Synthesis, Characterization, Single-Crystal X-ray Structure and Biological Activities of [(Z)-N′-(4-Methoxybenzylidene)benzohydrazide–Nickel(II)] Complex

Inas Al-Qadsy,Prem Lama,Lena Ahmed Saleh Al-Faqeeh,Mazahar Farooqui,Abdel-Basit Al-Odayni,Arwa Al-Adhreai,Abdulaziz Ali Alghamdi,Ali Alrabie,Waseem Sharaf Saeed

doi:10.3390/cryst11020110

Abstract

(Z)-N′-(4-methoxybenzylidene)benzohydrazide (HL) and its Ni(II) complex (Ni(II)-2L) were synthesized using eco-friendly protocols. The single X-ray crystal structure of Ni(II)-2L was solved. Moreover, the structural properties were evaluated using Fourier transform infrared, proton nuclear magnetic resonance, mass, and Ultraviolet/Visible spectroscopy. The diamagnetic and thermal stability were assessed using magnetic susceptibility and thermogravimetric analysis, respectively. The biological activities of both HL and Ni(II)-2L (62.5–1000 μg/mL) against Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial and fungal (Candida albicans, Aspergillus niger, and Aspergillus clavatus) species were studied using the minimum inhibitory concentration (MIC) tests method in reference to Gentamycin and Nystatin standard drugs, respectively. The results revealed an affordable, environmentally friendly, and efficient synthetic method of HL using water as a green solvent. The Ni(II)-2L complex crystallized in a distorted square planar, P21/n space group, and one Ni(II) to two bidentate negatively charged ligand ratio. The analysis of biological activity revealed higher activity of the complex against S. aureus and S. pyogenes (bacteria) and A. niger and A. clavatus (fungi) compared to the ligand. However, the highest activity was at a MIC of 62.5 μg/mL for the complex against S. pyogenes and for the ligand against E. coli. Therefore, both HL and Ni(II)-2L could be promising potential antimicrobials and their selective activity could be an additional benefit of these bioactive materials.

Highlights

The synthesis of hydrazones and their metal complexes has attracted considerable scientific interest [1]
The HL was successfully synthesized from anisole and benzoic hydrazide substrates (Figure 1)
Fragments with m/z values of 277.0977, 531.2043, and 785.2965 were assigned to the sodium adducts, [M+Na]+, Crystals 2021, 11, x FOR PEER REVI[E2WM+Na]+, and [3M+Na]+, respectively [55,56,57]. All these results provide evidence of9tohfe17 chemical structure of HL and, its successful synthesis

Summary

Introduction

The synthesis of hydrazones and their metal complexes has attracted considerable scientific interest [1] They are an essential class of biologically active compounds with unique properties, and they exhibit a broad spectrum of physiological and pharmacological activities [2]. Hydrazones possess an azomethine–NHN = CH- group, formed by the reaction of aldehydes or ketones with hydrazine or hydrazide motifs. They are a special class of Schiff bases, which are known to exhibit a wide range of interesting biological activities, including antioxidant, antimicrobial, anti-inflammatory, and anticonvulsant properties [3,4,5,6,7]. Complexation of aroylhydrazones with metal ions results in more reactive materials due to the presence of both imine and carbonyl groups, and it is an emerging class of Schiff base complexes, reported to have useful antimicrobial [10,11,12], antioxidant [13], antitumor [14,15], antidepressant [16], analgesic, anti-inflammatory [17], antitubercular [18,19], anti-convulsant [20], and sensor [21] properties

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