Synthesis, structural investigation and biological application of new mono- and binuclear cobalt (II) mixed-ligand complexes containing 1,10-phenanthroline, acetamide and ethylenediamine

Abstract

The intensive use of antibiotics has led to an increase of drug resistant bacteria against known antibiotics. To overcome the alarming problem of microbial resistance to antibiotics, the discovery of novel active compounds against new targets is a matter of urgency. Based on this, we report three new mixed ligand complexes of cobalt (II)viz. mononuclear ([Co(phen)2(Act)(H2O)]Cl2.H2O and [Co(phen)2(Act)(en)]Cl2), and binuclear [Co2(phen)4(Act)2(en)]Cl4 which were synthesized from CoCl2.6H2O, 1,10-phenanthroline monohydrate, acetamide and ethylenediamine. These complexes were characterized using spectroscopic (ESI-MS, ICP-OES, FT-IR, and UV-Vis), chloride determination as well as melting point and conductance measurement. Invitro antibacterial activity was also tested on two Gram positive (Staphylococcus aureus, Streptococcus pyogenes) and two Gram negative (Escherichia coli and Klebsiella pneumoniae) bacteria using disc diffusion method. The complexes performed well even against the Gram-negative bacteria. The antibacterial result was found comparable with the commercial drug Gentamicin even at lower concentration of complexes. Thus, the synthesized complexes may be considered as potential antibacterial agents after passing cytotoxicity testing.

Cytotoxic mixed-ligand complexes of Cu(II): A combined experimental and computational study

“…The absorption spectra of metformin was observed at 234 nm ( Supplementary Information ) and in complexes 1 this band has either shifted to 226 nm or appeared as overlapped peaks together with 1,10-phenathroline absorption peaks as shown in the HOMO-LUMO electron distribution ( Figure 3 ). In the UV-Vis spectra of 1,10-Phenathroline free ligand (experimental/TD-DFT) the absorption peaks at 228/226 nm and 263/258 nm corresponds with n→π* (C=N) and π→π*(C=C) transitions, respectively ( Tamiru et al, 2019 ). The peak at 263/258 nm is red shifted to 272/268 nm for the 1 complex.…”

Organic–inorganic hybrid salt and mixed ligand Cr(III) complexes containing the natural flavonoid chrysin: Synthesis, characterization, computational, and biological studies

“…In this study, the UV-Vis/TD-DFT calculated absorption spectra of chrysin in DMSO appeared at 267/261 nm and 320/325 nm for π→π* transitions of the benzoyl and cinnamoyl systems, respectively, consistent with previous reports ( Sundaraganesan et al, 2012 ; Halevas et al, 2021 ). The absorption spectra of the free ligand 1,10-phenanthroline (experimental/TD-DFT) showed absorption peaks at 228/226 nm and 263/258 nm, corresponding to n→π* (C=N) and π→π*(C=C) transitions, respectively ( Tamiru et al, 2019 ; Alem et al, 2022 ). The obtained UV-Vis absorption spectrum of the ligands chrysin and 1,10-phenanthroline, and their metal complexes in DMSO together with their TD-DFT calculated results, are presented in Figure 1 ; Figure 2 and Supplementary Figures S3–S5 in the Supporting Material.…”

Synthesis, structural investigations, and in vitro biological activity of Co(II) and Fe(III) mixed ligand complexes of 1,10‐phenanthroline and 2,2′‐bipyridine

“…It is important to note that 1,10‐phenanthroline and 2,2′‐bipyridine have high antibacterial activities against tested bacteria; however, they could not be used for medicinal applications directly due to cytotoxicity caused by its strong chelating nitrogen atoms binds with biometals and inhibiting metalloenzymes (Abebe et al, 2018). The most common scenario to minimize their toxicity and benefit from their antibacterial privilege is coordinating them with metal ions (Abebe & Hailemariam, 2016; Abebe et al, 2017, 2020; Tigineh et al, 2019, 2021; Tamiru et al, 2019). The observed change in antibacterial activity of complexes compared to the ligands can be explained based on Overton's concept of cell permeability (Anjaneyulu & Rao, 1986) and Tweedy's chelation theory (Tweedy, 1964).…”

“…Previously, our group also reported mono‐ and binuclear mixed ligand complexes with those metals having redox potentials such as Iron(III) (Tigineh et al, 2021), cobalt(II) (Abebe et al, 2020, 2021; Atakilt et al, 2019; Tigineh & Abebe, 2019; Tamiru et al, 2019), copper(II) (Abebe et al, 2017), and ruthenium(III) (Abebe & Hailemariam, 2016) with different ligand combinations for biological applications and obtained promising antibacterial results. However, to our knowledge, there is no report yet with the present form of combination from our group and elsewhere.…”

“…and benefit from their antibacterial privilege is coordinating them with metal ions (Abebe & Hailemariam, 2016;Abebe et al, , 2020Tigineh et al, 2019Tigineh et al, , 2021Tamiru et al, 2019). The observed change in antibacterial activity of complexes compared to the ligands can be explained based on Overton's concept of cell permeability (Anjaneyulu & Rao, 1986) and Tweedy's chelation theory (Tweedy, 1964).…”