A novel mononuclear complex of 4,4́́-azobis-(2,2́- bipyridine) coordinated to tetracyanoruthenium(II) can behave as a “molecular switch”

Abstract A novel tetracyanoruthenium(II) complex of formula K2[Ru(4,4-azobpy)(CN)4], (1) , with 4,4-azobpy = 4,4-azobis-(2,2'-bipyridine), has been synthesized and characterized by spectroscopic, electrochemical and photophysical techniques. The effects of reduction and protonation of the azo group of coordinated 4,4-azobpy in the UV-Visible absorption and emission spectra of (1) were explored by spectroelectrochemical techniques and by addition of L-Cysteine. The behavior of (1) as a “molecular switch” could be explained with the aid of quantum-mechanical calculations by using density functional theory.