Solid state photochromism of spiropyrans

Abstract

A series of spiropyrans possessing photochromic properties in solid state were investigated. UV irradiation (λmax=365nm) of the thin vacuum deposited spiropyran films results in conversion of the colorless form to the photocolored one. The reaction is photochemically and thermally reversible. The photochromic activity of the solid material and polystyrene matrix has been compared. Raman spectroscopy has been used for studying the influence of metallic surface on the adsorbed spiropyran layers.

A New Approach for Studying Bond Rupture/Closure of a Spiro Benzopyran Photochromic Material: Reactivity Descriptors Derived from Frontier Orbitals and DFT Computed Electrostatic Potential Energy Surface Maps

“…Recently, there has been an exponential growth of interest in photochromism for profitable applications in important technologies [1][2][3][4][5][6][7][8][9][10][11][12][13]. Spiropyrans are one of the major classes of organic photochromes [2,3].…”

“…When exposed to UV light, the spiropyran undergoes a molecular rearrangement to produce an open form. The open form of spiropyrans (also called merocyanine (MC)) is colored and shows solvatochromic behavior even in the solid state [7,12,13]. The open form of spiropyrans can revert back to the closed form thermally or photochemically by visible light.…”

“…The photochromism of the spiropyran/trans-merocyanine pair has been reviewed previously [3]. The rate and mechanism of the reaction of some spiropyrans and their analogues in different media have been examined with different spectroscopic techniques [4][5][6][7][8][9][10][11][12][13][14]. Spiropyran photoisomerization was studied using ion mobility-mass spectrometry and three major conformers were identified.…”

Spiropyrans Containing the Reactive Substituents in the 2H-Chromene Moiety

“…3,6 -dimethyl-8 -formyl-4-oxo-3,4-dihydro-2H-1,3-spirobenzoxazine-2,2 [2H]-chromene I (see Scheme 1) containing a free formyl group in 8 -position was synthesized earlier [9]. This spiropyran shows photochromic properties both in solution and in the solid state [10]. UV irradiation (365 nm) of the vacuum deposited thin films results in conversion of Spiropyrans possesing photochromic properties both in solution and solid states could be used as chemosensors for the detection of metal ions in the environment.…”

Pseudo crystalline state thermochromic and reverse-photochromic reactivity of spiroindolinobenzopyran upon encapsulation into Zn-MOF-74

“…[6][7][8][9] Unfortunately, at ambient temperatures, these photochemical reactions are feasible predominantly in solution and only very few compounds have been reported as having photo reactivity in the solid state too. [10][11][12] Thus, most of their valuable commercial applications are still restricted in the solid state or in solid matrices mostly due to tight packing in the solid state, which sterically hinders the reactivity of the molecules. 11,13 Another drawback reported is the low thermal stability of the coloured MC form.…”