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Substituent and solvent effect on the solvatochromic properties of some thiophene derivatives

M.D.Adeoye, N.O.Obi-Egbedi, I.Iweibo

In this paper, a variant of solvatochromic frequency shift equation that accommodates intensity parameters such as solvent molecular polarizability (á), the molar refraction (R), stark term(µ/r3) and Einstein Coefficient (k) and oscillator intensity (f) had been developed. This was applied to the study of photo-physical properties of three thiophene derivatives: 3, 4-diphenylthiophene; 3, 4-dicarboxylic-2, 5-diphenylthiophene and benzo[b] thiophene in order to determine their transition polarizability (Äá), transition dipole moment (Äì) and other molecular properties using UV-visible spectrophotometer. The magnitudes of both the experimental oscillator strength in solution and vapour phase were calculated using Lorentz- reaction field model while the frequencies of the transitions in polar and non-polar solvents were used to characterize the observed bands. The spectra behaviours of these molecules in the different solvents in terms of dipole moments in the ground and excited states and calculated values Äá have been interpreted and related to the transition energies, intensities and the molecular structures of the compounds.