Li Yingwei, Higaki Tatsuya, Du Xiangsha, Jin Rongchao
Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.
Adv Mater. 2020 Oct;32(41):e1905488. doi: 10.1002/adma.201905488. Epub 2020 Mar 17.
Chirality is ubiquitous in nature and occurs at all length scales. The development of applications for chiral nanostructures is rising rapidly. With the recent achievements of atomically precise nanochemistry, total structures of ligand-protected Au and other metal nanoclusters (NCs) are successfully obtained, and the origins of chirality are discovered to be associated with different parts of the cluster, including the surface ligands (e.g., swirl patterns), the organic-inorganic interface (e.g., helical stripes), and the kernel. Herein, a unified picture of metal-ligand surface bonding-induced chirality for the nanoclusters is proposed. The different bonding modes of M-X (where M = metal and X = the binding atom of ligand) lead to different surface structures on nanoclusters, which in turn give rise to various characteristic features of chirality. A comparison of Au-thiolate NCs with Au-phosphine ones further reveals the important roles of surface bonding. Compared to the Au-thiolate NCs, the Ag/Cu/Cd-thiolate systems exhibit different coordination modes between the metal and the thiolate. Other than thiolate and phosphine ligands, alkynyls are also briefly discussed. Several methods of obtaining chiroptically active nanoclusters are introduced, such as enantioseparation by high-performance liquid chromatography and enantioselective synthesis. Future perspectives on chiral NCs are also proposed.
手性在自然界中无处不在，且存在于所有长度尺度上。手性纳米结构应用的发展正在迅速兴起。随着原子精确纳米化学的最新成果，成功获得了配体保护的金及其他金属纳米团簇（NCs）的完整结构，并发现手性的起源与团簇的不同部分相关，包括表面配体（如漩涡图案）、有机 - 无机界面（如螺旋条纹）和内核。在此，提出了纳米团簇的金属 - 配体表面键合诱导手性的统一图景。M - X（其中M = 金属，X = 配体的结合原子）的不同键合模式导致纳米团簇上不同的表面结构，进而产生各种手性特征。金硫醇盐纳米团簇与金膦纳米团簇的比较进一步揭示了表面键合的重要作用。与金硫醇盐纳米团簇相比，银/铜/镉硫醇盐体系在金属和硫醇盐之间表现出不同的配位模式。除了硫醇盐和膦配体，炔基也进行了简要讨论。介绍了几种获得具有手性光学活性纳米团簇的方法，如高效液相色谱法进行对映体分离和对映选择性合成。还提出了手性纳米团簇的未来展望。
