Synthesis, characterization, electrochemical behavior, and biological activity of bisazomethine dye derived from 2,3-diaminomaleonitrile and 2-hydroxy-1-naphthaldehyde and its zinc complex

Abstract

Bisazomethine containing diaminomaleonitrile, (bhnmab) and its Zn-complex were synthesized by both classical and microwave-assisted methods and characterized by ¹H-NMR, ¹³C-NMR, UV-Vis, FT-IR, DSC, TG, fluorescence, and cyclic voltammetry. The solvatochromic responses of bhnmab in solvents of different polarities exhibited positive solvatochromism with a large bathochromic shift from benzene to DMF. The emission of [Zn(II)-(bhnmab)(sol)] is red-shifted and much more intense when compared with that of bhnmab. A square-pyramidal structure for the formed complex has been proposed using a CS Chem 3D Ultra Molecular Modeling and Analysis Program. The electrochemical behavior of bhnmab and its Zn(II) complex in B–R universal buffer containing 30% (v/v) of DMF was examined by cyclic voltammetry. In vitro antimicrobial activity of various concentrations of bhnmab and its Zn(II) complex were assessed using the cup plate diffusion method. The Zn(II) complex exhibited higher antimicrobial activity than the free ligand (p ≤ 0.05).

Keywords:

• Schiff base 2,3-Diaminomaleonitrile
• Zn(II) complex
• Solvatochromism
• Voltammetry
• Biological activity

Acknowledgments

The authors gratefully acknowledge King Abdulaziz University and the Deanship of Scientific Research for financial support (Grant No. 17-013/430), and the authors express their gratitude to the Department of Botany and Microbiology, Faculty of Science, Tanta University, Egypt for providing the great facilities for collecting the test microorganisms required for the biological activity.