Metal Ion Complexes Research Articles

Metal ion complexes of 2-thioxoimidazolidine-4-one derivatives mixed ligand synthesis, characterization, in-vitro biological activities and in-silico studies

A series of complexes of [Mn (III), Co(II), Cu(II), and Cd(II)] were synthesized with two new 2-thioxoimidazolidin-4-one derivates ligands. These ligands were characterized using an elemental analyzer (CHNS), 1H NMR spectroscopy, FT-IR spectroscopy, and UV–Vis spectroscopy. The synthesized complexes were characterized by magnetic susceptibility measurements, electrical conductance analysis, and atomic absorption spectroscopy. The biological activity of the ligands and complexes were determined against E. coli, B. subtilis, A. niger, and P. chrysogenum. To determine the influence of different metal-ion concentrations on microbial growth, we used molecular docking to evaluate antibacterial activity targeting antimicrobial sites. Our findings indicate that the metal ion complexes exhibited varying degrees of antimicrobial activity, affecting the growth of the tested organisms.

Stability of metal ion complexes with the synthetic phytosiderophore proline-2'-deoxymugineic acid.

Adequate micronutrient concentrations in crops are essential for human health and agricultural productivity. However, 30% of plants growing on cultivated soils worldwide are deficient in iron (Fe). Because of low micronutrient bioavailability, graminaceous plants have evolved to exude small molecules, called phytosiderophores, into the soil environment, which strongly complex and promote uptake of trace elements. The development of a synthetic phytosiderophore, proline-2'-deoxymugeneic acid (PDMA), has been shown to promote Fe uptake in rice plants; however, its binding capabilities with other metals, which may impact the ability to promote the uptake of Fe and other trace nutrient metals commonly found in soils, remain unknown. We conducted spectrophotometric titrations to determine the stability constants (logK) of PDMA complexes with Mn(II), Co(II), Cu(II), Ni(II), and Zn(II). We determined that PDMA complex stability constants correlated with: (1) the hydrolysis constants of metal ions (logKOH) in complexes; (2) the ionic potential of complexed metals; and (3) the corresponding complex stability constants of other mugineic acid type phytosiderophores, as well as the trishydroxamate microbial siderophore DFOB. These correlations demonstrate the potential, and limitations, on our ability to predict the stability of phytosiderophore complexes with metal ions with different physicochemical properties and with potentially different coordination structures.

Gingerol-zinc complex loaded 3D-printed calcium phosphate for controlled release application.

The therapeutic potential of natural medicines in treating bone disorders is well-established. Modifications in formulation or molecular structure can enhance their efficacy. Gingerol, an osteogenic active compound derived from ginger roots (Zingiber officinale), can form metal ion complexes. Zinc (Zn), a trace element that combats bacterial infections and promotes osteoblast proliferation, can be complexed with gingerol to form a G-Zn+2 complex. This study investigates a porous 3D-printed (3DP) calcium phosphate (CaP) scaffold loaded with the G-Zn+2 complex for drug release and cellular interactions. The scaffold is coated with polycaprolactone (PCL) to control the drug release. Diffusion-mediated kinetics results in 50% releaseof the G-Zn+2 complex over 6weeks. The G-Zn+2 complex demonstrates cytotoxicity against MG-63 osteosarcoma cells, indicated by the formation of apoptotic bodies and ruptured cell morphology on the scaffolds. G-Zn+2 PCL-coated scaffolds show a 1.2 ± 0.1-fold increase in osteoblast cell viability, and an 11.6 ± 0.5% increase in alkaline phosphatase compared to untreated scaffolds. Treated scaffolds also exhibit reduced bacterial colonization against Staphylococcus aureus bacteria, highlighting the antibacterial potential of the G-Zn+2 complex. The functionalized 3DP CaP scaffold with the G-Zn+2 complex shows significant potential for enhancing bone regeneration and preventing infections in low-load-bearing applications.

Synthesis, crystal Structure, theoretical calculation and luminescence properties of Cu(Ⅱ), Co(Ⅱ), Ni(Ⅱ) and Zn(Ⅱ) quinolinyl benzimidazole complexes with multiple coordination number induced by proton

The innovative ligand H2L, featuring a benzimidazole structure substituted with 8-hydroxyquinoline and equipped with N,O donor sites, underwent successful synthesis and meticulous characterization. Notably, this ligand was exclusively synthesized through catalysis under protonated conditions, accompanied by an in-depth exploration of the catalytic mechanism. Employing single-crystal X-ray diffraction, we acquired and authenticated four distinct asymmetric double-decker sandwich mononuclear transition metal complexes: [Cu(HL)2]·2H2O, [Co(HL)2]·CH3OH, [Ni(HL)2] and [Zn(HL)2]·CH2Cl2. Among these, complex 1 revealed an intriguing five-coordinate Cu(II) center adopting a distorted square pyramidal geometry, whereas the central metal ions in complexes 2–4 exhibited a six-coordinate configuration, characterized by a distorted octahedral geometry. Noteworthy is the observation that the dihedral angles within the crystal structures of complexes 2–4 approached approximately 90° to a significant extent. To delve deeper into the electronic properties and transitions, meticulous DFT and TD-DFT calculations were performed on both the ligand H2L and complexes 1–4. Furthermore, a comprehensive investigation into the luminescence properties of both H2L and its complexes was conducted, revealing a pronounced luminescence quenching effect in the complexes compared to the ligand. Through thorough analysis utilizing Hirshfeld surface examination and IRI analysis, various weak intermolecular interactions within the system were elucidated.

Detection of Pb(II) and Cr(III) Using Dy(III) Ion with Pyrazoline Derivatives Ligand

Exposure to heavy metal ions Pb2+ and Cr3+ in Indonesia is getting more attention, especially in various industries and transportation. The sensor complex compound Dy3+ with fluorescence-based pyrazoline-derived ligands (fluorosensor) has the potential to detect heavy metal ions Pb2+ and Cr2+. This research was initiated by synthesizing the pyrazoline derivative ligand and then reacting it with Dy3+ metal ion. The formed Dy3+ complex compounds was then characterized using spectroscopic methods. The results of scanning complex compounds using a UV-Vis spectrophotometer obtained two maximum wavelengths namely at 255 and 359 nm are indicating the presence of a transition type n→π* and π→π*. The results of fluorescence spectrophotometer analysis obtained maximum fluorescence intensity of Dy3+ complex compound was in the wavelength at 370 nm with fluorescence intensity of 4273 a.u. Fluorescence based sensor studies of the Dy complex when Pb2+ and Cr3+ metal ions were added showed changes in fluorescence intensity so that the fluorosensor type was obtained for the Dy3+ metal ion complex compound with Pb2+ and Cr3+, namely "turn-on-off" and "turn-off" respectively.

Evaluating polyanthranilic acid as a polymeric template for the production of Prussian blue nanoclusters

The electropolymerization of anthranilic acid (2-aminobenzoic acid) has been shown to lead to the production of a redox polymer functionalized with carboxylate groups capable of complexing metal ions. The polymer was exploited as a means of capturing ferric ion from solution with the iron decorated polymer chains used as seeding points for the formation of Prussian blue (PB). Nanoclusters of PB were dispersed throughout the three-dimensional polymer matrix with deposition achieved through direct electrochemical means or via a dip process. The latter exploited the chemical combination of Fe(III) + Ferrocyanide to yield PB allowing its dispersal of the PB throughout the polymer film. The polymer film and its subsequent modification have been characterized by electron microscopy, X-ray analysis, Raman spectroscopy and electrochemical analysis. The stability toward peroxide has also been explored.Graphical

Closo-B10H8-10-PhI-1-COOH]- Anion: An Intermediate for Functional Anionic Carboxylate Ligands.

A potentially general intermediate, [closo-B10H8-10-PhI-1-COOH]-, for a class of functional anionic carboxylic acids, [closo-B10H8-10-X-1-COOH]2-, was obtained in four steps and 26% overall yield from [closo-B10H10]2-. It was converted to the pyridinium derivative (X = C5H5N+) and subsequently to coordination complexes with (phen)2Cu2+ and (phen)2Zn2+ ions. Both the acid and Zn(II) complex exhibit a cage-to-pyridine charge-transfer band. The availability of such acids opens access to functional metal-ion complexes with compensated charges.

Native Mass Spectrometry-Centric Approaches Revealed That Neuropeptides Frequently Interact with Amyloid-β.

Amyloid-β (Aβ) aggregates are recognized as initiators of Alzheimer's disease, and their interaction with the nervous system contributes to the progression of neurodegeneration. Herein, we investigated the frequency at which neuropeptides interact with Aβ and affect the aggregation kinetics and cytotoxicity of Aβ. To this end, we established a native mass spectrometry (MS)-centric workflow for screening Aβ-interacting neuropeptides, and six out of 12 neuropeptides formed noncovalent complexes with Aβ species in the MS gas phase. Thioflavin-T fluorescence assays and gel separation indicated that leptin and cerebellin decreased Aβ aggregation, whereas kisspeptin increased this process. In addition, leptin and cerebellin attenuated Aβ-induced cytotoxicity, which was independent of the influence of metal ions. Leptin can chelate copper from copper-bound Aβ species, reducing the cytotoxicity caused by the aggregation of Aβ and metal ion complexes. Overall, our study demonstrated that neuropeptides frequently interact with Aβ and revealed that leptin and cerebellin are potential inhibitors of Aβ aggregation, providing great insight into understanding the molecular mechanism of Aβ interacting with the nervous system and facilitating drug development.

Terpyridine-Decorated Polymer Nanosphere Latex: Template Nanocarriers for the Synthesis of Cu-CeO2 Hollow Spheres.

Water-soluble polymers with the ability to complex metal ions through complexing ligands have attracted significant interest in diverse domains, such as optical or catalyst applications. In this paper, we successfully synthesized, through a one-pot process combining polymerization-induced self-assembly and reversible addition-fragmentation chain transfer polymerization, aqueous dispersions of terpyridine-decorated poly[poly(ethylene glycol)methyl ether methacrylate]-b-poly(methyl methacrylate) (tpy-PPEGMA-b-PMMA) amphiphilic block copolymers. The in-situ formation of well-defined amphiphilic block copolymers and their self-assembly led to nanosphere latex with the hydrodynamic diameters increasing from 17 to 52 nm and the length of the copolymers increasing from 21,000 to 51,000 g·mol-1. These aqueous dispersed tpy-PPEGMA-b-PMMA nanospheres effectively complex metal ions, such as Cu2+, in a stoichiometric ratio of 2:1. Subsequently, these metal-complexed nanospheres were employed as soft template nanocarriers to control, on the nanometer scale, the dispersion of metal on a nanostructured support. This is exemplified by the synthesis of copper supported on cerium oxide hollow spheres (Cu-CeO2) using Cu2+-tpy-PPEGMA-b-PMMA as template nanocarriers and CeO2 nanoparticles. This novel assembly engineering strategy for the preparation of atomically dispersed metal on a nanostructured support was highlighted through the utilization of Cu-CeO2 hollow spheres as an electrocatalyst for the nitrate reduction reaction (NO3RR) to NH3. These encouraging outcomes emphasize the potential of metal-metal oxide-nanostructured materials to treat contaminated water sources with nitrate while allowing the green production of ammonia.

Design and photophysical characterization of dinuclear lanthanide complexes incorporating spacer ligands along with their mononuclear analogues: A comparative study

Two heteroleptic homo-dinuclear complexes of Dy(III) and Sm(III) with pyrazine (pyz) as spacer ligand [Ln(TFPB)3(μ-pyz)Ln(TFPB)3], along with their mononuclear analogue [Ln(TFPB)3(pyz)2] were synthesized and characterized. Diketone TFPB (4,4,4-trifluoro-1-phenyl-1,3-butanedione) was incorporated as main ligand. NMR analysis depicted single peak for pyz protons for dinuclear complexes and two for mononuclear ones, which confirmed the bridging nature of pyz in former complexes. UV spectra revealed two absorption bands despite of the different metal ion and nuclearity of complex, suggesting the absorption of UV-radiation by coordinated moieties inspite of the metal ion involved. The emission spectra exhibited significant intensity of yellow and orange-red peaks for Dy(III) and Sm(III) complexes, respectively, indicating effective sensitization of metal center. The enhanced emission intensity observed in dinuclear Sm-complexes, compared to their mononuclear counterparts, indicates a synergistic effect of the two metal ions on the overall emission properties, rather than a mere additive effect that would be expected from two independent mononuclear units. The photoluminescent properties of synthesized complexes were examined and discussed, suggesting potential applications in display devices. The Correlated Color Temperature (CCT) of these complexes falls within a range suitable for warm light sources and the highest branching ratio observed for 4G5/2 → 6H9/2 (for Sm3+ ion) and 4F9/2 → 6H13/2 (for Dy3+ ion) transitions suggests potential application in laser amplification. The alignment between band gap measurements obtained from UV and CV analyses highlight the possibility of employing these complexes in semiconductor technologies.

Solid-state structures of some fluorescent macrocyclic complexes of alkali metal ions studied by single-crystal X-ray diffraction studies, vibrational spectroscopy and NMR spectroscopy: a review

Solid-state structures of some fluorescent macrocyclic complexes of alkali metal ions studied by single-crystal X-ray diffraction studies, vibrational spectroscopy and NMR spectroscopy: a review

In-Vitro Study of the Binding of Atorvastatin with Adenine using Multi-Spectroscopic Approaches.

Atorvastatin-an oral lipid regulating drug is a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), which is the rate determining enzyme for cholesterol synthesis. Adenine is a purine nucleobase that is found in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) to generate genetic information. The binding mechanism of atorvastatin and adenine was studied for the first time utilizing various techniques, including UV-visible spectrophotometry, spectrofluorimetry, synchronous fluorescence spectroscopy (SF), Fourier transform infrared (FTIR), fluorescence resonance energy transfer (FRET), and metal ion complexation. The fluorescence spectra of the complex indicated that atorvastatin is bound to adenine via hydrophobic interaction through a spontaneous binding process, and the fluorescence quenching mechanism was found to be static quenching with a binding constant of 1.4893 × 104 Lmol-1 at 298 K. Various temperature settings were used to investigate thermodynamic characteristics, such as binding forces, binding constants, and the number of binding sites. The interaction parameters, including the standard enthalpy change (ΔHο) and standard entropy change (ΔSο) were calculated using Van't Hoff's equation to be 42.82 kJmol-1 and 208.9 Jmol-1K-1, respectively. The findings demonstrated that the adenine- atorvastatin binding was endothermic. Furthermore, the results of the experiments revealed that some metal ions (K+, Ca+2, Co+2, Cu+2, and Al+3) facilitate the binding interaction between atorvastatin and adenine. Slight changes are observed in the FTIR spectra of adenine, indicating the binding interaction between adenine and atorvastatin.

Noncovalent Assembly Strategy for Efficient Synthesis of Dual‐Atom Catalysts

AbstractDiatomic catalysts (DACs), as a frontier of research on atomically dispersed catalysts, have drawn great attention, especially in electrocatalysis. However, most of the current synthetic strategies for DACs suffer from poor efficiency and high cost. In this work, a novel noncovalent assembly strategy is reported for the efficient synthesis of DACs. By the aid of two kinds of noncovalent intermolecular force, the π–π stacking and Coulomb forces, a pair of metal complex ions with opposite electrical charges is spontaneously loaded onto the carbon substrate and transformed into diatomic sites via thermal treatment. This noncovalent assembly approach shows universal feasibility for a broad spectrum of DACs (Ir–Fe, Pt–Fe, Pt–Co, and Pt–Ni). To prove the practical utility, the as‐prepared PtFe‐DAC is deployed as oxygen reduction reaction catalyst, performing excellent activity with a half‐wave potential of 0.935 V (vs RHE) and a 2.3 times higher turnover frequency than that of the single‐atomic Fe‐SAC. In situ characterization and theoretical calculation indicate that the adjacent Pt sites could endow moderate activation of oxygen molecule on Fe sites by lowering the electron pairing energy as well as the modulation of the d‐band center and spin states of Fe centers propelling the desorption of the intermediates.

Synthesis and Characterization of Some 5-Bromouracil Metal ion Complexes

Synthesis and Characterization of Some 5-Bromouracil Metal ion Complexes

Ultrasmall Metal TPZ Complexes with Deep Tumor Penetration for Enhancing Radiofrequency Ablation Therapy and Inducing Antitumor Immune Responses.

Radiofrequency ablation (RFA) is one of the most common minimally invasive techniques for the treatment of solid tumors, but residual malignant tissues or small satellite lesions after insufficient RFA (iRFA) are difficult to remove, often leading to metastasis and recurrence. Here, Fe-TPZ nanoparticles are designed by metal ion and (TPZ) ligand complexation for synergistic enhancement of RFA residual tumor therapy. Fe-TPZ nanoparticles are cleaved in the acidic microenvironment of the tumor to generate Fe2+ and TPZ. TPZ, an anoxia-dependent drug, is activated in residual tumors and generates free radicals to cause tumor cell death. Elevated Fe2+ undergoes a redox reaction with glutathione (GSH), inducing a strong Fenton effect and promoting the production of the highly toxic hydroxyl radical (•OH). In addition, the ROS/GSH imbalance induced by this treatment promotes immunogenic cell death (ICD), which triggers the release of damage-associated molecular patterns, macrophage polarization, and lymphocyte infiltration, thus triggering a systemic antitumor immune response and noteworthy prevention of tumor metastasis. Overall, this integrated treatment program driven by multiple microenvironment-dependent pathways overcomes the limitations of the RFA monotherapy approach and thus improves tumor prognosis. Furthermore, these findings aim to provide new research ideas for regulating the tumor immune microenvironment.

Effect of diastereoisomeric composition on the chromatographic retention of phosphorothioated oligonucleotides using three different liquid chromatography systems

To increase understanding of the interactions and effects of the diastereoisomeric character of phosphorothioate (PS) oligonucleotides on chromatographic retention, three chromatographic methods [in-series reversed phase-strong anion exchange (RP-SAX), ion pair-reversed phase and metal ion complexation chromatography (MICC)] were applied to the characterization of stereo-enriched compounds. Chromatographic systems are widely available, amenable to routine applications, and simple to deploy in comparison to more advanced instrumentation (e.g., 31P NMR) and procedures (e.g., enzymatic digestion). Analogous diastereoisomeric distribution profiles were obtained by RP-SAX and IP-RP based on their common mechanism of separation involving the combination of hydrophobic and electrostatic interactions. Similar linear relationships between retention time (tR) and the numbers of stereo random, Rp, and Sp PS linkages were obtained with both methods. Sp-enriched diastereoisomers were retained longer than stereo random and Rp-enriched diastereoisomers. MICC produced much broader diastereoisomeric peak distributions than the other two methods due to its more complicated nature of interaction. Average mass spectra showed a smaller number of Ag ions (1-7) complex with early eluting diastereoisomers than with later eluting diastereoisomers (which complex between 6-12 Ag ions). A higher late-to-early peak UV area ratio was obtained for a sample containing 10 Sp linkages vs one containing 10 Rp linkages pointing to the tendency of the Sp diastereoisomers for increased interactions which could be explained by structures with more open or stretched configurations. Consideration of the peak shapes of the MICC distributions led to comparable hierarchical cluster analysis (HCA) classification to that produced by the IP-RP method, indicating a good orthogonality between the two methods. Preliminary analysis of the data using partial least squares showed that it should be possible to determine the diastereoisomeric composition of PS oligonucleotides from chromatographic data following appropriate data training.

Tough and conductive double-network hydrogel based on PVA/poly(ionic liquids) strengthened by metal ion complexation for flexible sensors

Hydrogels have attracted extensive attention for their promising applications as flexible sensors. Developing conductive hydrogels with excellent mechanical properties still remains a significant challenge. Herein, double-network (DN) hydrogels composed of poly(vinyl alcohol) (PVA) and poly(ionic liquids) (PILs) are prepared through repetitive freezing/thawing process. The hydrogels are further treated with Fe3+ ions to enhance the mechanical properties due to the complexation between carboxyl groups and Fe3+ ions. The influence of the amount of PILs and concentration of Fe3+ on mechanical properties and conductivity is investigated. The optimal DN hydrogel P(VMCA-AA)1/PVA-Fe3+ 4 shows excellent mechanical properties, whose tensile strength, elongation at break, and toughness are 2.2 MPa, 350%, and 3.5 MJ m−3, respectively. P(VMCA-AA)1/PVA-Fe3+ 4 also displays a good conductivity of 1.04 S m−1. Moreover, the hydrogel demonstrates a high sensing sensitivity with a gauge factor (GF) of 3.36, indicating its application potential as a flexible sensor.

Complexes of Alkali Metal and the Ammonium Ion with the Cyclodimethylsiloxane Ligands D7 and D8 (D=Me2SiO)

AbstractWe present complexes of alkali metal ions and the ammonium ion with the large cyclodimethylsiloxanes D7 and D8 (D=Me2SiO). The formation of such complexes is accompanied by rearrangements of the ligands to form complexes with a suitable ring size for the metal used. These rearrangements could be suppressed by suitable reaction conditions and rapid work‐up of the reaction mixtures. This enabled the isolation of [Li(D7)][GaI4] (1), [Li(D8)][GaI4] (2), [Na(D8)][GaI4] (3), [K(D8)][GaI4] (4) and [NH4(D8)][GaI4] (5). All of the prepared compounds were analysed using single‐crystal X‐ray diffraction as well as multinuclear NMR spectroscopy. This reveals very different coordination modes in the compounds obtained.

Insights on multi‐spectroscopic approaches for estimating the in vitro binding of favipiravir with adenine nucleotide

AbstractFavipiravir (FVP) is an oral antiviral drug approved in 2021 for the treatment of COVID‐19. It is a pyrazine derivative that can be integrated into anti‐viral RNA products to inhibit viral replication. While, adenine is a purine nucleobase that is found in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) to generate genetic information. For the first time, the binding mechanism between FVP and adenine was determined using different techniques, including UV–visible spectrophotometry, spectrofluorimetry, synchronous fluorescence (SF) spectroscopy, Fourier transform infrared (FTIR), fluorescence resonance energy transfer (FRET), and metal ion complexation. The fluorescence spectra indicated that FVP is bound to adenine via Van der Waals forces and hydrogen bonding through a spontaneous binding process (ΔGο < 0). The quenching mechanism was found to be static. Various temperature settings were used to investigate thermodynamic characteristics, such as binding forces, binding constants, and the number of binding sites. The reaction parameters, including the enthalpy change (ΔHο) and entropy change (ΔSο), were calculated using Van't Hoff's equation. The findings demonstrated that the adenine‐FVP binding was endothermic. Furthermore, the results of the experiments revealed that some metal ions (K+, Ca+2, Co+2, Cu+2, and Al+3) might facilitate the binding interaction between FVP and adenine. Slight changes are observed in the FTIR spectra of adenine, indicating the binding interaction between adenine and FVP. This study may be useful in understanding the pharmacokinetic characteristics of FVP and how the drug binds to adenine to prevent any side effects.

Evaluation of DNA and BSA-Binding, Nuclease Activity, and Anticancer Properties of New Cu(II) and Ni(II) Complexes with Quinoline-Derived Sulfonamides

Four complexes of essential metal ions, Cu(II) and Ni(II), with the new sulfonamide ligand N-(pyridin-2-ylmethyl)quinoline-8-sulfonamide (HQSMP) were synthesized and physicochemically and structurally characterized. Complex [Cu(QSMP)Cl]n (2) consists of a polymeric chain formed by distorted square pyramidal units. In 2, the sulfonamide ligand acts as a bridge coordinating to one Cu(II) through its three N atoms and to another metal ion via one O atom in the sulfonamido group, while the pentacoordinate complex [Cu(QSMP)(C6H5COO)] (3) presents a highly distorted square pyramidal geometry. Complex [Ni(QSMP)(C6H5COO)(CH3OH)][Ni(QSMP)(CH3COO)(CH3OH)] (4) consists of two mononuclear entities containing different anion coligands, either a benzoate or an acetate group. Both units exhibit a distorted octahedral geometry. The interaction of the complexes with CT-DNA was studied by means of UV-Vis and fluorescence spectroscopy, interestingly revealing that the Ni(II) complex presents the highest affinity towards the nucleic acid. Complexes 1 and 2 are able to cleave DNA. Both compounds show promising nuclease activity at relatively low concentrations by mediating the production of a reactive oxygen species (ROS). The interaction of the four complexes with bovine serum albumin (BSA) was also investigated, showing that the compounds can bind to serum proteins. The antitumor potential of complexes 1 and 2 was evaluated against the A549 lung adenocarcinoma cell line, revealing cytotoxic properties that were both dose- and time-dependent.