LIQUID-CRYSTALS BASED ON HALOGOLD(I) COMPLEXES WITH 4-ISOCYANO-4'-ALKOXYBIPHENYL DERIVATIVES

Rod-like complexes [AuCl(CNC6H4C6H4OCnH2n+1-p)] (n = 4,6,8,10,12) have been prepared by reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with the isonitriles CNC6H4C6H4OCnH2n+1-p. Metathetical reactions with KBr or Kl afford the corresponding [AuX(CNC6H4C6H4OCnH2n+1-p)] (X=Br, I). While the free isonitriles are liquid crystals displaying nematic and (some of them) smectic A phases with a short range of existence a t moderate temperatures (40-85 degrees C), their coordination to AUX ( X=Cl, Br, I) produces a marked increase in the melting points of the m aterials, and also an enormous expansion of the range of existence of the mesophase. The order in the mesophase also increases and only the smectic A phase is formed in most of the complexes (for X=Cl, Br and n =4 a nematic phase is also formed). All the biphenyl halogold(I) deriv atives are mesogenic (except far X=I and n=4) and their melting points decrease in the order I > Br > Cl. Ranges of mesophase of nearly 140 degrees C are attained. Most of the complexes decompose to the isotrop ic state (above 220 degrees G), but seem thermally stable below 200 de grees C.