Excited state solvation dynamics of 6-methoxyquinoline

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 1991-02, Vol.56 (2), p.207-217
• Main Authors: Pant, Debi, Tripathi, H.B., Pant, D.D.
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Exact sciences and technology; Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion); Molecular properties and interactions with photons; Physics
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/1010-6030(91)80021-9

Steady state and transient studies of 6-methoxyquinoline (6MQ) were undertaken. 6MQ undergoes a large change of dipole moment on excitation. The low energy absorption band L b does not change in position with solvent polarity whereas the emission maxima shift towards lower frequencies with broadening of the spectra. The edge excitation red shift, which is associated with the time-dependent red shift of emission, is observed in all polar solvents. The fluorescence decay is monoexponential and is dependent on emission wavelength. The data are explained with the help of the Bakhshiev model of solvent relaxation. The solvent relaxation time τ r and the fluorescence lifetime τ f increase with the polarity of the solvent. In aqueous solution, 6MQ undergoes a protolytic reaction in the excited state. The rate constant for the proton transfer is 1.2×10 8 s −1.