New benzimidazolic 3-hydroxychromone derivative with two alternative mechanisms of the excited state intramolecular proton transfer reaction

The 2-(benzimidazol-2-yl) derivative of 3-hydroxychromone was synthesized and studied by X-ray structure analysis, 1H NMR and fluorescence spectroscopy. The possibility of the alternative H-bonds formation and thus – two alternative mechanisms of the excited state intramolecular proton transfer reaction was discussed on the base of the spectral data, X-ray structure analysis and quantum-chemical calculations.