gao
authors: G
authors: Li