Solvent Effect on the Fluorescence Properties of Two Biologically Active Thiophene Carboxamido Molecules

Abstract

The absorption and fluorescence spectra of two thiophene carboxamido molecules namely 2–( - trimethoxy phenyl) imino–3–N–ethylcarboxamido–4, 5, tetramethylene thiophene (X) and 2-( -N, N-dimethylaminophenyl) imino-3-(N- methylphenyl carboxamido)-4, 5, tetramethylene thiophene (Y) have been recorded at room temperature. The ground (mg) and excited (me) state dipole moments are estimated from Lippert, Bakhshiev, Kawski-Chamma-Viallet equations by using the variation of Stokes shift with microscopic solvent dielectric constant (e) and refractive index (n). The excited dipole moments were also estimated by using the variation of Stokes shift with microscopic empirical solvent polarity parameter and the values are compared. It was estimated that dipole moments of the excited state were higher than those of the ground state of both the molecules. Further, the change in dipole moment (Dm) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter .