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Solvent Effects on the Steady‐state Absorption and Fluorescence Spectra of Uracil, Thymine and 5‐Fluorouracil †

We report a comparison of the steady‐state absorption and fluorescence spectra of three representative uracil derivatives (uracil, thymine and 5‐fluorouracil) in alcoholic solutions. The present results are compared with those from our previous experimental and computational studies of the same compounds in water and acetonitrile. The effects of solvent polarity and hydrogen bonding on the spectra are discussed in the light of theoretical predictions. This comparative analysis provides a more complete picture of the solvent effects on the absorption and fluorescence properties of pyrimidine nucleobases, with special emphasis on the mechanism of the excited state deactivation.