Hydrogen bond in the excited state of [2.2.2.2](1,2,4,5)cyclophane quinhydrones

Intra- and intermolecular hydrogen bond was studied in electron-donor-acceptor complexes in the excited state. It was shown that low-frequency shifts of electron-transfer bands are correlated with the strength of the hydrogen bond in the ground electron state. A satisfactory agreement was obtained between the results of quantum-chemical calculations of [2.2.2.2](1,2,4,5)cyclophane bisquinones and their reduced forms, [2.2.2.2] (1,2,4,5)cyclophane quinhydrones, with experimental data, and unusual physicochemical properties of quinhydrones are noted.