The Amide Group as Modulator of Crystalline and Liquid Crystalline Structures in Isocyano-alkylanilide Silver (I) Complexes

Abstract

Silver(I) complexes [AgX(CNR] and [Ag(CNR)2]X (X = anionic ligand), containing an amide-functionalized isocyanide, CNR = CN-C6H4-NHCOR, have been synthesized and their X-ray structures have been determined for [Ag(X)(CN-C6H4-NHCOCH3)] (X = NO3ˉ, CF3SO3ˉ) and [Ag(CN-C6H4-NHCOCH3)2]X (X = NO3ˉ, CF3SO3ˉ, BF4ˉ). All the crystal structures show a packing of polymeric chains formed through Ag–O=Camide interactions. These chains associate in layers through hydrogen bonds involving the amide group, and by further interactions of the metal ion with oxygen-donor moieties. Substitution of the Me group in the amide by a nonyl chain (R = C9H19) leads to neutral [Ag(NO3)(CN-C6H4-NHCOC9H19)] and ionic [Ag(CN-C6H4-NHCOC9H19)2]X (X = NO3ˉ, CF3SO3ˉ, H25C12OSO3ˉ, BF4ˉ) mesomorphic complexes. All of them display smectic liquid crystalline phases compatible with the crystal structures found for the methyl derivatives, and FTIR/ATR spectroscopy confirms that the intermolecular interactions observed in the solid state are preserved in the mesophase.