Metal-ligand Complexes Research Articles

Photo-electrochemical decomplexation of cobalt complexes and enhanced cobalt recovery through electrified membranes

The increasing presence of cobalt-chelated species in semiconductor manufacturing poses significant challenges for wastewater treatment because of their structural stability and high solubility. Efficient decomplexation of these metal–ligand complexes is critical for mitigating heavy metal pollution and enabling resource recovery. This study investigates the (photo)electrochemical decomplexation of cobalt-ethylenediaminetetraacetic acid (Co-EDTA) complexes using a TiO2-encapsulated electrified carbon membrane, with a focus on cobalt recovery. Compared to electrochemical oxidation alone, the photoelectrochemical (PEC) system with 365 nm UV-LED illumination demonstrated better performance, achieving over 90 % EDTA-Na2 removal within 20 min and approximately 50 % Co-EDTA decomposition within 180 min. Kinetic analysis confirmed enhanced reaction rates under PEC conditions, and system robustness was validated across varying applied voltages and electrolyte concentrations, as well as real-world semiconductor wastewater. Mechanistic studies revealed that the PEC process is driven by the generation of hydroxyl radicals (•OH), formed through the interaction of photoinduced electron-hole pairs with surface hydroxyl groups on the TiO2 membrane. These radicals facilitate stepwise decomplexation, breaking down Co-EDTA complexes and releasing cobalt ions. This work highlights the potential of TiO2 electrified membrane-based photo-electrochemical systems for efficient decomplexation and cobalt recovery, offering a sustainable solution for advanced wastewater treatment and resource recovery.

Triskelion-shaped Hexabenzocoronenes: Synthesis and Characterization of tris-substituted HBC derivatives.

The synthesis of unprecedented triskelion-shaped hexa-peri-hexabenzocoronenes with C3, C3h or D3h symmertry is reported. We present a new, five step synthetic access to tris-iodinated HBC derivatives carrying different solubilizing moieties (tert-butyl and mesityl), which serve as suitable building blocks for further functionalization. These molecules can undergo Sonogashira cross coupling reactions to obtain a series of seven ethynyl tris-substituted HBCs. The coupling partners range from carbon-based aromatic scaffolds (tBu-benzene, naphthalene, phenanthrene) to ligands for metal complexes (bipyridine, phenanthroline, terpyridine, acetylacetone). The optoelectronic properties were investigated by UV/vis absorption spectroscopy resulting in a significant batho-chromic shift of the absorption maximum compared to the iodinated starting material. Semiempirical calculations were used to determine the conformation and symmetry of the compounds.

Zwitterionic 2-Phosphaethene-thiolates [(LC)P=CS(LC/P)]+ as PCS Building Blocks (LC=NHC, LP=PR3).

The zwitterionic compounds [(LC)P=CS(LC/P)]+ (3+, LC=NHC, LP=PR3), featuring cationic substituents at the phosphorus and carbon atoms, are synthesized as their triflate salts at a multi-gram scale from the reaction of Lewis base adducts of CS2, namely LC/P-CS2 (4), with a combination of [(LCP)4][OTf]4 (1[OTf]4) and Ph3P. The feasibility of using 3+ as PCS building blocks is showcased in their reactions with representative electrophiles (MeOTf) and nucleophiles (MesMgBr, Ph3PCH2), leading to selective functionalization of the PCS core at the S- and P-terminus, respectively. Additionally, it is reported that 3+ can function as ambident nucleophiles with AgOTf (2 equivalents), affording unprecedented linear coordination polymer [Ag2(OTf)3-μ2:κP,κS-((LC)P=CS(PCy3))]+ (6 b), where the PCS moiety acts as a bridging ligand in transition metal complexes for the first time. Reduction of 3+ facilitates the cleavage of the P- and C-bound substituents leading to the formation of the [PCS]- anion. Moreover, cycloaddition reactions of 3+ with 1[OTf]4 are shown to selectively yield five- and eight-membered polyphosphorus heterocycles. Preliminary results suggest the possibility of activating the C-S bond in [(LC)P=CS(LC)]+, resulting in the formation of [(LC)P=C(LC)-P(LC)][OTf]2, 12[OTf]2, which may serve as a synthon for the PCP unit in future studies.

Zwitterionic 2‐Phosphaethene‐thiolates [(LC)P=CS(LC/P)]+ as PCS Building Blocks (LC = NHC, LP = PR3)

The zwitterionic compounds [(LC)P=CS(LC/P)]+ (3+, LC = NHC, LP = PR3), featuring cationic substituents at the phosphorus and carbon atoms, are synthesized as their triflate salts at a multi‐gram scale from the reaction of Lewis base adducts of CS2, namely LC/P–CS2 (4), with a combination of [(LCP)4][OTf]4 (1[OTf]4) and Ph3P. The feasibility of using 3+ as PCS building blocks is showcased in their reactions with representative electrophiles (MeOTf) and nucleophiles (MesMgBr, Ph3PCH2), leading to selective functionalization of the PCS core at the S‐ and P‐terminus, respectively. Additionally, it is reported that 3+ can function as ambident nucleophiles with AgOTf (2 equivalents), affording unprecedented linear coordination polymer [Ag2(OTf)3‐μ2:κP,κS–((LC)P=CS(PCy3))]+ (6b), where the PCS moiety acts as a bridging ligand in transition metal complexes for the first time. Reduction of 3+ facilitates the cleavage of the P‐ and C‐bound substituents leading to the formation of the [PCS]– anion. Moreover, cycloaddition reactions of 3+ with 1[OTf]4 are shown to selectively yield five‐ and eight‐membered polyphosphorus heterocycles. Preliminary results suggest the possibility of activating the C–S bond in [(LC)P=CS(LC)]+, resulting in the formation of [(LC)P=C(LC)–P(LC)][OTf]2, 12[OTf]2, which may serve as a synthon for the PCP unit in future studies.

Tridentate N-donor Schiff base metal Complexes: Synthesis, Characterization, computational Studies, and assessment of biomedical applications in cancer Therapy, Helicobacter pylori Eradication, and COVID-19 treatment

A unique Schiff base ligand (BCA), 4-(2-((1E,2E)-1-(2-(p-tolyl)hydrazono)propan-2-ylidene)hydrazinyl)quinazoline, was synthesized and complexed with Mn [II], Co [II], Cu [II, and Cd [II] ions, with 1,10-Phenanthroline (PHN) as an auxiliary ligand. The unique Schiff base ligand BCA and its metal complexes were characterized using multiple analytical techniques, including elemental analysis, UV–visible spectroscopy, FT-IR, mass spectrometry, and conductometric measurements. These methods provided detailed insights into the compounds’ structural and electronic properties. Density Functional Theory (DFT) computations complemented the experimental data, elucidating electronic configuration stability, HOMO-LUMO energy gaps, chemical hardness, and dipole moments. The computational results confirmed the distorted octahedral structure of the complexes. Antimicrobial testing against various bacterial and fungal strains revealed that the Cd (II) complex exhibited the highest activity, with inhibition zones ranging from 19.7 ± 0.6 mm to 35.0 ± 1.0 mm, surpassing the activity of standard antibiotics in some cases. Notably, the compounds displayed significant efficacy against Helicobacter pylori, with the Cd (II) complex showing an inhibition zone of 32.67 ± 0.58 mm and a minimum inhibitory concentration (MIC) of 7.8 μg/ml. Anticancer properties were evaluated against MCF-7 (Breast carcinoma) cells, with the [(BCA)(PHN)Cd(H2O)].2Cl·2H2O complex demonstrating superior activity (IC50 = 29.97 μg/ml) compared to the free ligand (IC50 = 183.96 μg/ml) and other metal complexes. Notably, the Cd(II) complex showed reduced cytotoxicity towards normal VERO cells, suggesting potential selectivity for cancer cells. Molecular docking simulations evaluated the complexes’ binding interactions with protein targets associated with Helicobacter pylori, MCF cancer cells, and the COVID-19 virus. The main objective of this research was to design and synthesize a unique Schiff base ligand and its new corresponding Ternary metal complexes and then investigate their potential medical applications. Specifically, the study aimed to evaluate the compounds’ effectiveness as antibiotics, antitumor agents, and possible treatments for COVID-19.

Synergistic Dual-Cross-Linking Gelation: Exploring the Impact of Metal-Ligand Complexation on Ionogel Performance.

Owing to the growing interest in wearable ionotronics, the demand for ionogels with outstanding mechanical and electrochemical characteristics has increased dramatically. Nevertheless, it remains challenging to simultaneously enhance the mechanical robustness and conductivity of ionogels because of their trade-off relationship. In this work, we propose physically/chemically dual-cross-linked ionogels designed to improve the mechanical strength without reducing ionic conductivity by introducing metal-ligand complexation only within the physically cross-linked domains. In particular, the impact of metal-ligand complexation, a crucial parameter in this strategy, on ionogel performance is systematically examined using various metal ions. The mechanical resilience and thermal stability of ionogels are effectively enhanced with Co3+ having the highest coordination number, which can be explained by the highest metal-ligand complexation (i.e., chemical cross-linking) density. Additionally, there is no degradation in ionic conductivity when compared to the pristine ionogel because these complexations occur within physically cross-linking domains that are irrelevant to the ion conductive channels. The dual-cross-linked ionogels are successfully applied to alternating-current electroluminescent displays (ACEDs). Moreover, a versatile mixed-emitter strategy is suggested to improve practicality, enabling the realization of frequency-controlled multicolor ACEDs.

Elucidation of the Decomplexation and Reverse Migration Mechanism of Uranyl Ions from the Oil Phase to the Aqueous Phase Using Microsecond (0.2 μs) Molecular Dynamics Simulations.

Interphase ion transfer is ubiquitous in chemistry, physics, biology, and various engineering sciences. Ion transfer from the aqueous phase to the oil phase or vice versa is a complex chemical phenomenon, and its fundamental understanding is crucial for efficient and economical mass transfer. This ion transfer is much more complex for radionuclide metal ions. Therefore, an attempt has been made to elucidate the decomplexation and mechanism of reverse migration of uranyl ions from the loaded oil phase to the aqueous phase using large time-scale molecular dynamics simulations (microseconds) and density functional theory (DFT). The strength of the metal-ligand complex is the key factor for stripping among other mass transfer parameters. Stronger the metal-ligand complex, the lower the tendency for reverse migration into the aqueous phase, which was demonstrated by three different ligands for reverse migration using water as the stripping agent. The interaction energy of the metal-ligand complex has been calculated using DFT. The reverse migration is validated by the distance between the centers of mass. Higher interface thickness and lower interfacial tension belong to N,N,N',N'-tetra-octyldiglycolamide (TODGA), which are favorable for mass transfer across the liquid-liquid interface. The computed distribution coefficient (KD) is favorable for tributyl phosphate (TBP) and tri-iso-amyl phosphate (TiAP), whereas TODGA shows a higher KD, indicating a less favorable value for reverse migration. The distance between the uranyl ion and the TODGA molecule confirms that the entrapment of uranyl ions in the TODGA phase might be attributed to aggregation. Further, the aggregation tendency of TODGA molecules reduces the back extraction and the recovery of uranyl ions into the aqueous phase. The present MD results might be important for predicting an efficient back-extracting agent for the recovery of the metal ions from the oil phase.

The chromatin remodeler SMARCA5 binds to d-block metal supports: Characterization of affinities by IMAC chromatography and QM analysis.

The ISWI family protein SMARCA5 contains the ATP-binding pocket that coordinates the catalytic Mg2+ ion and water molecules for ATP hydrolysis. In this study, we demonstrate that SMARCA5 can also possess an alternative metal-binding ability. First, we isolated SMARCA5 on the cobalt column (IMAC) to near homogeneity. Examination of the interactions of SMARCA5 with metal-chelating supports showed that, apart from Co2+, it binds to Cu2+, Zn2+ and Ni2+. The efficiency of the binding to the last-listed metal was influenced by the chelating ligand, resulting in a strong preference for Ni-NTA over the Ni-CM-Asp equivalent. To gain insight in the preferential affinity for the Ni-NTA ligand, QM calculations were performed on model systems and metal-ligand complexes with a limited protein fragment of SMARCA5 containing the double-histidine (dHis) motif. The calculations correlated the observed affinity with the relative stability of the d-block metals to tetradentate ligand coordination over tridentate, as well as their overall octahedral coordination capacity. Likewise, binding free energies derived from model imidazole complexes mirrored the observed Ni-NTA/Ni-CM-Asp preferential affinity. Finally, similar calculations on complexes with a SMARCA5 peptide fragment derived from the AlphaFold structural prediction, captured almost accurately the expected relative stability of the TM complexes, and produced a large energetic separation (~10 kcal∙mol-1) between Ni-NTA and Ni-CM-Asp in favour of the former.

The Synthesis of Melamine Cored Schiff Bases and Investigation of Heteronuclear Metal Complexes

In this study, 2,4,6-triamino-s-triazine (melamine) is the starting material. The condensation reaction of melamine and 4-hydroxybenzaldehyde resulted in the formation of the monopodal Schiff base. An oxygen-bridged monopodal complex of [(Fe(III)Salophen)Cl] ligand complex with monopodal Schiff base ligand was then obtained. Tripodal Schiff base ligand was obtained by condensing 2-hydroxybenzaldehyde with a monopodal complex and this ligand in some transition metal complexes were synthesized. As a result, the ligand and complexes of this ligand were isolated, as well as elemental analyses, FT-IR, 1H-NMR, TGA and magnetic susceptibility measurements of the obtained compounds were taken to elucidate their structures.

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.

Influence of Sodium Lauryl Sulfate Anionic Micelles on the Complex Equilibria of Divalent Metal Ions with Isoleucine Amino Acid

The main objective of the present investigation is the formation analysis of metal-ligand complexes of isoleucine with divalent calcium, magnesium and zinc metal ions in various concentrations of sodium dodecyl sulphate (0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 percent w/v). To look into the impact of the concentration of negatively charged micelles, the parameters were changed and the possible chemical species of isoleucine that interact with the metal ions, are being studied. The experiment was performed using pH meter at 303 K using NaCl to keep ionic strength stable at 0.16 mol dm-3 in the presence of anionic surfactant sodium dodecyl sulphate (SDS). The determination of the correction factor was conducted via the computer program SCPHD. The computational software MINIQUAD75 is utilized to determine the stability constants of ligand-metal complexes through the analysis of titration data. Based on statistical features such as skewness, 2, kurtosis and crystallographic R-factor, the best fit to the complicated speciation was selected. The metal ions Ca (II), Mg (II) and Zn (II) formed complexes ML, ML2 and ML2H2 for Ca (II), Mg(II) and ML, ML2 and ML2H for Zn (II) through the complexation of isoleucine. In order to validate the accuracy of the final established model, deliberate defects were introduced into the relevant components.

SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL ACTIVITY OF SOME SCHIFF BASE METAL COMPLEXES

This study presents the synthesis and characterization of five metal complexes (C1–C5) derived from the reaction of a newly synthesized ligand (HL) with various metal chlorides, specifically Zn, Co, Ni, Mn, and Fe. General Background: Transition metal complexes have garnered significant interest due to their diverse biological activities and potential therapeutic applications. Specific Background: The ligand (HL) was synthesized from equimolar amounts of p-anisidine and salicylaldehyde, yet the influence of different metal ions on the biological properties of such complexes remains underexplored. Knowledge Gap: While several metal complexes exhibit antimicrobial properties, there is limited research on the biological activities of complexes formed with this specific ligand. Aims: This work aims to synthesize and characterize the metal complexes and evaluate their antibacterial activity against various bacterial strains. Results: Characterization via FT-IR and ¹H NMR spectroscopy confirmed the successful formation of the complexes, indicating strong metal-ligand interactions. Preliminary biological testing revealed varying degrees of antibacterial activity among the complexes, with notable effectiveness against certain bacterial strains. Novelty: The study contributes to the understanding of how different metal ions influence the biological properties of metal-ligand complexes. Implications: These findings suggest that the synthesized metal complexes could serve as potential candidates for further development in antimicrobial therapies, prompting additional research into their mechanism of action and broader biological applications.

Transition metal complexes of benzimidazole-based ligands: Synthesis, characterization, biological, and catecholase activities

Heterocyclic ligands 5a and 5b and their metal complexes (1–10) and (11–20) respectively, were synthesized and characterized by mass spectrometry, FT-IR, ESR, 1H, 13C NMR and UV–visible spectroscopy. In vitro antifungal activity of the heterocyclic analogs 5a, 5b and metal complexes (1–20) was evaluated against the fungal strains: Candida albicans, Candida glabrata, and Candida tropicalis., The results showed that Fe(III) 2 and Co(II) complex 13 display considerable antifungal activity with MIC values of 350, 375 and 435 μg/mL and 450, 455, and 455 μg/mL against C. albicans, C. glabrata, and C. tropicalis, respectively. Promising 5a, 5b, Fe(III) 2, and Co(II) complex 13 show groove binding mode with Ct-DNA, which has been confirmed by several techniques, including UV–visible, fluorescence spectroscopy, and cyclic voltammetry. PDB ID: 1BNA was used for the molecular docking investigation of the heterocyclic analogs 5a and 5b. The active Fe(III) complex 2 and Co(II) complex 13 are effectively catalyzed for the oxidation of catechol in acetonitrile to its corresponding quinone with turnover number 5.44 × 104 and 9.78 × 104 h−1, respectively with first order that follow Michaelis-Menten enzymatic kinetics. The pharmacokinetics properties of the all compounds showed good oral bioavailability. Antioxidant potential of ligands 5a, 5b, Fe(III) 2 and Co(II) complex 13 was further approximated through DPPH free radical and H2O2 with remarkable antioxidant activity.

Ligation and Antimicrobial Studies on Synthetic Metal Complexes of Novel Asymmetric Polydentate Hydrazonic Ligand Incorporating Oxime Moiety Derived Arom 4,6-Diacetylresorcinol

Ligation and Antimicrobial Studies on Synthetic Metal Complexes of Novel Asymmetric Polydentate Hydrazonic Ligand Incorporating Oxime Moiety Derived Arom 4,6-Diacetylresorcinol

Improving the Accuracy in the Prediction of Transition-Metal Spin-State Energetics Using a Robust Variation-Based Approach: Density Functional Theory, CASPT2 and MC-PDFT Applied to the Case Study of Tris-Diimine Fe(II) Complexes.

Designing ligands for transition metal complexes with a specified low-spin, high-spin or spin-crossover behavior is challenging. A major advance was recently made by Phan et al. [J. Am. Chem. Soc. 2017, 139, 6437-6447] who showed that the spin state of a homoleptic tris-diimine Fe(II) complex can be predicted from the N-N distance in the free diimine. They could thus predict the change in magnetic behavior on passing from the complexes of 2,2'-bipyridine (bpy), 2,2'-biimidazole (bim) and 2,2'-bis-2-imidazoline (bimz) ligands to those obtained with the modified analogs 4,5-diazafluoren-9-one (dafo), 1,1'-(α,α'-o-xylyl)-2,2'-bisimidazole (xbim) and 2,3,5,6,8,9-hexahydrodiimidazo[1,2-a:2', 1'-c]pyrazine (etbimz), respectively. Theoretically, the challenge lies in the accurate determination of the HS-LS zero-point energy difference ΔEHL°. The issue can be circumvented by using a variation-based approach, wherein ΔEHL° is not directly evaluated but obtained from the estimate of its variation Δ(ΔEHL°) in series of related systems, which include one whose ΔEHL° is accurately known [Phys. Chem. Chem. Phys. 2013, 15, 3752-3763; J. Phys. Chem. A 2022, 126, 6221-6235]. In this study, density functional theory (DFT), second-order multireference perturbation theory in its CASPT2 formulation, multiconfigurational pair DFT (MC-PDFT) and its hybrid formulation (HMC-PDFT) have been applied to the determination of Δ(ΔEHL°) in the pairs of complexes , , , and , . In DFT, we used several semilocal functionals and their global hybrids, as well as their D2, D3, D3BJ and D4 dispersion-corrected forms; and in MC-PDFT, different translated and fully translated functionals. The results are consistent with one another and in very good agreement with experiments. They show small to vanishing dependence on key details of the methods used: namely, the exact-exchange contribution to global hybrids; the ionization potential-electron affinity shift and basis sets used in the CASPT2 calculations; and the active spaces employed for the CASSCF wave functions used in the MC-PDFT and HMC-PDFT calculations. Insights into the change in the spin-state energetics accompanying the ligand exchanges were gained through a complexation energy analysis. Using the accurate CCSD(T) estimate of the HS-LS adiabatic energy difference in [J. Chem. Theory Comput. 2012, 8, 4216-4231], the Δ(ΔEHL°)-approach has been applied to the determination of ΔEHL° in the diimine complexes. The CASPT2 and DFT-D2 methods only give results in agreement with experiments. This suggests for the other methods a limitation in their treatment of dispersion which prevents them from accurately describing the spin-state energetics change accompanying the passing from with the tetragonal arrangement of its nitrile ligands to the tris-diimine complexes with the trigonal packing of their bulkier ligands.

When Metal Nanoclusters Meet Smart Synthesis.

Atomically precise metal nanoclusters (MNCs) represent a fascinating class of ultrasmall nanoparticles with molecule-like properties, bridging conventional metal-ligand complexes and nanocrystals. Despite their potential for various applications, synthesis challenges such as a precise understanding of varied synthetic parameters and property-driven synthesis persist, hindering their full exploitation and wider application. Incorporating smart synthesis methodologies, including a closed-loop framework of automation, data interpretation, and feedback from AI, offers promising solutions to address these challenges. In this perspective, we summarize the closed-loop smart synthesis that has been demonstrated in various nanomaterials and explore the research frontiers of smart synthesis for MNCs. Moreover, the perspectives on the inherent challenges and opportunities of smart synthesis for MNCs are discussed, aiming to provide insights and directions for future advancements in this emerging field of AI for Science, while the integration of deep learning algorithms stands to substantially enrich research in smart synthesis by offering enhanced predictive capabilities, optimization strategies, and control mechanisms, thereby extending the potential of MNC synthesis.

Synthesis and Photo/Radiation Chemical Characterization of a New Redox-Stable Pyridine-Triazole Ligand.

Photocatalysis using transition-metal complexes is widely considered the future of effective and affordable clean-air technology. In particular, redox-stable, easily accessible ligands are decisive. Here, we report a straightforward and facile synthesis of a new highly stable 2,6-bis(triazolyl)pyridine ligand, containing a nitrile moiety as a masked anchoring group, using copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction. The reported structure mimics the binding motif of uneasy to synthesize ligands. Pulse radiolysis under oxidizing and reducing conditions provided evidence for the high stability of the formed radical cation and radical anion 2,6-di(1,2,3-triazol-1-yl)-pyridine compound, thus indicating the feasibility of utilizing this as a ligand for redox active metal complexes and the sensitization of metal-oxide semiconductors (e. g., TiO2 nanoparticles or nanotubes).

Synthesis, Characterization and Antimicrobial Analysis of Nickel and Cobalt Complexes of Condensates of Salicylaldehyde and 2-Hydroxy Aniline

This study on the synthesis, characterization and antimicrobial analysis of Nickel and Cobalt complexes of condensates of salicylaldehyde and 2-hydroxy aniline constitutes an attempt towards the development of new molecular compounds that could destroy the barrier of resistance of pharmaceutical products. The ligands of 2-phenyliminomethylphenol (PMP) and 2,2-hydroxy benzylidene aminophenol (HAP) were first prepared by separately reacting Aniline with Salicylaldehyde on the one hand, and 2-aminophenol with Salicylaldehyde on the other hand. The unmixed metal complexes were prepared by reacting either of 0.29 mmol 2-phenylimino methyl phenol ligand with the metal salt or 0.29 mmol 2,2-hydroxybenzylideneaminophenol ligand with the metal salt while the mixed metal complexes were prepared by addition of equimolar amount of ligands of 2-phenyliminomethylphenol and 2,2-hydroxybenzylideneaminophenol into the metal salt. The molecular structures of the ligands and their complexes have been determined and characterized using GC-MS, FTIR, UV-Vis, 1H-NMR, and X-ray diffraction techniques. The melting point and solubility of the ligands and synthesized complexes were equally determined. Antimicrobial studies were carried out with ligands PMP and HAP and the metal complexes using clinical isolates of Gram Positive Bacteria (Staphylococcus aureus and Bacillus substilis), Gram Negative Bacteria (Escherichia coli and Pseudomonas aeruginosa) and Fungi (Candida albicans and Aspergillus niger). All complexes and ligands were found to be soluble in dimethylsulfoxide (DMSO). Asymmetric Octahedral geometry is observed for Nickel (II) and Cobalt (II) complexes with PMP, HAP, and the mixed ligands. A bidentate ligand is coordinated to metal ions through oxygen atoms of carbonyl groups and nitrogen atoms of two imine groups for Nickel (II) and Cobalt (II) complexes. The findings from the XRD pattern indicate that the ligand and metal complexes are crystalline with a high crystallite size of 119.23nm to 638.67nm. The FTIR spectra for 2-phenyliminomethylphenol (PMP) showed IR absorption band at 1569.2 cm-1 suggesting the stretching vibration of the C=C bond in the benzene rings, while the bands at 1613.9 cm-1 indicated the =C-N stretching in the benzene ring. The complexes showed electronic spectra which suggest that energy was absorbed in the ultraviolet/visible region, producing changes in the electronic energy of the compound and resulting from the transition of valence electrons in the complexes. The XRD findings reveal that the crystal formed by the ligands and their respective complexes are large. The ligands were found to be larger in size than the complexes and this could be due to the complexation reactions. The X-ray diffractograms of the metal complexes produced good intense peaks that suggest high crystallinity. The ligand of 2-phenyliminomethylphenol (PMP) and 2,2-hydroxy benzylidene aminophenol (HAP) showed partial inhibitory action on the clinical isolates of Gram Postive, Gram Negative and zero inhibitory effect on the fungi while the divalent metal complexes of both mixed and unmixed ligands exhibited either stronger or strongest inhibition. The study concludes that the synthesized ligands and their metal complexes are purely crystalline as revealed by the chemical analysis, exhibited inhibitory actions on Gram Positive, Gram Negative and fungi species.

Influence of Sodium Dodecyl Sulfate Anionic Micelles on The Complex Equilibria of Divalent Metal Ions with L-Leucine Amino Acid

The main objectives of the present investigation are the formation analysis of metal-ligand complexes of L-Leucine with divalent calcium, magnesium, and zinc metal ions in various concentrations of sodium dodecyl sulphate (0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 percent w/v). To also look into the impact of the concentration of negatively charged micelles, the parameters that were changed, and the possible chemical species of L-Leucine that interact with the metal ions that were being studied. The experiment was performed using pH meter at 303 K using NaCl to keep your ionic strength stable of 0.16mol dm-3 in the presence of anionic surfactant, sodium dodecyl sulphate (SDS). The determination of the correction factor was conducted via the computer program SCPHD. The computational software MINIQUAD75 is utilized to determine the stability constants of ligand-metal complexes through the analysis of titration data. Based on statistical features such as skewness, 2, kurtosis, and crystallographic R-factor, the best fit to the complicated speciation was selected. The metal ions Ca (II), Mg (II), and Zn (II) formed complexes ML, ML2, and ML2H2 for Ca (II), and ML, ML2, and ML2H for Mg (II) and Zn (II) through the complexation of L-Leucine. In order to validate the accuracy of the final established model, deliberate defects were introduced into the relevant components.

Ionic Liquid-Based Extraction Strategy for the Efficient and Selective Recovery of Scandium.

The recovery of scandium (Sc) from highly acidic industrial effluents is currently hindered by the use of large quantities of flammable and toxic organic solvents. This study developed an extraction system using ionic liquids (ILs) and phenylphosphinic acid (PPAH) as diluents and an extractant, respectively, to selectively recover Sc from the aqueous phase. The effect of IL chemical structure, aqueous pH and temperature on the extraction of Sc was systematically investigated and the findings revealed that ILs with longer alkyl side chains had reduced Sc extraction ability due to the presence of continuous nonpolar domains formed by the self-aggregation of the IL alkyl side chain. The IL/PPAH system maintained high extraction ability toward Sc across a wide temperature range (288 K to 318 K) and the extraction efficiency of Sc could be improved significantly by increasing the aqueous pH. The extraction process involved proton exchange, resulting in the formation of a metal-ligand complex (Sc(PPA)3).