Perfluorocyclopentene

As for the relevant application, recently, a specific photochromic compound, 1,2-bis(2 -methyl-5 -phenyl-3 -thienyl)perfluorocyclopentene (BP-BTE), and the analogs of HBO, 2,5-bis(5,-0 rt-butyl-benzooxazol-2 -yl)hydroquinone (DHBO), were employed in the high-contrast, reversible, photochromic switching of fluorescence emission and its perfect nondestructive readout (Fig. 14). Due to the large... 

Photochromic dithienyl- and dibenzothienylethenes, particularly those containing the central 1,2-perfluorocyclopentene fragment, belong to the major group of compounds, which have attracted the attention of researchers in the field of information storage (optical memory) and optical switches because their starting (A) and cyclic (B) forms are, in most cases. 

Here typical syntheses of symmetrical products are considered. In Scheme 2, the treatment of bromide 1 with butyllithium under standard conditions in the presence of perfluorocyclopentene affords photochrome 2 (31 %) (99IZV979). Derivatives 3 and 4 were synthesized in a similar way (98KGS927). 

Typical syntheses of unsymmetrical derivatives include 27 (98CL1123), 28 (08SA1065), and 29 (Scheme 10). The perfluorocyclopentene fragment in the latter compound is bound to different positions in the thiophene moieties (95CL969, 04CC1010). 

In addition to thiophenes, the above reactions of perfluorocyclopentene, as well as of fluorinated derivatives of cyclobutene and cyclohexene, can be carried out with fused thienyl derivatives and various heterocycles forming relatively stable anions. 

New macromolecules 99 and 100 can easily be synthesized in four steps from l,2-bis(5-bromo-2-methyl-3-thienyl)perfluorocyclopentene by the Sonogashira coupling reaction (05T12256). 

A comparative analysis of the spectroscopic and photochromic properties of dithienylperhydro- and perfluorocyclopentenes were reported in 03EJO1887 and 05JPC9437. Their photochromic properties are similar, but the perhydro derivatives were shown to be thermally and photochemi-cally less stable. 

Unsaturated perfluoro- or polyfluorohalocycloalkenes are hydrolyzed in alkaline media. Perfluorocyclopentene, when treated with alkali, gives 2//-pentafluorocyclopenta-l,3-dione (14).21... 

Perfluorocyclopentene when treated with potassium hydroxide in methanol gives heptafluoro-2-methoxycyclopentene (19) in 62% yield and with sodium methoxide yields product 19, hexa-fluoro-l,2-dimethoxycyclopentene (20), and pentafluoro-3-methoxycyclopent-2-enone (21).72... 

Figure 1 shows a typical diarylethene derivative absorption spectral change.1121 Upon irradiation with 313 nm light, a colorless hexane solution of l,2-bis(2,4-dimethyl-5-phenylthiophen-3-yl)perfluorocyclopentene la turned blue, in which an absorption maximum was observed at 562 nm. 

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