EFFECTS OF ISOCYANIDE SUBSTITUENTS ON THE MESOGENIC PROPERTIES OF HALOGENO (ISOCYANIDE) GOLD COMPLEXES - CALAMITIC AND DISCOTIC LIQUID-CRYSTALS

The liquid crystal behaviour of linear [AuX(CNC6H4OCnH2n+1)] (X=haloge n) 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-lik e structure of the complexes by addition of two alkoxy chains at the m eta positions. None of the free isocyanides used here are liquid cryst als, but all the gold complexes prepared display mesomorphic propertie s, 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 phas e, while the (3,4,5-trialkoxyphenyl isocyanide)gold compounds display columnar hexagonal phases at room temperature.