Induction of Liquid Crystalline Phases and Influence of Chain Length of Fatty Acids in Linear Hydrogen-Bonded Liquid Crystal Complexes

A novel series of linear hydrogen-bonded liquid crystals (HBLCs), viz., Py14BA:nFAs synthesized from nonmesogenic moieties, such as an N(p-n-pyridene carboxaldehyde), p-n-tetradecyl aniline, and the long-chain-bearing aliphatic acids (nFAs for n = 10, 12, 14, 16, and 18), are reported. The chemical stability, purity of the sample, and the presence of hydrogen bonding (HB) are confirmed by polarized thermal microscopy and 1H NMR and IR spectroscopy. The LC phase abundance is characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) techniques. Py14BA:nFAs are found to exhibit BF liquid crystalline phase variance. The Iso-SmBcryst and SmBcryst-SmF transitions are found to be of first-order nature. Phase diagram for Py14BA:nFAs infers the induction and enhancement of LC phase stability. The growth of tilted LC phases due to HB interaction is discussed. Analysis of the influence of chain length (n) on LC phase stability, viz., Delta T-LC and Delta T-Tilt, suggests for a tunable molecular pair potential given by U-12(n) = [A x e(alpha n) - 1]. The tilted LC phase stability is found to grow with a relative exponential strength in Py14BA:nFA series.