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A series of new dimesogenic compounds were prepared and their thermotropic and liquid crystalline properties were studied by differential scanning calorimetry and on a hot-stage of a polarizing microscope. These compounds, 1,10-bis[2,5-bis(4-substitutedphenoxycarbonyl)phenoxy]decanes, consist of two bis(ρ-substitutedphenoxy)terephthalate units interconnected through a oxydecamethyleneoxy spacer on the central terephthaloyl units resulting in the structure of "H-shaped" dimeric twin compounds. The terminal substitutent groups were changed; X=-F, -H, -I, -Cl, -Br, -NO2, -CF3, -OC4H9, -CN and -C6H5. The compounds with X=-OC4H9, -CN and -C6H5 were monotropically nematic. In contrast, the compounds with X=-F, -H, -I, -Cl, -Br, -NO2 and -CF3 were non-liquid crystals. The nematic group efficiency of these compounds was in the order of -C6H5 > -CN > -OC4H9.
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