Coordination Behavior of N‐Donor Schiff Base Derived from 2‐Benzoylpyridine Toward Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), and Cr(III) Metal Ions: Synthesis, Spectroscopic and Thermal Studies, and Biological Activity

Abstract

A new Schiff base was prepared from the reaction of 4,4′‐methylenedianiline with 2‐benzoylpyridine in 1:2 molar ratio, as well as its different metal chelates. The structures of the ligand and its metal complexes were studied by elemental analyses, spectroscopic methods (infrared [IR], ultraviolet–visible [UV–vis], 1H nuclear magnetic resonance [NMR], electron spin resonance [ESR]), magnetic moment measurements, and thermal studies. The ligand acts as tetradentate moiety in all complexes. Octahedral geometry was suggested for Mn(II), Cu(II), Cr(III), and Zn(II) chloride complexes and pentacoordinated structure and square planar geometry for Co(II), Ni(II), Cu(NO3 )2, CuBr2 , and Pd(II) complexes. ESR spectra of copper(II) complexes (4)–(6) at room temperature display rhombic symmetry for complex (4) and axial type symmetry for complexes (5) and (6), indicating ground state for Cu(II) complexes. The derivative thermogravimetric (DTG) curves of the ligand and its metal complexes were analyzed by using the rate equation to calculate the thermodynamic and kinetic parameters, which indicated strong binding of the ligand with the metal ion in some complexes. Also, some of these compounds were screened to establish their potential as anticancer agents against the human hepatic cell line Hep‐G2 . The obtained IC50 value of the copper(II) bromide complex (4.34 µg/mL) is the highest among the compounds studied.