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New salts of photochromic indoline spiropyrans capable of reversibly responding to UV radiation were synthesized to develop light-controlled materials. Photoinduced reactions of the synthesized compounds were studied using absorption and luminescence spectroscopies, and the quantum yields of photoisomerization and other spectral and kinetic characteristics were measured. It was shown that the light sensitivity and photostability of the synthesized compounds are considerably influenced by the length of the spacer between the indole and ammonium nitrogen atoms.

Fluorescence (FL) from Eu2+ ion solid individual compounds was observed for the first time using the examples EuCl2, EuI2 and EuBr2. Fluorescence was detected at excitation by ultraviolet (UV) light from powdered samples of Eu (II) halides at room temperature (RT) in an argon atmosphere. In air, FL of all Eu2+ compounds studied was stable, and intensity persisted for weeks. Depending on the nature of the halide anion and due to a nephelauxetic effect, the position of the maxima in the FL spectra underwent a red shift in the series: EuCl2 (409 nm) < EuBr2 (428 mm) < EuI2 (432 nm). The lifetimes of the excited states of the Eu2+* ions for EuI2, EuCl2 and EuBr2 were 355, 76 and 54 ns, respectively.