LaIII and ZnII Cooperatively Template a Metal–Organic Capsule

An organic subcomponent was designed
with 2-formyl-8-aminoquinoline
and triazole-pyridine ends. The relative orientations and geometries
of these two ends enabled this subcomponent to assemble together with
ZnII and LaIII cations to generate a heterobimetallic
tetrahedral capsule. The LaIII cations each template three
imine bonds that hold together a 3-fold-symmetric metallo-ligand,
defining the center of each tetrahedron face. The ZnII cations
occupy the other ends of these C3 axes,
defining the vertices of the tetrahedron. This is the first example
where subcomponent self-assembly brought into being the faces of a
polyhedron, as opposed to the vertices. Host–guest studies
show positively cooperative binding toward ReO4–, the encapsulation of which also resulted in the quenching of capsule
fluorescence.

本设计了一种有机亚组分，该组分由2-甲酰基-8-氨基喹啉和三唑-吡啶端基构成。这两种端基的相对取向和几何结构使得亚组分能够与ZnII和LaIII阳离子组装，形成一种异金属四面体胶囊。LaIII阳离子各自模板化三个亚胺键，这些键维系着三重对称的金属-配体结构，从而界定每个四面体面心的结构。ZnII阳离子占据这些C3轴的其余端点，界定四面体的顶点。这是首次通过亚组分自组装形成多面体的面而非顶点的实例。宿主-客体研究显示，对ReO4–的绑定呈现正协同效应，其封装过程亦导致胶囊荧光的淬灭。