SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL STUDIES OF NI (II) COMPLEXES WITH SCHIFF BASE CO-LIGAND DERIVED FROM 5,6-DIAMINO-1,10-PHENANTHROLINE AND BENZENE-1,4-DICARBALDEHYDE

M. I. Idris,A. A. Abubakar,A. H. Sadi

doi:10.33003/fjs-2020-0403-354

Abstract

The Schiff base (PDB) was synthesized by refluxing ethanolic solution of 5,6-diamino-1,10-phenanthroline with Benzene-1,4-dicarbaldehyde for 3 hours. Similarly the complexes were synthesized by refluxing equimolar solution of PDB with [Ni(phen)2Cl2] and [Ni(bpy)2Cl2] for 5 hours each and characterized by FTIR, UV-visible, Mass and Elemental Analysis. The absorption band in IR spectrum of PDB at 1593 cm-1 was assigned to C=N stretching frequency which was shifted to 1550 cm-1 and 1549 cm-1 in the spectra of [Ni(phen)2PDB](PF6)2 and [Ni(bpy)2PDB](PF6)2 respectively. The new absorption bands at 721 cm-1 and 754 cm-1 in the spectra of both complexes were due to M-N coordinate bond. The UV- visible absorption band at 390 nm was due to p®p* transitions for azomethine. The low energy band at 450 nm for both complexes is due to MLCT Ni(dp) ®PDB(p*) transition. The molecular ion peak (M)+ in the mass spectra for PDB and the complexes were observed at 443 m/z, 984.75 m/z and 940.95 m/z respectively. The compounds were evaluated for antimicrobial activities, by well diffusion method against bacteria using agar nutrient as the medium and fungi using potato dextrose agar as medium. The free Schiff base has low activity compared to the complexes with inhibition zone between 4.0 mm to 6.6 mm whereas the complexes ranges from 7.5 mm to 11.2 mm.

Highlights

Schiff bases are compounds containing imine or azomethine (– C=N–) functional group
Which are produced through the condensation reaction of primary amines with carbonylcontaining compounds (Fig.1) and they were firstly reported by Hugo Schiff (Khudheyer and Murad, 2018)
Research has shown for supramolecular assemblies, and in analytical chemistry, significant progress in utilization of transition metal complexes catalysis, electrochemistry, ring-opening metathesis polymerization and biochemistry, FUDMA Journal of Sciences (FJS) Vol 4 No 3, September, 2020, pp 132 - 141

Summary

INTRODUCTION

Schiff bases are compounds containing imine or azomethine (– C=N–) functional group. Which are produced through the condensation reaction of primary amines with carbonylcontaining compounds (Fig.1) and they were firstly reported by Hugo Schiff (Khudheyer and Murad, 2018). The red coloured crude complex was obtained on adding saturated solution of NH4PF6 It was purified by column chromatography (alumina, CH3CN – Toluene (3:2, v/v) mixture) and was further recrystallized from acetone-ether mixture (1:5, v/v). Yield = 0.67 g (71%).The chloride salt of [Ni(phen)2(pdb)]2+ was obtained by dissolving the above hexafluorophosphate complex in minimum amount of acetone and precipitated out upon addition of a saturated solution of TBACl. Analytical data: Anal. The orange crude complex was obtained on adding saturated solution of NH4PF6 The chloride salt of [Ni(phen)2(pdb)]2+ was obtained by dissolving the above hexafluorophosphate complex in minimum amount of acetone and precipitated out upon addition of a saturated solution of TBACl. Analytical data: Anal. Streptomycin and Ketoconazole were used as standard reference compounds for antibacterial and antifungal studies respectively (Sheikh et al, 2004)

97 Ω-1cm2mol-1

CONCLUSION