Chiral chemistry in metal nanoclusters : Fundamentals and applications

我们发现由一对青霉胺对映体保护的金纳米团簇(~lt；2 nm)具有很高的光学活性。观察到的旋光性归因于手性配体诱导的不对称场。我们还成功地合成了一对银纳米团簇的光学异构体。它们的手部反应比核心大小相当的类似金纳米团簇的反应大几倍。手性配体的不对称场效应应该是其旋光性的普遍来源，但在小尺寸银区观察到的这种增强可能归因于手性银核的额外贡献。其次，对青霉胺保护的银纳米团簇的VCD光谱进行了实验研究，并进行了理论分析。光谱归属表明，溶剂效应是解释VCD实验光谱与理论光谱的一致性所必需的，导致P_N型构象是最可能的异构体。此外，我们还利用手性相转移或硼酸化学实现了光学不活跃的金和银纳米团簇的不对称变换或对称性破缺。

We found large optical activity in gold nanoclusters (<2nm) protected by a pair of penicillamine enantiomers. The observed optical activity was attributed to a dissymmetric field induced by the chiral ligands. We have also succeeded in synthesizing a pair of optical isomers of silver nanoclusters. Their chiroptical response was several-fold larger than that of the analogous gold nanoclusters with comparable core size. The dissymmetric field effect from chiral ligands should be a universal origin for their optical activity, but its enhancement observed in a small size region of silver might be attributed to additional contributions from a chiral silver core. Next, the VCD spectra of penicillamine-protected silver nanoclusters have been studied experimentally, and analyzed theoretically. The spectral assignment suggested that the solvent effect was necessary to account for an agreement between the experimental and theoretical VCD spectra, resulting in the P_N-type conformation as the most probable isomer. Furthermore, we have achieved asymmetric transformation or symmetry breaking of the optically inactive gold and silver nanoclusters using chiral phase-transfer or boronic-acid chemistry.