Synthesis and study the liquid crystalline properties of compounds containing benzoxazole core and terminal vinyl group |
| |
| Authors: | Liyuan Ren Longyan Duan Qaing Weng Pei Chen Aiai Gao |
| |
| Affiliation: | 1. Key Laboratory of Applied Surface and Colloid Chemistry (MOE);2. Shaanxi Key Laboratory for Advanced Energy Devices;3. Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi?an, PR China;4. Xi?an Modern Chemistry Research Institute, Xi?an, PR China |
| |
| Abstract: | Terminal vinyl-based benzoxazole liquid crystalline compounds, 2-(3-fluoro-4?-alkoxy-1,1?-biphenyl ?4-yl)-5-(2-propenyloxymethyl)-benzoxazole (nPPF(2)BP), were synthesised and their structures were confirmed by infrared (IR) spectra, proton nuclear magnetic resonance (1H-NMR) spectra, gas chromatography with electron impact-mass spectrometry (GC/EI-MS), matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry and elemental analysis (EA). The compounds show enantiotropic smectic/nematic phases with mesophase ranges are 71–97 °C and 87–136°C on heating and cooling processes for nPPF(2)BP, respectively. They give low melting points due to lateral fluoro substituent and flexible terminal 2-propenyloxymethyl chain. It is found that the compounds nPPF(2)BP with shorter alkoxy chain (n = 3, 4) exhibit a wide range of nematic mesophase, which is ascribed to enhanced π–π interaction caused by terminal vinyl moiety, whereas further elongation of the terminal alkoxy chain results in supressing nematic phase and increasing smectic mesophase. Compared with methyl terminated analogues, 2-propenyloxymethyl terminated compounds nPPF(2)BP display much lower melting points and wider or comparable mesophase range both in heating and cooling. |
| |
| Keywords: | Benzoxazole-based compounds enantiotropic smectic/nematic phases lateral fluoro substituent terminal vinyl group |
|
|
