A New Dithiophene Fused p -Phenylene Vinylene Conducting Polymer. Synthesis And Study
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13-(ET)2AuI 2 Tc = 5 K (ambient pressure) V-(ET) 2 13 Tc = 8 K (0.5 kbar) ic-(ET) 2Cu[N(CN) 2 ]Cl Tc = 12.8 K (0.3 kbar) 0 S 0
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Kc-(MDT-TTF) 2AuI 2 Tc = 4.5 K (ambient pressure)
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ic-(DMET) 2AuBr 2 TC = 1.9 K .m-(BEDO-TTF)3Cu2 (SCN) 3 Tc = 1.1 K (ambient pressure) (ambient pressure) Figure 1. Several representative superconducting charge-transfer complexes. 227 Mat. Res. Soc. Symp. Proc. Vol. 328. ©1994 Materials Research Society
EXPERIMENTAL SECTION General. FT-IR spectra were obtained in KBr with a diffuse reflectance unit. NMR spectra were obtained at 300 MHz for 1H or 75 MHz for 13C in CDC13 or D2 0. Elemental analysis were done on a Perkin-Elmer 2400 CHN analyzer or by Texas Analytical Laboratories, Stafford, TX. TGA was done from 40 to 800 'C with a heating rate of 10 'C/min. UV-vis-NIR spectra were recorded on polymer thin films cast onto quartz cuvettes. Conductivity of doped polymer 6 films was measured using the four-in-line probe method. ,7 2,5-Bis(2,2-dimethoxyethylthio)-1,4-dimethylbenzene (4). In a three-necked flask equipped with a magnetic stirrer, a condenser with a drying tube, an addition funnel, and a nitrogen inlet was put 2,5-dibromo-p-xylene (5.28 g, 0.02 mol) and 40 mL of dry THF. The mixture was cooled to -78 'C and 12.5 mL of 1.6 M of n-BuLi in hexanes (0.02 mol) was added dropwise in about 15 min. The mixture was stirred for 30 min, 2,2,2'2'tetramethoxyethyldisulfide (3) (4.84g, 0.02 mol), prepared essentially as reported, 8 in 5 mL of dry THF was added dropwise over about 15 min and the mixture was stirred for 30 additional min. The second part of the n-BuLi (13.75 mL, 1.6 M, 0.022 mol) was added dropwise in about 15 min, and the mixture was stirred for 30 min. Disulfide 3 (4.84 g, 0.02 mol) in 5 mL of dry THF was added dropwise over about 15 min, and the mixture was stirred for 1 h. The mixture was warmed to room temperature, 15 mL of water was added, and it was extracted with diethyl ether (3 x 100 mL). The combined ether layer was washed with distilled water (3 x 100 mL), dried (MgSO4) and the ether was distilled. The crude product was purified by flash chromatography [ethyl acetate/hexanes (1:10)] to give 2.29 g of 4 (33% yield. An additional 46% of two eliminated enol ether products were formed which could also produce 5 with PPA.); mp 74-75 'C; 'H NMR: 8 7.14 (2H, s), 4.53 (2H, t, J = 5.5 Hz), 3.37 (12H, s), 3.05 (4H, d, J = 5.5 Hz), 2.36 (6H, s); 13C NMR: 5 136.23, 133.00, 130.73, 102.91, 53.39, 36.04, 19.98. Anal. Calcd for C16H 26 S2 0 4 : C, 55.46; H, 7.56. Found: C, 55.33; H, 7.77. 4,8-Dimethylbenzo[1,2-b:4,5-b']dithiophene (5). A solution of 3.50 g of 4 in 60 mL of benzene was added to 20 g of polyphosphoric acid, and the mixture refluxed for 24 h, cooled to room temperature and the benzene layer was decanted. Another portion of benzene (40 mL) was added, the mixture was refluxed for another 12 h, cooled to room temperature and the benzene again decanted. The residue was washed with benzene (2 x 10 mL), the c
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