Regioselective Deuteration and Resonance Raman Spectroscopic Characterization of Biliverdin and Phycocyanobilin

Abstract

Abstract 5‐Deuteriophycocyanobilin ( 4 ), 5,15,18 2 ,18 2 ‐tetradeuteriobiliverdin IXα dimethyl ester ( 6 ), and 5,15‐dideuteriomesobiliverdin IXα dimethyl ester ( 8 ) have been prepared and analyzed by resonance Raman spectroscopy in the C–H out‐of‐plane region, based on a previous normal‐mode analysis of biliverdin XI α dimethyl ester ( 5 ). In this way most of the modes containing out‐of‐plane vibrations of the methine bridges could be assigned unambiguously. These results are of special relevance with regard to the interpretation of the resonance Raman spectra of the chromoprotein phytochrome.