1. Asymmetric Synthesis of Chiral Bimetallic [Ag28Cu12(SR)24]4- Nanoclusters via Ion Pairing
- Author
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Yan, Juanzhu, Su, Hai-Feng, Yang, Huayan, Hu, Chengyi, Malola, Sami, Lin, Shui-Chao, Teo, Boon K., Häkkinen, Hannu, and Zheng, Nanfeng
- Subjects
ion pairing ,asymmetric synthesis ,nanoclusters - Abstract
In this work, a facile ion-pairing strategy for asymmetric synthesis of optically active negatively charged chiral metal nanoparticles using chiral ammonium cations is demonstrated. A new thiolated chiral three-concentric-shell cluster, [Ag28Cu12(SR)24] 4- was first synthesized as a racemic mixture and characterized by single-crystal X-ray structure determination. Mass spectrometric measurements revealed relatively strong ion-pairing interactions between the anionic nanocluster and ammonium cations. Inspired by this observation, the as-prepared racemic mixture was separated into enantiomers by employing chiral quaternary ammonium salts as chiral resolution agents. Subsequently, direct asymmetric synthesis of optically pure enantiomers of [Ag28Cu12(SR)24] 4- was achieved by using appropriate chiral ammonium cations (such as Nbenzylcinchoninium vsN-benzylcinchonidinium) in the cluster synthesis. These simple strategies, ion-pairing enantioseparation and direct asymmetric synthesis using chiral counterions, may be of general use in preparing chiral metal nanoparticles. peerReviewed
- Published
- 2016