Theoretical study on the effects of substituents and solvent polarity on the ESIPT properties and electronic spectra of 2-((E)-(naphthalene-3-ylimino)-methyl) phenol derivatives

In this work, the excited state intramolecular proton transfer (ESIPT) properties of the 2-((E)-(naphthalene-3-ylimino)-methyl) phenol (NMP) derivatives (NMP-NH2, NMP-OMe) in different solvents are investigated by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The results indicate NMP-OMe is more inclined to undergo the ESIPT process among the two derivatives, and the greater the polarity of solvent, the more likely the ESIPT process is to take place. Meaningfully, the two derivatives can generate the fluorescence spectra from the blue region (548 nm) to orange region (628 nm).