A Bio-inspired Approach for Chromophore Communication: Ligand-to-Ligand and Host-to-Guest Energy Transfer in Hybrid Crystalline Scaffolds

Efficient multiple-chromophore coupling in a crystalline metal-organic scaffold was achieved by mimicking a protein system possessing 100 % energy-transfer (ET) efficiency between a green fluorescent protein variant and cytochrome b₅₆₂. The two approaches developed for ET relied on the construction of coordination assemblies and host-guest coupling. Based on time-resolved photoluminescence measurements in combination with calculations of the spectral overlap function and Förster radius, we demonstrated that both approaches resulted in a very high ET efficiency. In particular, the observed ligand-to-ligand ET efficiency value was the highest reported so far for two distinct ligands in a metal-organic framework. These studies provide important insights for the rational design of crystalline hybrid scaffolds consisting of a large ensemble of chromophore molecules with the capability of directional ET.