ИСТИНА

One of the promising types of photoactive molecules for the research of supramolecular self-organization are the crown-containing compounds in which two chelating crown-ether moieties are separated by a photochemically active central core (Figure). The interest to the studies of such compounds is caused by their ability to self-assembly to supramolecules and supramolecular ensembles resulting from the complexation with metal and ammonium ions followed by considerable changes in their spectral characteristics, as well as by a possibility of changing their structure and properties upon irradiation. The most typical photochemical processes taking place in the indicated supramolecular systems that proceed with considerable changes in the properties (including receptor ones) are the trans/cis-isomerization and [2+2]- cycloaddition reactions.The efficient methods for the synthesis of symmetric biscrown-containing cross-conjugated dienones1 and 1,4- and 1,3-distyrylbenzenes2 were suggested. The structures of compounds were established by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. Spectrophotometric and fluorescent methods were applied to study the photophysical behavior of the products.3,4 The electrochemical oxidation and reduction potentials of the biscrown-containing 1,4-distyrylbenzenes and dienones in solution were determined. The linear correlation between electrochemical and photochemical characteristics was established. Spectrophotometric and fluorescent titrations were used to determine spectral properties, stoichiometry, and stability of complexes of biscrown-containing receptors with alkali and alkaline-earth metal cations.5 The stability of the complexes was found to depend on the metal cation size and charge, as well as on the size of the crown ether fragment and the nature of the central core. Acknowledgment. The authors thank Russian Science Foundation, grant # 14-13-00076. References 1. Patent RU, 2568614, 2015. 2. Patent RU, 2603135, 2016. 3. High Energy Chemistry 2016, 50, 27. 4. High Energy Chemistry 2016, 50, 442. 5. Russ. Chem. Bull. 2016, 65, 2686.