Novel compounds of the general formula are introduced, containing 5-arylidene-3,5-dihydro-4h-imidazol-4-one core. These compounds can be used for fluorescent staining of cell membranes, biomolecules' labeling in vivo and in vitro, a number of compounds also have photoacidic properties. This allows to use them, for example, as instruments to drastically change pH of a medium, and also as dynamic fluorescent probes for investigation of complex objects like proteins and micellae, as well as in studies of hydration dynamics and in photolithography.