Synthesis of photochromic bisfulgimides by the condensation of (3Z)-3-[1-(2,5-dimethyl-3-thienyl)-ethylidene]-4-isopropylidene-2,5-furandione with aromatic diamines

Abstract

The first representatives of thiophene derivatives with two fulgimide fragments in one molecule have been obtained by the condensation of (3Z)-3- [1-(2,5-dimethyl-3-thienyl)ethylidene]-4-isopropylidene-2,5-furandione with aromatic diamines. The photochromic properties of the obtained compounds have been investigated and the effect of a spacer, linking the two fulgimide fragments, on the reaction rates of photocoloration and photodecoloration of these compounds has been studied.Fulgimides of the thiophene series are considered at the present time as one of the promising classes of photochromic compounds. They possess photochemical characteristics valuable in practice, such as thermal irreversibility and high chemical stability, which enables these compounds to be considered as components for constructing molecular switches, and also systems of recording, storage, and treatment of information [1][2][3][4][5].The aim of the present work was the preparation of thiophene fulgimides, not reported in the literature, containing two fulgimide fragments in one molecule linked by various aromatic bridges, and clarification of the effect of the spacer on their photochromic properties.The approach developed by us to the synthesis of this type of compounds includes the preparation of (3Z)-3-[1-(2,5-dimethyl-3-thienyl)ethylidene]-4-isopropylidene-2,5-furandione (1) (Scheme 1), which is described in the literature [6]. Compound 1 is then converted into the desired products by interaction with aromatic diamines.Hemiester 5 was obtained by the Stobbe condensation of 3-acetyl-2,5-dimethylthiophene (3), obtained by the acylation of 2,5-dimethylthiophene (2) according to Friedel-Crafts, with diethyl isopropylidenesuccinate (4) in the presence of t-BuOK as base. It should be noted that the use of t-BuOK as base in this reaction, in place of NaOEt reported in the literature [7], enabled a purer product to be obtained. Subsequent alkaline

Multiphotochromic molecular systems

“…Fulgimide derivatives have been only scarcely used in dimers. To the best of our knowledge, only one series has been reported by Luyksaar et al, 142 who have synthesized bisfulgimides, connected through various types of aromatic bridges (42). In the case of the FG open form, a Z/E isomerisation also occurs (and thus provides a third photoactive state).…”

“…Chindam et al have rationalised the optical properties of the di-fulgimide series reported by Luyksaar et al (compound 42), 142 and they investigated the effect of chemical substitution on the optical properties of new dissymmetric compounds, designed to access multi-addressable systems. 262 From the calculations on the experimentally available compounds, the mixed co form was predicted to exist though it was not detected experimentally, an apparent discrepancy that might be ascribed to the symmetric nature of the compounds, yielding hardly distinguishable optical signatures for the co and cc isomers.…”

Theoretical investigation on the spectroscopic properties of furylfulgide with different substituents and design of novel bis‐furylfulgimide photochromes

“…To our knowledge, multifunctional molecular switches are one of the most prospective photoswitches, fulgide/fulgimide, and diarylethene have attracted considerable attention as the most promising candidates. Currently, many photochromic switches which consist of two or more monomers have been reported . Two photochromic units can be combined into a new multifunctional photochromic molecule by a bridged linker, one can be converted to another by proper wavelength irradiation.…”

“…Currently, many photochromic switches which consist of two or more monomers have been reported. [18][19][20][21] Two photochromic units can be combined into a new multifunctional photochromic molecule by a bridged linker, one can be converted to another by proper wavelength irradiation. These multifunctional molecules need to display different optical signals when they proceed a mutual transformation for their different states.…”