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The most important area of modern pharmacology is the targeted delivery of drugs, and one of the most promising classes of chemical compounds for creating drugs of this kind are the photochromic spiropyrans, capable of light-controlled biological activity. This work is devoted to the synthesis and study of the photochromic properties of new triphenylphosphonium salts of spiropyrans. It was found that all the synthesized cationic spiropyrans have high photosensitivity, increased resistance to photodegradation and the ability for photoluminescence. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Graphical abstract The reversible acid-base isomerization of fullerene C 60 hybrid compounds with spiropyrans has been performed for the first time. It has been found that irradiation induces isomerization only for hybrid bearing NO 2 group in the photochromic spiropyran part, while the treatment with trifluoroacetic acid induces isomerization for compounds containing NO 2 , Cl or F, i.e. irrespective of the nature of substituent in the spiropyran moiety. [ABSTRACT FROM AUTHOR]

[Display omitted] Reversible transformations of a hybrid molecule based on [60]fullerene and a spiropyran moiety under conditions of combined photo- and electrochemical exposure were found. It has been established that the electrochemical oxidation of the UV-photoinduced colored form of the hybrid spiropyran in solution significantly accelerates the discoloration process and does not affect the fullerene part of the hybrid molecule. The research results are promising for designing a photo-electrochromic device that modulates electromagnetic radiation in the visible range of the spectrum. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Absorption and PL properties of fullerene[60]-containing spiropyrans were studied. • First example of luminescence switching for photochromic fullerenes is demonstrated. • The fulleropyrrolidine 1 is the brightest compound among the fullerene monoadducts. • Photochrome is more exothermic process for C60-containing spiropyran than for initial. Abstract Molecular switch is a widespread concept of molecular machinery. It consists on creating the molecules, which are able to exist in two stable states with significantly different physicochemical properties. Spiropyrans are widely used for this purpose as they readily undergo photoisomerization and reveal suitable spectral parameters to monitor the switch. Novel photo-switchable spiropyrans can be obtained by their linking with fullerene[60], a well-known electron acceptor with a unique π-electronic system. In the present work, we have synthesized such a hybrid fullerene-containing spiropyran and studied its switching with UV–vis and luminescent spectroscopies. We have found that the photo-impact induces the transit of the C 60 -spiropyran molecular system from its closed form to the open one. This switch is accompanied with a significant increase in the intensity of luminescence. The measured quantum yield of the photoluminescence of the open form of the C 60 -spiropyran adduct is high (ϕ PL = 0.09), so it has a record luminescent properties among the mono-adducts of the C 60 fullerene with typical ϕ PL values lower than 0.001. The outstanding properties of the fullerene-spiropyran adducts may be further used in molecular devices and systems of three-dimensional memory. [ABSTRACT FROM AUTHOR]