ИСТИНА

During the last two decades, considerable research interest has been devoted to the design of crown ether substituted chromophores. These compounds were mainly studied for their photochromic and fluorescence properties. In order to elucidate the possibility to construct photoactive supramolecular systems based on dienones we synthesized symmetrical dienones substituted with two azacrown ethers moieties. The behavior of dienones in acetonitrile in the presence of alkanediammonium ions +NH3(CH2)nNH3+ (n = 1-12) was studied by UV/vis absorption spectroscopy, fluorescence and NMR 1H spectroscopy. The formation of complexes and alkanediammonium ions is caused by interaction of the ammonium groups of with the crown ether moieties. Spectra of the dienones undergo significant changes in the presence of alkanediammonium ions. The stability constants of the formed complexes were determined. It was shown that in a dilute solution bis(azacrown)dienones forms stable 1:1 and 1:2 complexes with alkanediammonium ions. The stoichiometry and the stability constants of the complexes the dienone with alkanediammonium ions depends on the geometric matching of components, which is manifested as the distance between the terminal ammonium groups of alkanediammonium ions and the dienones binding sites. The dienones form 1:2 complexes with short alkanediammonium ions (n = 1-5) and high stable 1:1 complexes with long ions. Protonation of azacrown moieties which competes with complexation takes place in some cases. Influence of rigidity of central cycle on complexation was also demonstrated. The results of this study can be used for directional design of photoactive supramolecular assemblies and optical molecular sensors. This work was supported by the Russian Science Foundation (project № 19-13-00020).