Bulg. J. Phys. vol.36 no.4 (2009), pp. 274-285

Occurrence of Ambient Temperature and Re-Entrant Smectic Ordering in an Inter Molecular Hydrogen Bonding between Alkyl Aniline and Alkoxy Benzoic Acids

T. Chitravel, M.L.N. Madhu Mohan
Liquid Crystal Research Laboratory (LCRL), Bannari Amman Institute of Technology, Sathyamangalam 638 401, India
Abstract. A homologous series of inter hydrogen bonded complexes between p-n-alkoxybenzoic acids (12A+nBA) and alkyl aniline were isolated. The mesogenic p-n-alkoxybenzoic acids formed a hydrogen bond with liquid crystal intermediate 4-dodecyl aniline respectively. The isolated homologous series compounds were analyzed by FTIR, Polarizing optical microscope, dielectric studies and DSC. Interesting feature of these homologous series was the occurrence of an ambient smectic ordering in some of the isolated mesogens. The phase diagrams of the p-n-alkoxybenzoic acids and the present homologous series were computed and compared respectively. The hydrogen bond formation was evinced through FTIR spectral studies. Two higher member mesogens of the present homologous series were found to exhibit monotropic smectic G phase. Results of free p-n-alkoxybenzoic acids and the hydrogen bonded homologous series were discussed in the light of increment alkoxy carbon number, mesogenic phases exhibited and mesogenic thermal range.

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