Trithiatruxenes: A Family of Disc-like Mesogens with a New Polymorphism

A homologous series of hexa-n-alkanoyloxy trithiatruxenes (2,3,7,8,12,13-hexa-n-alkanoyloxybenzo-[1, 2-b : 3, 4-b': 5,6-b”]trisbenzothiophenes) (Cn HATXS) has been prepared with n = 9 to n = 13 in order to study the influence of the substitution of the three methylenes of the truxene core by three sulphur atoms on the mesomorphic properties. Phase transitions were studied by hot stage microscopy and DSC. This series shows another example of an inverted sequence (crystal-ND nematic-D columnar-isotropic) and a new polymorphism with a columnar phase between Dh and Drd phases.