Synthesis, characterisation and antifungal activity of a series of Cobalt(II) and Nickel(II) complexes with ligands derived from reduced N, N′-o-Phenylenebis(Salicylideneimine)

Abstract

The synthesis and characterisation by elemental analysis, conductivity, FTIR, UV-Visible, ESR and magnetic measurements are described for a series of complexes of nickel(II) and cobalt(II) with three ligands (H 2 L 1-3 ) derived from reduced N, N 0 -o-Phenylenebis(salicylideneimine). The complexes formed are identified as neutral species, where the ligands are coordinated through N and O donor atoms. The formulae obtained for the complexes are: [CoL(H 2 O) 2 ] with octahedral geometry and [NiL] with tetrahedral geometry. Their antifungal activity is evaluated towards human pathogenic fungi including yeasts of the Candida genus, some opportunistic moulds belonging to the Aspergillus, Scedosporium genus and some dermatophytes. The cobalt complexes show a significant growth inhibition of yeasts tested and also to fungi of the genus Scedosporium which is of interest because these fungi are usually poorly susceptible to current antifungal including Amphotericin B and Itraconazole, chosen as reference in this study. The activity data show that the metal complexes are more potent than the parent ligand.

Cobalt(II) and nickel(II) chelates of some 5-pyrazolone-based, Schiff-base ligands

“…In 2 ], 2 band is obscured; (a) was used to calculate 2 , 10D q , and B 35 [27,28]. The magnitude of B determined for all complexes may be compared with that for free Co(II) ion (971 cm À1 ).…”

“…The equations used to calculate B 35 are [27]: 2 1 } 1/2 ] The above expressions correspond to the method of fitting; (a) the second band, (b) the third band, (c) the sum of the second and third band, and (d) the difference between the second and third band [27]. In all the complexes, the best fit is according to the method (c).…”

“…Schiff bases derived from -diketone and primary amine provide imino or ketimino with hydroxyl for coordination [1][2][3][4][5][6][7]. There are many reports on metal chelates of this class of compounds but very little on the bisketimino compound derived from heterocyclic -diketone [1][2][3][4][5], which give ONNO donor array towards metal ions.…”

“…There are many reports on metal chelates of this class of compounds but very little on the bisketimino compound derived from heterocyclic -diketone [1][2][3][4][5], which give ONNO donor array towards metal ions. We have previously reported Cr(III) and Ni(II) chelates of Schiff bases derived from 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5-one [1,3] and report here the cobalt(II) and nickel(II) chelates of Schiff bases derived from 4-butyryl-3-methyl-1-phenyl-2-pyrazolin-5-one with o-, m-, p-phenylenediamine, benzedine, and ethylenediamine.…”

Complexation of manganese(II), cobalt(II), nickel(II) and copper(II) by a ligand derived from 1,2,4-triazole: Potentiometric studies and Density Functional Theory calculations

“…Literature survey reveals that the biological activities of ligands are often enhanced after coordination to a metal [10,11]. Therefore this paper reports some potentiometric studies on the coordination behavior of the ligand towards essential metal (II) such as manganese (II), cobalt (II), nickel (II) and copper (II) ions.…”