A Review on Effect of Solvents on Fluorescent Spectra

When absorption spectra are measured in solvents of different polarity, it is found that the positions, intensities, and shapes of the absorption bands are usually modified by these solvents. These changes are a result of physical intermolecular solute–solvent interaction forces (such as ion-dipole, dipole-dipole, dipole-induced dipole, hydrogen bonding, etc.), which above all tend to alter the energy difference between ground and excited state of the absorbing species containing the chromophore. When excited states of a molecule are created in solution by continuous or flash excitation, the excited-state molecule interacts to a varying degree with the surrounding solvent molecules, depending on their polarity, before returning to the ground state. These excited-state solute/solvent interactions found in fluorescent molecules are often reflected in the spectral position and shape of the emission bands as well as in the lifetimes of the excited-state molecules. The solvent-dependence of the position of emission bands in fluorescence spectra is termed as solvatochromism. These review paper presents detail discussion on solvatochromism, Electrochromism, and reaction field theory.