In order to gain further insight into the physical basis of flavin-catalyzed reactions, the interactions of a flavin with a second flavin and with other aromatic ring systems were studied. For this purpose compounds through 1 were synthesized These compounds contain the interacting units in defined geometric orientation. A monomeric flavin and glutathione reductase a flavoenzyme of known active-site chemistry, were included as reference molecules. The present report deals with excited triplet states of the flavin compounds as studied by optical spectroscopy and optically detected magnetic resonances (ODMR) at 1.3K.
(1992) Gückel, Friedemann; Maki, August H.; Neugebauer, Franz A.; Schweitzer, Dieter; Vogler, Helmut
We report on the electronic and triplet state ODMR spectroscopy of s-tetrazine, 3,6-dimethyl-, 3,6-dimethoxy- and 3,6-bis(methylthio)-s-tetrazines. Zero field splitting parameters were obtained by ODMR monitoring both the delayed fluorescence and the phosphorescence in neat single crystals. The S1 and T1 exciton electronic origins are reported. The zero field splitting tensor is nearly axially symmetric with |D| approximately 0.4 cm-1. This value is found to be in good agreement with calculations based on magnetic dipole-dipole coupling in a 3B3u (nπ*) state. The calculations predict a positive value for D with the major axis passing through the C atoms at the 3 and 6 positions.