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Abstract A method was developed for preparing high purity Al 30 O 8 (OH) 56 (H 2 O) 24 18 + (Al 30) through elimination of impurities by complexation. Polyaluminum chloride II (PAC 30) with Al c content of 75% was adopted as the source of Al 30. The PAC 30 was prepared under conditions of total aluminum concentration 0.1 mol/L and OH−/Al ratio 2.2 to obtain the highest content of Al 30. A precipitation/metathesis method, organic solvent precipitation method and organic complexation method were examined to separate and purify Al 30. It was found that only by the organic complexation method could high purity Al 30 products be obtained in large yield economically. In the experiments, benzoic acid was used as the coordinating reagent to decompose the main impurity AlO 4 Al 12 (OH) 24 (H 2 O) 12 7 + (Al 13), and the Al 30 product could be obtained by precipitation and metathesis operations. It was noteworthy that the decomposition of impurities by benzoic acid could be completed in 2 hr. The Al 30 product was characterized by Ferron assay, 27Al-NMR, SEM, XRD and TGA. The results showed that the purity of the Al 30 product could exceed 92%. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract This paper describes the guest-host complex formation of anthranilic acid (2-aminobenzoic acid, AA) and different natural and modified cyclodextrins (CDs), using steady state fluorescence. The experimental data point to the formation of 1:1 inclusion complexes with natural (ß and ɣ-CD) and modified (HP-ß, HE-ß and M-ß-CD) CDs. Of the natural CDs, the ß-CD complex showed the highest encapsulation constant (K F) value (14056 ± 1241 M−1). However, modified ß-CDs showed higher binding constants than ß-CDs. Of the modified CDs, M-β-CD showed the highest K F (18622 ± 897 M−1). To gain information on the encapsulation process of M-ß-CD/AA, the thermodynamic parameters of the complexation (ΔH, ΔS and ΔG), were studied. The results showed positive entropy (66 ± 7.9 J mol−1 K−1), negative enthalpy (−5.74 ± 2.96 kJ mol−1) and a change in Gibbs free energy at 25 °C (−24.30 ± 0.27 kJ mol−1). Finally, a computational study carried out using molecular docking simulations showed the high correlation between experimental values and computed scores. The complexation of M-ß-CD/AA depends on several physicochemical factors including temperature and pH. The values of K F exhibited a strong negative relation with temperature and pH. Moreover, the interaction of AA and M-ß-CD was most effective in the pH region where the molecule presents intramolecular hydrogen bonds that neutralize the charge of the protonated species of AA. Graphical abstract Image 108662 Highlights • Inclusion complexation of anthranilic acid with methyl beta cyclodextrin. • Stoichiometry of complexation is 1:1. • The binding constant decreases linearly with increasing temperature. • Anthranillic acid MbCD compleixation constant is higher below pKs region. [ABSTRACT FROM AUTHOR]

• The mixture precursors of Acorus calamus Linn. and feather waste were used for biochar preparation. • The adsorption capacity of biochar for Cr(VI) is enhanced 40%. • It promotes a cleaner production for biochar. • The adsorption mechanism of Cr(VI) by Mix-BC were explained by FTIR and XPS techniques. As an initial attempt, the biochars were prepared from the mixture precursors of Acorus calamus Linn. and feather waste to enhance the physicochemical properties and adsorptive performance of Cr(VI). The biochars were characterized by N 2 adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), elemental analysis and Boehm titration. The newly prepared biochar were produced to have increased microporous structures and functional groups, and consequently, exhibited an improved adsorption capacity for Cr(VI) (i.e., 20% higher than that of traditional biochar). The adsorptive mechanisms of Cr(VI) included porous filtration, ion exchange, electrostatic attraction, complexation reaction, and most importantly, the reduction of Cr(VI) to Cr(III). [ABSTRACT FROM AUTHOR]

Magnetic iron oxide nanoparticles in humic substances shell - Fe 3-δ O 4 @HS were synthesized by oxidative in situ method in aqueous solutions of humic substances from metallic iron precursor. Humic substances interacting with metallic iron under natural conditions act as a complex reagent that participates in acid-base, redox, complexation reactions and adsorption processes. The Fe 3-δ O 4 @HS particles is the final product of corrosion of metallic iron in the presence of HS. Products were characterized by dynamic light scattering, scanning and transmission electron microscopy, X-ray powder diffraction, Mössbauer spectroscopy, magnetometry, infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and evolved gas analysis. It was demonstrated that the samples contained particles with sizes of 40–50 nm comprised of ∼24 nm magnetite-like crystalline cores coated by humic substances. The synthetic approach used in this article can be used as a model of corrosion processes of ferrous metals in nature. In addition, magnetite-like nanoparticulates stabilized with humic substances can be promising as bioavailable iron additives for agricultural applications. Image 1 • Corrosion of metallic iron in the presence of humic substances was studied. • Humic substances as acid-base, redox, chelation, and surface-active agents. • Core of magnetic iron oxide nanoparticles in humic substances shell. • Green Chemistry method for the synthesis of magnetic nanoparticles are present. • This method is marked by good reproducibility and lack of reaction by-products. Magnetic iron oxide nanoparticles for agricultural applications can be obtained by the simple interaction of metallic iron with aqueous solutions of humic substances. [ABSTRACT FROM AUTHOR]

This study aims to investigate the adsorption behavior and mechanism of Cu(II) over microwave-assisted titanate nanotubes (MTNTs, NaxH2−xTi3O7). The effect of power level of microwave irradiation during MTNT synthesis on the adsorption mechanism is also examined. Regarding the adsorption potential of Cu(II) over MTNTs, more than 80% of Cu(II) is removed within the first minute, and the adsorption equilibrium is reached by half an hour. The adsorption capacities of MTNTs obtained from Langmuir model fall in the range of 1.86–2.46 mmol g−1. According to the characterizations including ICP–AES, XRD, FT–IR/DRIFT, XPS, and H2-TPR, the amount and binding intensity of intercalated Na+ within MTNTs, which are greatly dependent upon the power level of microwave irradiation during MTNT synthesis, dominate the adsorption kinetics, the adsorption capability, the adsorption stabilization, and the extent of copper complexation. An adsorption mechanism is also proposed such that ion exchange process and complexation reaction are both involved in the Cu(II) adsorption over MTNTs. [ABSTRACT FROM AUTHOR]

The ternary complexation of calcium uranyl tricarbonate species, CaUO2(CO3)32− and Ca2UO2(CO3)3(aq), which are the predominant U(VI) complexes in groundwater and seawater, was investigated at variable temperatures from 10 to 70 °C. Time-resolved laser fluorescence spectroscopy (TRLFS), calcium ion-selective electrode potentiometry, and ultraviolet/visible (UV/Vis) absorption spectroscopy were complementarily employed to determine the formation constants (log Kx13, x = 1 and 2 for mono- and dicalcium complexes, respectively). at infinite dilution (zero ionic strength) was determined by correction using specific ion interaction theory (SIT), and an increasing tendency of with temperature was observed. In addition, the molar enthalpy of complexation (ΔrHm) was measured by calorimetry at 25 °C. Based on thermodynamic data obtained in this work, the approximation models were examined for the prediction of the temperature effect on the complexation, and the constant enthalpy approximation with the chemical complexation reaction modified to an isoelectric reaction showed a satisfactory prediction of in the temperature range of 10–70 °C. Finally, the results of U(VI) speciation in groundwater indicated that the dominance of calcium uranyl tricarbonate complexes would be weakened at elevated temperatures by the strongly enhanced hydrolysis of U(VI). [ABSTRACT FROM AUTHOR]

In this work, a thermodynamic study of the Zn(II)/L systems (L− = acetate, AcO− or indomethacin anion, Indo− or diclofenac anion, Dic−) in ethanolic solution was carried out by isothermal titration calorimetry (ITC). Thermodynamic properties such as enthalpy (∆H), entropy (ΔS), Gibbs energy (ΔG) and formation constant (reported as logβi) associated with the complexation reactions were determined; the stoichiometry of the formed species was also found. Zn(II)/AcO− was used as a model system for the complexation of Zn(II) with indomethacin and diclofenac anions, because all of them coordinate through the carboxylate functional group. To determine the thermodynamic properties of each system under study, from the experimental results, a binding model has been devised to calculate the heat Qcalc that is released or absorbed in terms of the molar ratio r L/Zn II in the complexation process between Zn(II) and L−. Calculated data (Qcalc) are adjusted to the ITC experimental results (Qexp), by means of MicroCal PEAQ-ITC analysis software to determine the enthalpy and formation constants of the MLj(2−j) formed complexes. Distribution diagrams of the fractions of the M and L species were obtained as a function of the molar ratio to discuss the predominance of the species in the systems as the titration was carried out. [ABSTRACT FROM AUTHOR]

A better understanding of adsorption mechanism is vital for the effective reduction of tungsten mobility and potential human health risk such as its suspected link to the childhood leukemia clusters. This study investigated tungstate (WO42-) adsorption characteristic onto montmorillonite under environmentally relevant solution properties such as the influence of reaction time, solution pH, initial concentration, the competitive anion (PO43-), and ionic strength. The results of the adsorption isotherm studies suggested that both the Langmuir (R²= 0.9117) and Freundlich (R²= 0.9913) equations can be well consistent with WO42- adsorption process and the maximal WO42- adsorption capacity was 26.73 mmol kg-1. The amount of WO42- adsorbed onto montmorillonite strongly dependent on pH and slightly dependent on ionic strength. Specifically, WO42- adsorption reached the maximum (17.41 mmol kg-1) at pH 4.15, but becoming negligible (<10%) when pH increase above 9. PO43- competed for adsorption sites on montmorillonite with WO42-. The results of this study indicated that the adsorption mechanism of WO42- onto montmorillonite involved ion exchange, inner-sphere surface complexation reaction, and electrostatic attraction. Collectively, our study will aid the understanding of tungsten fate and these results suggest that montmorillonite can be advantageous to the adsorption and recovery of tungsten from real wastewater. [ABSTRACT FROM AUTHOR]

Density functional theory calculations, using the B3LYP parameterisation, were performed to determine structures, vibrational frequencies, and binding energies for complexation of Ni+ and Ni2+ cations with benzene and naphthalene molecules and clusters. The calculations employed the Stuttgart basis set with ECP pseudo potentials for the Ni cations and basis sets of at least triple ζ plus polarisation, and diffuse quality for C and H. The effect of electron correlation on non-bonded interactions was accounted for by the Grimme GD3 dispersion correction. Counterpoise computations were made for BSSE. Comparison between experiment and theory provide fascinating new insight into the bonding for these prototypical organometallic (OM) complexes. These structures have a sandwich topology, indicating major structural reorganisations occuring when benzene or naphthalene interact with Ni cations. Adiabatic electron affinities and ionisation potentials agree well with experiment when available. Binding energies were also determined, providing insight into the stability of the complexes. The results presented here provide important information for future studies to address additional investigations of both problems of the electronic structure properties of these complexes, as well as the role of the polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM) and soot formation in combustion. The Ni+/Ni2+ + aromatic organometallic bonding is of the same order of stability as an aromatic C–H bond. Such bonding modifies the IR spectrum of the complexed aromatic molecules by enhancing the 3.3 μm feature and decreasing the C–H bands in the 11–12 μm range (γ C–H). Organometallic complexation reactions may contribute significantly to metal depletion in the ISM. [ABSTRACT FROM AUTHOR]

Abstract This study aims at the further expansion of knowledge on the antimicrobial activities of the tetramic acid moiety and the effect of metal complexation. Complexes of the N -acetyl-3-acetyl-5-benzylidenetetramic acid with Mn, Co, Ni, Cu, Zn and Cd were synthesized and screened against 5 key ESKAPE pathogens (Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa) and 2 fungi (Cryptococcus neoformans and Candida albicans). The cadmium complex was found to effectively inhibit the fungus Cryptococcus neoformans with minimum inhibitory concentration (MIC) of 8 μg/mL, with no human cell toxicity and hemolytic activity within the tested concentration range. The biologically active tetramic acid‑cadmium complex was structurally characterized by single-crystal X-ray analysis. Furthermore, the thermal stability of the ligand and the complexes was investigated along with NMR and EPR studies of the Cd(II) and Co(II) complexes respectively. Graphical abstract A series of metal(II)-tetramic acid complexes was synthesized and investigated for antimicrobial activities. The novel compounds were structurally characterized by single-crystal X-ray, NMR, EPR, UV and thermogravimetric (TG) analyses. The Cd(II) complex displayed effective inhibition activity against Cryptococcus neoformans , being at the same time non-cytotoxic and non-hemolytic. Unlabelled Image Highlights • Synthesis of four novel metal(II) complexes of a 5-benzylidene tetramic acid • EPR studies of the Co(II) complex • Cd(II) complex displayed high antifungal activity against Cryptococcus neoformans. • The active Cd(II) complex was found to be non-toxic and non-hemolytic. • Single-crystal X-ray analysis of the bioactive Cd(II) complex [ABSTRACT FROM AUTHOR]

Abstract Owing to its excellent mechanical properties, processability, and biodegradability, poly(lactic acid) (PLA) has been widely investigated in the past few decades as a biomaterial. However, the poor heat resistance of PLA severely limits its applicability. In this review, several heat resistance modification methods, such as nucleating agent addition, fiber reinforcement, compounding, blending, stereoisomer complexation, and chemical modification, have been reviewed and their related mechanisms have been discussed in brief. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The isothermal titration calorimetry was applied to the complexation of humic acid, which was isolated from deep groundwater. • The complexation thermodynamic quantities of humic acid with copper (II) ions and uranyl (VI) ions were determined. • The unique complexation character of deep groundwater humic acid was revealed by reaction thermodynamics. • Determination of complexation enthalpy of in situ humic substances is helpful for the prediction of radionuclides migration. Abstract Although the thermodynamic quantities (Gibbs free energy, reaction enthalpy, and entropy) of the complexation of humic acid are necessary for the discussion of the reaction thermodynamics, their accurate determination, especially concerning dissolved humic acid in deep groundwater, has not been carried out. In this study, a combination of potentiometry and calorimetry was used for the determination of the thermodynamic values of complexation of typical humic acid and groundwater humic acid, which was isolated from deep groundwater at Horonobe, Hokkaido, Japan, with copper (II) ions and uranyl (VI) ions. The apparent complexation constant of Horonobe humic acid was independent of the pH of the bulk solution, whereas that of typical humic acid was dependent on the pH. This observation indicates that the polyelectrolyte effect of Horonobe humic acid is negligible because of its relatively small molecular size. In addition, the effect of the heterogeneity of Horonobe humic acid was not significant. Moreover, the complexation enthalpy of Horonobe humic acid was consistent with that of homogeneous poly(acrylic acid), which means the complexation of Horonobe humic acid was not affected by the functional group heterogeneity. Consequently, the unique complexation mechanism of Horonobe humic acid was revealed based on the determined thermodynamic quantities. The migration of radionuclides in the deep underground environment must be affected by these characteristics; thus, the accurate determination of thermodynamic quantities of in situ humic substances is very helpful for the safety assessment of geological disposal, when disposal sites for radioactive waste are chosen. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Incorporating nanochitin into hydrogels greatly improves Cu(II) adsorption ability. • Magnetic microparticles endow hydrogels with remote separation capacity. • Hydrogel's ions adsorption comes from nano/micro-effect and complexation interactions. • Adsorption occurs via the models of pseudo-second-order kinetic and Langmuir isotherm. Abstract In this study, Fe 3 O 4 -nanoparticles-contained polyamide 6 (PA 6) microparticles (FP) were developed by a first dispersion of Fe 3 O 4 -nanoparticles in ε-caprolactam (CL) monomer in the presence of polystyrene (PS) and a subsequent in situ CL open polymerization into PA 6, followed by PS removal. The FP microparticles (as magnetic separation material) and nanochitin (n-CT, as an effective metal-cation natural adsorbent) were then in situ encapsulated into poly(vinyl alcohol)-enhanced chitosan hybrids (PVA/CTS) to form biodegradable nanocomposite hydrogels (FPCC) with magnetic separation ability. The FPCC hybridized hydrogels enabled about 1.7-fold Cu(II) adsorption capacity as compared to the pure PVA/CTS hydrogels with a Cu(II) adsorption value of 38.7 mg/g. More attractively, the adsorption equilibrium could be achieved within 10 min, which is quicker than many previous adsorbents. Furthermore, simulation results indicated that Cu(II) adsorption behaviors of the hybrid hydrogels conform to a pseudo-second-order kinetic model and a Langmuir isotherm model. [ABSTRACT FROM AUTHOR]

In this study, we measured the effect of EPS on Cd and proton adsorption behaviors by measuring the extent of adsorption onto biomass with and without the EPS removed via a cation exchange resin. We conducted both Cd adsorption experiments and potentiometric titrations of biomass using three common bacterial species: one Gram-positive (Bacillus subtilis) and two Gram-negative (Shewanella oneidensis, Pseudomonas putida) species. The Cd adsorption experiments were conducted as a function of metal loading in order to probe whether environmentally-low metal loadings lead to different adsorption mechanisms and roles for EPS than the higher metal loadings of most previous adsorption studies. We suspended each biomass sample in a solution of dissolved Cd in 0.01 M NaClO4 at metal loadings of 1, 2, 5, and 74 μmol/g. Surface complexation modeling (SCM) was used to determine stability constants for the important Cd-bacteria complexes, and the effect of metal loading on the resulting calculated stability constant values was determined. In general, the measured bulk Cd adsorption behavior is unaffected by EPS removal. However, our potentiometric titration results suggest that EPS removal does alter the distribution of site types, but not the mass-normalized total site concentration within the biomass. SCM suggests that high affinity sulfhydryl sites control Cd binding under low metal loading conditions for B. subtilis and P. putida, and that sulfhydryl sites are present both on the cells and within the EPS for these species. Conversely, the SCM results suggest that Cd-sulfhydryl binding is un-important on the EPS of S. oneidensis. [ABSTRACT FROM AUTHOR]

Applications of aluminium (Al) salt or lanthanum (La) modified bentonite (LMB) have become popular methodologies for immobilizing phosphorus (P) in eutrophic lakes. The presence of humic substances, has been shown to inhibit this form of treatment due to the complexation with La/Al. However, the effects of other dissolved organic matter (DOM), especially that derived from phytoplankton (the dominant source in eutrophic lakes) are unknown. In this study, the interaction with La/Al of Suwannee River Standard Humic Acid Standard II (SRHA) and algae-derived DOM (ADOM) were investigated and compared. Differed to SRHA which was dominated by polyphenol-like component (76.8%, C1-SRHA), majority in ADOM were protein-like substance, including 41.9% tryptophan-like component (C2-ADOM) and 21.0% tyrosine-like component (C3-ADOM). Two reactions of complexation and coprecipitation were observed between SRHA/ADOM and La/Al. Complexation dominated at low metal inputs less than 10 μM and coprecipitation was the main reaction at higher metal inputs. For ADOM, the tryptophan-like component (C2-ADOM) was the important component to react with metal. The reaction rate for C2-ADOM with La were about two-third of that for C1-SRHA, indicating that the influence of C2-ADOM was significant during the P immobilization by La/Al-based treatment in eutrophic lakes. The P removal data in the presence of ADOM confirmed the significant inhibition of ADOM. In addition, based on the composition of coprecipitates and relatively biodegradable character of tryptophan-like substances (C2-ADOM), the coprecipitation of ADOM was assumed to reduce the stability of precipitated P in eutrophic lakes. The release of P from the potential biodegradation of the coprecipitates and thus the possible decline of the performance of P immobilization by La/Al-based treatments is an important work in the future. Image 1 • Complexation and coprecipitation occurred between SRHA/ADOM and La/Al. • A tryptophan-like component of ADOM complexed strongly with La. • The tryptophan-like component has strong ability to coprecipitate with La and Al. • The behaviors of PARAFAC components explained the inhibitory effect of SRHA/ADOM on P removal. • The stability of coprecipitates of DOM, Al/La and P should be noted. [ABSTRACT FROM AUTHOR]

BACKGROUND Renewable resources have been considered for producing many advanced materials. In this respect, silver‐doped carbon‐based materials with a low loading capacity and high antibacterial activity can also be generated via environmentally friendly routes and from renewable resources. RESULTS: Silver‐doped carbon fibers were prepared from wood and cotton fibers via complexation and reduction reactions for depositing silver on the fibers and subsequently via carbonization of the loaded fibers. Silver loading before carbonization enhanced the stability of silver on the carbonized fibers, decreased silver loss (from 30 to 12%) and lowered the silver loading (5.66%) needed to achieve excellent antibacterial activity. However, wood‐based silver‐doped carbon fibers performed better than cotton‐based carbon fibers with respect to loss of antibacterial activity (12% at a silver loading of 5.66% versus 24% at a silver loading of 7.97% in 800 h respectively). These results are attributed to more uniformity in the distribution of silver nanoparticles in the porous structure of wood fibers than in cotton fibers. CONCLUSION: The wood‐based carbon fibers exhibited better antibacterial activity and stronger affinity for maintaining silver and lower required silver loadings, and the sequence of silver loading and carbonization was crucial in developing silver‐loaded carbon fibers with good antibacterial performance. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract Functional groups in natural organic matter have the potential to interact with and stabilize iron (Fe) redox species (ferric, ferrous) through complexation reactions. In this study, iron complexes with cysteine, arginine and histidine are used to investigate the extent to which specific functional groups present in these amino acids might hinder the oxidation of Fe2+ or promote the reduction of Fe3+. Iron complexes are synthesized by addition of ferrous or ferric salts to cysteine, arginine and histidine solutions at pH 7. The Fe-amino acid complexes are analysed using X-ray Absorption Spectroscopy (XAS), theoretical CTM4XAS (Charge Transfer Multiplet for XAS) calculations, and vibrational spectroscopy (FTIR and Raman). In addition, oxidation of the amino acids is determined by linear sweep voltammetry and chemical equilibrium modeling is used to predict the speciation of Fe in complexes with the amino acids. It is observed the extent of Fe redox transformation is affected by the electron donating capability of the ligand with which Fe reacts. In particular, the extent of Fe3+ reduction is related to the oxidation of the ligand with 80, 14 and 0% Fe3+ reduction by cysteine, arginine and histidine, respectively. Conversely, Fe2+ is preserved by cysteine (80%) > arginine (77%) > histidine (62%). The chemical forms of Fe in these mixed Fe oxidation-state systems include Fe-organic complexes and Fe precipitates. XAS and vibrational spectroscopy indicate thiol-S and amino-N bind Fe in complexes with cysteine. While amino-N and guanidyl-N functional groups of arginine bind Fe, carboxylate-O binding and the formation of Fe precipitates are only observed when Fe3+ is the predominant redox species. Whereas Fe precipitates seem to prevail in Fe(III)-histidine, distinct organic (Fe O/N C) and mineral (Fe O Fe) or mixed organic-mineral (Fe(O/N C) x (O Fe) y) coordination environments occur in Fe(II)-histidine with ∼60% Fe2+; in either case, Fe N(imidazole) binding is not evident. The ligand atoms to which Fe binds and the inherent reduction capacity of the ligand appear to mediate Fe redox transformations. The proportion of ferric iron (Fe3+) seems to determine whether a precipitate forms. Consistent with spectroscopic data, chemical equilibrium modeling using experimental solution conditions and fractional Fe2+ and Fe3+ concentrations obtained from CTM4XAS predict the formation of Fe(II)- and Fe(III)-amino acid complexes and hydrolyzed Fe species; these calculations however also predict the formation of Fe oxide precipitates in all Fe complexes. The results presented in this study help to explain the co-occurrence of Fe2+ and Fe3+ in natural environments where organic matter is present. They also highlight the role specific organic functional groups play on the formation and stabilization of Fe(II, III)-organic complexes and precipitates, and thus on the Fe redox cycle which affects Fe bioavailability and mobility in terrestrial and subsurface environments. [ABSTRACT FROM AUTHOR]

In this study, adding sugar alcohols to the aluminum-water reaction enables the one-step boehmite synthesis with energy savings and cost reduction. The obtained boehmite formed as stacked layers of embroidery, with particle size decreasing as the sugar alcohol concentration increased. The boehmite obtained in the sugar alcohol system possesses a substantial number of pores, a higher density of active sites, and a lower proportion of AlO 6 coordination bonds, exhibiting a specific surface area beyond 100 m2 g−1, greater than the boehmite obtained through the hydrothermal method (3.46 m2 g−1). This study proposes that sugar alcohols undergo a complexation reaction on the aluminum surface, directly forming aluminum oxo complexes (boehmite) without generating an intermediate. Subsequently, boehmite crystal growth preferentially along the (120), (031), and (200) crystal faces. This low-energy and non-polluting method for preparing high-purity (>99.99 %) boehmite with high activity holds significant potential for applications in adsorbents, carriers, and high-performance alumina materials. • One-step synthesis of boehmite in the aluminum-water reaction. • The obtained boehmite (>99.99 %) has a surface area greater than 100 m2 g−1. • Sugar alcohols promote the complexation reaction on aluminum surfaces. • The boehmite exhibits excellent adsorption and flame-retardant properties. • A low-energy and non-polluting method for preparing boehmite. [ABSTRACT FROM AUTHOR]

• Replacing MeOH with AN leads to decrease/increase in the exothermicity formation of [AgPy]+/[AgPy 2 ]+. • Changes in Δ tr H 0(r 1)/Δ tr H 0(r 2) are due mainly to a contribution from starting reagents/reaction products resolvation. • Ions and ligand solvation gives opposite contributions in the thermodynamic characteristics of complex formation reactions. • Solvation effects [Δ tr H 0([AgPy]+) – Δ tr H 0(Py)] and Δ tr H 0(Ag+) are proportional to each other with a coefficient k. • For pairs of «amphoteric – basic» solvents, a correlation between their physicochemical properties and k values was found. In this study, the enthalpies of stepwise complexation reactions between silver(I) ions and pyridine in methanol–acetonitrile mixed solvents (MeOH-AN, with molar fractions of AN varying from 0 to 1) were determined by the calorimetric method at 298.15 K. The analysis of the solvation contributions of the reactants to the alterations in the thermodynamic characteristics associated with the formation of [AgPy]+ and [AgPy 2 ]+ complexes as the solvent composition transitions, i.e. from methanol to its mixtures with acetonitrile (MeOH → χ AN), from methanol to its mixtures with N,N -dimethylformamide (MeOH → χ DMF) and from acetonitrile to its mixtures with dimethyl sulfoxide (AN → χ DMSO) was carried out. The research methodology was based on the provisions of the solvation-thermodynamic approach, based on the relationship between changes in the thermodynamic characteristics of the reactions of complex formation and solvation of reagents with a change in the composition of the solvent. [ABSTRACT FROM AUTHOR]

A series of new benzoxazaborinines was prepared from the salicylaldehyde Schiff bases derived from amino acid esters by a simple complexation reaction between the Schiff bases and boron trifluoride with up to 85 % yield. Single crystal X-ray diffraction studies on 4b further threw light on the three-dimensional structure of the compound. The absorption and emission maxima for all the compounds were observed in the range of 330–353 nm and 435–517 nm, respectively. Compounds 4f and 4l with a tryptophan moiety displayed significantly higher Stokes shifts of 187 and 151 nm respectively, compared with the other derivatives which were in the range of 86–94 nm. Most of the compounds displayed significant quantum yields of up to 80.8 %. The band gaps of the compounds were also calculated by DFT calculations and were found to complement the same calculated by the UV–Vis spectra and were in the range of 2.46–3.93 eV. The tryptophan derivatives, 4f and 4l were found to possess the lowest band gap. [Display omitted] • 12 Novel benzoxazaborinines were prepared by a simple complexation reaction. • Three-dimensional structure of the compound 4b obtained by single crystal X-ray diffraction studies. • All compounds displayed Stokes shifts and significant quantum yields. • The band gap of the compounds was calculated by DFT calculations. [ABSTRACT FROM AUTHOR]

Triethanolamine (TEA) is a widely employed cement accelerator that has been demonstrated to have a favorable impact on the early strength of cement at moderate dosing levels, while having a slight or negative impact on the later strength. This study systematically investigates the hydration pattern and strength development of Portland cement systems with the incorporation of fly ash microspheres and silica fume at a dosage of 0.02 % triethanolamine. The results proved that the addition of TEA had a positive impact on the early strength of the pure Portland cement system, while the later strength was reduced. However, the presence of high pozzolanic activity supplementary cementitious materials (SCMs) altered this reduction and even reversed it, resulting in an increase in strength. Specifically, TEA inhibits the crystallization nucleation growth of hydration products through complexation, resulting in the inhibition of the hydration of silicate minerals. The nucleation effect of silica fume, however, eliminates this inhibition and promotes the hydration of all minerals. Moreover, the presence of SCMs leads to the formation of more amorphous calcium hydroxide (CH) due to the demand of pozzolanic reaction, and the addition of TEA promotes the formation of amorphous CH, effectively lowering the reaction threshold of the pozzolanic reaction and facilitating it. The results confirm that the interaction of the complexation reaction of TEA with the pozzolanic reaction provides a beneficial complement to cement strength development. [ABSTRACT FROM AUTHOR]

Aqueous two-phase systems (ATPS) utilizing polyethylene glycol (PEG) have been successfully used for the separation of various organic and inorganic compounds as an environmentally benign extraction method. However, a fundamental understanding of the role of the hydration structures around PEG chains in solute partitioning in ATPS remains elusive although it has been considered that PEG molecules are involved in separation. In the present work, the equilibria of Co(II) thiocyanate complexation reaction in aqueous PEG solutions were studied by spectrophotometry with varying ethylene oxide chain length and concentration of PEG. From the formation constants of the tetrahedral and octahedral Co(II) thiocyanate complexes obtained, a microheterogeneous structure consisting of pseudo phases formed by hydration of ethylene oxide (EO) chain and terminal hydroxyl (OH) groups in the PEG molecule in addition to the bulk water phase was estimated. It was revealed that the formation of tetrahedral Co(NCS) 4 2− complex proceeds in the EO pseudo phase by the involvement of hydrophobic ethylene groups, while the OH phase and the bulk phase inhibit the progress of the reaction. This indicates that Co(NCS) 4 2− is stable in hydrophobic hydration structure of water around the EO moiety. The EO phase imparts hydrophobicity to aqueous PEG solutions and plays a predominant role in partition of solute molecules in PEG-based ATPS. [Display omitted] • Hydration structures of PEG were studied using complexation of Co(II) with SCN−. • PEG solutions contain microphases formed around ethylene oxide and hydroxyl groups. • Formation of Co(NCS) 4 2− complex proceeds in hydrated ethylene oxide pseudo phase. • Hydrated ethylene oxides play a main role in solute partitioning in PEG-based ATPS. [ABSTRACT FROM AUTHOR]

Utilization of aluminosilicate-rich solid waste via geopolymerization, such as mine tailings (MTs), possesses a dual advantage of reducing CO 2 release from cement manufacturing and increasing tailings utilization. However, a major challenge for this technology is the low reactivity of MTs. In this study, an alkali-hydrothermal method at 200 °C was developed for MTs activation, and MTs were converted into an active alkaline aluminosilicate precursor that could play an alkaline activator-like role. Geopolymers were subsequently prepared from activated MTs and slag by simply adding water, and to improve the performance of geopolymers, steel slag (SS) was added as a supplementary alkali source. Results showed that the advantage of SS as a calcium-based alkaline material could be fully exerted in this system. The Ca(OH) 2 phase derived from SS hydration increased the pH of the pore solution, on the one hand, and complexation reactions between Ca2+ ionized from Ca(OH) 2 and Si and Al monomers dissolved from activated MTs might occur and generate calcium aluminosilicate hydrate gel, on the other hand. As a result, the addition of SS accelerated the hydration process, prompted the production of hydration products, and thus enhanced the strength of geopolymers. The 3-day and 28-day strengths of geopolymers achieved as high as 31.10 and 44.79 MPa, respectively, when SS content was kept at 10 wt%. In addition, SS-doped geopolymers had satisfactory soundness because the fast consumption of Ca2+ prevented the growth of Ca(OH) 2 crystals and the resulting expansion effect. • Alkali-hydrothermal activation converted tailings into an active alkaline aluminosilicate precursor. • The advantage of steel slag as a calcium-based alkaline material was fully exerted. • Both the low reactivity of tailings and the poor volume stability of steel slag were overcame. • This study provided a new route to improving the comprehensive utilization of tailings and steel slag. [ABSTRACT FROM AUTHOR]

Magnetically modified carbon-based adsorbent (BC@γ-Fe 2 O 3) was prepared through facile route using activated sludge biomass and evaluated for the simultaneous removal of Sb(III) and Pb(II). BC@γ-Fe 2 O 3 exhibited outstanding Sb(III) and Pb(II) adsorption capacity when 200 mg of adsorbent was employed at pH 5.0 for 240 min, with the removal efficiency higher than 90%. The experiments demonstrated the excellent reusability and the potent anti-interference properties of the prepared absorbent. Freundlich and pseudo-second-order kinetic were prior to describe the adsorption process. The adsorption of Sb(III) and Pb(II) onto BC@γ-Fe 2 O 3 was spontaneous and endothermic. BC@γ-Fe 2 O 3 with high specific surface area revealed the exceptional competence to absorb Sb(III) and Pb(II) through pore filling, electrostatic adsorption and complexation. The adsorption mechanisms of Sb(III) and Pb(II) showed similarities with slight disparities. The removal of Sb(III) involved the Fe–O–Sb bond and π-π bond, while the adsorption of Pb(II) was closely related to ion exchange. Moreover, Sb(III) was oxidized to Sb(V) in a minor part during adsorption. The Fe–O–Cl active sites on BC allowed for the binding of γ-Fe 2 O 3 , guaranteeing the abundant adsorption sites and stability. BC@γ-Fe 2 O 3 provides an efficient and green insight into the simultaneous removal of complex heavy metals with promising application in wastewater treatment. [Display omitted] • BC@γ-Fe 2 O 3 could remove Sb(III) and Pb(II) from water simultaneously. • Magnetism is provided by γ-Fe 2 O 3 in activated sludge biochar, which is useful for adsorbent extraction and separation. • Sb(III) was mainly removed via an Fe–O–Sb bond complexation reaction and π–π bond adsorption. • Pb(II) was mainly removed via ion exchange. [ABSTRACT FROM AUTHOR]

• Na 4 Fe 3 (PO 4) 2 P 2 O 7 /C was synthesized by sol-gel using phosphate and pyrophosphate • pH determines the type of Fe-based complex and therefore polyanionic composition • CV and FTIR as assisting tools to XRD for identification of Na 2 FeP 2 O 7 traces • Na 2 FeP 2 O 7 presence deteriorates the performance of the heterostructure • Na 4 Fe 3 (PO 4) 2 P 2 O 7 liberated from Na 2 FeP 2 O 7 reaches theoretical capacity at ≈8 C M 4 Fe 3 (PO 4) 2 (P 2 O 7) specific family has appeared as a new class of polyanionic compounds for sodium-ion batteries, capable of offering a higher operating voltage than individual phosphates and pyrophosphates. The study addresses the issue of Na 4 Fe 3 (PO 4) 2 P 2 O 7 (NFPP) sol-gel synthesis when both phosphates and pyrophosphates act as reactants, leading to successful production of NFPP under controlled synthesis conditions, capable of reaching the theoretical capacity. Spontaneous citric-assisted sol-gel reaction, between PO 4 3− and P 2 O 7 2− units occurring at pH of 3 (which follows NFPP stoichiometry), leads to the formation of pyrophosphate (Na 2 FeP 2 O 7 , NFP) with a certain amount of the mixed phase. Fe-oxalate coordination is dominant at low pH while the citric acid protonation suppresses direct Fe-citric complexation. pH adjustment to a neutral value changes the complexation and reaction pathway, allowing direct Fe(II)-citric coordination and subsequent oxidation. The exchange of Fe-oxalate with the soluble ferric ammonium citrate complex happens under neutral pH and therefore leads to the formation of NFPP as the dominant phase, liberated from NFP. Furthermore, a series of samples, developed by varying citric-to-Fe molar ratio and controlling pH, served as a platform to identify and solve problems regarding the unambiguous FTIR assignment of the polyanionic NFP/NFPP mixture. FTIR and CV methods are proposed as assisting tools for XRD to identify NFP admixture. Finally, and most importantly, NFPP phase formed under neutral pH has a higher sodiation/desodiation capacity than NFPP/NFP heterostructure, reaching a theoretical value at a rather high current of 1 A g−1, which has not been attained in the literature. [Display omitted] [ABSTRACT FROM AUTHOR]

The purpose of this study is to detect the electrochemical reduction of a novel N-(benzo[ d ]thiazol-2-yl)-3-oxo-3-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)propenamide ligand (o-H 2 BMP) at varying pH by using a gold electrode in the presence of tetra butyl ammonium bromide as a supporting electrolyte at room temperature. The outcomes results showed that the effective reduction mechanism of the o -H 2 BMP ligand consumes 8 electrons and 8 hydrogen ions at pH 5, which belong to the reduction of azomethine and two carbonyl groups at (0.0518 V – 0.678 V), respectively. Also, the electrochemical behavior of Cd(II) ions in a cell containing 0.1 M KCl in 50 % (DMSO-water) mixed solvent by using glassy carbon electrode was proceeded with two electrons transfer as Cd+2/Cd0 in reversible mechanism. This work presents a novel structural analysis of the complexes that can be formed in solution and which exhibit stochiometric ratios of (M:L, 1:1, 2:3, 1:2). Moreover, the degree of reversibility of Cd(II) ions redox behavior was evaluated in the absence/presence of the o -H 2 BMP ligand which indicated that the redox behavior of Cd(II) ions more reversible in the case of free Cd(II) according to the ∆E p , α, and k h values. While, in the presence of the o -H 2 BMP ligand, the degree of reversibility was decreased and the number of electrons transferred in the rate-determining step increased which confirming the complexation reaction of Cd(II) with the ligand. [ABSTRACT FROM AUTHOR]

Heavy metal stabilization is an effective method to treat chromium in tannery sludge. Here we show that mainly investigated NaH 2 PO 4 (MSP) and organic matter (OM) to stabilize chromium in tannery sludge. The experimental investigation revealed that the addition of montmorillonite (MMT) and MSP samples showed a significant increase in the percentage of reducible and oxidizable Cr in the former compared to the samples with the addition of MMT. This is attributed to the formation of Cr–O bond, which allows the MSP to undergo an inner-sphere complexation reaction with the metal oxide of Cr via ligand exchange. Significantly, the MSP moiety adsorbs on the surface of OM through monodentate, which increases the adsorption sites of OM for Cr6+ and promotes the reduction of Cr6+ to Cr3+. Moreover, PO 4 3− reacts with Cr3+ to produce CrPO 4 precipitation, thus reducing the free Cr3+ content. Finally, DFT calculations confirmed that a ternary system is formed between PO 4 3−, OM, and Cr, and the binding energy is negative, which indicated that PO 4 3− could co-stabilize Cr with OM. [Display omitted] • Stabilization of Cr by MSP is achieved through ligand exchange. • MSP amplifies the adsorption sites of OM and promotes the reduction of Cr6+. • PO 4 3− from the dissociation of MSP reacts with Cr3+ to form CrPO 4 precipitate. • Results from DFT indicate the presence of PO 4 3−, OM, and Cr in a ternary system. [ABSTRACT FROM AUTHOR]

Spent nuclear fuel from the Finnish and Swedish nuclear power plants will be permanently disposed of in deep geological disposal facilities located on the coast of the Baltic Sea. As a part of the disposal's safety case, the migration properties of the safety-relevant spent nuclear fuel-borne radionuclides, such as the radionuclide progeny of the waste component 238U, 226Ra, need to be assessed in the lithosphere surround the facility. To this end, the sorption of Ra on disposal-relevant rock and groundwater types was studied in batch sorption experiments in a wide Ra and Ba concentration isotherm (2.6 × 10−9 M to 1 × 10−3 M). The experimental results of the batch sorption experiments were further interpreted using a PHREEQC geochemical model with ion exchange and surface complexation reactions considered. Additionally, the sorption of Ra was studied with thin section sorption studies where autoradiography analysis was combined with mineralogical data obtained in SEM/EDX to establish spatial distribution and mineral specific sorption of Ra on the studied rocks. In the study, it was observed that Ra sorbs well on all tested rock types and water conditions of low ionic competition, regardless of the rock type's projected sorption affinity based on its highly sorbing mica mineral content. In conditions of high ionic competition, Ra tends to stay in the sorption solution, facilitating migration in the disposal context. The obtained experimental and modeled Ra sorption data will be used in the safety case calculations and modeling of the Finnish and Swedish spent nuclear fuel disposal. • Radium gets strongly retarded on rock in conditions of low ionic competition. • Spatial distribution of radium sorption can be used to study its sorption mechanism. • Radium sorption can be modeled accurately in deep geological disposal context. [ABSTRACT FROM AUTHOR]

The simultaneous presence of heavy metals and surfactants in runoff induces complexation and ecological harm during migration. However, interactions between these pollutants are often overlooked in past studies. Thus, investigating heavy metal-surfactant complexes in runoff is imperative. In this work, Cu (II) and sodium dodecyl sulfate (SDS) were selected to investigate the interaction between heavy metals and surfactants due to the higher detected frequency in runoff. Through 1H NMR and FTIR observation of hydrogen atom nuclear displacement and functional group displacement of SDS, the change of SDS and Cu (II) complexation was obtained, and then the complexation form of Cu (II) and SDS was verified. The results showed that solution pH values and ionic strength had significant effects on the complexation of Cu (II). When the pH values increase from 3.0 to 6.0, the complexation efficiency of SDS with Cu (II) increased by 12.12% at low concentration of SDS, which may be attributed to the excessive protonation in the aqueous solution at acidic condition. The increase of ionic strength would inhibit the complexation reaction efficiency by 19.57% and finally reached the platform with concentration of NaNO 3 was 0.10 mmol/L, which was mainly due to the competitive relationship between Na (I) and Cu (II). As a general filtering material in stormwater treatment measures, natural zeolite could affect the interaction between SDS and Cu (II) greatly. After the addition of SDS, the content of free Cu (II) in the zeolite-SDS-Cu (II) three-phase mixed system was significantly reduced, indicating that SDS had a positive effect on the removal of Cu (II) from runoff. This study is of great significance for investigating the migration and transformation mechanism of SDS and Cu (II) in the future and studying the control technology of storm runoff pollution. [Display omitted] • The complexation characteristics of (SDS) and Cu (II) in runoff was investigated. • pH value and ionic strength showed influence on the complexation reaction between Cu (II) and SDS. • Natural zeolite could eliminate SDS-Cu (II) complex and improved removal efficiency of Cu (II). • The complexation mechanism and environmental implications were examined in stormwater runoff. [ABSTRACT FROM AUTHOR]

• Stable inclusion complexes are formed between gliclazide and β-cyclodextrin in aqueous solutions. • The inclusion process was spontaneous and enthalpy driven. • The complexes were stabilized by hydrogen bonds between CO—HO and SO—HO groups and van der Waals contacts. • Gliclazide-β-cyclodextrin complexes can be considered as potential carriers for targeted drug transport and delivery. Gliclazide (GLC) inclusion complexes with β-cyclodextrin (βCD) were studied by UV–VIS and FT-IR spectroscopy. The recorded spectra confirmed formation of GLC-βCD binary complexes and GLC-(βCD) 2 ternary complexes in aqueous solutions. UV–VIS measurements carried out for a number of temperatures allowed to determine the binding constants of the complexation reactions. The bioavailability of GLC-βCD and GLC-(βCD) 2 was determined using the n-octanol/water partition coefficient. Experimental studies were supplemented with theoretical calculations. Quantum-chemical calculations and classical molecular dynamics simulations were used to describe the interactions in the host-guest inclusion complexes. [Display omitted] [ABSTRACT FROM AUTHOR]

• Two 1-D, 2-D and 3-D supramolecular Cu(II) and Ni(II) complexes based on the quinazoline-type ligand L containing pyrazole ring were structural characterized. • The activity data showed the metal complexes to be more antibacterial than the quinazoline-type ligand L. • The experimental investigations match with those obtained from TD-DFT calculations. • ESP calculation results confirmed the charge distribution in the molecule and Hirshfeld surface analyses of both complexes were also discussed. The ligand 2-(3-pyrazolyl)-4-methyl-1,2-dihydroquinazoline-N3-oxide (L) was synthesized, and two transition metal complexes, namely [Cu(L) 2 ]·(NO 3) 2 (1) and [Ni(L) 3 ]·(NO 3) 2 ·3CH 3 OH (2) were prepared through complexation reaction between L and the corresponding metal salt. L and both complexes were characterized by elemental analysis, as well as compared with spectrographic technique for example FT-IR and UV–Vis spectroscopy. X-ray single-crystal diffraction demonstrated that 1 was tetra-coordinated square planar whereas 2 was hexa-coordinated slightly distorted octahedral geometry. Meanwhile, the metal-ligand ratios were 2:1 in 1 whereas 3:1 in 2. Through the superposition of hydrogen bonds and other weak interactions, both complexes formed 1-D chain-like, 2-D layered, and 3-D supramolecular structures. Theoretical investigations explained the optimized geometries of complexes and the electrostatic potential distribution in molecules, and also analyzed the electron transition types of L and both complexes in combination with UV–vis spectroscopy, which provided theoretical support for the experimental conclusions. Electrostatic potential (ESP) was computed for both complexes to predict the reaction positions of electrophilic and nucleophilic assaults. Hirshfeld Surface Analysis quantified interactions in molecules and analyzed the contribution of various weak interactions to stabilize the structure of complexes. Especially, antibacterial experiments displayed compounds had certain antibacterial activities against both Gram-positive and Gram-negative bacterial strains. The ligand 2-(3-pyrazolyl)-4-methyl-1,2-dihydroquinazoline-N3-oxide (L) was synthesized, and two metal complexes, namely [Cu(L) 2 ]·(NO 3) 2 (1) and [Ni(L) 3 ]·(NO 3) 2 ·3CH 3 OH (2) were prepared through complexation reaction between L and the corresponding metal salt. Both complexes were characterized by X-ray crystallography, spectroscopic methods such as FT-IR and UV–Vis spectroscopy, and electrochemical property, as well as Hirshfeld surface analysis and DFT studies. The antimicrobial activities of all compounds were also compared. [Display omitted] [ABSTRACT FROM AUTHOR]

• influence of the substitution decoration in ferrocenyl selenophen-2-yl thioketone and ferrocenyl furan-2-yl thioketone utilized as a proligand in complexation reactions with Fe 3 (CO) 12. • Electrochemical investigation of [FeFe]-hydrogenase mimics. • Investigate the catalytic activity of [FeFe]-hydrogenase mimics in the presence of acetic acid. In this report, the influence of the substitution decoration in ferrocenyl selenophen-2-yl thioketone (1) and ferrocenyl furan-2-yl thioketone (2) utilized as a proligand in complexation reactions with Fe 3 (CO) 12 was examined. As a result, three new complexes, considered [FeFe]-hydrogenase mimics, were prepared and characterized by IR, 1H, 13C{1H}, and 77Se{1H} NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray single-crystal diffraction methods. Moreover, the obtained complexes were compared with the analogous ferrocenyl α-thienyl thioketone as a starting material. Respectively, the reaction of compound 1 with Fe 3 (CO) 12 is found to give two complexes that have similar structures to those obtained in analogous reactions with ferrocenyl α-thienyl thioketone. Conversely, compound 2 gives only an α,β-unsaturated aldehyde moiety as a result of the furan ring being opened. Furthermore, the electrochemical properties of the resulting complexes were investigated using cylic voltammerty in the absence and presence of acetic acid (AcOH) as a proton source and compared with their structurally related thiophene derivative. Accordingly, the nature of the linkage of these synthetic approaches has a significant effect in determining its redox properties. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the diversity and variability of harmful ions in polluted water bodies, the selective removal and separation for specific ions is of great significance in water purification and resource processes. Capacitive deionization (CDI), an emerging desalination technology, shows great potential to selectively remove harmful ionic pollutants and further recover valuable ions because of the simple operation and low energy consumption. Researchers have done a lot of work to investigate ion selectivity utilizing CDI, including both theoretical and experimental studies. Nevertheless, in the investigation of selective mechanisms, phenomena where carbon materials exhibit entirely opposite selectivity require further analysis. Furthermore, there is a need to summarize the specific chemical reaction mechanisms, including the formation of hydrogen bonds, complexation reactions, and ligand exchanges, within selective electrodes, which have not been thoroughly examined in detail previously. In order to fill these gaps, in this review, we summarized the recent progress of CDI technologies for ion selective separation, and explored the selective separation mechanism of CDI from three aspects: selective physical adsorption, specific chemical reaction, and the utilization of selective barriers. Additionally, this review analyzes in detail the formation process of chemical bonds and ion conversion pathways when ions interact with electrode materials. Finally, some significant development prospects and challenges were offered for the future selective CDI systems. We believe the review will provide new insights for researchers in the field of ion selective separation. [Display omitted] • Pore size distribution and ion dehydration impact sieving effects and ion selectivity. • Target ions exhibit specific coordination with electrode materials. • Selective membrane modifications applied in ED show great potential in CDI. [ABSTRACT FROM AUTHOR]

Copper(II) complexes are interesting for cancer treatment due to their unique properties, including their redox potential, possible coordination structures with different ligands, the most diverse geometries, and different biomolecule reactivity. The present work synthesized new copper(II) complexes with Schiff-base (imine) type ligands using natural aldehydes such as cinnamaldehyde, vanillin, or ethyl vanillin. The ligands were obtained through the reaction of these aldehydes with the amines 1,3-diaminopropane, 2,2-dimethyl-1,3-propanediamine, or 1,3-diamino-2-propanol and characterized by 1H and 13C NMR, FTIR and ESI-HRMS. The complexation reaction used copper(II) as perchlorate salt, obtaining six new copper(II) complexes. The complexes were characterized using FTIR, UV–vis, elemental analysis, ESI-HRMS, and EPR. In addition, the interaction with the copper(II) complexes and serum albumin was investigated by electronic absorption, showing complex incorporation in the albumin structure. The cytotoxicity of the complexes was evaluated using MTT assay in neuroblastoma cell lines SH-SY5Y, CHP 212, and glioblastoma LN-18, and presented EC 50 values between 90 and 300 μM. Based on our results, a square-planar copper(II) complex derived from Schiff-base cinnamaldehyde was found here to possess significant potential as an anti-cancer treatment. Further investigation is required to explore this compound's benefits in cancer co-treatment approaches fully. Brazilian natural products for synthesizing Schiff bases formed new active Copper(II) complexes in neuroblastoma and glioblastoma cells. [Display omitted] • Schiff-bases derived from Brazilian natural products were utilized in the formation of Copper(II) complexes. • The newly synthesized copper(II) complexes have been found to exhibit cytotoxicity. • It appears that the geometry of complexes is crucial to ensuring biological activity. • Serum albumin can transport the complexes. [ABSTRACT FROM AUTHOR]

A facile method for preparing various functional cycloalkynes, including proteins incorporated with a cycloalkyne moiety, from the corresponding azides is developed. Treatment of diynes bearing strained and terminal alkyne moieties with a copper salt enabled terminal alkyne-selective click conjugation with azides, whereas a more azidophilic strained alkyne moiety was transiently protected from the click reaction via complexation with copper. [ABSTRACT FROM AUTHOR]

An efficient and practical strategy has been established to enhance the configurational stability of chiral tricyclic dipeptide, which readily undergoes spontaneous racemization under environmental conditions. Complexation of the chiral dipeptide with racemic diols via non‐covalent interaction results in the corresponding heterocomplexes (HCs), which are able to preserve chirality of the dipeptide as long as 24 months. A nearly quantitative recovery of enantiopure dipeptide and racemic diols was achieved by simple treatment of the HCs with a biphasic system of H2O‐ethyl acetate and subsequent separation from aqueous and organic layers, respectively. This study not only provides a facile and handy method for the configurational stabilization of the chiral dipeptide, but also opens a further prospect for the long‐term chirality preservation of other instable enantiomeric compounds via heterocomplexation approach. An efficient and practical strategy has been established to enhance the configurational stability of chiral tricyclic dipeptide via heterocomplexation with chiral diols. A nearly quantitative recovery of enantiopure (S,S)‐1 and racemic diols was achieved by simple treatment of the heterocomplex with a biphasic system of H2O‐ethyl acetate and subsequent separation from aqueous and organic layers, respectively. [ABSTRACT FROM AUTHOR]

Abstract In our previous work, we highlighted the thermodynamic and spectroscopic characteristics of the 1:1 charge transfer (CT) complexation of TCNE acceptor with various medically important drugs. Continuing that work, we further examine drugs that react with the TCNE acceptor via a 1:2 interaction. The examined drugs are atenolol, quinidine, cimetidine, reserpine, and levofloxacin. We aimed through this study to: i) make the spectrophotometric and thermodynamic data of the examined drugs, both initially and when reacted via a 1:2 M ratio with the TCNE acceptor, available to use in the determination or detection of these drugs in pharmaceuticals and other environments; and ii) compare the mode of interactions and the spectrophotometric and thermodynamic properties between drugs that react via a 1:1 or 1:2 ratio with the TCNE acceptor. To achieve these aims, the five examined drugs were reacted with TCNE in acetonitrile (MeCN) solvent at room temperature. Several thermodynamic and spectroscopic data were experimentally estimated using the van't Hoff and the Benesi–Hildebrand equations and discussed. Graphical Abstract Electronic absorption spectrum of the CT product that formed form the reaction of drug Qui with TCNE acceptor in MeCN solvent. Unlabelled Image Highlights • CT complexes were obtained by the reaction of different drugs with TCNE. • Electronic spectra show a very strong absorption band at 405 nm with two heads. • Experimental data suggest that the complexation occurs via n→π* and π→π* interactions. • The van't Hoff plot was employed to determine the thermodynamic data. • The Benesi–Hildebrand plot was employed to determine the spectroscopic data. [ABSTRACT FROM AUTHOR]

Abstract Kinetic study on the complexation of caffeic acid with ferric chloride was performed in aqueous solution at pH 9.0. The complex was characterized by IR, UV–Vis spectroscopy and FE-SEM techniques. Kinetic data were obtained and used to model the reaction kinetics for the disappearance of the caffeic acid. The operational variables have been studied in the temperature range from 25 to 45 °C, initial iron and caffeic acid concentration from 0.6 mg/100 ml (ranging from 2.0 ml to 8 ml/100 ml). The complexation reaction was found to be a first-order with rate constants for k 1 (formation) 4.7 × 10−3 s−1. Additionally, the effect of concentration and temperature on the complexation reaction was investigated. Apparent kinetic parameters of the complex formation of Fe(III) with caffeic acid were found as; pre-exponential factor A (−1.17 min−1), enthalpy of activation (ΔH°)# (−2188 J mol−1), entropy of activation, (ΔS°)# (−7.34 J mol−1 K−1) and Gibbs free energy of activation, (ΔG°)#(−0.68 J). The apparent activation energy of the complexation reaction was evaluated to be 289.29 J mol−1 which is consistent with the chemistry of Fe(III) with polyphenols which are supposed to mimic the interaction of Fe(III) with transferrin in biological media. Various theoretical parameters of the studied complex such as hardness, electronegativity, softness, total energy, dipole moment and point group symmetry were calculated employing Density functional theory (DFT) and found as 0.04465, 0.2130, 22.39, 0.5201 × 10−8 eV, 15.13 Debye, and C1, respectively. Graphical Abstract Unlabelled Image Highlights • The aim of the present work was to study the kinetics of the complexation of Fe(III) with caffeic acid in aqueous solution at pH 9.0. • The complex was characterized by IR, UV-Vis spectroscopy and FE-SEM techniques. • The complexation reaction was found to be a first-order with rate constants for k 1 (formation) 4.7×10-3 sec-1. • Additionally, the effect of concentration and temperature on the complexation reaction was investigated. • Apparent kinetic parameters of the complex formation of Fe(III) with caffeic acid were evaluated. • The apparent activation energy of the complexation reaction was evaluated to be 289.29 J mol-1 which is consistent with the chemistry of Fe(III) with caffeic acid. • Various theoretical parameters of the studied complex were also investigated. [ABSTRACT FROM AUTHOR]

Highlights • Stability and phase behavior of chitosan/casein complexes were systematically studied for the first time. • Bridging flocculation was determined to be highly dependent on the charge density of polysaccharide. • The complexation granted casein with higher stability over wider range of pH. • The effect of pH and ionic strength on the complexation behavior was thoroughly investigated. Abstract The interaction between polysaccharides and proteins has attracted great interests and the phase behavior and colloidal properties of complexes between chitosan, a positively charged polysaccharide, and proteins still need careful investigation. Here, we use chitosan/casein as model system and monitor their complex size, zeta-potential, light scattering intensity and phase behavior as functions of chitosan deacetylation degree, pH and ionic strength. Chitosan flocculates casein at low polysaccharide concentrations, while stabilizes casein at moderate to high concentrations. Such flocculation and stabilization ability are dependent on the linear charge density of chitosan, where high charge density chitosan saturates casein surface charge and stabilizes the complexes at lower polysaccharide concentration. The complexes are stable at acidic pH where chitosan is highly protonated and the addition of NaCl leads to the reduction in both size and zeta-potential and facilitates complex aggregation. The phase maps are constructed to provide guidelines for further studies on chitosan/casein and other chitosan/protein complexes. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Selective adsorption and regeneration of adsorbents are great challenges for fluoride removal in drinking water. In this study, a NiAl-layered metal oxide (NiAl-LMO) electrode was successfully prepared and used as an electro-adsorption electrode. With its structural memory effect for anions and high specific capacitance of 575 F·g−1, the NiAl-LMO electrode exhibits capacitive deionization performance. The maximum adsorption capacity of F− by the electrode reached 49.28 mg/g, which was 4 times that of Cl− and 2 times that of SO 4 2−, respectively. The good selectivity for F− electrosorption was ascribed to the high electronegativity of F− and the complexation between F− and hydroxyl aluminum groups. The electrode material has good stability and can be regenerated easily by applying a reverse voltage. After 10 cycles, the F− adsorption rate by the NiAl-LMO electrode was 94. 4% of the initial adsorption rate. The applied voltage enhanced the selectivity of F− adsorption by the NiAl-LMO electrode, and this electrosorption process was mainly dominated by electrical double layer adsorption. Under the conditions of 1.0 V and pH 7, the electrode showed a maximum adsorption efficiency of 73.5%. [ABSTRACT FROM AUTHOR]

Graphical abstract Enhanced extraction of rare earths by using ionic liquids originate from the synergism of Hofmeister bias and the complexation behavior of salt anions. Abstract Separation and recycling of rare-earths using ionic liquids as extractant are becoming a promising approach to replace traditional volatile organic solvents in recent years. Generally, the addition of some special salts could improve the extraction efficiency of rare-earths by numerous non-functional ionic liquids. However, knowledge behind the nature of the salt effect is limited. Here, we found that the enhancement in the extraction of rare-earth ions, Pr3+ ions, using non-functional ionic liquid, [A336][NO 3 ] (Tricaprylmethylammonium nitrate) was driven by the synergism of Hofmeister bias and complexation behaviors of salt anions with Pr3+ ions. Molecular dynamic simulations offered a new insight into the interaction mechanism of the ionic liquid with Pr3+ ions at liquid/liquid interface. It was revealed that salt anions could perform as a bridge to connect Pr3+ ions and the ionic liquid, so that promoted the extraction of Pr3+ ions. Therefore, the strong complexation ability of salt anions with Pr3+ ions and poor hydration of salt anions faciliated the transport of Pr3+ ions across liquid/liquid interface. [ABSTRACT FROM AUTHOR]

The host-guest complexations of fifteen protonated azaspirocyclic, oxa,azaspirocyclic, and diazaspirocyclic guests, three-dimensional analogues of morpholinium, piperidinium, and piperazinium cations, respectively, with cucurbit[7]uril (CB[7]) were investigated using 1H NMR spectroscopy in an acidic aqueous solution. The host-guest stability constants (KCB[7]) for the protonated spirocyclic guests were determined to range from 104-1011 M−1. The relative stability constants have been analyzed in terms of ring sizes and molecular volume (packing coefficient), and the presence and positions of additional oxygen and quaternary nitrogen heteroatoms. The larger the size of both the rings of the guest molecules the higher the observed binding constants for these guests with CB[7]. The largest values for KCB[7] were found for 1- and 2-azaspiro[3.5]nonane, 2- and 8-azaspiro[4.5]decane, and 2-azaspiro[5.5]undecane, when the guest contained 9-11 heavy atoms. Adding oxygen heteroatoms decreased the binding constants by 2-3 orders of magnitude for the azaspirocyclic guests. [ABSTRACT FROM AUTHOR]

Although computer-aided drug design has greatly improved over time, its application in the pharmaceutical industry is still limited by the accuracy of association constant (Ka) predictions. Towards improving this situation, the Statistical Assessment of the Modeling of Proteins and Ligands (SAMPL) is a series of community-wide blind challenges aimed to advance computational techniques as standard predictive tools in rational drug design (https://en.wikipedia.org/wiki/SAMPL%5fChallenge). As an empirical contribution to SAMPL6, we report here the Ka and thermodynamic parameters (∆G, ∆H, - T∆S) of eight guests binding to two hosts (OA and TEMOA) using ITC. Both hosts contain a unique, well-defined binding pocket capable of storing guests with up to ten non-hydrogen atoms, whilst the selection of amphiphilic guests contain a range of saturated and unsaturated substituents. The thermodynamic data from this study will allow the challenge participants of SAMPL6 to test the accuracy of their computational protocols for calculating host-guest affinities. [ABSTRACT FROM AUTHOR]

Abstract Fluoride (F−) pollution is a worldwide issue. Coagulation with aluminum (Al) salts is an efficient and economical method for the removal of F−. However, due to the strong complexation between Al3+ and F−, the residual F− and Al after coagulation usually exceed the limits. Zirconium (Zr) coagulants have drawn increasing attention due to their excellent flocculation ability for organic matter. In this work, the performance and mechanism of ZrCl 4 coagulation for F− removal were investigated with the widely used Al 2 (SO 4) 3 as a reference. The optimum pH range is 4.0–6.0 for ZrCl 4 and 8.0–10.0 for Al 2 (SO 4) 3. ZrCl 4 was superior to Al 2 (SO 4) 3 for F− removal as the initial F− concentration was less than 30.0 mg L−1. Coexisting substances at environmental concentration levels showed negligible effects on F− removal by ZrCl 4. Besides the better F− removal, another advantage of ZrCl 4 over Al 2 (SO 4) 3 was the much lower residual metal concentration in the pH range of 4.0–11.0. The hydrolysis of Al 2 (SO 4) 3 was significantly inhibited due to the formation of Al-F complexes while the hydrolysis of ZrCl 4 was not influenced even under strongly acidic conditions. Therefore, F− removal by Al 2 (SO 4) 3 was mainly achieved by preliminary complexation between Al3+ and F− and subsequent hydrolysis and polymerization of these complexes, while adsorption onto hydrolysates and ion exchange with surface hydroxyl groups were the main ways of F− removal by ZrCl 4. The work here provides a new method for F− removal and may shed light on the application of Zr coagulants for other pollutants. Graphical abstract Image 1 Highlights • ZrCl 4 exhibited a better coagulation performance than Al 2 (SO 4) 3 for F− removal. • The strong complexation with F− is an unfavorable characteristic in Al coagulation. • ZrCl 4 led to a much lower residual metal concentration as compared with Al 2 (SO 4) 3. • Phosphate, arsenate and turbidity could be effectively removed by ZrCl 4 coagulation. • Adsorption onto positively charged hydrolysates played a key role in defluorination. [ABSTRACT FROM AUTHOR]

Graphical abstract A pictorial representation of two benzo crown ethers assembling together to accommodate a potassium ion to form 2:1 ligand-metal ion complex. The cation is held in the cavity by ion-dipole interactions. The coordination number of the potassium ion is ten. Complexation enhanced fluorescence produced by suppression of PET mechanism is masked by FRET. Highlights • Complexes of two crown ethers, benzo-15-crown-5 and dibenzo-15-crown-5, were prepared with potassium halides in acetonitrile and characterized by FTIR, UV, ESI-MS, 1H NMR and 13C NMR techniques. • Fluorescence studies showed that the fluorescence emission intensity is a residual value after suppression of photoinduced electron transfer (PET) mechanism and energy resonance transfer (FRET) mechanism operative in complexes of benzo-15-crown-5 and dibenzo-15-crown-5. • These complexes can be used as FRET based sensors for potassium ions. Abstract Cation recognition plays a vital role in defining advanced functions of macromolecules in nature. An example of such an interaction is the action of a natural antibiotic, valinomycin, that behaves as a potassium ionophore. It encages the cation to transport it across a cell membrane and easily releases it inside the cell. Macrocyclic complexes of some crown ethers mimick alkali ion interactions with natural ionophores. We have synthesized complexes of two crown ethers namely benzo-15-crown-5 (2,3,5,6,8,9,11,12-octahydrobenzo[ b ][1,4,7,10,13]pentaoxacyclopentadecine) and dibenzo-15-crown-5 (6,7,9,10,17,18-hexahydrodibenzo[ b,h ][1,4,7,10,13]pentaoxacyclopentadecine with potassium halides (fluoride, chloride, bromide and iodide) in acetonitrile and characterized them by IR, UV, ESI-MS, 1H NMR and 13C NMR techniques. The effect of the anion on the stability of the complexes was observed by 1H NMR studies. The alkali metal ion is held to the oxygen donor atoms of the macrocyclic ring by ion-dipole interactions. The potential of the small ring oxacrown ethers, benzo-15-crown-5 and dibenzo-15-crown-5, to act as probes for potassium ions in dilute solutions (4.1 × 10−4 M) was investigated by recording the variation in the fluorescence spectra of benzo-15-crown-5 and dibenzo-15-crown-5 on complexation with potassium fluoride in acetonitrile and chloroform. The rigidity of the macrocyclic ring and proximity of fluorophore units affected the fluorescence intensity of the complexes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Binding of group IA/IIA cations to N -phenylaza-15-crown-5 substituted Schiff bases. • Spontaneous complexation process in the gas phase for all metal cations. • Spontaneous complexation process for the smaller cations in acetonitrile. • More negative ΔG values for the complex formation with group IIA metal cations. Abstract N -Phenylaza-15-crown-5 containing Schiff bases act as excellent ligands for alkali and alkaline-earth metal ions. The complex formation ability of two differently N -phenylaza-15-crown-5 substituted Schiff bases has been investigated using density functional theory methods. The structures of the ligands and of the respective complexes with alkali and alkaline earth metal ions have been optimized and the thermodynamic parameters of the complex formation reactions have been determined. According to the obtained results there is a rough correlation between the metal cation radius and ΔG values in the gas phase and in acetonitrile solution: the smaller the cationic radius is, the more thermodynamically favorable is the complex formation. The results for the Gibbs free energy of the complex formation reaction of these ligands with seemingly ordinary structure with IA and IIA group metal ions indicate a spontaneous and energy-favorable process in the gas phase (for all metal cations) and in the acetonitrile environment (for the smaller ones). [ABSTRACT FROM AUTHOR]

Abstract A clay mineral (synthetic hectorite) was complexed with titanium dioxide (anatase with the average particle size of 20 nm) as a film on a glass substrate for photocatalyst application. The mass ratio of the hectorite to the anatase was optimized to be 1(hectorite):10(anatase) to obtain homogeneous coatings. The photocatalytic decolorization of organic dyes (methyl orange and methylene blue) by UV irradiation was examined as a model reaction to find a synergy effect of the hybridization, an efficient methylene blue decomposition in an acidic solution. Graphical abstract Unlabelled Image Highlights • A clay mineral was complexed with a titanium dioxide particle (anatase with the average particle size of 20 nm) as a film. • The smectite-titania hybrid film on a glass substrate was used as photocatalyst. • The mass ratio of the hectorite to the anatase was optimized to be 1(hectorite):10(anatase) to obtain homogeneous film. • The photocatalytic decolorization of organic dyes (methyl orange and methylene blue) by UV irradiation was examined. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Types of copper(II) complexes immobilized on silica and their stability constants. • Heterogeneous titration for classification of dynamic equilibria in a wide pH range. • XPS and EPR show strong interactions between Cu(II) and immobilized ligand on surface. Abstract Identification of the copper(II) ions complexes deposited on the amorphous silica surface was conducted using four different research techniques. The potentiometric titration in heterogeneous system was used to establish the forms of complexes with ligands immobilized on the surface. The types of Cu(II) complexes depend on the pH value. In the pH range 4–11, the presence of the following four types of Cu(II) complexes was evidenced: CuHSGL, CuSGL, Cu(SGL) 2 , and Cu(SGL) 2 (OH). Their stability constants were found to be log β CuHSGL = 14.01, log β CuSGL = 7.51, log β Cu(SGL)2 = 14.12, and log β Cu(SGL)2(OH) = 4.84 for I = 0.1 M KNO 3. These complexes were characterized by X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and UV–Vis methods. According to the XPS results, close to pH 6, the partly protonated ligand can additionally form surface ion compounds of the type [R-NH 2 + (CH 2) 2 NH 2 ][NO 3 –]. EPR permitted determination of the spin-Hamiltonian, showing that Cu(II) ion was in the ground state d x 2 -y 2, and the Cu(II) ions symmetry can be described as that of deformed tetragonal octahedrons. UV–Vis measurements in a flow cell confirmed the course of reaction in the heterogeneous system between Cu(II) and diamine ligand, N-(2-amineethyl-3-aminepropyl)trimethoxysilane, immobilized on the surface of amorphous silica gel. [ABSTRACT FROM AUTHOR]

Abstract Waste activated sludge (WAS) contains many anionic functional groups which can interact with heavy metal ions through electrostatic action and complexation reactions. The transition metals adsorbed in WAS can catalyze sludge pyrolysis in anaerobic conditions and improve structural properties of organic matter. In this work, a multistage WAS utilization process for preparing the carbon-based Fenton-like catalysis materials is proposed. More specifically, WAS is firstly used as an adsorbent for heavy metals (Cu and Ni) removal, and then complexes are converted into heterogeneous Fenton-like carbon-based catalysts through oxygen-free pyrolysis. The mechanisms of interactions between extracellular polymeric substances (EPS) and metals are investigated, and the physicochemical properties of sludge-based carbons (SBC) are comprehensively characterized using varies techniques. It is found that WAS is an excellent adsorbent for Cu and Ni removal, which is mainly due to the coordination and electrostatic interactions between EPS and heavy metals. Cu and Ni adsorbed in WAS significantly improved the porous structure of SBC. Both adsorption and catalytic oxidization of Cu/Ni-SBC contribute the removal of E2 in real wastewater. The E2 removal mechanism is explored by electron-spin resonance spectroscopy (ESR) analysis, and it is found that both of .O 2 − and .OH radicals are responsible for E2 degradation in Cu(II)-SBC-H 2 O 2 , while .O 2 − radicals contributes to E2 degradation in Ni(II)-SBC-H 2 O 2 system, so the former performed better than the latter in total removal of E2. Besides, Cu(II) and Cu(I) are both formed in Cu(II)-SBC during the oxidation process, while only Ni(II) is found in the Ni(II)-SBC-H 2 O 2 process, confirming that different catalytic oxidation reactions are occurred in the Cu(II)-SBC-H 2 O 2 and Ni(II)-SBC-H 2 O 2 processes. This study facilitates a great strategy to the sludge multi-stage circulating utilization and a better understanding about the role of the Cu/Ni existed in SBC during the estrogens removal process. Graphical abstract Image 1 Highlights • Proposed multistage WAS process to initiate carbon-based Fenton-like catalysis for the first time. • Cu(II)/Ni(II) adsorbed in sludge improved the porous structure of SBC materials. • The coordination interactions mechanisms between EPS and heavy metals were determined. • The combination of Cu(II)/Ni(II) and sludge carbon (SBC) enhanced E2 removal from wastewater. [ABSTRACT FROM AUTHOR]

Graphical abstract Two new symmetrical Schiff base ligands were derived from condensation of new synthesized polyamine (A) and 2-hydroxybenzaldehyde (H 2 L1) or 2-hydroxy-3-methoxybenzaldhyde (H 2 L2). Six macroacylic Schiff base complexes were prepared by direct reaction of H 2 L1 or H 2 L2 and Mn(II), Zn(II) and Cd(II) metal ions in equimolar ratios. The crystal structure of H 2 L1 was confirmed by single crystal X-ray analysis. A competitive 7Li NMR manner was used to probe the complexation of Mn2+, Zn2+and Cd2+ ions with (H 2 L1) and (H 2 L2) in the same solvent systems. Cytotoxic and antibacterial properties of complexes were also investigated. Abstract In this work, two new symmetrical, potentially N 6 O 2 coordinating, macroacyclic Schiff base ligands (H 2 L1 and H 2 L2) were derived from the condensation of a newly synthesized polyamine, 2,2′-(ethane-1,2-diylbis(piperazine-4,1-diyl))bis(ethan-1-amine) (A), with 2-hydroxybenzaldehyde and 2-hydroxy-3-methoxybenzaldhyde respectively. Six macroacylic Schiff base complexes were prepared by direct reaction of H 2 L1 or H 2 L2 with Mn(II), Zn(II) or Cd(II) metal ions in equimolar ratios. The products were characterized by several physicochemical measurements. As well, the crystal structure of H 2 L1 was confirmed by a single crystal X-ray structural analysis. Competitive 7Li NMR experiments were used to probe the complexation of Mn2+, Zn2+ and Cd2+ ions with (H 2 L1) and (H 2 L2) in both acetonitrile and methanol. The stabilities of the final complexes were found to be in the order M–(H 2 L1) > M–(H 2 L2) and Cd2+ > Zn2+ > Mn2+. The cytotoxic and antibacterial properties of these complexes were also investigated. [ABSTRACT FROM AUTHOR]