SPECTROSCOPY AND PHOTOCHEMISTRY OF 8-SUBSTITUTED 5-DEAZAFLAVINS |
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| Authors: | Paul A J Link Henk C VAN DER Plas Franz Müller |
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| Institution: | Laboratory for Organic Chemistry, Agricultural University, De Dreijen 5, 6703 BC Wageningen, The Netherlands;Laboratory for Biochemistry, Agricultural University, De Dreijen 11, 6703 BC Wageningen, The Netherlands |
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| Abstract: | Abstract— Absorption, fluorescence and phosphorescence spectra as well as fluorescence and phosphorescence quantum yields of 8-X-5-deazaflavins (X = C1, NO2, p -NO2-C6H4, N(CH3)2, NH2, p -NH2-C6H4, p -N(CH3)2-C6H4-N=N) were determined. It was found that all these data are highly influenced by the substituent at position 8 of the 5-deazaisoalloxazine skeleton. Also the photoreduction of 8-X-5-deazaflavins in the presence of electron donors was studied. It was established that the photoreduction leads to the formation of a 5,5'-dimer and/or a 6,7-dihydro compound. Reduction of the C(6)-C(7) bond is promoted by strong electron-donating substituents and bulky electron donors. 5-Deazaftavins with a reducible substituent at position 8 exhibit reduction of the substituent prior to the reduction of the 5-deazaisoalloxazine skeleton. |
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