Sonochemical synthesis, crystal structure and catalase interaction of a new 2D coordination polymer based on isoniazid and oxalato bridges

Abstract

A new Mn(II) complex based on oxalato (ox2−) and isoniazid (INH), formulated as [Mn(µ-ox)(µ-NIH (N,O)) (µ-NIH (N)Cl]n (1) has been synthesized under sonochemical irradiation. The molecular structure of complex 1 was studied by elemental analysis, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), vibrating sample magnetometer (VSM), and single-crystal X-ray diffraction (SC-XRD). This complex belongs to a monoclinic system with space group P21/c. X-ray crystallography data revealed Mn(II), adopts a distorted octahedral geometry formed by two nitrogen atoms, three oxygen atoms, and one chloride anion. The results of VSM revealed that in the applied magnetic field up to 15,000 Oe, complex 1 is a weak ferromagnet. The interaction of complex 1 with bovine liver catalase (BLC) was investigated by spectroscopic methods. The enzymatic function of BLC decreased to 45.6% when the concentration of the complex was 6.0 × 10−6 M. Fluorescence results revealed that the combination of BLC with the complex is subjected to static quenching mechanism (Kb = 1.73 and 0.38 × 105 M−1at 300 and 310 K, respectively). The interaction process was spontaneous, exothermic, and enthalpy-driven, with a major role of Van der Waals and hydrogen bond forces. UV-Vis, 3D, and synchronous fluorescence measurements indicated the changes in the microenvironment residues of BLC in the presence of complex 1. In conclusion, the above complex can interact with catalase and so inhibit its catalytic activity for the decomposition of hydrogen peroxide.