PHOSPHORESCENCE OF NUCLEIC-ACIDS AND DNA COMPONENTS AT 77-K

The emission spectra of nucleic acids, pyrimidine and purine nucleotides, nucleosides and bases and a series of pyrimidine derivatives were obtained using UV light excitation in glasses (ethanol and 2:1 mixtures of ethylene glycol and water (EGH2O); also partly in butyronitrile and 2-methyltetrahydrofuran) at 77 K. The quantum yields of fluorescence Φf and phosphorescence Φp of some 30 compounds are presented; for several substituted uracils they are reported for the first time. The values cover a range from Φf = 0.0002 and Φp = 0.001 for uracil in ethanol to Φf = 0.50 for guanosine in acidic ethanol and Φp = 0.095 for guanosine-5′-monophosphate in EGH2O (pH 6 - 7). The phosphorescence lifetime τp at 77 K ranges from about 0.3 s (uracil moiety) to 3 s (adenine moiety). The measured τp, Φf and Φp values are compared with those available in the literature. © 1990.