货币金属纳米团簇的配体工程:杯芳烃-货币金属纳米团簇的合成与性质

Ligand engineering of coinage metal nanoclusters: The synthesis and properties of calixarene stabilized nanoclusters

自胶体金的理性合成起,货币金属团簇/颗粒的功能配体一直以膦配体和硫醇配体为主.近10年间,碳配体——炔烃配体及卡宾配体才被用于系统研究.随后,大批配位原子的同族元素被开发,用于团簇的合成;同时,对特殊骨架进行化学修饰也成为拓宽配体库的现实方法.聚焦新型配体的研究加深了对团簇构效关系的理解,启发了纳米团簇的配体工程.如今,从配体角度探究金属团簇已然成为重要的研究方法.同时,配体的发展也拓展了金属纳米材料的性质,深刻影响着此类材料的现实应用.功能配体的引入是将团簇发展为多功能材料的一个重要途径,因此也获得了日渐深入的研究.由于结构的多样性、化学可修饰性及诸多特殊的物化性质(主客体作用、刺激响应能力、手性、光学性质等),杯芳烃一直是广受关注的功能配体骨架.本文首先概述了配体对团簇性质的普遍影响,随后从杯芳烃修饰团簇的合成、稳定性及功能性方面进行了总结,展望了通过引入功能配体以获取多功能金属纳米团簇的前景.

Recent years have seen the increasing interest in the studies of metal nanoclusters especially on their structure-propertyrelationships. It has been accepted that the ligands are able to exert impacts on the stability, catalysis as well as the opticalproperties of nanoclusters. Ever since the rational synthesis of colloidal gold nanoparticles, phosphines and thiols havebeen the most widely studied ligands in coinage metal nanoclusters and nanoparticles. Only within 10 years, carbonbondedligands including alkynes and N-heterocyclic carbenes (NHCs) are emerging prevalent and being systematicallyinvestigated. Afterwards, the ligating atoms of the same group in the periodic table with carbon, sulfur and phosphine areexplored to passivate the metal clusters. Meanwhile, incorporation of ligating units onto various skeletons has also becomea practical approach to broaden the ligand library of metal clusters. The enriched ligands provide unprecedentedopportunities in studying such materials from another angle that was previously neglected. Hence, studies specifically onthe ligands are increasing and indeed are providing important insight into this area. On the other hand, the investigation ofligand effects and the expansion of ligand library are also broadening the properties of the ligated clusters, thus expandingtheir applications.This review will first summarize the recent advances in the ligand engineering of metal nanoclusters, mainly focusing onthe ligands for manipulating the stability, catalysis and optical properties of corresponding nanoclusters. The first sectiondescribes the ligand effects and lays the basis for understanding the second half of this review which presents the detaileddescription of calixarene stabilized coinage metal nanoclusters. Incorporation of functional ligands onto metal nanoclustersrepresents an important approach to broaden the applications of such materials and is gaining increasing attention. Owingto the versatility of skeletons, easy chemical modification combined with many other unique properties including robusthost-guest interactions, fast stimuli-induced responses, intrinsic chirality, optical properties among others, calixarenes haslong been investigated as functional molecules. On the other hand, these molecules are often decorated to synthesizepolynuclear metal complexes as multidentate ligands. These features enable calixarenes attractive in producing multifunctionalmetal clusters.The second section summarizes the synthesis, stability studies and the function of calixarene-metal clusters, providingperspectives on the future of multi-functional materials based on functional ligand stabilized metal clusters. From thepioneer work of calixarene stabilized metal clusters, it shows that metal clusters stabilized by these ligands are unique interms of their synthesis and stability. However, their capability in functioning metal clusters have not been widely provedyet.