The Ni(II) Complex of 2-Hydroxy-Pyridine-N-Oxide 2-Isothionate: Synthesis, Characterization, Biological Studies, and X-ray Crystal Structures Using (1) Cu Kα Data and (2) Synchrotron Data | Chapter 09 | New Advances in Materials Science and Engineering Vol. 2

C₁₂H₂₀N₆NiO₆S₂ or NiL₂(SCN)₂](NH₄)_2.2H2O, where L is 2-hydroxy-pyridine-N-oxide, has been prepared and characterized using elemental analyses, IR, UV and visible spectrometry, magnetic moment measurements, thermal analyses and single crystal X-ray analyis. The results indicate that the complex reacts as a bidentate ligand and is bound to the metal ion via the two oxygen atoms of the ligand (HL). The activation energies, ∆E*, entropies ∆S*, enthalpies ∆H* and order of reactions have been derived from differential thermo-gravimetric (DTA) curves. Based on inhibition zone diameter measurements, the complex exhibited significant antibacterial activity against both Staphylococcus aureus and Escherichia coli. It also exhibited significant antifungal activity against Candida albicans, but no activity was found against Aspergillus flavus. The crystal structure of the Ni(II) complex [C₁₂ H₂₀ N₆ Ni O₆ S₂], Mr = 467.17, was determined from Cu Kα X-ray diffraction data, λ = 1.54178 Å, at 100 K using direct methods. The crystals are monoclinic, space group P2₁/n with Z = 4 and a = 8.9893(2) Å, b = 17.6680(5) Å, c = 12.5665(3) Å, β = 108.609(1)°. In parallel with this study corresponding results were derived for the crystal structure determined independently from synchrotron X-ray diffraction data, λ = 0.61990 Å, at 100 K. The unit cell parameters derived in this experiment are a = 9.000(2) Å, b = 17.700(4) Å, c = 12.590(3) Å, β = 108.61(3)°. Both studies show 4 O and 2 N atoms coordinating Ni in a distorted octahedral arrangement. Each of the Ni 2-hydroxy-pyridinium-N-oxide moieties is highly planar and the S=C=N-Ni ligands are approximately linear. The crystal structure is characterised by a number of strong hydrogen bonds.

Author(s) Details

Mohamed A. Makhyoun

Department of Chemistry, Alexandria University, Alexandria, Egypt.

Rex A. Palmer

Department of Crystallography, Birkbeck College, London, UK.

Amina A. Soayed

Department of Chemistry, Alexandria University, Alexandria, Egypt.

Heba M. Refaat

Department of Chemistry, Alexandria University, Alexandria, Egypt.

Dina E. Basher

Department of Chemistry, Alexandria University, Alexandria, Egypt.

James Raftery

School of Chemistry, University of Manchester, Manchester, UK.

Carina M. C. Lobley

Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot Oxfordshire, OX11 0DE, UK.

Anna J. Warren

Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot Oxfordshire, OX11 0DE, UK.

Thomas Sorensen

Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot Oxfordshire, OX11 0DE, UK.

Mark Ladd

Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.

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