Absorption and Luminescence Studies of Some Highly Fluorescent Derivatives of Vitamin B1; Solvent and pH Effects

Authors:

• Bronisław Marciniak,
• Jacek Koput,
• H. Kozubek

Abstract

The influence of solvent on the UV-virible absorption and luminescence spectra of some highly fluorescent vitamin B1derivatives, the products of the reaction of N-methylated vitamin with B1cytidinc (1), adenosine (II) and 2-amino-4“mcthylpyridinc (III) is studied. Spectroscopic manifestations of protonation of I and II are also investigated using a semiempirical INDO/S Cl method. Singlet and triplet energy levels of the free ion and several protonated species are calculated, and transition energies and oscillator strengths are compared with the experimental spectra. Calculated charge densities on heteroatoms in the ground and excited singlet and triplet states are correlated with changes of the experimental pKa values with excitation. The results for I and II are compared with those for the trimethylated pyrichrominium ion (III) previously studied. © 1990, Verlag der Zeitschrift für Naturforschung. All rights reserved.