Influence of flexible chain, polar substitution and hydrogen bonding on phase stability in Shiff based (4)PyBD(4I)BrA-nOBA series of liquid crystals

A. V.S.N.Krishna Murthy, P. V. Chalapathy, M. Srinivasulu, M. L.N. Madhumohan, Y. V. Rao, D. M. Potukuchi

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Shiff based Linear Hydrogen Bonded Liquid Crystalline homologues, viz., (4)PyBD(4I)BrA-nOBAs for n = 2,3,4,5,6,7,8,10,11 and 12 are synthesized. 1H-NMR and 13C-NMR studies confirm the formation of HBLC and IR confirms the linear hydrogen bonding. Liquid crystal phase abundance, transition temperatures, enthalpy and order of transition are investigated by Polarized Optical Microscopy textural studies and Differential Scanning Calorimetry. Nematic, Smectic-A, -D, -C, Bhexatic, -BCrystal, -F, -I and –G phases are identified. Large LC phase variances, viz., NABhexFG and NACFG are exhibited by intermediate chain length with n = 5 and 6. A-C transition exhibited unique II-order nature. II-order nature for G-Solid transition explained. Phase diagram drawn with flexible chain length infers INA, and ACF and CIF MultiCritical Points and Lifshitz behaviour. NA TriCiritical Point predicted in [3+7] binary. Influences of chain length, linear HB and end polar(-Br) substitution for LC phase stability are is discussed. Results of Phase stability are discussed in the wake of the body of the data and reports in other LCs. DSC enthalpy suggests for utility of intermediate and higher homologues for device savvy tilted Smectic LC phases.

Original languageEnglish
Pages (from-to)46-68
Number of pages23
JournalMolecular Crystals and Liquid Crystals
Issue number1
Publication statusPublished - 24-03-2018


All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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