1. Preparation and mesomorphic properties of 1-methyl-1H-benzimidazole-based compounds.
- Author
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Ren, Liyuan, Duan, Longyan, Weng, Qiang, Chen, Pei, Hou, Yafei, Gao, Aiai, Chen, Xinbing, and An, Zhongwei
- Subjects
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MESOPHASES , *METHYL groups , *BENZIMIDAZOLES , *SMECTIC liquid crystals , *HYDROGEN - Abstract
A series of 1-methyl-1H-benzimidazole-based compounds, 2-(4ʹ-alkoxy-1,1ʹ-biphenyl-4-yl)-1-methyl- 1H-1,3-benzimidazole derivatives (nPPMx-M) with terminal hydrogen, methyl and nitro moieties (coded as nPPMH-M, nPPMM-M and nPPMN-M, respectively), were prepared and their structures were characterised. The compounds display enantiotropic smectic mesophases for hydrogen and methyl terminated compounds (nPPMH-M and nPPMM-M), and enantiotropic nematic mesophases for nitro terminated compounds (nPPMN-M) with short alkoxy chain below than 10 carbon atoms, where the mesophase ranges are 24-72°C and 74-104°C on heating and cooling processes for nPPMH-M, 90-119°C and 110-135°C for nPPMM-M, and 102-129°C and 113-207°C for nPPMN-M, respectively. It is noted that the compounds nPPMx-M exhibit much lower melting points and much wider mesophase range both in heating and cooling than non-1-methyl substituted analogs, which are ascribed to the disruption of hydrogen bonding among the molecules caused by methyl substitution at 1-position of benzimidazole. Meanwhile, among the compounds nPPMx-M, much wider mesophase ranges are obtained for nPPMM-M and nPPMN-M, indicating a much high mesophase stability for the compounds bearing terminal moiety (CH3 and NO2). [ABSTRACT FROM AUTHOR]
- Published
- 2019
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