Abstract
The present work deals with the effect of solvents and temperature on the photophysical properties of 4-methyl-7-aminocoumarin (I), and 4-methyl-7-dimethylaminocoumarin (II). Change of solvent gives rise to Stokes’ shift but due to specific interactions, the excited state dipole moments cannot be calculated. Experimental values of percentage polarization in different polar solvents indicate the formation of 1∶1 solute-solvent exciplexes/intermolecular hydrogen bonding. Further, it is observed that the fluorescence intensity decreases with increase in temperature for the compound II, but remains constant for compound I. This difference in behaviour is examined in terms of intramolecular charge transfer (ICT) and twisted intramolecular charge transfer (TICT) states of the coumarin molecule.
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Giri, R., Rathi, S.S. & Machwe, M.K. Influence of solvents and temperature on the excited state characteristics of coumarin laser dyes. Acta Physica Hungarica 70, 3–13 (1991). https://doi.org/10.1007/BF03054204
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DOI: https://doi.org/10.1007/BF03054204