Metal Ion Complexes Research Articles

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.

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.

Elucidation of DNA binding properties of transition metal ion complexes of curcumin: An In Vitro study

Introduction: The present work aims to synthesize, characterize, and DNA binding properties of copper, nickel, zinc, and iron complexes of a well-known polyphenol drug curcumin. The metal ion complexes of curcumin's synthesized transition metal ion complexes were characterized by UV-vis spectroscopy and FTIR. Method: The complexation of curcumin with transition metal ion complexes changes the color of the curcumin based on the metal incorporated. Moreover, the shift in the absorption maxima of curcumin metal ion complexes may confirm the formation of coordination complexes. Then, FTIR results indicated that the coordination of curcumin with metal ions in the ketone group of curcumin confirms the formation of 1:2 (M: L) complexes. Results: Then, we evaluated the DNA binding properties of synthesized metal ion complexes of curcumin using electronic absorption spectra and agarose gel electrophoresis. The results indicated that the curcumin zinc complex exhibited less DNA binding constant among the four metal ion complexes than all the other compounds tested, confirming its weak interaction. Conclusion: Moreover, all the compounds degrade plasmid DNA, confirming their DNA cleavage activity. From our findings, these compounds will pave the way for developing new anticancer drugs with less toxicity.

Henkel‐like Decarboxylation Produces Mononuclear Arylalkalis, [4‐(CH3)3N(C6H4)M]+ which Hydrolyse and Undergo Surprising SN2 Reactions Between Alkali Hydroxides and (CH3)3NC6H5+

AbstractBenzoate substituted with a cationic quaternary ammonium group at the para‐position, [4‐(CH3)3N(C6H4)CO2], forms mononuclear alkali metal ion complexes, [4‐(CH3)3N(C6H4)CO2M]+ (M=Li, Na, K, Rb and Cs), which are observed by electrospray‐ionisation mass spectrometry. When mass selected and subjected to collision‐induced dissociation each of these complexes undergoes decarboxylation to produce the mononuclear arylalkali complex cations, [4‐(CH3)3N(C6H4)M]+, which subsequently react with water via hydrolysis to yield the quaternary ammonium cation, (CH3)3NC6H5+. The unexpected product ions, [M((CH3)2NC6H5)]+, [M(CH3OH)]+, and M+, which are associated with the hydrolysis pathway, suggest an unusual reaction occurring within the exit channel ion‐molecule complex, [(CH3)3NC6H5+MOH]+. DFT calculations were used to examine the: decarboxylation reaction of [4‐(CH3)3N(C6H4)CO2M]+, which readily proceeds via a four‐centred transition state; the hydrolysis and SN2 reactions accounting for formation of products in the exit channel, which are connected via a roaming mechanism in which the metal hydroxide moiety migrates from the para‐hydrogen of (CH3)3NC6H5+ to one of the methyl groups.

Resistive random access memory based on organic-metallic hybrid polymer

Abstract Resistive random access memories (ReRAMs) based on an organic-metallic hybrid polymer, Poly(Fe-btpyb) Purple, were fabricated. This material was synthesized by complexation of metal ion and organic ligand. When applying forward bias, an abrupt resistance change from a low resistance state (LRS) to a high resistance state (HRS), which is known as reset process, was observed. In contrast, a reverse bias switched the resistance from HRS to LRS (set process). The resistive switching phenomenon is probably caused by the electrochemical oxidation-reduction reaction of the metal ion (Fe(II)/Fe(III)). The nonvolatile memory characteristics were measured with data-retention tests, showing no significant degradation over 105 s. The endurance characteristics exhibited sufficient long-term durability, due to no conformational change of the organic ligand. It is proposed that the difference in charge-transfer efficiency between the reduced state (Fe(II)) and oxidized state (Fe(III)) might be the physical mechanism of the resistive switching.

Synthesis, diagnosis as well as Biological activity studies of some metal ion complexes of Schiff Bases Derived from 4-aminoantipyrine

قواعد شيف متعددة السن ذوات الصيغة L1= اورثو هايدروكسي انيلين -٤ - امینو انتبيرين N',N) بنزیلیدین) تم تحضيرها من تكثيف البنزايل و٤-امينو انتيبرين مع ۲-امينو فينول -۲،۱ امينو ٤ كلورو فينول بنسبة مولية (١:١:١) لكل مكون . واستخدمت هذه الليكاندات لتحضير المعقدات ذوات الصيغة [ML1 Cl]Cl و [ML2]Cl2 حيث ان Zn(II) M= Mn(II), Co(II), Ni(II),. تم استخدام التقنيات التالية لتشخيص الليكاندات والمعقدات: مطيافية الاشعة فوق البنفسجية والاشعة تحت الحمراء - المرئية وطيف الرنين النووي المغناطيسي للبروتون 1HNMR والتحليل الدقيق لايونات العناصر والكاربون والهيدروجين والنتروجين بالاضافة الى التوصيلية الكهربائية المولارية وقياسات الحساسية المغناطيسية. دلت القياسات التي تم الحصول عليها من التوصيلية الكهربائية المولارية والتي تم اجراؤها بمحلول DMSO ان جميع معقدات (L1) كانت الكتروليتية بنسبة (١:١) بينما معقدات (L2) كانت الكتروليتية بنسبة (1:2). كما اظهرت نتائج القياسات المستخدمة في هذه الدراسة ان مواقع التناسق لليكاند (L1) مع الأيون المركزي كانت من خلال ذرة الاوكسجين الفينولية وذرتين نيتروجين لمجموعتي الازوميثين اما بالنسبة لـ (L2)فبالاضافة للذرات المانحة المذكورة سابقا يتم التناسق مع ذرة الاوكسجين لمجموعة الكاربونيل الطرفية. جميع المعقدات اظهرت التناسق الرباعي بشكل هندسي رباعي السطوح ايضا تمت دراسة الفعالية البايولوجية للمركبات المحضرة ضد البكتريا موجبة الكرام (+)Staphylococcus aurous وسالبة الكرام (-) Klebsiella pneumonia.

Synthesis of some metal ion complexes of new imidazole derivative, characterization, and biological activity

Imidazole complexes with high biological activity for some metal complexes prepared by a new imidazole ligand from the reaction of a 1,3-oxazole derivative with hydroxylamine and utilizing this ligand in the preparation of some metal ion complexes. Many of the techniques available for all prepared compounds, such as elemental analysis (CHNS), (FT-IR), (UV-Vis) spectra, and 1H-NMR spectra, will be used in the diagnosis of these complexes, and the forms of the complexes will be deduced from the results obtained. The outcomes demonstrated that the octahedral geometries of all the produced complexes, except for the copper and palladium complexes, which were square planer shapes. The antimicrobial activity of both the ligand and its metal ionic complexes against various microbes was evaluated. KEY WORDS: Imidazole, Oxazole, Spectral data, Bioactivity Bull. Chem. Soc. Ethiop. 2024, 38(6), 1681-1690. DOI: https://dx.doi.org/10.4314/bcse.v38i6.14

Spectral studies of a selenium(IV) vitamin B3 compounds prepared in the form of nanometer using simple chemical reactions to further use as antioxidant in the preparation of drugs

The current study dealt with selenium metal ion complexes with mixed ligands, consisting of nicotinamide (vitamin B3) as the first ligand, and amino acids such as (histidine, tryptophan, and tyrosine) as the second ligand. It was synthesized in (1:1:1) (selenium: vitamin: amino acid) in molar ratio. By using different characterization techniques such as elemental analysis, the conductance, FTIR, XRD, UV-Vis, TG/DTG, 1H-NMR, XRD, SEM, TEM analyses, the chemical structures and the morphological properties of the synthesized complexes were checked and discussed. The nicotinamide was coordinated as monodentate ligand via the nitrogen of pyridine ring but all amino acids as a secondary ligand coordinated as bidentate through oxygen of carboxylic group and nitrogen of amino group. The complexes demonstrate antioxidant activity with potent scavenging property, the synthesized in the form of nanometer give great importance in increasing efficiency of absorption of human cells to selenium giving the highest efficiency of medical product. All complexes in this study were evaluated for their anticancer effect towards HepG2 and A2780 cell lines. From these data the complex (Se/Nia/ Tyr) can be used as antitumor agents. KEY WORDS: Selenium, Amino acids, Vitamin B3, Mixed ligand, Complexes, Antioxidant Bull. Chem. Soc. Ethiop. 2024, 38(6), 1759-1774. DOI: https://dx.doi.org/10.4314/bcse.v38i6.20

Novel utilization exploration for the dephosphorization waste of Ca–modified biochar: enhanced removal of heavy metal ions from water

Phosphorus-modified biochar has been proven to enhance the precipitation and complexation of heavy metal ions from wastewater. However, the current modification methods require large amounts of exogenous P and have high energy consumption. Hence, this study proposes and analyzes a strategy integrating biochar production, phosphorus wastewater treatment, dephosphorization waste recovery, and heavy metal removal. “BC-Ca-P” was derived from Ca-modified biochar after phosphorus wastewater treatment. The adsorption of Pb(II) by BC-Ca-P followed the Langmuir isotherm and pseudo–second–order kinetic models. The maximum adsorption capability of 361.20 mg·g−1 at pH 5.0 for 2 h was markedly greater than that of external phosphorous-modified biochar. The adsorption mechanisms were dominated by chemical precipitation and complexation. Furthermore, density functional theory calculations indicated that oxygen-containing functional groups (P-O and C-O) contributed the most to the efficient adsorption of Pb(II) onto BC-Ca-P. To explore its practical feasibility, the adsorption performance of BC-Ca-P recovered from an actual environment was evaluated. The continuous-flow adsorption behavior was investigated and well-fitted utilizing the Thomas and Yoon–Nelson models. There was a negligible P leakage risk of BC-Ca-P during heavy metal treatment. This study describes a novel and sustainable method to utilize dephosphorization waste for heavy metal removal.Graphical

Synthesis, Characterization, and Study of the Antimicrobial Activity for Complexes of Metal ions (Cu+ 2, Co+ 2, and Ni+ 2) Derived from Ligands of Schiff Bases

Synthesis, Characterization, and Study of the Antimicrobial Activity for Complexes of Metal ions (Cu+ 2, Co+ 2, and Ni+ 2) Derived from Ligands of Schiff Bases

From +I to +IV, Alkalis to Actinides: Capturing Cations across the Periodic Table with Keggin Polyoxometalate Ligands.

Coordination chemistry trends across the periodic table are often difficult to probe experimentally due to limitations in finding a versatile but consistent chelating platform that can accommodate various elements without changing its coordination mode. Herein, we present new metal/ligand systems covering a wide range of ionic radii, charges, and elements. Five different ligands derived from the Keggin structure (HBW11O398-, PW11O397-, SiW11O398-, GeW11O398-, and GaW11O399-) were successfully crystallized with six different cations (Na+, Sr2+, Ba2+, La3+, Ce4+, and Th4+) and characterized by single-crystal X-ray diffraction. Twenty-five new compounds were obtained by using Cs+ as the counterion, yielding a consistent base formula of Csx[M(XW11O39)2]·nH2O. Despite having a similar first-coordination sphere geometry (i.e., 8-coordinated), the nature of the central cation was found to impact the long-range geometry of the complexes. This unique crystallographic data set shows that, despite the traditional consensus, the local geometry of the cation (i.e., metal-oxygen bond distance) is not enough to depict the full impact of the complexed metal ion. The bending and twisting of the complexes, as well as ligand-ligand distances, were all impacted by the nature of the central cation. We also observed that counterions play a critical role by stabilizing the geometry of the M(XW11)2 complex and directing complex-complex interactions in the lattice. We also define certain structural limits for this type of complex, with the large Ba2+ ion seemingly approaching those limits. This study thus lays the foundation for capturing the coordination chemistry of other rarer elements across the periodic table such as Ra2+, Ac3+, Bk4+, Cf3+, etc.