A novel photochromic hetarylalkylideneisocromandione systemстатья
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Дата последнего поиска статьи во внешних источниках: 8 апреля 2022 г.
Аннотация:A novel photochromic system based on an alkylideneisochromanedione core with heterocyclic substituents wassynthesized, and its spectral luminescent and photoinduced properties were studied. The obtained isochromandionescontaining the hexatriene fragment exist in a ring-open E-form, confirmed by the data of 1H, 13CNMR spectroscopy and X-ray diffraction studies. The observed photoinitiated processes depend fundamentally onthe nature of the heterocyclic substituents. Thiophenyl, benzo[b]thiophenyl and 1H-indolyl derivatives 5c-f arenon-photochromic in the solid state, and in solutions their transformations are limited by thermally reversible E/Z-photoisomerization. Compound 5a with a furanyl substituent is photochromic in crystalline form due to thelight-induced rearrangement of the ring-open hexatriene isomer into the ring-closed cyclohexadiene structure.Upon irradiation with light of 436 nm, the yellow crystals of 5a turn dark blue-green. The reverse reaction of thecycle opening and restoration of the original color of the crystals occurs extremely easily upon irradiation withvisible light of 578 nm. In contrast to crystals, solutions of compounds 5a and 5b with furanyl substituents inhexane, 2-propanol, acetonitrile and DMSO are discolored when irradiated with light of 365 nm. The irreversiblephotorearrangement 5a,b → 6a,b includes the stages of cyclization, the opening of the furan cycle and theformation of highly fluorescent naphthalic anhydride derivatives 6 (the quantum yield of fluorescence reaches0.69 in hexane)), which can be used for the production of optical memory media for archive 3D discs.