Synthesis, characterization, and biological studies of novel Ni(II) and Zn(II) complexes with 5-chloro-2-(phenylazo)pyridine

Abstract

An azoimine compound, 5-chloro-2-(phenylazo)pyridine (Clazpy), reacted with Ni(II) and Zn(II) sulphate salts and formed divalent metal complexes with a general formula of [M(Clazpy) 2 (NCS) 2 ], where M is Ni(II) or Zn(II). The synthesized complexes were characterized on the basis of elemental analysis, nuclear magnetic resonance, and infrared and electronic absorption spectroscopy. The single crystal X-ray diffraction and infrared data of the Zn(II) complex show that the ligand coordinates through the donating nitrogen atoms of the pyridine ring and azo moiety of Clazpy and N atoms of the thiocyanate groups. Our density functional theory calculations used the B3LYP/6-31G(d,p)&LANL2DZ functional and basis sets to predict the most favourable structures of [Ni(Clazpy) 2 (NCS) 2 ] and [Zn(Clazpy) 2 (NCS) 2 ]. The TD-CAM-B3LYP/6-31+G(d,p)&LANL2DZ electronic transition energies agree with the electronic spectra and hence confirm their structures. Minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations or minimal fungicidal concentrations (MFC) of all tested compounds were determined against human pathogens by a colorimetric microdilution method. The Clazpy compound and its complexes are significantly active against yeast and filamentous fungus with MIC and MFC values of 32 and 200 µg/ml, respectively. The Clazpy ligand showed higher antimicrobial activities against pathogenic yeast Cryptococcus neoformans (MIC/MFC 32/32 µg/ml) than both complexes (MIC/MFC 64/128 µg/ml). The [Ni(Clazpy) 2 (NCS) 2 ] complex exhibited higher antimicrobial activities against fungal strains of Microsporum gypseum (MIC/MFC 64/128 µg/ml) than the [Zn(Clazpy) 2 (NCS) 2 ] complex. These new azoimine metal complexes might therefore be considered as prospective antifungal agents.

Structural and spectroscopic characterization of a new luminescent NiII complex: bis{2,4-dichloro-6-[(2-hydroxypropyl)iminomethyl]phenolato-κ3 O,N,O′}nickel(II)

“…During the last decade, transition-metal complexes have been of great interest since they have potential applications in coordination chemistry, catalysis and sensors, and display biological and magnetic properties (Sherino et al, 2018;Bang et al, 2016;Vittaya et al, 2017;Hajikhanmirzaei et al, 2015;Vamja & Surati, 2017;Keypour et al, 2017). Recently, Schiff base ligands and their metal complexes have attracted attention as organic photovoltaic materials since their use as potential substitutes for dye-sensitized solar cells (DSSCs) (Zhang et al, 2018;Yang et al, 2010;Wesley Jeevadason et al, 2014;Dinçalp et al, 2010).…”