Theoretical Insight on the Tautomerism and ESIPT Process in Some Hydroxyaryl(hetaryl)idene Azomethine Imines

The current study aims to model the potential energy surface (PES) of three much less investigated hydroxyaryl(hetaryl)idene azomethine imine derivatives, possessing the same proton crane unit-namely the azomethine imine moiety-but slightly differing in the structure of the proton transfer platform (stator), by applying the tools of computational chemistry. The obtained calculational results are compared with already reported experimental structural, ¹H NMR, and UV absorption spectra in an attempt to shed light on the observed data, mainly with regard to the efficiency of the excited state intramolecular proton transfer.