Mononuclear, homo- and hetero-binuclear complexes of 1-(5-(1-(2-aminophenylimino)ethyl)-2,4-dihydroxyphenyl)ethanone: synthesis, magnetic, spectral, antimicrobial, antioxidant, and antitumor studies

Abstract

A new Schiff base, H₂L, was prepared by condensation of 4,6-diacetylresorcinol with o-phenylenediamine in molar ratio 1 : 1. The ligand reacted with copper(II), nickel(II), cobalt(II), iron(III), zinc(II), oxovanadium(IV), and dioxouranium(VI) ions in the absence and presence of LiOH to yield mononuclear and homobinuclear complexes. The mononuclear dioxouranium(VI) complex [(HL)-(UO₂)(OAc)(H₂O)]·5H₂O was used to synthesize heterobinuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, ¹H-, and ¹³C-NMR, electronic, ESR and mass spectra, conductivity, and magnetic susceptibility measurements as well as thermal analysis. In the absence of LiOH, mononuclear complexes (1, 4, and 9) were obtained; in the presence of LiOH, binuclear complexes (3, 5, 7, and 10) as well as mononuclear complexes (2, 6, and 8) were obtained. In the mononuclear complexes, the coordinating sites are the phenolic oxygen, azomethine nitrogen, and amino nitrogen. In addition to these coordinating sites, the free carbonyl and phenolic OH are involved in coordination in binuclear complexes. The metal complexes exhibited octahedral, tetrahedral, and square planar geometries while the uranium is seven-coordinate. The antimicrobial and antioxidant activities of the ligand and its complexes were investigated. The ligand and the metal complexes showed antitumor activity against Ehrlich Acites Carcinoma.

Graphical abstract

Keywords:

• Schiff base ligand
• mono- and binuclear complexes
• 4,6-diacetylresorcinol
• ¹³C-NMR spectra
• ESR spectra
• antimicrobial
• antioxidant and antitumor activities

Disclosure statement

No potential conflict of interest was reported by the author.