Design and Synthesis of Tunable Ligands with 4,4′-Bipyridyl as an Electron-Accepting Unit and Their Rhenium Complexes

We have designed and prepared a series of rhenium complexes with 4,4′-bipyridyl as an electron-accepting unit. Electrochemical studies revealed that oxidation and reduction of these complexes occurred on the rhenium center and the 4,4′-bipyridyl skeleton, respectively. The redox potentials of the rhenium complexes are controllable by tuning the substituents on the 4,4′-bipyridyl skeleton and the coordinating groups to the rhenium center. We have also examined the reactivity of the rhenium complexes in electrochemical and photochemical CO 2 reduction.