Effects of isocyanide substituents on the mesogenic properties of halogeno(isocyanide)gold complexes: calamitic and discotic liquid crystals

Abstract

The liquid crystal behaviour of linear [AuX(CNC ₆ H ₄ OC _n H _{2n +1} )] (X=halogen) complexes is tuned by systematically changing the structure of the isocyanide ligand. The changes studied are lateral fluorination at the 2- and 3-positions of the phenyl ring and modification of the rod-like structure of the complexes by addition of two alkoxy chains at themeta positions. None of the free isocyanides used here are liquid crystals, but all the gold complexes prepared display mesomorphic properties, except iodo(2-fluoro-4-butoxyphenyl isocyanide)gold(i). The (2- and (3-fluorophenyl isocyanide)gold(i) complexes show smectic A mesophases, except the 2-fluoro derivative with n=6, which shows a nematic phase, while the (3,4,5-trialkoxyphenyl isocyanide)gold compounds display columnar hexagonal phases at room temperature.