Ground- and excited-state dipole moments of 1, 2-diazine nanomaterials using solvatochromic method

Abstract

The ground-state ðlg) and excited-state ðle) dipole moments of three 1, 2-diazine nanomaterials (pyrrolo-pyridazine derivatives) were determined using the solvatochromic shift methods, i.e. Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet and Reichardt equations. All these equations are based on the variation of Stokes shift with solvent’s dielectric constant and refractive index. Theoretical lg values were also evaluated by quantum chemical calculations using the DFT method by adopting B3LYP/6-31G* level of theory (Gaussian 03). It was observed that all the three 1, 2-diazine nanomaterials possess higher dipole moment values in the excited singlet-state than in the ground-state. This confirms that the excited state of these nanomaterials is more polar than the ground state. Therefore, the solvent–solute interactions should be stronger in the excited singlet-state than in the ground-state, demonstrating an important redistribution of charge densities between both electronic states.