A novel sulfate-bridged binuclear copper(ii) complex: structure, optical, ADMET and in vivo approach in a murine model of bone metastasis

Abstract

The novel sulfate-bridged binuclear copper(II) complex namely [Cu₂(μ₃-SO₄)₂(C₄H₆N₂)₄] (1) was obtained from the hydrothermal reaction of 2-methylimidazole (hereafter abbreviated as 2-MeIm) with copper(II) sulfate pentahydrate in methanol. Single-crystal X-ray diffraction analysis of 1 (space group P; cell parameters: a = 8.5712(6) Å, b = 8.7884(10) Å, c = 9.8797(6) Å, α = 115.22(1)°, β = 97.26(1)°, γ = 108.82(1)° and V = 606.26(12) ų) revealed the formation of a centrosymmetric dimeric species. Therein, two [Cu(C₄H₆N₂)₂] moieties are connected via two sulfate anions in a μ-1κ²O¹,O²,2κO³ fashion and resulting in a tricyclo[5.1.1^3,5] structure. The Cu atom adopts a distorted square pyramidal coordination geometry (τ = 19). Hydrogen bonds between the imidazole amino groups and non-coordinating sulfato oxygen atoms result in a two-dimensional network parallel to (010). To accumulate a greater knowledge on how molecular components engage with their local environment, a Hirshfeld surface (HS) analysis employing 3D molecular surface contours and 2D fingerprint plots have been undertaken. Heating of 1 above 89 °C initiates gradual decomposition stages, which lead to the metal oxide as a final product at 720 °C, as proven by TGA/DSC analysis. UV-visible spectroscopy was exploited to determine bandgap energy and the nature of the electron transition. In vivo, the synthesized complex showed significant ameliorative effects on tumor osteolytic lesions in malignant Walker 256/B breast cancer-induced bone metastases.