Synthesis, Photochromic and Luminescent Properties of Ammonium Salts of Spiropyrans

Abstract

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.

Is this how bromine spiropyran salt is converted to merocyanine under UV irradiation? A look through the prism of quantum chemical calculations

“…The experimental UV spectrum of the spiropyran form recorded in a THF solution before UV irradiation contains a weak band at 267 nm and an intense band at 324 nm. 9 The third singlet transition of spiropyran has the highest oscillator strength caused by the excitation from the HOMO to LUMO+1 according to TD-DFT calculations (Fig. 3).…”

“…Probably, high activation barriers for these stages determine a very long time for transformation during dark bleaching (180 s) and under irradiation with visible light (100 s), as we observed earlier in our experimental work. 9…”

“…1). 9 Their photophysical properties and the kinetics of reversible photoinduced reactions with their participation were studied. It was assumed that such compounds, consisting of a bulky organic cation and a compact bromide anion, would behave as ionic liquids that exhibit high cytotoxic activity against various tumor cells.…”

Photochromic and Luminescent Properties of a Salt of a Hybrid Molecule Based on C60 Fullerene and Spiropyran—A Promising Approach to the Creation of Anticancer Drugs

“…In view of the foregoing to attain our goal, that is, to prepare a new water-soluble hybrid compound, we chose spiropyran salt 1 containing several functional groups in the molecule as the model spirophotochrome. The desired spiropyran was synthesized using methods reported in the literature [ 22 , 23 ] according to Scheme 1 :…”

“…Together with water solubility this would open up prospects for the design of effective photoswitchable antitumor agents based on these hybrids for the treatment of cancer in humans. Previously we reported on the synthesis of spiropyran salts and the study of their spectral and luminescent properties, which are of interest as antitumor compounds [ 22 ]. By the beginning of our work, the feasibility of this approach was evidenced by only one study addressing the photoswitchable cytotoxicity against Hek293 cancer cells for one spiropyran example [ 23 ].…”