Comment on “Influence of Solvents and Halogenation on ESIPT of Benzimidazole Derivatives for Designing Turn-on Fluorescence Probes”

In the paper, listed in the title, unproper conformation analysis of a series of potentially tautomeric benzimidazole derivatives has been performed by Rivelino, Canuto, and coauthors (ACS Omega2024, 9 (20), 22102). They described existence of only 3 conformers of the enol tautomer and one for the keto form for each of the studied compounds. Actually, we found more than 50 additional conformers for the tautomers of the unsubstituted compound (<b>H</b>). When one bears in mind the structural similarity with the rest of the compounds, the situation with them should be the same. More importantly, Rivelino, Canuto, and coauthors discuss in detail the properties of the conformers that are not the most stable ones, which strongly limits the practical value of the published massive data output. Due to the improperly done theoretical work along with the lack of understanding of the existing experimental data and principles of excited state intramolecular proton transfer (ESIPT), the suggested photocycle in the Br substituted compound (<b>Br</b>) is doubtful.