Effect of solvents on the photophysical properties of substituted imidazonaphthyridine derivatives

The absorption and fluorescence characteristics of three substituted imidaz onaphthyridine derivatives are studied in a series of organic solvents. The variation of Stokes shift with the polarity parameter of the solvent is st udied and the excited state dipole moment of these derivatives is higher th an the ground state dipole moment. The fluorescence lifetime profile shows single exponential decay in all the solvents. The fluorescence quantum yiel d, radiative and non-radiative rate constants are also calculated and these parameters show much variation in the change in substitution of these deri vatives. (C) 2000 Elsevier Science B.V. All rights reserved.