New Tridentate Hydrazone Metal Complexes Derived from 2-Hydroxy-4-Methoxyacetophenone and some Acid Hydrazides: Synthesis, Characterization and Antibacterial Activity Evaluation

Dhufr A Omer,Abdul Ghany M Al-Daher

doi:10.33899/rjs.2019.159969

Abstract

A new series of complexes of Co(II), Ni(II), Cu(II), and Zn(II) with three hydrazones ligands(L) derived from 2-hydroxy-4-methoxy acetophenone (Paeonol) and 4-methylbenzoylhydrazide (AMBH), acetyl hydrazine (AAH), or picolinoyl hydrazine (APH) with the general formula [M(L-H)2].nH2O (n= 0, 1, or 2) where L-H = deprotonated AMBH, AAH or APH, have been prepared and characterized by elemental analyses, spectral (FT-IR, UV–visible) as well as molar conductance and magnetic measurements. The data revealed that the ligands AMBH and AAH act as mono-negative ONO chelates coordinated through the carbonyl group and the phenoxy oxygen atoms and azomethine nitrogen atom, while APH acts as NNO chelate, coordinated through the pyridine and azomethine nitrogen atoms and the phenoxy oxygen atom. On the basis of electronic spectral and magnetic moment data, an octahedral geometry is suggested for all complexes. Also, the ligands and some of their complexes were screened for antibacterial activities.

Highlights

A new series of complexes of Co(II), Ni(II), Cu(II), and Zn(II) with three hydrazones ligands(L) derived from 2-hydroxy-4-methoxy acetophenone (Paeonol) and 4-methylbenzoylhydrazide (AMBH), acetyl hydrazine (AAH), or picolinoyl hydrazine (APH) with the general formula [M(L-H)2].nH2O (n= 0, 1, or 2) where L-H = deprotonated AMBH, AAH or APH, have been prepared and characterized by elemental analyses, spectral (FT-IR, UV–visible) as well as molar conductance and magnetic measurements
In view of the significant role played by the metal complexes of aroylhydrazones in biological systems, catalysis and in various other fields, we were motivated to synthesize Co(II), Ni(II), Cu(II) and Zn(II) complexes with hydrazones derived from 4-methyl benzoyl hydrazine, acetyl hydrazine, and picolinoyl hydrazine with the biologically active ketone (Paeonol), 2-hydroxy-4-methoxy acetophenone, (Fukuhara and Yoshida, 1987) (Scheme 1), and to describe their structures, spectroscopic, and magnetic properties
The hydrazones of acid hydrazides (4-methylbenzoyl hydrazine, acetyl hydrazine and picolinoyl hydrazine) (AMBH, AAH, and APH respectively) were prepared in good yields by condensation with 2-hydroxy-4-methoxy acetophenone (Scheme 1). The reaction of these hydrazones with metal acetates in presence of triethyl amine (Sadhukhan et al, 2011) yield bis-complexes of the general composition [M(L-H)2].nH2O (L= AMBH, AAH, APH; n= 0,1,2), in which the ligands deprotonated during complexation with the metals (II) as indicated by analytical data (Table 1 and 2)

Summary

Introduction

RESULTS AND DISCUSSION The hydrazones of acid hydrazides (4-methylbenzoyl hydrazine, acetyl hydrazine and picolinoyl hydrazine) (AMBH, AAH, and APH respectively) were prepared in good yields by condensation with 2-hydroxy-4-methoxy acetophenone (Scheme 1). The appearance of ‫( ט‬C–O)- bands in the spectra of the complexes in the range (1349- 1311) cm-1, suggests the bonding of ligand through a deprotonated (C–O)- phenolate group to the metal (Singh et al, 2013 ; Swathy et al, 2016).

Results

Conclusion