Nature uses a complex array of chromophores, optimally organized both spatially and electronically, to carry out photoinduced energy and electron transfer from pigment molecules to a reaction center. The fundamental processes underpinning photosynthesis provide the basis for artificial solar conversion systems that include photovoltaic cells, photoanodes and photocathode catalysts to generate electricity or fuels. It is the supramolecular arrangement of multiple chromophores that results in the emergent properties associated with natural light harvesting complexes, including enhanced absorption, efficient energy transfer between pigments, and electron-transfer. We are interested in self-assembled discrete metal-organic assemblies containing multiple chromophores as functional models of supramolecular light harvesting architectures. Specifically, we are actively designing systems to identify the optimal alignment, spacing, and electronic structure to enable directional EnT and photoredox chemistry while maximizing broadband absorption matched to the solar flux. The formation of structurally complex metal-organic polygons, polyhedra, and prisms (MOPs) is greatly facilitated by coordination-driven self-assembly methods which furnish them in single, one-pot reactions. An ever-growing library of organic ligands (donors) and metal/organometallic complexes with substitutionally labile coordination sites (acceptors) serves as the basis for a suite of metallacycles and cages characterized by their well-defined internal cavities and predictable topologies. The rigid organic backbones that once served solely as structural elements have more recently been exploited for their ability to impart interesting photophysical properties to their parent MOPs. Strategies include tethering pendant fluorophores through covalent coupling chemistry and selecting inherently emissive building blocks, with an emphasis on exploiting Ru, Ir, and Pt-based complexes.








Timothy Cook (University of Buffalo)