Metal Ion Complexes Research Articles

Mechanism of copper activation and adsorption in marmatite enhanced via dissolution of iron and zinc by ethylenediaminetetraacetic acid complexation

ABSTRACT In this study, the impact of disodium ethylenediaminetetraacetic acid (EDTA-2Na) as a potent complexing agent on the enhanced activation flotation of marmatite was investigated through a series of characterization. Micro-flotation tests demonstrated a significant improvement in the recovery of marmatite upon the addition of EDTA-2Na. Furthermore, XPS analysis showed that under the EDTA-2Na activation system, the formation of copper – sulfur (Cu-S) products on the marmatite surface increased, thereby indicating enhanced Cu adsorption. The results of ICP-OES and UV-vis spectroscopy indicated that compared with the conventional Cu activation systems, the enhanced EDTA-2Na activation system facilitated the increased dissolution of zinc and iron. Additionally, it increased Cu adsorption on mineral surfaces, thereby promoting the efficiency of xanthate adsorption and collection. Conclusively, the combination of the strengthened activation of Cu ions via metal ions complexation and the improvement of xanthate efficiency enhanced the flotation recovery ability of marmatite. Thus, this study offered a novel sustainable strategy to enhance the marmatite flotation recovery rate.

Comprehensive Chemical Analysis of the Methyl 3-Nitrogen-2,3-Dideoxysaccharides Derivatives with d-ribo-Configuration: Synthesis, Reactivity of HIV-1 Reverse Transcriptase Inhibitors.

This study extends previous research, particularly focusing on patented scientific objects No. ID: PL 240 353 B1, investigating the physicochemical properties of the methyl 3-azido- and 3-amino-2,3-dideoxysaccharides with a nucleoside scaffold similar to 3'-azidothymidine (AZT). The study utilizes multiwavelength spectrophotometric and potentiometric methods to evaluate the ionization of the saccharide units in aqueous solutions. pKa values, obtained from two independent methods, reveal significant sugar ionization effects on UV spectra with varying pH levels. Stability constants for divalent metal ion complexes (Cu2+ and Ni2+) with the saccharide isomers indicate that complex stoichiometries and stabilities are highly dependent on the configuration of sugar ring substituents. Spectrophotometric results show a descending order of CT-DNA-binding affinity: BRNH2OMe > BRN3OMe > ARN3OMe > ARNH2OMe, suggesting varied interaction strengths. Molecular docking of models of synthesized O-glycosides confirmed their potential as reverse transcriptase inhibitors. Among the derivatives tested, the compound BRN3OMe displays the highest interaction with the enzyme active site residues and DNA, suggesting it may possess the greatest efficacy. Our reported results highlight the promising inhibitory properties of novel O-glycosides against HIV reverse transcriptase, supporting their potential development as antiviral agents.

Unlocking the intermediate-phase evolution in perovskite crystallization with an operando infrared FEWS sensor.

The intermediate phase produced by the complexation of metal ions and solvent molecules usually occurs in the crystallization process of perovskite single crystal or film. Effective in situ monitoring of intermediate-phase evolution is beneficial to the control of crystal quality. However, it is difficult to realize. In this work, infrared fiber evanescent wave spectroscopy (FEWS) was raised to monitor the intermediate-phase evolution in real time and non-destructively using GeAsSeTe chalcogenide optical fibers. The vibrational and rotational dynamics of specific molecular functional groups was operando captured, reflecting a perovskite precursor of different states. Taking BM2PbBr4 (BM = benzimidazole) perovskite as an example, the shift of the stretching vibration of -C=O groups in DMF (N,N-dimethylformamide) toward low wavenumbers and then recovered toward original position probed the complexion of Pb2+ and carbonyl groups into (DMF)2BMPbBr3 intermediate phase and then decomplexing to precipitate BM2PbBr4 perovskite crystal. Some anomalous emergence of new vibrational bands associating with -C-N and -N-H bonds suggest the variation of DMF-BMBr hydrogen bonds during intermediate-phase evolution. This technique provides new, to the best of our knowledge, insights into the control of perovskite crystallization processes and pushes the development of high-quality perovskite materials for high-performance photovoltaic or optoelectronic devices.

Growth, structural adaptations, and physiological dynamics of Alternanthera tenella Colla. toward lead toxicity

Anthropogenic activities have accelerated lead (Pb) accumulation across different trophic levels in the ecosystem. This study focused on the physiological mechanisms of an invasive plant, Alternanthera tenella in a controlled hydroponic setting to understand its response to Pb stress. A. tenella was exposed to 680 µM of lead acetate for 21 days, showing high tolerance (83%) with minimal growth inhibition. Pb exposure altered macro- and micronutrient concentrations, suggesting essential mineral reallocation to enhance stress tolerance. Scanning electron microscopy (SEM) revealed Pb2+ depositions in the vacuoles and cell walls of root (∼14%) and leaf (∼3%) cells, a key mechanism for reducing Pb toxicity. Fourier transform infrared spectroscopy (FTIR) indicated that Pb2+ ions interacted with hydroxyl (-OH) and amide (CO-NH) groups, important for metal ion complexation. Physiological responses included increased proline, malondialdehyde, protein degradation, and elevated catalase (CAT) and ascorbate peroxidase (POD) activity. A. tenella accumulated 46,866.92 mg/kg DW of Pb, primarily in roots (2682.5 mg/kg DW), with limited Pb translocation to shoots, suggesting a protective mechanism. High biological concentration (BCF 19.04) highlight its potential for Pb phytostabilization. These findings are specific to hydroponic conditions, and further research is needed to assess its phytoremediation potential in field conditions.

Flexible Electrochemical Biosensor Using Nanostructure-Modified Polymer Electrode for Detection of Viral Nucleic Acids.

In the biosensor field, the accurate detection of contagious disease has become one of the most important research topics in the post-pandemic period. However, conventional contagious viral biosensors normally require chemical modifications to introduce the probe molecules to nucleic acids such as a redox indicator, fluorescent dye, or quencher for biosensing. To avoid this complex chemical modification, in this research, mismatched DNA with an intercalated metal ion complex (MIMIC) is employed as the probe sequence. In addition, the MIMIC is fabricated on a lithography-assisted nanostructure-modified flexible polymer electrode. On this flexible electrode, as a proof-of-concept study, a human papillomavirus (HPV-16 and -18) was detected by the MIMIC with a high accuracy. The developed biosensor exhibits an ultrasensitive ability to detect HPV in viral DNA without target amplification and chemical modifications in a simple preparation manner. Moreover, it retains its nanostructures and high conductivity after bending. In conclusion, the use of the proposed biosensor suggests a novel approach to developing an ultrasensitive and flexible biosensor for the detection of important biomarkers in a simple manner that can be applied in point-of-care testing.

Synthesis, Characterization, Biological, and Antioxidant Activity of New Metal Ion Complexes with Schiff Base Derived from 2-Hydroxybenzohydrazide

The study involved the synthesis of new complexes with tetradentate ligand (LH). The general formula of complexes was [M(LH)(H2O)2] with M of Ni2+, Co2+, Cu2+, and Zn+. The ligand was synthesized by treating the 2-hydroxybenzohydrazide with salicylaldehyde. The structural characteristics of ligands and complexes were analyzed using various techniques, including elemental analyses, magnetic susceptibility, molar conductivity, infrared, ultraviolet absorption, mass, and NMR spectroscopy studies. The physical measurements indicated that the prepared complexes are non-electrolyte and showed that the ligand is tetradentate when coordinated with metal ions through the nitrogen of azomethine (–C=N–), two oxygen atoms of O–H phenolic, and an oxygen atom of carbonyl (C=O) for benzohydrazide. It was found that Co2+, Cu2+, and Zn2+ complexes are octahedral, while Ni2+ complexes are square planar. The biological screening of the complexes demonstrates that the Schiff base metal complexes exhibit remarkable efficacy in combating microorganisms by utilizing Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) bacteria, as well as Candida albicans fungi. Hence, their results were good in inhibition. Then, the potential of these prepared compounds as antioxidants was determined by inhibiting free radicals.

Synthesis, Characterization and Antioxidant Study of Some Metal Ion Complexes with Azo 1-(2,4,6-trihydroxy-3-((3-hydroxyphenyl) diazenyl) phenyl) Ethan-1-one.

اثناء تفاعل الديزنة تكونت صبغة أزو جديدة عن طريق تفاعل 3-امينوفينول مع 2,4,6-ثلاثي هيدروكسي اسيتوفينون . ثم تم تفاعل هذا الليكاند مع بعض ايونات العناصر الكروم والحديد الروديوم والروثينيوم بتكفؤهم الثلاثي والكوبلت الثنائي والموليبدينوم سداسي التكافؤ مكونة معقدات فلزية مختلفة بأشكال هندسية متعددة. تم ملاحظة تناسق مجموعة الازو مع ايونات العناصر من خلال ملاحظة ظهور حزم امتصاص الفلز مع النتروجين والاوكسجين بتقنية مطيافية الاشعة تحت الحمراءمشيرة إلى ارتباط النيتروجين والأكسجين مباشرة مع الفلز .تم تعيين الاوزان الجزيئية لليكاند ومعقداته بأستخدام مطيافية الكتلة وكذلك تم عمل تحليل للعناصر. تم قياس حزم امتصاص الاطياف الالكترونية لتحديد الشكل الهندسي للمعقدات , اضافة الى ذلك تم تحديد استقرارية المركبات من حيث احتواءها على جزيئات الماء من عدمه باستخدام تقنيتي المسح الحراري التفاضلي التحليل الحراري الوزني تم قياس تأثير المعقدات كمضادات اكسدة اتجاه 2,2-داي فينل بكريل هيدرازيل (DPPH) وهو عبارة عن جذر حر مستقر الذي يتم استخدامه لمعرفة فعالية كسح الجذور الحرة لنواع الاوكسجين النشطة ولوحظ التالي (H4L > Ascorbic acid > Mo-Complex > Fe-Complex > Cr-Complex > Rh-Complex > Ru-Complex) خلال ثلاثون دقيقة . اختبار DPPH قام باختزال الالكترون المنفرد لذرة النتروجين عن طريق استلام ذرة هيدروجين من المعقدات المضادة للكسدة لتكوين الهيدرازين المقابل . نتيجة الفحص تراوحت مابين قيم تثبيط لمركبات نشطة وغير نشطة تم ادراجها في البحث.

Synthesis, characterization, biological activity, and modelling protein docking of divalent, trivalent, and tetravalent metal ion complexes of new azo dye ligand (N,N,O) derived from benzimidazole

The ligand 2-[2′-(benzimidazole)azo]-4,6-dimethyl benzoic acid (BADMB) was employed to create coordination complexes with Pd(II), Co(III), and Pt(IV) ions. A variety of analytical methods were utilized to verify the structures of the synthesized chelates, including microanalysis, 1H NMR, 13C NMR, UV–Vis spectroscopy, FT-IR, mass spectrometry, magnetic susceptibility, molar conductivity, X-ray diffraction (XRD), and thermal analysis. The stoichiometry of the metal complexes was 1:1 [M:L] in the case of both Pd(II) and Pt(IV) complexes while that of the Co(III) complex was 1:2 [M:L]. The results of molar conductivity measurements confirmed that all of the complexes are electrolytes and that they fall within the range 15.74–40.11 Ω−1 cm2 mol−1. The findings indicated that the Co(III) and Pt(IV) complexes adopt an octahedral geometry, with the formulas [Co(BADMB)2]Cl·H2O and [Pt(BADMB)Cl3]·H2O, respectively. In contrast, the Pd(II) complex, represented by the general formula [Pd(BADMB)Cl]·H2O, has a square planar geometry. BADMB acts as a trident (N,N,O) ligand through two nitrogen atoms from the benzimidazole ring and an azo group and one oxygen atom of the carboxyl group. The antimicrobial activity of these compounds was evaluated against a variety of microorganisms, including Streptococcus, Staphylococcus aureus, Penicillium spp., and Aspergillus, as well as multidrug resistance. In addition, all compounds were active against Penicillium spp. fungi compared to the other microorganisms examined. Moreover, the cytotoxic effects of the BADMB, Pd(II), and Pt(IV) complexes were evaluated in a human hepatocellular carcinoma cell line (HepG2) and a normal cell line (WRL68). A molecular docking study was performed using MOE 2015 software and the PDBsum online server. The compounds showed a binding free energy greater than 5 kcal/mol and an RMSD value was present in the range of 1.41 to 2.01 Å, indicating their potential as ligands for further molecular studies with selected targets.

Complexes of Alkaline Earth Metal Ions with the Cyclodimethylsiloxane ligands D7, D8 and D9 (D = Me2SiO)

We present complexes of alkaline earth metal ions with the large cyclodimethylsiloxane D7, D8 and D9. The compounds prepared are [Mg(D7)(H2O)2][GaI4]2 (1), [Ca(D8)][GaI4]2 (2), [Sr(D8)][GaI4]2 (3), [Ba(D8)][GaI4]2 (4), [Ca(D9)][GaI4]2 (5), [Sr(D9)][GaI4]2 (6) and [Ba(D9)][GaI4]2 (7). Single‐crystal X‐ray diffraction and multinuclear NMR spectroscopy were used to analyze the prepared compounds and coordination modes in the solid state and in solution.

Electrostatic Confinement‐Induced Excited Charge Transfer in Ionic Covalent Organic Framework Promoting CO2 Reduction

We demonstrate an electrostatic confinement‐induced charge transfer pathway in a supramolecular photocatalyst comprising of an ionic covalent organic framework (COF) and cationic metal complexes. The dynamic electrostatic interactions not only attract cations around the COF to accept photogenerated electrons, but also allows for a retention of homogeneous catalytic characters of complexes, making a subtle balance. Accordingly, the electrostatic confinement effect facilitates the forward electron transfer from a photoexcited COF to cationic Co complex, realizing a remarkable photocatalytic CO2 reduction performance. Its catalytic efficiency is far superior to the supramolecular counterparts with Van‐der‐Waals or hydrogen bonding interactions. This work presents an insight for enhancing charge transfer in supramolecular systems, and provides an effective approach for construction of highly efficient photocatalysts.

Five novel Pb/Zn/Co metal-organic frameworks using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and carboxylate ligands: Synthesis, characterization, DFT calculation and catalytic PMS degradation of RhB

Five new metal-organic frameworks (MOFs), namely {Pb(atpt)(3-bpd)0.5}n (1); {Co(cbz)2(3-bpd)(H2O)2·2H2O}n (2); {Co(imdc)(3-bpd)(H2O)·H2O}n (3); {Co(tdca)(3-bpd)(H2O)2·DMF}n (4); {Zn(tdca)(3-bpd)(H2O)2·DMF}n (5), were assembled with metal ions Pb²⁺, Zn²⁺, and Co²⁺ using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (3-bpd) as the main ligand, combined with 2-aminoterephthalic acid (H2atpt), 4-cyanobenzoic acid (Hcbz), 4,5-imidazoledicarboxylic acid (H2imdc), and thiophene-2,5-dicarboxylic acid (H2tdca) as auxiliary ligands via hydro/solvothermal methods. Their molecular structures were analyzed by single-crystal X-ray diffraction and characterized by FT-IR and PXRD. Complex 1 has a three-dimensional structure with a hepta-coordinated, semi-directed {PbNO6} metal center. The central metal ions in complexes 2–5 exhibit a six-coordinated {MN2O4} (M = Co or Zn) octahedral geometry. In complex 2, the carboxylate ligand does not function as a bridging ligand, resulting in a 1D chain structure, while complexes 3- 5 extend into 2D layered structures. Thermogravimetric analysis indicates good thermal stability for complexes 1–5. Then, the prepared complexes were used as catalysts to degrade Rhodamine B (RhB) during the monopersulfate (PMS) activation. Complexes 3 and 4 demonstrated significant efficiency, achieving degradation rates of 93.61 % and 98.56 % within 10 min. Radical scavenging experiments and EPR analysis identified that the activation of PMS for dye degradation by the two catalysts occurs through both radical and non-radical pathways, with SO4•− and •OH radicals being the dominant species. Density functional theory (DFT) calculations explained the superior catalytic performance of complex 4 compared to complex 3.

Photoactivated Anticancer Activity of Cobalt(III) Complexes with Naturally Occurring Flavonoids Chrysin and Silibinin.

Photoactive metal complexes of bioessential transition metal ions with natural chelators are gaining interest as photocytotoxic agents for cancer photodynamic therapy (PDT). We report six new cobalt(III) complexes with a mixed-ligand formulation [Co(B)2(L)](ClO4)2 (Co1-Co6), where B represents a N,N-donor α-diimine ligand, namely, phenanthroline (phen; Co1, Co2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq; Co3, Co4), and dipyrido[3,2-a:2',3'-c]phenazine (dppz; Co5, Co6), and L is the monoanionic form of the naturally occurring flavonoids chrysin (chry; Co1, Co3, Co5) and silibinin (sili; Co2, Co4, Co6). Complexes displayed a d-d absorption band within 500-700 nm and exhibited excellent dark and photostability in solution. Cytotoxicity studies indicated significant activity of Co5 and Co6 against cervical (HeLa) and lung (A549) cancer cells under visible light (400-700 nm) irradiation giving low micromolar IC50 values (2.3-3.4 μM, phototoxicity index~15-30). The complexes demonstrated notably low toxicity against normal HPL1D lung epithelial cells. Flow cytometry assay revealed an apoptotic mode of cell damage triggered by the complexes when irradiated. ROS generation assay indicated the involvement of singlet oxygen species in the cell death mechanism when irradiated with light. Overall, complexes Co5 and Co6 with coordinated dipyridophenazine and flavonoid ligands are potential candidates for cancer PDT applications.

Putting the squeeze on valence tautomerism in cobalt-dioxolene complexes

Molecules that can reversibly switch between electronic states under an external stimulus are of interest to numerous applications. Complexes of open shell metal ions with redox active ligands undergo valence tautomerism, resulting in magnetic, colour and structural switching, relevant to data storage and actuators. However, the precise structural changes occurring during valence tautomerism in the solid state are unclear due to the lack of atomic-resolution characterization. Here, variable temperature and high-pressure single crystal X-ray diffraction is used to characterize valence tautomerism in two isostructural cobalt complexes, [Co(bis(6-methyl-2-pyridylmethyl) amine)(3,5-di-tert-butyl-1,2-dioxolene)]+ and [Co(tris(6-methyl-2-pyridylmethyl)amine)(3,5-di-tert-butyl-1,2-dioxolene)]+ to atomic resolution. The less sterically hindered dimethylated complex exhibits two-step thermally-induced interconversion between the high-spin CoII-seminquinonate and low-spin CoIII-catecholate forms (valence tautomerism) at 155 and 95 K due to the presence of two symmetry-independent complexes. In contrast, the more sterically hindered trimethylated complex does not display thermal valence tautomerism. Both complexes exhibit unique behaviour under high pressure. The dimethylated species undergoes gradual, one-step valence tautomerism in both symmetry-independent complexes concurrently between 0.43 GPa and 1.30 GPa. In the trimethylated species, pressure is sufficient to overcome steric hindrance, leading to one-step valence tautomerism between 2.60 GPa and 3.10 GPa, demonstrating pressure-triggered valence tautomerism in a thermally inactive complex. This study is among the few investigations using in situ high-pressure single crystal X-ray diffraction to achieve atomic-level structural characterization of valence tautomerism, aiding the development of robust structure-property relationships in these types of complexes.

Hybrid Silica Cage-Type Nanostructures Made from Triply Hydrophilic Block Copolymers Single Micelles.

Controlling the structure and functionality of porous silica nanoparticles has been a continuous source of innovation with important potential for advanced biomedical applications. Their synthesis, however, usually involves passive surfactants or amphiphilic copolymers that do not add value to the material after synthesis. In contrast, polyion complex (PIC) micelles based on hydrophilic block copolymers allow for the direct synthesis of intrinsically functional hybrid materials. While most previous studies have focused on bulk materials made from double-hydrophilic block copolymers (DHBC), in this work we have synthesized a triple-hydrophilic block copolymer (THBC) and demonstrated both its PIC micellization and its potential for hybrid mesoporous silica nanomaterials. Introducing this THBC has allowed to direct the transition from bulk three-dimensional (3D) materials to zero-dimensional (0D) nanomaterials with cage-type structures. The stabilization and isolation of these nanostructures formed around discrete individual micelles has been made possible by the careful design of the three different blocks that each play a key role. These nanostructures could also be synthesized from hybrid PIC micelles based on THBC-multivalent metal ions complexes, offering a direct route to metal/silica composite nanoparticles. This class of THBC polymers therefore creates significant opportunities for the synthesis of nanostructures with complex and functional architectures.

Biomineralized Nuclear Receptor Protein-Selection Mass Spectrometry for the Discovery of Drugs and Toxics.

Protein-selection mass spectrometry is cost-effective for the discovery of drugs and toxics. Nuclear receptors (NRs) are major targets for pharmaceuticals and endocrine-disrupting chemicals and are, thus, widely used as "bait" proteins. However, their application is limited due to the tendency to lose protein activity during cold storage. To address this problem, we introduced a novel biomineralization-based approach to preserve activity in NRs, exemplified by human retinoic acid receptor alpha (hRARα), a target for cancer and leucocythemia therapy. Since information on the coordination chemistry of metal ion and NR protein complexes is almost unavailable, we applied peptide mapping analysis for the first time for the rational design of his-hRARα-Co phosphate nanobiomaterial with high bioactivity. This nanobiomaterial successfully captured hRARα bioactive chemicals from a Chinese herb and environmental water and discovered an unsaturated fatty acid, (±)-(9Z,11E)-13-hydroxy-9,11-octadecadienoic acid ((±)13-HODE), which exhibited strong hRARα antagonistic activity.

A new insight on the effects of Schiff Base Iron (III) complexes in breast cancer cells for clinical radiotherapy

PurposeBreast cancer is a significant global health concern, and researchers strive to enhance radiotherapy outcomes while minimizing the side effects. Schiff Base Iron (III) Complexes are one of the prospective elements that can be used as radiosensitizer or radioprotective agents in cancer radiotherapy. This study investigates the potential effects of Schiff base (ligand 2; L2) with Fe(III) in MCF-7 breast cancer cells under clinical radiotherapy treatment. MethodsThe effects of the Schiff Base Iron (III) Complexes were measured using clonogenic assay with MCF-7 breast cancer cells. The cells were irradiated with megavoltage 6 MV photon, 6 MeV electron and high dose rate (HDR) brachytherapy with 192Ir source at different doses. Intercellular localization of Fe(III)-L2 complexes and antioxidant activities were also investigated. ResultsThe Fe(III)-L2 complexes were observed to be internalized by cellular nuclei without any effects on the cells. Interestingly, the Fe(III)-L2 complexes indicate radioprotective effects which provide intriguing insight towards application of metal ions complexes as radioprotector in cancer radiotherapy. The Fe(III)-L2 complexes also exhibit scavenging activities of free radical which further proved the antioxidative properties and radioprotective effects. ConclusionThe Fe(III)-L2 complexes show the radioprotective effects and antioxidant properties in MCF-7 cells, particularly for HDR brachytherapy. The findings suggest potential applications of the Fe(III)-L2 complexes as radioprotector agents in clinical radiotherapy.

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.

Preparation, Identification And Biological Activity Of Some Metals Complexes With A New Ligand (4-Nitro-N-((6-Oxo-6,9-Dihydro-1H-Purin-2-Yl)Carbamothioyl)Benzamid)

This study aimed to synthesize and characterize a novel guanine derivative, namely ( 4-nitro-N-((6-oxo-6,9-dihydro-1H-purin-2-yl)carbamothioyl)benzamid) (abbreviated as NPBL4). This compound possesses an intriguing chemical structure, consisting of a guanine moiety (a bicyclic heterocyclic base) linked to a benzamide group through a carbamothioyl linker. The synthesis of this nitrogenous base derivative involved two steps. Firstly 4-nitro-N-thioformylbenzamide was synthesized by reacting 4-nitrobenzoyl chloride with ammonium thiocyanate in acetone. Subsequently, the obtained 4-nitro-N-thioformylbenzamide was reacted with guanine to yield the desired ligand. In addition to the ligand synthesis, the study focused on preparing complexes of various metal ions (Mn+2, Co+2, Ni+2, Cu+2, Zn+2, Cd+2, and Pd+2) with the prepared guanine derivative. The ligand and complexes were subjected to comprehensive characterization using techniques such as infrared spectra, ultraviolet-visible spectra, 1H-NMR, 13C-NMR spectra, elemental analysis (C.H.N.S.), molar conductivity measurement, magnetic susceptibility, atomic absorption, melting point determination, and study the biological activity for the complexes. The results of these characterization studies led to the determination of the general formulas for the prepared complexes, which were found to be [MCl2(NPB)2], where M represents the respective metal ion (Mn+2, Co+2, Ni+2, Cu+2, Zn+2, Cd+2, and Pd+2). Notably, the geometric shape of all the prepared complexes was determined to be an octahedron. In summary, this study successfully synthesized and characterized a novel guanine derivative (NPB) and investigated its complexes with various metal ions. The findings provided valuable insights into the chemical properties and structural features of these compounds.

Design, synthesis, and evaluation of some metal ion complexes of mannich base derived from 2-Mercaptobenzimidazole as potential antimicrobial agents

This study aims to prepare new compounds and investigate them spectroscopically and biologically against selected types of positive and negative bacteria and fungi to demonstrate their biological effectiveness. The prepared ligand combining formaldehyde, indole, sulfa benzamide, and 2-mercapto benzimidazole, a Mannich base ligand (L) was synthesized. The six metal ions including Cobalt (II), Nickel (II), Copper (II), Palladium (II), Platinum (IV), and gold (III) have interacted with the ligand and formed new complexes. Different spectroscopic methods, including C.H.N.S., FTIR, UV- Range visible, 1HNMR, 13CNMR, mass spectra, magnetic moment, and molar conductivity were used to suggest the new geometry of the complexes. The result from the infrared spectrum showed that the ligand behaves as tridentate with all prepared complexes. Conductivity analysis revealed the electrolytic nature of palladium, platinum, and gold ions complexes and non-electrolytes. The antibacterial activity of the compounds that were produced was tested using an agar-well diffusion procedure towards two strains of gram-positive as well as two strains of gram-negative bacteria and fungi (Staphylococcus, Streptococcus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans) respectively at 0.02M. The standard (∆Eo) and (∆Hfo) of ligand and six complexes were calculated using the program Hyper chem 8.0.7. The research established that complexes are more stable than ligands. Calculated HOMO and LUMO and vibration frequencies using (parametric method 3 (PM3)) to find out the active sites in the ligand showed that they can coordinate and note the extent to which the results of theoretical vibrational frequencies are close to the process when calculating the vibrational frequency of the active aggregates.

Inaccuracy principle and dissolution mechanism of lithium iron phosphate for selective lithium extraction from brines

The electrochemical lithiation/delithiation (ELD) method with the typical active materials being LiFePO4 and LiMn2O4, is the next generation technique for the selective lithium extraction from slat-lake brines owning to the advantages of high selectivity and excellent capacity and feasibility. However, the dissolution of LiFePO4/FePO4 (LFP/FP) during the ELD is seldom studied and an inaccurate measurement method for dissolution may result in obtaining an incorrect feasible application range for LFP/FP. Here, electrochemical workstation-electrochemical quartz crystal microbalance (EW-EQCM) is first utilized in the brine system to acquire the in-situ dissolution behavior of LFP/FP redox couple and verify the inaccuracy principle of the dissolution measurement. Both experimental results and thermodynamic calculations demonstrated that the accurate dissolution ratios can only be obtained by iron ions and phosphates at pH < 2.7 and pH < 5.3, respectively, which is induced by the narrow soluble range of iron ions and the formation of Ca5(PO4)3OH and Mg3(PO4)2 precipitation. In addition, the stable pH range of LFP and FP is 4 to 10 and 3 to 5, respectively, and the dissolution is caused by the formation of thermodynamically more stable metal ions, metal ion complexes, and metal ion hydroxides. At the optimum pH, the capacity can maintain 35 mg/g with average dissolution ratios of the cathode and anode lower than 0.1 %. This research sheds light on the accurate dissolution measurement range and method, dissolution mechanism and feasible application range of the LFP/FP redox couple.