Excited state intramolecular charge transfer versus hydrogen bonding effect on the photophysical properties of fluorescent compounds

Abstract

The observation of solvent induced shifts of the absorption and fluorescence emission bands has been used extensively in order to study the changes in electronic distribution in excited states of solute molecules. An understanding of excited state properties helps not only in the design of new molecules but also for the best performance for specific application. Photoinduced intramolecular charge transfer (ICT) is one of the most widely studied phenomena as a primary function for photoelectronic devices. It is well known that the local environment, especially solvents, has a profound effect on the emission behaviour of ICT-type compounds. Molecules undergoing ICT often exhibit a large change in dipole moment in the excited state when compared with the ground state. As a result, these systems often show systematic variation of the fluorescence properties with solvent polarity.