Search Results (315)

Metabolic and cardiometabolic diseases are closely associated with mitochondrial dysfunction and redox imbalance. Ubiquinol–cytochrome c reductase core protein 2 (UQCRC2), a non-catalytic structural core subunit of mitochondrial respiratory chain Complex III, is increasingly recognized as a regulator of Complex III integrity, electron transfer, oxidative phosphorylation, and mitochondrial redox homeostasis. Under metabolic stress, reduced expression or functional impairment of UQCRC2 may promote electron leakage, mitochondrial reactive oxygen species (mtROS) generation, lipid peroxidation, impaired antioxidant defense, and disrupted glucose–lipid metabolism. These alterations may contribute to insulin resistance (IR), metabolic dysfunction-associated steatotic liver disease (MASLD), obesity, and cardiovascular disease (CVD). This review summarizes current evidence linking UQCRC2 dysfunction to mitochondrial bioenergetic failure, oxidative stress, inflammatory signaling, and cardiometabolic injury. We further discuss redox-regulatory pathways, including Nrf2, AMPK–SIRT1–PGC-1α, glutathione metabolism, and mitophagy, as well as pharmacological agents and natural compounds that may modulate UQCRC2-related mitochondrial responses. Collectively, these findings highlight UQCRC2 as a redox-sensitive mitochondrial node linking Complex III dysfunction to cardiometabolic injury and targeted redox-based interventions. Full article

The disadvantages of Cisplatin in anticancer treatment are connected to its poor selectivity, resistance developed of cancers to the drug, and its toxicity against normal organs. An important strategy in anticancer treatment is the synthesis and clinical investigation of non-platinum metal complexes with superior anticancer activity and improved selectivity compared to Cisplatin, combined with lower toxicity, fewer side effects and decreased resistance of cancer to the drug. In the current study, we aim to summarize the potential of important non-platinum metal-based organic compounds as therapeutic agents against different cancer cell types. The review covers the general principles of chemotherapy. A literature analysis shows that organic complexes of the metalloids arsenic (As), boron (B), antimony (Sb), and selenium (Se), and of metals, such as Ag, Au, Co, Cu, Fe, Mn, Mo, Ni, Zn, Ce, Ga, Gd, Ir, Os, Pd, Re, Rh, Ru, Ti, and V, have been investigated for potential applications in cancer therapy. This is due to their antiproliferative effects against different cancer types: lung [Cd(II), Co(II), Cu(II), Ni(II), Mn(II), Ru(II), Zn(II)]; breast [Ag(I), Cu(I), Cu(II), Ir(III), Ni(II), Mn(II),. Rh(III), Ru(II)]; gastric [Cu(II), Cu(II)-La(III)]; colon [Ag(I), Cu(II), Ir(III), Pd(II), Rh(III), Ru(II), vanadium(V)]; colorectal [Ag(I), Co(II), Cu(II), Zn(II)]; liver [Ag(I), Co(II), Cu(II), Gd(III), vanadium(V)]; pancreatic [vanadium(IV)]; bladder [Ag(I), Cu(II), Ru(II)]; cervical [Ag(I), Au(I), Cu(I), Cu(II), Fe(II), Ir(III), Rh(III), Ru(II)]; testicular [vanadium(IV)]; prostate [Cu(II), Pd(II), Zn(II)]; leukemia [Ag(I), Co(II), Cu(II), Pd(II), Zn(II)]; sarcoma [Co(II), Ni(II), Zn(II)]; mesothelioma [Cu(II)]; neuroblastoma [Cu(II)]; glioma [Cu(II)]; and melanoma [Au(I), Cu(II), Pd(II), Ru(II)]. The main goals for increasing anticancer metal-based complexes include increasing anticancer activity and selectivity, reducing toxicity, and avoiding cancer cell resistance. Compared to Cisplatin, organocomplexes of copper, ferrocene, and ruthenium are more active. Ruthenium and copper complexes, in particular, are also more selective. Notably, ruthenium and ferrocene derivatives are less toxic than Cisplatin. Lastly, cancers appear to exhibit less resistance against copper, gold, ruthenium, palladium, and ferrocene complexes. Full article

Transition metal complexes that can serve as photosensitizers (PSs) have attracted considerable scientific interest owing to their potential applications in photodynamic therapy (PDT), triplet-triplet annihilation for energy upconversion (TTA UC), photocatalysis, and time-resolved bioimaging techniques. In many of these applications, the efficiency of intermolecular triplet-triplet energy transfer (TTET) between the photosensitizer and acceptor is largely determined by the triplet excited-state lifetime of the photosensitizer. One of the most efficient strategies for extending the triplet lifetimes of transition metal complexes is the incorporation of organic chromophores possessing long-lived intraligand (³IL) excited states into the coordination sphere of transition metal complexes. Polycyclic aromatic hydrocarbons, particularly anthracene- and pyrene-based chromophores, have emerged as especially attractive building blocks for this purpose. The current contribution highlights the role of pyrene and anthracene groups in controlling the photophysical properties of cyclometalated iridium(III) metal complexes, with an emphasis on their applications as photosensitizers. Particular attention is devoted to elucidating the relationships between molecular structure and excited-state properties. A detailed discussion of these relationships has been performed for three classes of cyclometalated iridium(III) complexes: (1) charge-neutral Ir(III) complexes including pyrene and anthracene motifs, (2) cationic bis-cyclometalated iridium(III) complexes bearing pyrene-functionalized ligands, and (3) cationic mono- and bis-cyclometalated iridium(III) complexes bearing anthracene-functionalized ligands. Full article

Heavy rare earth elements (HREEs) are widely used in permanent magnets, phosphors, catalysts, and advanced electronic devices because of their unique optical, electrical, and magnetic properties. However, their efficient separation remains a major challenge in hydrometallurgy because neighboring rare earths have highly similar ionic radii and chemical behavior. In this work, a silane-grafted aminophosphonate resin, D152-AMPA, was used to systematically investigate the adsorption behavior, adjacent-pair separation, impurity effects, and dynamic column performance of a mixed rare-earth system under different pH conditions. In the presence of Al, Fe, Ca, and Mg, the Er/Ho separation factor increased from 1.031 at pH 2 to 2.298 at pH 4, indicating that the partitioning advantage of Er over Ho was retained and further strengthened despite the presence of impurities. During elution, the purities of the Er-rich and Ho-rich fractions reached 92.79% and 94.34%, with cumulative recoveries of 88.32% and 83.05%, respectively. XPS and FT-IR analyses further indicated that Lu(III) adsorption mainly involved the oxygen donor sites of the aminophosphonate groups. These results demonstrate that D152-AMPA is capable of selective adsorption and dynamic fractionated separation in mixed and impurity-containing rare-earth systems, providing an experimental basis for greener separation and enrichment of complex rare-earth solutions. Full article

The growing demand for gold in various high-technology applications necessitates the development of efficient and selective methods for its recovery and analysis, which can be achieved using such macrocyclic ligands as crown esters and their aza-substituted derivatives. The present paper reports on the equilibrium constants for the formation of gold(III) complexes with 18-crown-6, 1-aza-18-crown-6, 1,10-diaza-18-crown-6, and the cryptand 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix 222) in aqueous solution at T = 298.2 K, p = 0.1 MPa, I → 0. The equilibrium constants (log β) for the substitution of chloride ions by macrocycles were determined to be 4.52 ± 0.04, 9.15 ± 0.03, 9.08 ± 0.07, and 11.51 ± 0.08, respectively. Equilibrium constants for protonated and polyligand species are also provided. The complexation mechanism was elucidated using a combination of spectroscopic techniques. UV-Vis and IR spectroscopy confirm the substitution of chloride ligands by the nitrogen donor atoms of the aza-macrocycles within the tetrachloroaurate(III) ion. Furthermore, ¹H NMR analysis reveals that the diaza-substituted ligands can form both inclusion complexes, where the gold cation is encapsulated within the macrocyclic cavity, and exclusion complexes. These findings provide a quantitative foundation for the design of novel macrocycle-based extractants and sensors for gold(III). Full article

This study reports the synthesis, spectroscopic characterization, and biological evaluation of a novel moxifloxacin hydrazide derivative (MOX-H) and its metal complexes with Co(II), Ni(II), Cu(II), VO(IV), and Gd(III). The ligand was synthesized by hydrazinolysis of moxifloxacin hydrochloride, and the resulting hydrazide was subsequently complexed with the respective metal salts. The interaction between MOX-H and the metal ions yielded the corresponding complexes, formulated as [Co(H₂O)Cl(MOX-H)₂]Cl·2.5H₂O, [Ni(H₂O)Cl(MOX-H)₂]Cl.4.5H₂O, [VO(MOX-H)₂]SO₄.3.5H₂O, [Gd (H₂O)(MOX-H)₂(NO₃)₂]NO₃.2H₂O, and [Cu(MOX-H)₂(H₂O)Cl]Cl·xH₂O (where x = 2, 2.5, 0.5, for products synthesized via template, microwave-assisted, and hydrothermal methods, respectively). The synthesized analogues were characterized by elemental analysis (CHN), FT-IR, UV-visible, and ¹H NMR spectroscopy, and mass spectrometry, as well as thermogravimetric (TG/DTG) and magnetic measurements. FT-IR spectra confirmed coordination through the hydrazide carbonyl and amine groups, while UV–visible and magnetic data indicated predominantly octahedral geometries. The thermal behavior exhibited multistep decomposition with activation parameters supporting exothermic processes. When compared to the free ligand, the metal complexes showed increased antimicrobial activity against both Gram-positive and Gram-negative bacteria and fungus species, particularly for the Co(II) and Cu(II) complexes, which showed the largest inhibition zones. The Cu(II)–MOX-H complex exhibited the lowest MIC values (4.88–9.76 µg/mL) among all tested compounds, confirming its outstanding antibacterial potency and high sensitivity compared to the free ligand and standard drug. Cytotoxicity assays demonstrated selective anticancer activity, with the Cu(II)–MOX-H complex showing the highest potency (IC₅₀ ≈ 2.95 µM against MCF-7 and IC₅₀ ≈ 0.98 µM against HepG-2), while maintaining minimal toxicity toward normal cells. These findings were corroborated by molecular docking investigations, which showed that the MOX-H complexes had substantial binding affinities (−9 to −10 kcal/mol) toward DNA topoisomerase II, consistent with their observed biological effects. Full article

Salophen-type Schiff base ligands derived from salicylaldehyde and naphthalene aldehydes were synthesized and coordinated to Ni(II) to obtain three nickel complexes (NiL1–NiL3), which were evaluated as heterogeneous electrocatalysts for the methanol electro-oxidation reaction (MOR) in alkaline media. The ligands and complexes were fully characterized by FT-IR, ¹H NMR, EPR, DART-MS, and elemental analysis, confirming tetradentate coordination through imine nitrogen and phenoxide oxygen donors. Electrochemical studies were carried out using carbon paste electrodes modified with 15 wt % of each complex. Cyclic voltammetry revealed that the electrocatalytic activity is mediated by the Ni(II)/Ni(III) redox couple, with Ni(III) oxohydroxide species acting as the active sites for methanol oxidation. Among the evaluated systems, NiL1@CPE showed superior performance at low methanol concentrations, while NiL2@CPE and NiL3@CPE exhibited higher current densities at elevated methanol concentrations. Scan-rate studies indicated that the oxidation process is diffusion-controlled, and a linear response to methanol concentration was observed over a wide concentration range. The results demonstrate that ligand structure and coordination geometry play a crucial role in modulating the electrocatalytic behavior of Ni(II) Schiff base complexes, highlighting their potential as cost-effective molecular catalysts for alkaline methanol oxidation. Full article

The technological promise of nonlinear optical (NLO) compounds has stimulated intense interest in optoelectronic devices, data storage, photonics, and anticancer therapy. Thiosemicarbazone ruthenium materials are of growing interest because of their tunable ligand framework and coordination sphere, allowing fine control over geometry, electronics, and functional properties. Here, we report an N-substituted salicylaldehyde thiosemicarbazone ligand and a series of octahedral Ru(III) complexes bearing triphenylphosphine or triphenylarsine and halide (Cl, Br) co-ligands. The complexes were characterized by elemental analysis, FT-IR, UV–Vis, EPR, mass spectrometry, and magnetic susceptibility measurements, which together confirm NS-chelation to a low-spin Ru(III) center in a distorted octahedral environment. Their photophysical and NLO responses were assessed by UV–Vis spectroscopy and powder second-harmonic generation measurements (Kurtz–Perry method), revealing promising NLO behavior. In parallel, antioxidant activity and in vitro anticancer effects against HeLa cells were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assays. These results provide insight into ligand-controlled structure–activity relationships, in which the halide (Cl/Br) and ancillary triarylphosphine co-ligands regulate electronic interactions and lipophilicity and ultimately increase biological performance, underscoring the dual materials and medicinal potential of these Ru(III) complexes. Full article

Three novel metal complexes of the tridentate ligand 4-nitro-2-(quinolin-8-yliminomethyl)phenol (NQP) were synthesized and fully characterized using elemental analysis, TGA, magnetic susceptibility, FT-IR, NMR, and UV–Vis spectroscopy. Stoichiometric studies and characterization data proposed square-planar Pd(II), tetrahedral Zn(II), and octahedral Fe(III) geometries. Density functional theory calculations (B3LYP and B3LYP/6-311G(d,p) with LANL2DZ for metals) showed good agreement with experimental findings and revealed enhanced nonlinear optical properties, as evidenced by increased polarizability and hyperpolarizability values. Biological studies demonstrated significant antimicrobial activity, with the Pd–NQP complex exhibiting superior efficacy against bacterial and fungal strains compared to ofloxacin and fluconazole, following the order NQP < Zn < Fe < Pd. Cytotoxicity assays against Hep-G2, MCF-7, and HCT-116 cell lines revealed strong anticancer activity, particularly for the Pd(II) complex (IC₅₀ = 6.35–12.95 μ_g/μL), comparable to cisplatin. All complexes showed higher DPPH radical scavenging activity than ascorbic acid and strong DNA-binding affinity. Antimicrobial activity was further validated experimentally, while molecular docking studies elucidated favorable binding interactions with microbial proteins and cancer-related targets. Full article

Background: Silver(I) complexes with aromatic heterocyclic ligands are well known for their broad antimicrobial potential, largely attributed to their ability to interact with biomolecular targets. Results and Discussion: In this study, a new polynuclear silver(I) complex with N-(3′-phenylpropyl)quinoxaline-2-carboxamide (pqx-2ca), [Ag(NO₃)(pqx-2ca)]_n, was synthesized. Its structure was confirmed by single-crystal X-ray diffraction and comprehensively characterized using NMR, IR, and UV–Vis spectroscopy, while its behavior in solution was further elucidated through density functional theory (DFT) calculations combined with spectral simulations. The complex demonstrated significantly enhanced antimycobacterial activity compared with the free ligand when tested against the avirulent Mycobacterium tuberculosis H37Ra, fast-growing model organisms M. smegmatis and M. aurum, as well as the nontuberculous species M. avium and M. kansasii. Experimental and docking studies confirmed stable binding of the complex to subdomain III of bovine serum albumin (BSA) and to the minor groove of DNA. Furthermore, docking to validated mycobacterial targets revealed inhibitory potential toward the InhA and MmpL3 proteins, with binding affinities comparable to those of standard inhibitors. Conclusions: These results highlight [Ag(NO₃)(pqx-2ca)]_n as a promising candidate for the development of silver-based antimycobacterial agents with a dual mechanism of action involving both DNA and protein targets. Full article

Background/Objectives: First row transition metal ions have recently regained attention in coordination chemistry as alternatives to gadolinium-based paramagnetic contrast agents, motivated by emerging safety concerns associated with certain Gd³⁺-based contrast agents. In this study, we report the development of a novel homoleptic diketonate Fe³⁺ complex functionalized with biocompatible indole moieties. We investigate its potential as a paramagnetic relaxation agent by evaluating its ability to modulate the T₁ and T₂ relaxation times of water proton. Methods: Iron(III) tris-1,3-(1-methylindol-3-yl)propanedionate [Fe(BIP)₃] was synthesized via a thermal method from bis(1-methylindol-3-yl)-1,3-propanedione (HBIP) using Fe(ClO₄)₃∙6 H₂O as the metal source. The complex was characterized by UV-Vis, IR and NMR spectroscopy, differential scanning calorimetry–thermogravimetric analysis, and single-crystal X-ray diffraction. Fe(BIP)₃ aggregation behavior in aqueous environment, including size and morphology of aggregates, was investigated using dynamic light scattering and scanning electron microscopy. Incorporation of the aggregates into phospholipid vesicles was evaluated by fluorescence resonance energy transfer and fluorescence correlation spectroscopy. The paramagnetic properties of monomeric Fe(BIP)₃ were probed in solution by nuclear magnetic resonance recurring to the Evans bulk magnetization method. Results: The designed synthetic procedure successfully afforded Fe(BIP)₃, which was fully characterized by UV-Vis and IR spectroscopy, as well as single-crystal X-ray diffraction. Aqueous solutions of Fe(BIP)₃ spontaneously formed rice-grain-shaped nanoscale aggregates of hydrodynamic radius ≈ 30 nm. Incorporation of these aggregates into phospholipid vesicles enhanced their stability. The longitudinal r₁ and transverse r₂ relaxivities of Fe(BIP)₃ aggregates were assessed to be 1.92 and 52.3 mM⁻¹s⁻¹, respectively, revealing their potential as paramagnetic relaxation agents. Conclusions: Fe(BIP)₃ aggregates, stabilized through incorporation into phospholipid vesicles, demonstrate promising potential as novel paramagnetic relaxation agents in aqueous environments. Full article

The separation of rare earth elements (REEs) with similar chemical properties remains a relevant challenge today, most often addressed using liquid–liquid and solid-phase extraction with various chelating agents. Excellent complexing agents for REEs are 1,3-diketones and their analogs. We have for the first time proposed a method for preparing a material consisting of a covalently immobilized 3-acyl-4-hydroxycoumarin ligand on silica. For its synthesis, we employed a strategy based on the “click” reaction of 3-azidopropyl silica with a propargyl-containing coumarin–chalcone conjugate—this approach is the most tolerant and does not affect the coordinationally active fragment of the ligand. The material was characterized by thermal analysis, IR spectroscopy, and ¹³C NMR. The potential of the synthesized material for REE preconcentration was demonstrated at pH 5–5.5: high extraction efficiency for Gd(III), Dy(III), Er(III), Eu(III), Sm(III), and Yb(III) was observed, with fast adsorption kinetics (30 min) and extraction degrees of ~98%. Under unified conditions of static and dynamic extraction for Gd(III), Dy(III), Er(III), Eu(III), Sm(III), and Yb(III), affinity series toward the surface were obtained as a function of the distribution coefficient. It was shown that 10-fold molar excesses of Fe(III), Al(III), Cu(II), Ni(II), and Co(II) allow retention of more than 95% extraction for Dy(III) and Er(III). After adsorption of Dy(III) and Er(III), shifts in the carbonyl group absorption bands are visible in the IR spectra of the material, indicating a chelating mechanism of sorption. Additional studies are required for implementation in analytical and preparative REE separation schemes; however, preliminary data show that the material is a highly active adsorbent. Full article

Countries like Saudi Arabia receive abundant sunshine with exceptionally high solar irradiance. High temperatures in desert regions and the sunray angle dependence of solar modules are some of the key challenges of conventional solar cells. Dye-sensitized solar cells present a compelling alternative with the simple cell design and use of non-toxic materials without angle dependence, but their performance hinges on the solid redox mediators used for dye regeneration. These mediators must have an electrical conductivity (σ_25°C) of more than 10⁻⁴ S cm⁻¹ with an activation energy of less than 0.3 eV for device application. Our work focused on novel solid Co(II/III) redox mediators using cobalt complexes and LiClO₄ in different matrices: pure PEO (an abbreviation for poly(ethylene oxide) with its redox mediator as M1), a [PEO–SN] blend (M2A and M2B with ethylene oxide to lithium ions molar ratio of 112.9 and 225.8, respectively), and pure SN (an abbreviation for succinonitrile with its redox mediator as M3). Impedance spectroscopy was the key technique, showing M1 and M2 behave like a mediator explainable with an (R₁–C)-type circuit, while M3 is explainable with an (R₁ − [R₂‖C])-type circuit. M3 achieved the highest value of σ_25°C with 2 × 10⁻³ S cm⁻¹, while M1 had the lowest σ_25°C, 3 × 10⁻⁵ S cm⁻¹. M2 achieved an optimal balance with σ_25°C of 4 × 10⁻⁴ S cm⁻¹ (M2A) and 1.5 × 10⁻⁴ S cm⁻¹ (M2B). M2 exhibited a remarkably low pseudo-activation energy of 0.042 eV and a Vogel–Tammann–Fulcher behavior ideal for consistent performance across temperatures. In contrast, M1 and M3 showed higher Arrhenius-type activation energies (>0.74 eV) in their solid states. These results correlated with those of the XRD, FT-IR spectroscopy, XPS, SEM, DSC, and TGA analyses. Ultimately, the [PEO–SN] blend emerges as a robust matrix, enabling the combination of high conductivity and low activation energy needed for a durable device in harsh environments. Full article

This work presents the design of a novel electrochemical sensor for highly sensitive determination of LEV, utilizing a sensing platform based on a newly synthesized, high-purity manganese (III) porphyrin complex [5,10,15,20-tetrayltetrakis(2-methoxybenzene-4,1-diyl) tetraisonicotinateporphyrinato] manganese (III) porphyrin (MnTMIPP). The successful synthesis of the MnTMIPP complex was verified using ultraviolet–visible (UV–Vis) and infrared spectroscopy (IR). The sensing electrode was fabricated by depositing the synthesized material onto an indium tin oxide (ITO) electrode via a drop-coating method. Under optimized experimental conditions, the proposed sensor demonstrated a wide dynamic range, from 10⁻⁹ M to 10⁻³ M, with a low calculated detection limit of 4.82 × 10⁻¹⁰ M. Furthermore, the MnTMIPP/ITO electrode displayed interesting metrological performance: high selectivity, reproducibility, and stability. Successful application in spiked river water and saliva samples with satisfactory recovery rates confirms the sensor’s potential as a reliable and cost-effective platform for monitoring LEV in real-world environments. Full article

Siderophores are low-molecular-weight chelating agents secreted by microorganisms under iron-limiting conditions, playing a crucial role in metal bioavailability and microbial survival. In this study, siderophores produced by Glutamicibacter sp. strain Al-Teq-24-F2, isolated from plant-associated samples, were characterized through a combination of spectroscopic and analytical methods. ESI-MS analysis of the crude extract revealed several abundant ions between 175 and 800 m/z, suggesting a mixture of secondary metabolites. After chromatographic purification, FT-IR and NMR analyses indicated the presence of amide, hydroxyl, and carboxylate functional groups. Integrating these data allowed for the proposal of a siderophore structure with a molecular weight of 438.25 Da. Thermogravimetric analysis showed thermal stability below 115 °C. During Fe (III) complexation, the zeta potential shifted from −21.15 mV to +42 mV, confirming strong interaction between the ligand and the metal. UV–Vis and fluorescence spectroscopy displayed characteristic bathochromic and hypochromic shifts, together with pronounced fluorescence quenching upon iron binding. These findings provide new insight into the structural and physicochemical properties of siderophores produced by Glutamicibacter sp. and highlight their potential applications in biosensing and metal chelation processes. Full article