Regensburg 2010 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Electronic and Optical Properties of Organic Systems I

CPP 6.4: Talk

Monday, March 22, 2010, 12:30–12:45, H39

Absorption and Emission Spectroscopic Characterisation of 8-Amino-Riboflavin — •Amit Tyagi¹, Peyman Zirak¹, Alfons Penzkofer¹, Tilo Mathes², Peter Hegemann², Matthias Mack³, and Sandro Ghisla⁴ — ¹Institut II - Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg — ²Institut für Biologie / Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstr. 42, 10115 Berlin — ³Institut für Technische Mikrobiologie, Hochschule Mannheim, Paul-Wittsack-Str. 10, 68163 Mannheim — ⁴Universität Konstanz, Fakultät für Biologie, Postfach 5560 M644, 78457 Konstanz

The flavin dye 8-amino-8-demethyl-D-riboflavin (AF) in the solvents water, DMSO, and methanol was studied by absorption and fluorescence spectroscopy. The first absorption band is red-shifted compared to riboflavin, and blue-shifted compared to roseoflavin. The fluorescence quantum yields are 0.22 for AF in water, 0.37 for AF in methanol, and 0.50 for AF in DMSO. The fluorescence lifetimes were found to be 2.3 ns in water, 4.9 ns in methanol, and 5.1 ns in DMSO. The non-radiative decay is thought to be dominated by internal conversion and intersystem crossing. The photo-stability of AF was studied by prolonged light exposure. For blue-light exposure (425-500 nm) quantum yields of photo-degradations were determined to be 0.000018 for AF in water and methanol, and 0.000089 for AF in DMSO. The main degradation product of AF was found to be 8-amino-lumichrome (AL, absorption rise in 310-380 nm region). AF in DMSO additionally degraded to 8-aminoflavin quinine-methide tautomer.