Effect of anisotropic and isotropic solvent on the dipole moment of coumarin dyes

The ground state (mu(g)) and the excited state (mu(e)) dipole moments of two coumarin laser dyes, coumarin 440 and 460, were studied at room temperature in various solvents, viz., general solvents, alcohols and liquid crystals at 298K. In this work, we report dipole moment of laser dyes in different anisotropic (liquid crystal) and isotropic environments for understanding the effects of environments on the molecular dipole moment and comparing them. Ground and excited state dipole moments of coumarin dyes were evaluated by means of solvatochromic shift method. It was observed that dipole moment values of excited states (mu(e)) were higher than the corresponding ground state values (mu(g)) in all media. (C) 2010 Elsevier B.V. All rights reserved.