Synthetic Approach, Structural Performance and in vitro Antibacterial Activity: Nitrogen and Oxygen Donor Atoms containing Bidentate Schiff Base Ligand and its Mononuclear Complexation with Co(II) and Cu(II) Metal Ions

A synthetic approach has been designed and followed for the synthesis of new bidentate Schiff base ligand 2-acetylthiophenenicotinic hydrazone (L) (which possessed nitrogen and oxygen donor atoms) and its Co(II) and Cu(II) mononuclear complexes. All the compounds were examined IR, 1H NMR, mass, EPR, conductivity, elemental analysis, etc. Octahedral geometry has been assigned to all synthesized compounds on the basis of magnetic, IR and electronic spectral analysis. In vitro activity i.e. antibacterial (E. coli and P. aeruginosa) and antifungal (A. niger, M. phasolina and P. glomerata) had been examined for these compounds following well diffusion and poisoned food methods, respectively. During the performance of antifungal activity, antifungal agent was incorporated into the molten agar at various concentrations and mixed well. After performance of in vitro activity, it has been resulted out that metal(II) complexes exhibited remarkable activity than free ligand but less active compared to the standard drugs..

Platinum(II) complex with 4-nitro-N-(pyridin-2-ylmethylidene)aniline: synthesis, characterization, crystal structure and antioxidant activity

A novel complex has been prepared using the (E)-4-nitro-N-(pyridin-2-ylmethylidene)aniline bidentate Schiff base ligand and PtCl2, namely, dichlorido[(E)-4-nitro-N-(pyridin-2-ylmethylidene)aniline-κ2 N,N′]platinum(II) acetonitrile hemisolvate, [PtCl2(C12H9N3O2)]·0.5CH3CN, 1. According to the X-ray measurements of the crystal structure, the PtII ion adopts a PtCl2N2 square-planar coordination. The coordination of the Schiff base ligand to the PtII ion occurs in a cyclic bidentate fashion, as a result of which a five-membered metallacycle is formed. Furthermore, in the structure of 1, the neutral molecules form a one-dimensional chain structure through C—H...Cl and C—H...O hydrogen bonds. The characterization of the complex was performed via single-crystal X-ray diffraction, IR spectroscopy and elemental analysis, and the antioxidant activity of the complex was evaluated using spectrophotometry by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method.

Crystal structures and Hirshfeld surface analysis of trans-bis(thiocyanato-κN)bis{2,4,6-trimethyl-N-[(pyridin-2-yl)methylidene]aniline-κ2 N,N′}manganese(II) and trans-bis(thiocyanato-κN)bis{2,4,6-trimethyl-N-[(pyridin-2-yl)methylidene]aniline-κ 2 N,N′}nickel(II))

Two new mononuclear metal complexes involving the bidentate Schiff base ligand 2,4,6-trimethyl-N-[(pyridin-2-yl)methylidene]aniline (C15H16N2 or PM-TMA), [Mn(NCS)2(PM-TMA)2] (I) and [Ni(NCS)2(PM-TMA)2] (II), were synthesized and their structures determined by single-crystal X-ray diffraction. Although the title compounds crystallize in different crystal systems [triclinic for (I) and monoclinic for (II)], both asymmetric units consist of one-half of the complex molecule, i.e. one metal(II) cation, one PM-TMA ligand, and one N-bound thiocyanate anion. In both complexes, the metal(II) cation is located on a centre of inversion and adopts a distorted octahedral coordination environment defined by four N atoms from two symmetry-related PM-TMA ligands in the equatorial plane and two N atoms from two symmetry-related NCS− anions in a trans axial arrangement. The trimethylbenzene and pyridine rings of the PM-TMA ligand are oriented at dihedral angles of 74.18 (7) and 77.70 (12)° for (I) and (II), respectively. The subtle change in size of the central metal cations leads to a different crystal packing arrangement for (I) and (II) that is dominated by weak C—H...S, C—H...π, and π–π interactions. Hirshfeld surface analysis and two-dimensional fingerprint plots were used to quantify these intermolecular contacts, and indicate that the most significant contacts in packing are H...H [48.1% for (I) and 54.9% for (II)], followed by H...C/C...H [24.1% for (I) and 15.7% for (II)], and H...S/S...H [21.1% for (I) and 21.1% for (II)].