Photoreduction of deazaflavin. Spectroscopic investigations

Abstract

Photophysical and photochemical properties of deazaflavin (3,10-dimethylpyrimido[4,5-b]quinoline- 2,4-(3H,10H)-dione) and some of its 1,5-dihydro derivatives have been investigated. Contrary to earlier reports the photodimer of deazaflavin is non-luminescent throughout the temperature range 77-295 K. Excitation of deazaflavin in the presence of oxalate anion (acetate buffer pH 5.0) causes photodimerization with quantum efficiencies exceeding unity. A mechanism involving a triplet excimer of deazaflavin has been proposed for this reaction.