Multinuclear Coordination Chemistry: From Molecular Self-Assembly to Solar Energy Conversion
The spontaneous formation of metal-ligand bonds can be used as the impetus for the self-assembly of nanoscopic metallacycles, cages, and prisms. These discrete architectures consist of organic donor and metal-containing acceptor building blocks that combine in specific stoichiometries as defined by the number of faces, edges, and/or vertices of a target structure. The multinuclear coordination complexes thus obtained are distinguished by their high degree of modularity, affording size, shape, and functional group tunability. New design strategies encompassing multicomponent self-assembly, hierarchical self-assembly, and pre- and post-self-assembly modifications illustrate the versatility of coordination-based supramolecular chemistry for the development of new materials, sensors, drug design, and delivery. The theme of multinuclear chemistry extends to the study of small molecule activations relevant to energy conversion. Polynuclear designs are attractive in that the redox and coordination site demands of HX (X = Cl, Br, OH) splitting for hydrogen production are spread across multiple metals, leading to efficient scaffolds upon which to explore photochemical bond activations. Specifically, the reductive elimination of halogen, an energy storing transformation and requisite step of HX splitting schemes, can be achieved using late-metal, bimetallic phosphine complexes.