Synthesis and physical properties of a pi-conjugated ruthenium(II) dinuclear complex involving an azobenzene-bridged bis(terpyridine) ligand

A novel pi-conjugated Ru(II) dinuclear complex containing a new azobenzene- bridged bis(terpyridine) ligand was synthesized and its photochemical and e lectrochemical properties were investigated. The ligand underwent reversibl e trans-cis photoisomerization, whereas the Ru complex did not show such ph otoisomerization behavior. Cyclic voltammetry of the complex displayed a re versible one-step 2e(-) oxidation wave due to Ru(III)Ru(III)/Ru(II)Ru(II) a nd four le(-) reduction waves indicating the formation of mixed-valence sta tes when the electrons are accumulated at the ligand-based orbitals.