Estimation of the ground and the first excited singlet-state dipole moments of 1,4-disubstituted anthraquinone dyes by the solvatochromic method.
The both, ground-state (mu(g)) and the excited-state (mu(e)) dipole moments of three 1,4-disubstituted anthraquinones, namely 1,4-diaminoanthracene-9,10-dione (1,4-DAAQ), 1-amino-4-hydroxyanthracene-9,10-dione (1,4-AHAQ), and 1,4-dihydroxyanthracene-9,10-dione (1,4-DHAQ) were estimated in binary solvent mixtures (methylcyclohexane-ethyl acetate and ethyl acetate-acetonitrile). The dipole moments (mu(g) and mu(e)) were estimated from Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet, McRae, and Suppan equations by using the variation of Stokes shift with the solvent's relative permittivity and refractive index. The ground-state dipole moments were also calculated theoretically by Gaussian 03 software using B3LYP/6-31 G* level of theory. Further, the change in dipole moment values Deltamu were also calculated by using the variation of Stokes shift with the molecular-microscopic empirical solvent polarity parameter (E(T)(N)). The excited-state dipole moments observed are larger than their ground-state counterparts, indicating a substantial redistribution of the pi-electron densities in a more polar excited state for all the molecules investigated.
Department of Physics, Gulbarga University, Jnana Ganga, Gulbarga 585106, Karnataka, India.
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Siddlingeshwar
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Hanagodimath
D000880:Anthraquinones / Q000737:chemistry*; D002625:Chemistry, Organic / Q000379:methods*; D004396:Coloring Agents / Q000737:chemistry*; D004560:Electricity; D008956:Models, Chemical; D012997:Solvents / Q000737:chemistry; D013057:Spectrum Analysis
D000880:Anthraquinones; D004396:Coloring Agents; D012997:Solvents