Multiple hydrogen bonded mesomorphic complexes between complementary 1,3,5-triazine and pyrimidine derivatives

Abstract

A 2,4-diamino-6-phenyl-1,3,5-triazine grafted with two semiperfluorinated chains at the phenyl substituent has been investigated in binary mixtures with complementary orotic acid and barbituric acid derivatives carrying either a lipophilic alkyl or a semiperfluoroalkyl tail. Equimolar mixtures of the triazine with nucleobases form triple hydrogen-bonded heterodimers with an elongated central core. Mesomorphic properties are observed only if the pyrimidinone component provides an additional free NH function not involved in triple H-bonding with the triazine nucleus. In that case, additional H-bond interactions orthogonal to the rod-shaped core of the heterodimers initiate the formation of cyclotrimeric rosette-type associates with circular geometry of the polar core region. Rosettes of heterodimers involving an alkyl substituted nucleobase organize to hexagonal columnar mesophases. Replacing the alkyl tail of the pyrimidine with a semiperfluorinated fragment leads to the formation of a micellar cubic phase. The individual micelles are composed of segmented columns three-dimensionally surrounded by a continuum of the semiperfluorinated segments.