Role of Substituents in Excited State Intramolecular Proton Transfer (ESIPT) Processes

The increasing interest in molecular systems exhibiting ESIPT reaction has triggered – due to their broad field of potential applications – an extensive search for properly substituted compounds with well-tailored properties. This review is based on selected papers dealing with some commonly known ESIPT systems modified by specific substituents. The results of several studies concerning the rate of ultrafast ESIPT reactions in supersonic molecular beams are presented. Articles reporting on phototautomeric fluorescence in solutions illustrated a big role of substituents, which influence the emission quantum yield. Theoretical works pointed to the increasing role of advanced calculations in predicting and understanding the structural, electronic, and spectroscopic properties of diverse ESIPT-capable compounds.