Liquid crystalline behaviour in gold(I) and silver(I) ionic isocyanide complexes:: smectic and columnar mesophases

The synthesis, characterization and mesomorphic properties of gold(I) and silver(I) ionic isocyanide complexes [Au(CNR)(2)]Y [RC6H4OCnH2n+1, C(6)H(4)C(6)H(4)OCnH(2n+1), C6H2(3,4,5-OCnH2n+1)(3); Y = PF6- , BF4- (n = 4, 8, 12), Y = NO3- (n = 8)] and [Ag(CNR)(2)]Y [R = C6H4OCnH2n+1 (n = 8, 12), C6H4C6H4OCnH2n+1 (n = 4, 8, 12), C6H2(3,4,5-OCnH2n+1)(3) (n = 4, 8 12); Y = NO3-, BF4-] are described. The free phenyl and 3,4,5-trialkoxyphenyl isocyanides are not liquid crystals but most of the gold and silver derivatives prepared are mesogens. Only the nitrate series of gold, which decompose on melting, and the complexes [Au(CNR)(2)]PF6 [R = C6H4OC4H9, C6H2(3,4,5-OC4H9)(3)] do not display mesogenic behaviour. The phenyl and biphenyl gold derivatives show smectic A phases and the analogous silver complexes display SmA and SmC mesophases, while the 3,4,5-trialkoxyphenyl isocyanide complexes of gold and silver show hexagonal columnar mesophases. The influence of the metal atom, the anion and the isocyanide on mesogenic behaviour for these kinds of complexes is discussed.