Diarylethenes with thiophene

Diarylethenes with thiophene or benzothiophene moieties exhibit excellent thermal stability and outstanding fatigue resistance (88JOC803 ... 

Regarding the closed-ring isomers, the difference in behavior between those diarylethenes with furan, thiophene, or thiazole rings and those with pyrrole, indole, or phenyl rings agrees well with the theoretical prediction that the thermal stability depends on the aromatic stabilization energy of the aryl group.1201... 

At present the most robust photochromic molecules are diarylethenes with benzo-thiophene aryl groups [13]. They undergo more than 1.3 x 10" photochromic cycles in the presence of oxygen without destruction. Recently crystalline photochromic diarylethenes have been developed [57, 58] which could repeat the cycles more than 10 times. 

A new class of photochromic diarylethenes containing thieno[3,2-b] thiophenes, dithieno[3,2-b 2, 3 -d]thiophene (08CC5203), and dithieno [3,2-fc 2, 3 -d]pyrroles (09CEJ10005) with photoswitchable luminescence properties were synthesized by Suzuki cross-coupling reactions (Scheme 48). 

The Tgs of diarylethenes bearing triphenylamino groups, 10a and 12a, are relatively high. The absence of methyl groups at the 4 position of the thiophene rings in 12a decreased Tg in comparison with that of 10a. 

Why is the thermal stability of diarylethene derivatives enhanced by replacing phenyl groups with furan or thiophene groups In molecular orbitals calculation, the photochromic reaction is treated as a typical electrocyclic reaction between hexatriene and cyclohexadiene. The thermal reaction proceeds disrotatorily and the photoreaction, conrotatorily. Disrotatory cyclization of A to B requires an increase in free energy larger than 138 kJ/mol, and hence no thermal ring-closure occurs in the case of either phenyl- or furan-substituted molecules (see... 

The Dithienylethene System and Related Compounds. The area of diaryl-ethenes has been the subjeet of a review.Calculations have been carried out dealing with the photochromism of such compounds.A description of the preparation of diarylethene nanoparticles has been published, and a decrease in photocyclization was attributed to aggregation. Some novel photochromic diarylethenes have been synthesized. The photochemistry exhibited by these compounds suggests that they could be of use as optical switches.Tian and Yang have reviewed the area of diarylethene photochromic switches. 1,2-Bis(2-methylbenzo[b]thiophen-3-yl)hexafluorocyclopentene is at the basis of a new photochromic liquid crystal system. Yokoyama and his co-workers have patented details for such photochromic materials." ... 

Photoswitching of the electronic communication between two metal centers using the photochromic diarylethene bridging ligand with both thiophene moieties substituted with two cyclometallated phenylpyridines (Figure 23a) was first reported by Coudret and Launay. Although the comproportionation constants (Kc) for the dinuclear mixed-valence ruthenium complexes in both the open and closed forms were similar, the intervalence charge-transfer (IVCT) transitions were observed only in the closed... 

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