A MODEL FOR MOLECULES WITH TWISTED INTRAMOLECULAR CHARGE-TRANSFER CHARACTERISTICS - SOLVENT POLARITY EFFECT ON THE NONRADIATIVE RATES OF DYES IN A SERIES OF WATER ETHANOL MIXED-SOLVENTS

The model of Grabowski et al. has been modified and used to account for the absence of a fluorescence band from the twisted form of molecules with torsional mechanisms. We have measured the ground and excited state spectroscopic properties of rhodamine B dissolved in a series of water-ethanol mixed solvents, and used the data to test the model. We also applied our model to 8-anilino-1-naphthalenesulfonate (ANS) in the same solvent system, using previously published decay and quantum yield data. The results show that the variation of the nonradiative rates may be attributed to changes in solvent polarity for both systems. © 1990.