Microwave-assisted template synthesis of diazacyclam-based macrocyclic copper complex and forming octahedral, square planar and square pyramidal geometries by ion exchanging and introducing a novel 2D square-grid copper–mercury coordination polymer

Abstract

The microwave-assisted template reaction of copper(II) nitrate with N-(2-aminoethyl)-1,3-diaminopropane and formaldehyde yields the macrocyclic copper complex of 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane (L), [CuL(NO3)2] (1), with octahedral geometry. Replacement of nitrate with bromide and iodide ions gives [CuL]Br2 (2) and [CuLI][CuLI]′I2·H2O (3) complexes respectively with square planar and distorted square pyramidal geometry. The reaction between 1 and HgCl2 forms the 2D square-grid coordination polymer, {[CuL(NO3)]2[Hg5(μ-Cl)8(μ3-Cl)2]Cl2} (4). The complexes were characterized by FT-IR and Raman spectroscopies, electronic absorption, cyclic voltammetry and X-ray crystallography. Photoluminescent properties of 1 were also investigated. Cyclic voltammetry experiments show two one-electron waves corresponding to CuII/CuIII and CuII/CuI processes. In the structure of 4, expansion of the Hg–Cl bonds in two directions gives rise to a 2D polymeric chain. The [CuL(NO3)]+ unit is coordinated to main chain as a lateral branch by its nitrogen atom. There are two different geometries around the mercury atoms including octahedral and distorted square pyramidal. The chains are linked by N–H⋯Onitrate hydrogen bonds between two [CuL(NO3)]+ units belonging to the parallel chains. Hydrogen bonds including N–H⋯A and C–H⋯A (A: N, O, Br, I) present in the crystal networks of 1–3.