Coordination of an amino alcoholic Schiff base ligand toward the zinc(II) ion: spectral, structural, theoretical, and docking studies

A new zinc(II) complex of 2-(((2-((2-hydroxyethyl)amino)ethyl)imino)methyl)phenol (L), [Zn(L^z)Br₂] (1), is prepared and identified by elemental analysis, FTIR and ¹H NMR spectroscopy, and single crystal X-ray diffraction. The X-ray structure analysis of 1 reveals a tetrahedrally coordinated zinc(II) complex containing the NO-donor amino alcoholic Schiff base ligand and two bromo ligands. After complexation, the ligand (L) converts to its zwitterionc form (L^z) of phenol → phenolate; amine → ammonium. In this structure, hydrogen bonds between amine and alcohol units form different types of hydrogen bond motifs, including R¹₂(7),R²₂(7), R²₂(10), R⁴₄(24), R⁴₄(30), R⁶₆(38), and R⁶₆(44). In addition to the hydrogen bonds in this crystal network, there are π–π stacking interactions between the phenyl ring and the imine group. The ability of the ligand and its isostructural complexes [Zn(L^z)Br₂] (1), [Zn(L^z)Cl₂] (2), and [Zn(L^z)I₂] (3) to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II, and B-DNA) is investigated by docking studies. The results show that in some cases, the studied compound can interact with proteins and DNA better than doxorubicin. The charge distribution pattern of the ligand and complex 1 is studied by the NBO analysis.