Improving the Fatigue Resistance of Diarylethene Switches
摘要:
When applying photochromic switches as functional units in light-responsive materials or devices, an often disregarded yet crucial property is their resistance to fatigue during photoisomerization. In the large family of diarylethene photoswitches, formation of an annulated isomer as a byproduct of the photochromic reaction turns out to prevent the desired high reversibility for many different derivatives. To overcome this general problem, we have synthesized and thoroughly investigated the fatigue behavior of a series of diarylethenes, varying the nature of the hetaryl moieties, the bridging units, and the substituents. By analysis of photokinetic data, a quantification of the tendency for byproduct formation in terms of quantum yields could be achieved, and a strong dependency on the electronic properties of the substituents was observed. In particular, substitution with 3,5-bis(trifluoromethyl)phenyl or 3,5-bis(pentafluorosulfanyl)phenyl groups strongly suppresses the byproduct formation and opens up a general strategy to construct highly fatigue-resistant diarylethene photochromic systems with a large structural flexibility.
anionic complex as a key intermediate, a regio- and stereoselective multicomponent coupling reaction of perfluoroarenes, aryl Grignard reagents, and 1,3-butadiene in a 1:1:2 ratio was achieved, resulting in the formation of 1,6-octadiene derivatives containing two aryl groups, one from the perfluoroarene and the other from the aryl Grignard reagent, at the 3- and 8-positions, respectively.
A nickel-catalyzed three-component coupling reaction between perfluoroarenes and two molecules of a 1,3-diene in the presence of an alkyl Grignardreagent, which acted as a hydride source, provided 3-perfluoroarylated-1,7-octadienes via 1,3-diene dimerization and subsequent perfluoroarylation upon C–F bond cleavage. The reaction proceeded smoothly in a regioselective manner by simply combining NiCl2
Copper complexes, generated by the treatment of CuCl2 with EtMgCl, catalyze a reductivecoupling reaction of perfluoroarenes with 1,3-dienes via C–F bond cleavage, in which the internal carbon of 1,3-dienes preferably reacts with perfluoroarenes giving rise to branched allylated perfluoroarenes as a major coupling product.
Palladium-Catalyzed Aerobic Dehydrogenative Cross-Coupling of Polyfluoroarenes with Thiophenes: Facile Access to Polyfluoroarene–Thiophene Structure
作者:Chun-Yang He、Qiao-Qiao Min、Xingang Zhang
DOI:10.1021/om200873j
日期:2012.2.27
We report a Pd-catalyzed aerobic dehydrogenativecross-coupling of polyfluoroarenes with thiophenes via 2-fold C–H functionalization. The advantages of this reaction are its high reaction efficiency, excellent functional group compatibility, and use of molecular O2 as terminal oxidant. This reaction provides a useful and facile protocol for the preparation of polyfluoroarene–thiophene structure of
The reactions of pentafluorobenzenesulfonyl chloride with benzene and thiophene derivatives in the presence of a ruthenium(II) catalyst proceeded at 240°C, with extrusion of sulfur dioxide and hydrogen chloride, to give the corresponding perfluorophenylated compounds.