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

Abstract

Neutral and ionic complexes of organic–inorganic hybrids having general formulas of [M(C_nH_2n+1-im)₂Cl₂] (C_nH_2n+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(C_nH_2n+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.