Postclustering Dynamic Covalent Modification for Chirality Control and Chiral Sensing

Cluster-based functional materials are appealing, because clusters are well-defined building units that can be rationally incorporated for the tuning of structures and properties. Postclustering modification (PCM) allows for tailoring properties through the structural modification of a cluster with preorganized funtional groups. By introducing aldehydes into a robust gold–silver cluster via a protection–deprotection process, we manage to synthesize a new cluster bearing six reactive sites, which are available for PCM through dynamic covalent imine bonds formation with chiral monoamines. Chirality is transferred from the amine to the gold–silver cluster. The homochirality of the resulted cluster has been confirmed by X-ray structural determination and CD spetroscopy. Intense CD signals make it practical for chiral recognition and ee value determination of chiral monoamines. The strategy of prefunctionalizing of cluster and the concept of PCM open a broader prospect for cluster design and applications.基于团簇（cluster）的功能材料极具吸引力，这是因为团簇是结构明确的构筑基元，可通过理性引入以调控材料的结构与性能。团簇后修饰（Postclustering modification, PCM）可通过对带有预组织官能团的团簇进行结构修饰，实现性能的定制化调控。本研究通过保护-脱保护过程将醛基引入至稳定的金-银团簇中，成功合成了一种带有六个活性位点的新型团簇；该团簇可通过与手性单胺形成动态共价亚胺键，完成团簇后修饰。手性可从胺分子转移至金-银团簇中，所得团簇的同手性已通过X射线晶体结构测定与圆二色光谱（CD spectroscopy）得到证实。强烈的圆二色信号使其可应用于手性识别以及手性单胺的对映体过量（ee）值测定。团簇预功能化策略以及团簇后修饰的理念，为团簇的设计与应用开辟了更为广阔的前景。