The effect of partial substitution of chloride by bromide in the 0-D hybrid material (C4H12N2)[CuCl4]·2H2O: Structural, vibrational, thermal, in silico and biological characterizations

Abstract

A new organic-inorganic hybrid material with copper(II) as the transition metal, piperazine as the organic component and mixed bromide/chloride as halide ions, (C4H12N2)[CuBr4]0.42[CuCl4]0.58·2H2O (1), has been prepared and crystallographically investigated by single-crystal X-ray diffraction. Unlike the parent chloride or bromide-based materials which adopt the monoclinic system, this mixed halide hybrid material crystallizes in the space group Pnma of the orthorhombic system with the following parameters: a = 12.3496(6) Å, b = 16.3147(11) Å, c = 6.4415(3) Å, V = 1397.83(12) Å3 and Z = 4. Its 0-D crystal packing is built of isolated entities, a copper(II) ion surrounded by four chloride/bromide ions [CuBr4]2- and [CuCl4]2-, a diprotonated diamine (C4H12N2)2+ and free water molecules. Additionally, these entities are linked through different types of intermolecular hydrogen bonds N-H…Br, N-H…Cl, N-H…Ow, Ow-H…Br, Ow-H…Cl, and weak non-covalent interactions C-H…Br and C-H…Cl [Ow = water oxygen]. The thermal decomposition of the precursor proceeds through four stages leading to copper(II) oxide as a final product. The title compound possesses antimicrobial and anti-tumoral effects comparable to two previously described compounds, as assessed by in silico examinations. Compound 1 inhibited in a dose dependent manner, the proliferation of gram negative and positive bacteria and exhibited a microbial lipase inhibition from Candida rugosa.