Organic–inorganic hybrids of imidazole complexes of palladium(II), copper(II) and zinc(II). Crystals and liquid crystals

Neutral and ionic complexes of organic–inorganic hybrids having general formulas of [M(CnH2n+1-im)2Cl2](CnH2n+1-im, represents N-alkyl substituted imidazoles; n= 10, 12 and 18 for M = Pd(II); n= 12 and 18 for M = Cu(II) and Zn(II)) and [M(CnH2n+1-im)4][NO3]2(for M = Cu(II), Zn(II), n= 10, 12, 14, 16 and 18), have been investigated. Three neutral compounds, [Pd(C12H25-im)2Cl2], [Cu(C12H25-im)2Cl2] and [Zn(C18H37-im)2Cl2] and one ionic compound [Cu(C12H25-im)4][NO3]2 were structurally determined by single crystal X-ray diffraction. Among them, the Zn(II) compound is tetrahedral and the others are square planar. Among the neutral compounds synthesized, only the zinc compound with n= 18 exhibits liquid crystalline behavior upon cooling from isotropic liquid. All the ionic Zn(II) compounds exhibit SmA mesophases, except that with n= 10, which is a room-temperature ionic liquid. Ionic Cu(II) compounds exhibit a highly ordered lamellar mesophase.