The synthesis and mesomorphic behaviour of tetracatenar di-hydrazine derivatives |
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Authors: | Peng Zhang Songnan Qu Binglian Bai Haitao Wang Xia Ran Chengxiao Zhao |
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Institution: | Key Laboratory of Automobile Materials, Ministry of Education , Institute of Materials Science and Engineering, Jilin University , Changchun, 130012, People's Republic of China |
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Abstract: | Symmetrical four-chained (tetracatenar) di-hydrazine derivatives, namely oxalyl N',N'-bis(3,4-dialkoxybenzoyl)-hydrazide (BFH-n, n?=?4, 6, 8, 10), were synthesised. Investigations on the liquid crystalline properties by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and polarising optical microscopy (POM) showed that the di-hydrazine derivatives exhibited columnar mesophases and the symmetry of the mesophase changes from rectangular to hexagonal on increasing the temperature. The rectangular columnar mesophases of BFH-n (n?=?6, 8, 10) remained stable down to 10°C during cooling and the subsequent recrystallisation from the Colr phase of BFH-n (n?=?6, 8, 10) was observed on the second heating runs. Furthermore, the average number of molecules packing in a column slice was estimated to be three, based on their X-ray diffraction results. Intermolecular hydrogen bonding between –C=O and ?N?H groups in crystalline and liquid crystalline phases was confirmed. |
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Keywords: | di-hydrazine derivatives rectangular columnar phase hexagonal columnar phase polycatenar |
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