Photochemical investigation of a photochromic diarylethene compound that can be used as a wide range actinometer

Abstract

The photochromic diarylethene derivative 1,2-bis(5-(4-ethynylphenyl)-2-methylthiophen-3-yl)perfluorocyclopentene (1) was submitted to photochemical, thermal stability and fatigue resistance studies in acetonitrile, also to evaluate its possible application as a new actinometer. This photochromic system covers a wide spectral absorption range, with intense bands in the UV and visible regions for the open-ring and closed-ring isomers, respectively. Very high ring-closure quantum yield values were obtained, in contrast with the low ring-opening quantum yields, which are nevertheless high enough to exploit 1 as an actinometer. The procedure required to determine the photon flux of an irradiation source with this fatigue resistant compound is indeed very simple.

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

“…The photoirradiation wavelength dependence of the photocycloreversion quantum yield of the diarylethene was examined in solutions (toluene and n-hexane), 31,128,129 and the quantum yield was reported to increase upon irradiation with light at shorter wavelengths, as shown in Figure 18. The wavelength dependence of the photocycloreversion quantum yield was also reported for other diarylethene derivatives, such as 1,2-bis(2,4,5-trimethyl-3-thienyl)maleic anhydride (71), 7 1,2-bis(5-(4-ethynylphenyl)-2-methyl-3-thienyl)perfluorocyclopentene (73), 130 and 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene (12) 31 in solutions and 1-(2-methyl-5-p-cyanophenyl-3-thienyl)-2-(2-methyl-5-p-methoxyphenyl-3-thienyl)perfluorocyclopentene (74) 131 in a polymer film. The dependence is attributed to the existence of an energy barrier on the potential energy surface in the excited singlet state, as shown in Figures 5 and 6, and Scheme 3.…”

Kinetics and mechanism of photochromic transformations of a 2,3-diarylcyclopentenone

“…Additional experiments are necessary for determining the products of diarylcyclopentenones photodestruction and understanding its mechanism. APPENDIX In work [17] the quantum yields of photochromic reactions of diarylcyclopentenones were calculated using the following equation [38] (two evident typos in Eq. (1) [17] were corrected):…”

A revised experimental protocol for implementing the actinometry method with the Reinecke’s salt

“…The use of the Reinecke's salt presents however some drawbacks: (i) the experiments should be performed in a dark room, (ii) the reaction medium is sensitive to the temperature and (iii) toxic reactant is used (perchloric acid). Consequently, alternative actinometers for the visible light have been proposed to determine the incident photon flux in the visible spectrum, mostly with irradiated volumes in the range of milliliter [3][4][5][6][7]. Unfortunately, these latter actinometers are either not commercially available (i. e. synthetically obtained), or expensive.…”