Synthesis, structural and antimicrobial studies of half-sandwich ruthenium, rhodium and iridium complexes containing nitrogen donor Schiff-base ligands

Aminoquinoline-based Re(I) tricarbonyl complexes: Insights into their antiproliferative activity and mechanisms of action

In an effort to develop new potent anticancer agents, two Schiff base rhenium(I) tricarbonyl complexes, containing the ubiquitous aminoquinoline scaffold, were synthesized. Both aminoquinoline ligands and Re(I) complexes showed adequate stability over a 48-h incubation period. Furthermore, the cytotoxic activity of the precursor ligands and rhenium(I) complexes were evaluated against the hormone-dependent MCF-7 and hormone-independent triple negative MDA-MB-231 breast cancer cell lines. Inclusion of the [Re(CO)3Cl]+ entity significantly enhanced the cytotoxicity of the aminoquinoline Schiff base ligands against the tested cancer cell lines. Remarkably, the incorporation of the Schiff-base iminoquinolyl entity notably enhanced the cytotoxic activity of the Re(I) complexes, in comparison with the iminopyridyl entity. Notably, the quinolyl-substituted complex showed up to three-fold higher activity than cisplatin against breast cancer cell lines, underpinning the significance of the quinoline pharmacophore in rational drug design. In addition, the most active Re(I) complex showed better selectivity towards the breast cancer cells over non-tumorigenic FG-0 cells. Western blotting revealed that the complexes increased levels of γH2AX, a key DNA damage response protein. Moreover, apoptosis was confirmed in both cell lines due to the detection of cleaved PARP. The complexes show favourable binding affinities towards both calf thymus DNA (CT-DNA), and bovine serum albumin (BSA), and the order of their interactions align with their cytotoxic effects. The in silico molecular simulations of the complexes were also performed with CT-DNA and BSA targets.

Synthesis, spectroscopic findings, SEM/EDX, DFT, and single-crystal structure of Hg/Pb/Cu-SCN complexes: In silico ADME/T profiling and promising antibacterial activities

This work contemplates synthesizing M-SCN crystal compounds (M = Hg/Pb/Cu) in the presence of respective metal salts and exogenous ancillary SCN^- ion by slowly evaporating the mixed solvent (CH₃OH + ACN). The complexes were characterized by spectroscopy, SEM/EDX, and X-ray crystallography. The Hg-Complex, Pb-Complex, and Cu-Complex crystallize in the monoclinic space group (Z = 2/4). The crystal packing fascinatingly consists of weak covalent bonding and Pb⋯S contacts of tetrel type bond. Here are the incredible supramolecular topographies delineated by the Hirshfeld surface and 2D fingerprint plot. The B3LYP/6-311++G (d, p) level calculations in the gas phase optimized the compound's geometry. The energy difference (Δ) between HOMO-LUMO and global reactivity parameters investigates the complex's energetic activity. MESP highlights the electrophilic/nucleophilic sites and H-bonding interactions. Molecular docking was conceded with the Gram- + ve bacterium Bacillus Subtilis (PDB ID: 6UF6) and the Gram-ve bacterium Proteus Vulgaris (PDB ID: 5HXW) to authenticate the bactericidal activity. ADME/T explains the various pharmacological properties. In addition, we studied the antibacterial activity with MIC (μg/mL) values and time-kill kinetics against Staphylococcus aureus (ATCC 25923) and Bacillus subtilis (ATCC 6635) as Gram-positive, Pseudomonas aeruginosa (ATCC 27853) and Escherichia coli (ATCC 25922) as Gram-negative bacteria.

New rhodium(II)-ED3AP-complex: Crystal structure, characterization and computational chemistry

Only one (trans(O5)-Na[Rh(ed3ap)]?3H2O) of possible two isomers was synthesized and characterized by single crystal X-ray analysis, IR, and UV-Vis spectroscopy. Computational analysis of both isomers was performed with three levels of theory (B3LYP/TZV, BP86/TZV, OPBE/TZV), which gave consistent results. The more stable isomer by total energy and ligand field stabilization energy (LFSE) was trans(O5) which appeared in synthesis. Calculation of excited state energies complied with UV-Vis spectra, especially with OPBE functional. The results of excited state energy pointed out the differences among isomers in means of a splitting pattern of 1T2g excited state term. Both isomers have a strongly delocalized structure according to the natural bonding orbital (NBO) analysis. The trans(O5) geometry has the stabilization of the whole system for roughly 87 kJ/mol and makes this isomer as the only one present in the reaction mixture.

Ruthenium Complexes in the Fight against Pathogenic Microorganisms. An Extensive Review

The widespread use of antibiotics has resulted in the emergence of drug-resistant populations of microorganisms. Clearly, one can see the need to develop new, more effective, antimicrobial agents that go beyond the explored 'chemical space'. In this regard, their unique modes of action (e.g., reactive oxygen species (ROS) generation, redox activation, ligand exchange, depletion of substrates involved in vital cellular processes) render metal complexes as promising drug candidates. Several Ru (II/III) complexes have been included in, or are currently undergoing, clinical trials as anticancer agents. Based on the in-depth knowledge of their chemical properties and biological behavior, the interest in developing new ruthenium compounds as antibiotic, antifungal, antiparasitic, or antiviral drugs has risen. This review will discuss the advantages and disadvantages of Ru (II/III) frameworks as antimicrobial agents. Some aspects regarding the relationship between their chemical structure and mechanism of action, cellular localization, and/or metabolism of the ruthenium complexes in bacterial and eukaryotic cells are discussed as well. Regarding the antiviral activity, in light of current events related to the Covid-19 pandemic, the Ru (II/III) compounds used against SARS-CoV-2 (e.g., BOLD-100) are also reviewed herein.

Synthesis, spectroscopic properties, crystal structures, DFT studies, and the antibacterial and enzyme inhibitory properties of a complex of Co(II) 3,5-difluorobenzoate with 3-pyridinol

A new complex, [Co(DFB)2(3-Pyr)2(H2O)2] (where DFB = 3,5-difluorobenzoate, 3-Pyr = 3-pyridinol), is synthesized and characterized using different techniques (elemental analysis, Fourier transform infrared spectroscopy, and single-crystal X-ray diffraction). Looking at the crystal structure of the complexes, the cobalt atom is coordinated by two nitrogen atoms from two 3-Pyr ligands, two carboxylate oxygen atoms from two DFB anions, and two oxygen atoms from two water molecules. The complex has distorted octahedral geometry around the cobalt atom center complex and crystallizes in the P21/n space group (monoclinic system). Geometry optimization, frequency analysis, and energy quantum chemical calculations on the complex are performed by Density Functional Theory [B3LYP/6-31G (d,p) basis set] to predict the molecular properties. The novel complex is tested against the metabolic isoenzymes human carbonic anhydrases I and II. The novel complex shows Ki values of 317.26 ± 23.25 µM against hCA I and 255.41 ± 48.05 µM against hCA II; the IC50 values for these isoenzymes are 274.37 and 204.33 µM.

Recent Studies on the Antimicrobial Activity of Transition Metal Complexes of Groups 6–12

Antimicrobial resistance is an increasingly serious threat to global public health that requires innovative solutions to counteract new resistance mechanisms emerging and spreading globally in infectious pathogens. Classic organic antibiotics are rapidly exhausting the structural variations available for an effective antimicrobial drug and new compounds emerging from the industrial pharmaceutical pipeline will likely have a short-term and limited impact before the pathogens can adapt. Inorganic and organometallic complexes offer the opportunity to discover and develop new active antimicrobial agents by exploiting their wide range of three-dimensional geometries and virtually infinite design possibilities that can affect their substitution kinetics, charge, lipophilicity, biological targets and modes of action. This review describes recent studies on the antimicrobial activity of transition metal complexes of groups 6–12. It focuses on the effectiveness of the metal complexes in relation to the rich structural chemical variations of the same. The aim is to provide a short vade mecum for the readers interested in the subject that can complement other reviews.