Three novel unsymmetrically substituted 2,2'-bipyridine ligands were prepared by introducing a 2-hydroxyphenyl group at the 6-position and either a 4-methoxyphenyl, 3,4-dimethoxyphenyl or 3,4-methylenedioxyphenyl group at the 4-position, using a modified Kröhnke protocol. Their corresponding rhenium(I) tricarbonyl iodido complexes, fac-[Re(L)(CO)3I], 1-3, were synthesized and comprehensively characterized by single-crystal X-ray diffraction (SCXRD), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, cyclic voltammetry (CV), high-resolution mass spectrometry (HRMS), and elemental analysis. The common 6-(2-hydroxyphenyl) moiety predominantly influences the spectroscopic and redox properties of the complexes. SCXRD confirms the facial arrangement of the fac-[Re(CO)3N2I] core in all three cases, although solid-state conformational isomerism was observed only in complex 1. In contrast, two NMR-distinguishable isomers are observed in solution for all three complexes. The cytotoxicity of 1-3 was evaluated by MTT assay after 48 h of continuous exposure in several human tumor cell lines (HeLa, PANC-1, MDA-MB-231, A549) and in non-malignant human lung fibroblasts (MRC-5). Notably, all three complexes displayed low-micromolar IC50 values comparable to cisplatin, with the highest activity observed in HeLa cells (5.11-7.45 μM). However, significant activity was also recorded in MRC-5 cells (IC50 = 8.19-8.95 μM), suggesting higher overall toxicity and weaker selectivity compared to cisplatin. Analysis in HeLa cells using bright-field microscopy confirmed a substantial antiproliferative effect.

A novel heterobimetallic ruthenium(II)–gold(I) complex featuring a bridging bis(diphenylphosphino)butane (dppb) ligand was prepared and fully characterized. Single-crystal X-ray diffraction revealed a piano-stool geometry around Ru(II) with η6-cymene, two chlorido ligands, and one phosphorus atom from dppb, while the Au(I) center adopts a linear P–Au–Cl coordination. Structural integrity in the solution was confirmed by 1D and 2D NMR spectroscopy, while solution behavior was further monitored by variable solvent 31P NMR and UV/Vis spectroscopy, indicating that the organometallic Ru–arene core remains intact, whereas the chlorido ligands coordinated to Ru exhibit partial lability. Complementary characterization included elemental analysis, FTIR, and UV/Vis spectroscopy. Spectrofluorimetric and FRET analyses showed that Au(dppb), Ru(dppb), and the heterobimetallic AuRu complex bind to BSA with apparent constants of 1.41 × 105, 5.12 × 102, and 2.66 × 104 M−1, respectively, following a static quenching mechanism. In vivo biological evaluation in Wistar rats revealed no significant hepatotoxicity or nephrotoxicity, with only mild and reversible histological alterations and preserved hepatocyte nuclear morphology. Hematological analysis indicated a statistically significant reduction in leukocyte populations, suggesting immunomodulatory potential, while elevated serum glucose levels point to possible endocrine or metabolic activity. These findings highlight compound structural stability and intriguing bioactivity profile, making it a promising platform for further organometallic drug development and testing.

Four new heteroleptic neutral paramagnetic mononuclear oxidovanadium(IV) complexes, designated as [VOL(phen)], where L corresponds to acetophenone isoniazid hydrazone or its 5-halogenated derivatives and phen stands for 1,10-phenanthroline, were synthesized and thoroughly characterized using chemical analysis, various spectroscopic techniques, and diffraction methods. Single-crystal X-ray diffraction revealed the molecular and crystal structures of two complexes, showing an octahedral coordination environment around the vanadium(IV) center. The coordination includes a tridentate ONO donor hydrazone ligand in its deprotonated enol-imine form, 1,10-phenanthroline as a bidentate NN donor ternary ligand, and one terminal oxygen atom. The biochemical and hematological effects of these complexes were evaluated in a streptozotocin-induced diabetic rat model. All synthesized complexes showed cholesterol-lowering effects compared to the diabetic rat group, with the vanadium complex lacking a substituent on the acetophenone ring of hydrazone showing the strongest effect. Complexes exhibited comparable and significant antidiabetic activity in vivo, effectively reducing hyperglycemia within 1 week of treatment. Additionally, the histopathological effects of complex (4) on liver, kidney, and brain tissues were investigated. All four complexes were found to have low bioaccumulation levels, with total absolute bioaccumulation in all tested organs less than 0.35% of the administered dose.

Extensive research into platinum-based chemotherapeutics has been underway for decades with ruthenium-based complexes emerging as interesting and potent candidates. Even still, there is no evidence of a single mechanism of action across all synthesized and tested Ru-based complexes, prompting the continuance of research in this field. In addition, the mechanism of action varies according to cell line and/or animal model and is seemingly highly individualized and personalized. In accordance with this, the ruthenium complexes are able to activate specific molecular pathways and interact with certain targets within the cell, sometimes reported simultaneously. In this review, we attempt to give a new perspective on ruthenium complexes’ anti-cancer properties and organize selected results from the past 15 years of research connecting their structure with the reported mechanism of action. These results corroborate the previously reported great potential that ruthenium complexes have on cancer in vitro. In addition, the review provides insight into Ru drugs in their clinical trials and their efficacy against cancer including a historical context on metallodrugs, particularly platinum-based complexes, and their antitumor capability.

Wet synthesis approach afforded four new heteroleptic mononuclear neutral diamagnetic oxidovanadium(V) complexes, comprising salicylaldehyde-based 2-furoic acid hydrazones and a flavonol coligand of the general composition [VO(fla)(L-ONO)]. The complexes were comprehensively characterized, including chemical analysis, conductometry, infrared, electronic, and mass spectroscopy, as well as 1D 1H and proton-decoupled 13C(1H) NMR spectroscopy, alongside extensive 2D 1H1H COSY, 1H13C HMQC, and 1H13C HMBC NMR analyses. Additionally, the quantum chemical properties of the complexes were studied using Gaussian at the B3LYP, HF, and M062X levels on the 6-31++g(d,p) basis sets. The interaction of these hydrolytically inert vanadium complexes and the BSA was investigated through spectrofluorimetric titration, synchronous fluorimetry, and FRET analysis in a temperature-dependent manner, providing valuable thermodynamic insights into van der Waals interactions and hydrogen bonding. Molecular docking was conducted to gain further understanding of the specific binding sites of the complexes to BSA. Complex 2, featuring a 5-chloro-substituted salicylaldehyde component of the hydrazone, was extensively examined for its biological activity in vivo. The effects of complex administration on biochemical and hematological parameters were evaluated in both healthy and diabetic Wistar rats, revealing antihyperglycemic activity at millimolar concentration. Furthermore, histopathological analysis and bioaccumulation studies of the complex in the brain, kidneys, and livers of healthy and diabetic rats revealed the potential for further development of vanadium(V) hydrazone complexes as antidiabetic and insulin-mimetic agents.

The need for a systematic approach in developing new metal-based drugs with dual anticancer-antimicrobial properties is emphasized by the vulnerability of cancer patients to bacterial infections. In this context, a novel organometallic assembly was designed, featuring ruthenium(II) coordination with p-cymene, one chlorido ligand, and a bidentate neutral Schiff base derived from 4-methoxybenzaldehyde and N,N-dimethylethylenediamine. The compound was extensively characterized in both solid-state and solution, employing single crystal X-ray diffraction, nuclear magnetic resonance, infrared, ultraviolet-visible spectroscopy, and density functional theory, alongside Hirshfeld surface analysis. The hydrolysis kinetic was thoroughly investigated, revealing the important role of the chloro-aqua equilibrium in the dynamics of binding with deoxyribonucleic acid and bovine serum albumin. Notably, the aqua species exhibited a pronounced affinity for deoxyribonucleic acid, engaging through electrostatic and hydrogen bonding interactions, while the chloro species demonstrated groove-binding properties. Interaction with albumin revealed distinct binding mechanisms. The aqua species displayed covalent binding, contrasting with the ligand-like van der Waals interactions and hydrogen bonding observed with the chloro specie. Molecular docking studies highlighted site-specific interactions with biomolecular targets. Remarkably, the compound exhibited wide spectrum moderate antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, coupled with low micromolar cytotoxic activity against human colorectal adenocarcinoma cells and significant activity against human leukemic monocyte lymphoma cells. The presented findings encourage further development of this compound, promising avenues for its evolution into a versatile therapeutic agent targeting both infectious diseases and cancer.