Determination of Excited State Electric Dipole Moments and Polarizabilities of positional Isomeric Nitroaniline using Modified Abe Solvatochromic Model and Quantum Chemical Calculations

The dipole moments and polarizabilities in various excited states of o-, m- and p-nitroanilines were estimated using Linder’s variant of Abe solvatochromic model. The ground and excited state dipole moments of these molecules were computed from experimental and theoretical studies using solvatochromic technique and Density Functional Theory (DFT) respectively. The trend observed for the various excited states dipole moments of the o-, m- and p- isomers of nitroaniline follow the order ortho>meta>para.  The excited state polarizabilities obtained for the electronic transitions in each of the compounds are reflective of the oscillator strength f values for these transitions.  Also, the excited singlet-state dipole moments obtained were higher than the calculated ground state dipole moments which shows that the excited singlet-state is more polar than the ground state for all the compounds studied. The effects of solvent manifest in form of enhancement to the electronic intensities. The results of the present analysis show internal consistency and agree reasonably with Abe’s theory.