Dipentoxy-bithiophene

Through the preparation of either blends or composites of conjugated electrochromic polymers with insulating polymers, the electrochromic and electronic properties of the electrochromic polymer can be typically preserved while introducing the favorable mechanical properties and processability associated with the insulating polymer. For example, when Hydrin C (a vulcanizable elastomeric copolymer of epichlorohydrin and ethylene oxide) is coated onto an electrode surface followed by electrochemical polymerization of 4,4 -dipentoxy-2,2 -bithiophene, a film is produced that switches between dark blue in the neutral state to colorless in the oxidized state [219]. 

Nonlinear optical properties of PTs which exhibit ultrafast responses and large nonlinearities attributed to one-dimensionality and delocalization of n-electrons along the polymer chains are also described [403,404]. Poly(4,4 -dipentoxy-2,2 -bithiophene) and poly(4,4 -dipentoxy-2,2 5, 2"-terthiophene) show a fast and high third-order nonlinearity [405]. Third-order nonlinearities depend on the nature of the polymer backbone and only slightly on the substituents [406], The optical transparency and the third-order optical nonlinearities can be tailored in random copolymers of 3-methylthiophene and methyl methacrylate [407]. A solution-processable thiophene copolymer with a side... 

Fig. 5. Thermogravimetric curve (dotted line) of poly(4,4 -dipentoxy-2,2 -bithiophene) powder and its first derivative (full line), recorded in air. Sample weight, 1.289 mg scan rate, 10° C min"L Insets Expanded scale of the thermogravimetric curve and the formula of the polymer. Reprinted with permission from G. Casalbore-Miceli et al., Synth. Met. 94,179 (1998). Copyright 1998, Elsevier Science Ltd., Oxford.

The regioisomeric 4,4 -dipentoxy-2,2 -bithiophene 327 bearing the pentoxy groups in the outer /3-positions was synthesized in 70% yield by oxidative coupling of lithiated 3-pentoxythiophene 321 with copper chloride. 4-Pentoxy-2-thiophene-boronic acid 326 which was synthesized from 3-pentoxythiophene 321, lithiumdiiso-propylamid and trimethylborate was coupled with I-Tj-I 54 and I-T2—I 306,... 

Figure 3. Crystal packing of (a) 3,3 -dipentoxy-2,2 -bithiophenes and (b) 4,4 -dipentoxy-2,2 -bithio-phenes viewed along respectively b and c. From [73].

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