Polymesomorphism in a homologous series of 2-(4-alkoxyphenyl)-5-(4-methylphenyl) pyridines

A new series of 2-(4-n-alkoxypheny)-5-(4-methylphenyl)pyridines (CH3C6 H4C5 H4NC6H4-OCnH2m+1, n = 1-10) (APMPP), which ale teraryl compounds containing a pyridine ring in the centre position of the rigid core, was synthesized and the phase transitions of the homologues were studied using DSC measurements, polarizing optical microscopy and miscibility tests with terephthalylidene-bis-4-n-pentylaniline (TBPA). Only a nematic phase was found for the shorter alkoxy homologues with n < 4. The longer alkoxy homologues with n greater than or equal to 4 showed the sequence of enantiotropic phase transitions CrG-SmF-SmC-SmA-N-I, while a monotropic CrH phase was observed for the n = 5-10 homologues. Interestingly, the polymesomorphisms appear when it is larger than 4.