Design, synthesis and characterization of a linear hydrogen bonded homologous series exhibiting reentrant smectic C ordering

作者：Kavitha C; Mohan M L N Madhu^*

来源：Journal of Physics and Chemistry of Solids, 2012, 73(10): 1203-1212.

DOI：10.1016/j.jpcs.2012.05.013

• Organic compounds
• Chemical synthesis
• Differential scanning calorimetry (DSC)
• Infrared spectroscopy
• Phase transitions

Design, synthesis and characterization of seven linear hydrogen bonded liquid crystal complexes derived from mesogenic p-n-decyloxy benzoic acid and p-n-alkyl benzoic acids designated as 100empty setn (where n varied from ethyl to octyl) are reported. FTIR studies confirm the hydrogen bond formation in all these complexes. The phase transition temperatures and their corresponding enthalpy values are experimentally deduced from Differential Scanning Calorimetry (DSC) studies. POM and DSC data are further utilized for the construction of 100empty setn phase diagram. Two Odd-even effects have been evinced, one in enthalpy values and the other in corresponding transition temperatures across the isotropic to nematic phase transition. An interesting result is the observation of re-entrant smectic ordering, designated as smectic C-R in three higher ordered mesogens. A new smectic ordering, smectic X, has been observed which is sandwiched between traditional smectic C and re-entrant smectic C-R. Magnitudes of optical tilt angle in smectic C, smectic X and smectic C-R are experimentally found to attain saturation with decrement of temperature in the corresponding phase. The occurrence of smectic X and smectic C-R are discussed with relation to the molecular chemical structure. The optical filtering action in smectic C and re-entrant smectic C-R phases have been analyzed.

• 出版日期2012-10