TRI-SUBSTITUTED S-TRIAZINES AS MESOGENIC CORES

Two series of equivalently-and inequivalently-tri-substituted s-triazi nes (as ESTs and ISTs, respectively) were synthesized and characterize d in this study. More than one mesogenic biphenyl substituent were req uired to display mesomorphic properties, and two or three biphenyl sub stituents resulted in liquid crystalline textures under polarizing lig ht. The mesophase transition temperatures for both IST and EST series are quite close despite their molecular weight difference. With longer sidechains, s-triazine for IST series formed a columnar hexagonal dis ordered mesophase (D-hd); while for the analogous compound in EST seri es, a perfectly aligned layered structure was found to be co-existed w ith the D-hd phase. With shorter sidechains, the s-triazines exhibited nematic mesomorphism.