Influence of chemical moieties and the flexible chain for the tilted smectic phases in linear hydrogen bonded liquid crystals with Schiff based pyridene derivatives

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• 作者：M. Muniprasad^a ; M. Srinivasulu^b ; P.V. Chalapathi^c ; D.M. Potukuchi^a ; ^{potukuchidm@yahoo.com}
• 关键词：Hydrogen bonded liquid crystals ; Tilted smectic phases ; Textures ; Transition temperatures ; Chain length ; Inductomeric effect
• 刊名：Journal of Molecular Structure
• 出版年：2012
• 期刊代码：62_00222860
• 类别：ch
• 出版时间：16 May, 2012
• 卷：1015
• 期：Complete
• 页码：181-191
• 文件大小：1540 K

摘要

A novel series of hydrogen bonded liquid crystals (HBLC鈥檚) prepared from non-mesogenic 4-pyridine carboxaldehyde, p-n-tetradecyl aniline and mesogenic 4-n-alkoxy benzoic acids (nOBA鈥檚) are isolated by a condensation reaction followed by an HB complexation. Formation of HB complex and purity of product is confirmed by ¹H NMR and IR spectroscopic techniques. The phase variance exhibited by the present HBLC series of compounds viz., Py14BA:nOBA鈥檚 (for n = 3-5, 7-9 and 12) is found to be AB in lower homologues and CF in higher homologues. Odd-even effect is exhibited by the series at I-SmA, I-SmC and LC to Solid transitions. Iso-SmA, Iso-SmC, SmA-SmB and SmC-SmF transitions are found to be of 1st order nature. The even higher homologues (for n = 8 and 12) exhibit a paramorphotic textural transition of 2nd order nature in their SmC phase. The influence of HB (soft-covalent) interaction and the inductomeric effect contributed by the end chains for the enhancement of transverse dipole moment 渭_t, the stability of tilted LC phases (SmC and SmF) are discussed. An ACF Multi-Critical Point is predicted in the phase diagram for Py14BA:nOBA series of HBLC鈥檚 in the vicinity of n = 5.