Trivalent Metal Research Articles

Features of isomorphism of post-spinel phases: result of computer simulation of the composition of inclusions in lower mantle diamonds

The mixing properties of solid solutions of post-spinel phases of the composition CaCr2O4–CaAl2O4, CaCr2O4–CaFe2O4, MgCr2O4–MgAl2O4 and MgCr2O4–MgFe2O4 in the temperature range 1873– 2223 K and pressures 18–25 GPa were studied using the method of semi-empirical modeling. With these PT parameters, the energies of formation of impurity defects of trivalent metal ions (aluminum and iron) in isomorphic sites were estimated. It is shown that (1) the studied binary solid solutions are characterized by complete miscibility, (2) the incorporation of the Fe3+ impurity ion into the post-spinel phases of MgCr2O4 and CaCr2O4 is less favorable in terms of energy than the incorporation of Al3+ ions over the entire range of pressures and temperatures under study. The results obtained were used to interpret the composition of post-spinel phases forming inclusions in lower mantle diamonds.

Solution and Surface Solvation of Nitrate Anions with Iron(III) and Aluminum(III) in Aqueous Environments: A Raman and Vibrational Sum Frequency Generation Study.

Hydrated trivalent metal nitrate salts, Fe(NO3)3·9H2O and Al(NO3)3·9H2O, in both solid and aqueous phases are investigated. Raman and surface-selective vibrational sum frequency generation (SFG) spectroscopy, are used to shed light on ion-ion interactions and hydration in several spectral regions spanning low frequency (440-550 cm-1) to higher frequency modes of nitrate and water (720, 1050, 1250-1450, and 2800-3750 cm-1). These frequencies span the metal-water mode, nitrate in-plane deformation, nitrate symmetric and asymmetric modes, and the OH stretch of condensed phase water molecules. Comparison to NaNO3, and in some cases KNO3, is also shown, providing insight. Splitting and frequency shifts are observed and discussed for both the solid state and solution phase. The Lewis acidity of Fe3+ and Al3+ ions plays a significant role in the observed spectra, in particular for the nitrate asymmetric band splitting and frequency shift. The spectral response from water solvation for iron and aluminum nitrates is nonlinear as compared to linear for sodium nitrate, suggesting significantly different solvation environments that are limited by water hydration capacity at higher concentrations. Moreover, a non-hydrogen bonded OH, dangling OH, from hydrating water molecules is observed spectroscopically for Al and Fe nitrate solutions. Furthermore, aluminum nitrate perturbs the surface water structure more than iron nitrate despite aluminum being a weaker Lewis acid. The surface water structure is thus found to be unique for the Al(NO3)3 solutions as compared to both Fe(NO3)3 and NaNO3, such that surface solvation is more pronounced. This observation exemplifies the nature of the Fe(III) and Al(III) ions and their substantial influence on the surface water structure.

Effect of branching in the alkyl chain of diglycolamide on the sequestration of tetravalent actinides: solvent extraction and theoretical studies.

DGA (diglycolamide) ligands show a different extraction behavior of trivalent metal ions by changing the branching alkyl chain length as well as the branching at the methylene position. There are no studies of these factors on the extraction efficiency of these DGA derivatives for the extraction of tetravalent actinides. We have evaluated four different DGA derivatives for the extraction of Np, Pu, and Th from molecular diluents. The n-butyl derivative shows enhanced extraction efficiency and branching gives rise to a reduction in the extraction efficiency of tetravalent ions. The distribution ratios are higher in pure octanol than in a mixture of 30% octanol and 70% n-dodecane. This behavior is in marked difference to that of the extraction of trivalent ions where the addition of an alcohol generally decreases the distribution ratio of trivalent ions due to the ligand-modifier intercation, poor aggregation or micelle formation tendency of DGAs in polar solvents. This suggests that micelle-mediated extraction may not be the dominating factor for the extraction of tetravalent metal ions. Slope analysis suggests the involvement of only two DGA molecules in the extracted species suggesting no/poor possibility of micelle formation in the present system. The higher extraction in pure octanol may be due to a better solubility of the extracted complexes in this polar medium compared to the mixture of octanol and n-dodecane. The water and acid uptake, the back extraction, and the radiation stability of the solvent systems were also investigated. DFT studies were performed to get a better insight into the extraction and complexation of the different DGA solvent systems.

Trivalent transition metal ion mediated template synthesis: In silico molecular docking, DNA binding, antimicrobial evaluation and DFT studies

In order to reduce the chances of multiple drug resistance, there is an urgent requirement for the designing of new antimicrobial agents. In this current research, series of novel hexaazamacrocyclic trivalent transition metal complexes of ChromiumIII and IronIII have been prepared by adopting the pathway of metal ion mediated template condensation. The newly synthesized macrocyclic complexes were analyzed by Infra-Red Spectroscopy, Carbon-Hydrogen-Nitrogen analyzer, UltraViolet–visible, Powder X-Ray Diffraction, Electron Paramagnetic Resonance, Magnetic Susceptibilities, Molar conductance, Electron Spray Ionisation-Mass Spectrometry and Thermogravimetric analysis techniques. The electro-lytic behaviour of the complexes was suggested by conductance (molar) values. All the complexes (T7-T12) can be formulated or represented as [MLX] X2·yH2O, where M = FeIII, CrIII and L is the macrocyclic ring resulting from 1,8-diaminonaphthalene and succinimide and X = NO3−, Cl−, CH3COO− and y = 1 or 2. All the macrocyclic complexes have been anticipated to have a penta coordinated square pyramidal shape using several physico-analytical approaches. Monomeric nature of the complexes was confirmed by CHN analysis and mass spectral data. Powder X-Ray Diffraction studies were carried out for interpreting the crystallinity of the complexes. Density Functional Theory studies were performed for energy optimization and theoretical calculations of UV & IR. The DNA interaction studies showed intercalative mode of binding is present in the newly designed complexes with the DNA. In addition to these, all the metal complexes were screened for their antibacterial and antifungal activity against pathogenic strains of bacteria and fungi, Complex T7 has effective bactericidal action against B. cereus and E. coli. Molecular docking studies were also performed on SARS Cov-2 and Mycobacterium tuberculosis. The used proteins are NSP15 Endoribonuclease from SARS CoV-2 and DNA of Mycobacterium tuberculosis H37Rv. The results revealed that complex T10 is having good binding affinity against DNA of Mycobacterium tuberculosis H37Rv.

Transforming contaminant ligands at water–solid interfaces via trivalent metal coordination

In environmental matrices, the migration and distribution of contaminants at water–solid interfaces play a crucial role in their capture or dissemination. Scientists working in environmental remediation and wastewater treatment are increasingly aware of metal–contaminant coordination; however, interfacial behaviors remain underexplored. Here, we show that trivalent metal ions (e.g. Al3+ and Fe3+) mediate the migration of pollutant ligands (e.g. tetracycline (TC) and ofloxacin) to the organic solid interface. In the absence of Al3+, humic acid (HA) colloids (50 mg/L) capture 26.1 % of the TC in water (initial concentration: 10 mg/L) via weak intermolecular interactions (binding energy: −5.71 kcal/mol). Adding Al3+ (2.5 mg/L) significantly enhances the binding of TC to an impressive 94.2 % via Al3+ mediated coordination (binding energy: −84.89 kcal/mol). The significant increase in binding energy results in superior interfacial immobilization. However, excess free Al3+ competes for TC binding via direct binary coordination, as confirmed based on the unique fluorescence of Al3+–TC complexes. Density functional theory calculations reveal the intricate process of HA–Al3+ binding via carboxyl and phenolic hydroxyl sites. The HA–Al3+ flocs then leverage the remaining coordination capacity of Al3+ to chelate with TC. As well as providing insights into the pivotal role of metal ion on the self-purification of natural water bodies, our findings on the interfacial behavior of metal–contaminant coordination will propel coagulation technology to the capture of microscale pollutants.

Influence of Al-clustering in the catalytic activity of layered double hydroxides for the Baeyer-Villiger oxidation

The utilization of efficient and environmentally friendly heterogeneous catalysts in the Baeyer-Villiger (BV) reaction gained significant importance in the field of green chemistry. In this study, the catalytic properties of magnesium-aluminium hydrotalcite in the BV oxidation of cyclic ketones using H2O2 were investigated. The research focused on the influence of two different synthetic routes on the clustering of aluminium centers and its impact on catalytic activity in the Baeyer-Villiger reaction. Surprisingly, the catalyst with a high degree of aluminium clustering exhibited superior performance compared to the ordered aluminium solid. Moreover, the most active catalyst displayed sustained activity even after three successive reaction cycles. This study presented the first report on the influence of trivalent metals in the BV reaction, thus opening up a new avenue for further exploration of such catalysts in the context of Baeyer-Villiger oxidation.

Single-Probe-Based Sensor Array for Fingerprint Recognition of Trivalent Metal Ions and Application in Water Identification.

Abnormal concentration levels of trivalent metal ions (M3+) might hinder their natural biological activities in physiological processes and cause severe health hazards. Herein, a dual-chromophore probe (RhB-TPE) composed of rhodamine and tetraphenylethene (TPE) units was synthesized and explored for discriminating M3+ ions. It exhibited special aggregation and AIE properties in aqueous media. Its ensemble with anionic surfactant SDBS assemblies (RhB-TPE/SDBS) could be utilized as fluorescent sensors for selective and sensitive detection of M3+ ions such as Fe3+, Al3+, and Cr3+ by illustrating quenched TPE emission and switched-on rhodamine emission. Moreover, the use of SDBS assemblies at two concentrations could provide a single-probe-based sensor array and realize four-signal pattern recognition of different concentrations of the three M3+ ions and identify M3+ mixtures or unknown samples. The cross-reactive fluorescence variation was attributed to the M3+ influence on the FRET process from TPE to open-ring form rhodamine in the two ensemble sensors. With the coexistence of Al3+, the optimized RhB-TPE/SDBS ensemble sensor array was successfully applied to differentiate commercially available brand mineral water and purified water, as well as tap water. The present work provides a novel strategy to generate a single-probe-based sensor array and realizes fingerprint recognition of three trivalent metal ions and efficient discrimination of different types of water. The modulation FRET process of a dual chromophore in different surfactant ensembles inspires the future construction of novel and effective sensing platforms.

Two polymorph modifications of tris(hexafluoroacetylacetonato)iron(III) revealed: is that common for other trivalent metals?

A long-standing issue about the correct identification of an important starting reagent, iron(III) hexafluoroacetylacetonate, Fe(hfac)3 (1), has been resolved. The tris-chelated mononuclear complex was found to crystallize in two polymorph modifications which can be assigned as the low-temperature (1-L) monoclinic P21/n and the high-temperature (1-H) trigonal P-3. Low-temperature polymorph 1-L was found to transform to 1-H upon sublimation at 44 °C. Two modifications are clearly distinguished by powder X-ray diffraction (PXRD), single-crystal X-ray diffraction, differential scanning calorimetry (DSC), and melting-point measurements. On the other hand, the two forms share similar characteristics in direct analysis in real-time mass spectrometry (DART-MS), attenuated total reflection (ATR) spectroscopy, and some physical properties, such as color, volatility, sensitivity, and solubility. Analysis of the literature and some of our preliminary data strongly suggest that the appearance of two polymorph modifications for trivalent metal (both transition and main group) hexafluoroacetylacetonates is a common case for several largely used complexes not yet accounted for in the crystallographic databases.

Expanding the Phase Space for Halide-Based Solid Electrolytes: Li-Mg-Zr-Cl Spinels.

Chloride-based solid electrolytes are intriguing materials owing to their high Li+ ionic conductivity and electrochemical compatibility with high-voltage oxide cathodes for all-solid-state lithium batteries. However, the leading examples of these materials are limited to trivalent metals (e.g., Sc, Y, and In), which are expensive and scarce. Here, we expand this materials family by replacing the trivalent metals with a mix of di- and tetra-valent metals (e.g., Mg2+ and Zr4+). We synthesize Li2Mg1/3Zr1/3Cl4 in the spinel crystal structure and compare its properties with the high-performing Li2Sc2/3Cl4 that has been reported previously. We find that Li2Mg1/3Zr1/3Cl4 has lower ionic conductivity (0.028 mS/cm at 30 °C) than the isostructural Li2Sc2/3Cl4 (1.6 mS/cm at 30 °C). We attribute this difference to a disordered arrangement of Mg2+ and Zr4+ in Li2Mg1/3Zr1/3Cl4, which may block Li+ migration pathways. However, we show that aliovalent substitution across the Li2-z Mg1-3z/2Zr z Cl4 series between Li2MgCl4 and Li2ZrCl6 can boost ionic conductivity with increasing Zr4+ content, presumably due to the introduction of Li+ vacancies. This work opens a new dimension for halide-based solid electrolytes, accelerating the development of low-cost solid-state batteries.

Application of Bifunctional Layered Double Hydroxide Electrocatalysts to Water Splitting

Water splitting is an area of research which is of pressing interest in addressing climate change. Water splitting provides oxygen and hydrogen as products, with hydrogen finding use as a potential high-density fuel to replace fossil fuels. Water splitting manifests as two half-cell reactions, namely the anodic oxygen evolution reaction and the cathodic hydrogen evolution reaction. The purpose of this project is to synthesise a bifunctional electrocatalyst to use in the water splitting reaction, replacing the rare and expensive transition metals catalysts currently in use such as platinum and ruthenium. The ideal material would exhibit strong performance for both the oxygen evolution reaction and the hydrogen evolution reaction.In this project, Layered Double Hydroxides (LDHs) have been synthesised for use in water splitting. LDHs are a group of ionic compounds characterised by their layered structure of positively charged sheets and an interlayer region consisting of the corresponding anions. LDHs typically contain a bivalent and a trivalent metal as part of the generic formula [M2+ 1–xM3+ x(OH)2][An–]x/n·zH2O. In this project the bivalent metal in use is typically cobalt and the trivalent metal is typically iron. The synthesis developed is a simple, one pot hydrothermal synthesis which can be seen in Figure 1. In this synthesis, the process begins with the precursor materials dissolved in solution. These solutions are mixed and stirred until homogenous. The resultant solution is then heated to form an impure product. Following washing steps and centrifugation a purified powder product is obtained. A variety of metallic salts have been tested for their use in these LDHs with the optimum LDHs selected for further study. The metallic salts used to provide the metals for the LDHs are typically hydrated transition metal nitrates.The LDHs have been characterised and their structure confirmed by a variety of analytical techniques including X-Ray Diffraction and Scanning Electron Microscopy. Simple qualitative analysis has been performed with FTIR spectroscopy. These LDHs have been immobilised on a variety of porous, high surface area materials, including nickel foam and copper foam, to enhance the properties seen in the screening study. These materials allow synthesis of high surface area, reactive electrocatalysts. To enhance the stability of the LDHs, carbon materials have been integrated with the LDHs. Examination of a variety of carbon materials involved post-synthesis mixing of the carbon material and the LDH product or inclusion of the carbon material in the LDH synthesis to form a composite. A variety of carbon materials have been analysed including graphene oxide, carbon black and carbon nanotubes. Figure 1

Oxidative and Reductive Manipulation of C1 Resources by Bio-Inspired Molecular Catalysts to Produce Value-Added Chemicals.

ConspectusTo tackle the energy and environmental concerns the world faces, much attention is given to catalytic reactions converting methane (CH4) and carbon dioxide (CO2) as abundant C1 resources into value-added chemicals with high efficiency and selectivity. In the oxidative conversion of CH4 to methanol, it is necessary to solve the requirement of strong oxidants due to the large bond-dissociation energy (BDE) of the C-H bonds in methane and achieve suppression of overoxidation due to the smaller BDE of the C-H bond in methanol as the product. On the other hand, to efficiently perform CO2 reduction, proton-coupled electron transfer (PCET) processes are required since the reduction potential of CO2 becomes positive by using proton-coupled processes; however, under the acidic conditions required for PCET, hydrogen evolution by the reduction of protons becomes competitive with CO2 reduction. Thus, it is indispensable to develop efficient catalysts for selective CO2 reduction. Recently, we have developed efficient catalytic reactions toward the alleviation of the concerns mentioned above. Concerning CH4 oxidation, inspired by metalloenzymes that oxidize hydrophobic organic substrates, a hydrophobic second coordination sphere (SCS) was introduced to an FeII complex bearing a pentadentate N-heterocyclic carbene ligand, and the FeII complex was used as a catalyst for CH4 oxidation in aqueous media. Consequently, CH4 was efficiently and selectively oxidized to methanol with 83% selectivity and a turnover number of 500. In contrast, when methanol was used as a substrate for catalytic oxidation by the FeII complex, oxidation products were obtained in a negligible yield, which was comparable to that of the control experiment without the catalyst. Therefore, the hydrophobic SCS of the FeII complex can capture only hydrophobic substrates such as CH4 and release hydrophilic products such as methanol to the aqueous medium for suppressing overoxidation ("catch-and-release" mechanism). On the other hand, for photocatalytic CO2 reduction, we have developed NiII complexes with N2S2-chelating ligands as catalysts, which have been inspired by carbon monoxide dehydrogenase, and have also introduced a binding site of Lewis-acidic metal ions to the SCS of the Ni complex. When Mg2+ was applied as a moderate Lewis acid, a Mg2+-bound Ni catalyst allowed us to achieve remarkable enhancement of the photocatalytic CO2 reduction to afford CO as the product with over 99% selectivity and a quantum yield of 11.4%. Divalent metal ions besides Mg2+ also showed similar positive impacts on photocatalytic CO2 reduction, whereas monovalent metal ions exhibited almost no effects and trivalent metal ions exclusively promoted hydrogen evolution. In this Account, we highlight our recent progress in the catalytic manipulations of CH4 and CO2 as C1 resources.

Harvesting high-performance electro-water oxidation and selective MB degradation through dual functional Gd2O3–La2O3 photo-electrocatalysts

Interestingly, catalytic oxygen evolution reaction (OER) in an alkaline medium with minimizing the overpotential is the most trustworthy electrocatalyst for the output of hydrogen energy from copious water electrochemical activity. Currently, amalgamated trivalent cations metal oxides have gained desirability as a low-cost anode electrocatalyst to replace noble metal-supported electrocatalysts for water oxidation and are also used for photo-degradation applications. In the present work, we have successfully synthesized Gd2O3 supported La2O3 composites via hydrothermal pathways for efficient OER and selective methylene blue (MB) degradation applications. XRD, UV–Vis DRS, FT-IR, XPS, SEM-EDX, HR-TEM, DLS, and BET analyzers confirmed the successful synthesis of photo-electrocatalysts. Gd2O3–La2O3 composites achieved 5.66 and 3.37-fold larger surface areas than La2O3 and Gd2O3, respectively. The results of the Gd2O3 supported La2O3 composite electrode demonstrated better OER performance under 1 M KOH, and it exhibited a lower Tafel slope and overpotential of 72 mV dec−1 and 310 mV at 10 mA cm−2. A chronoamperometry examination confirms that the fabricated Gd2O3–La2O3 electrode has good stability at a fixed potential of 1.540 V vs. RHE for water oxidation. Although the, Gd+3 inspired La2O3 electrode actively takes part in OER activity owing to its high Cdl value of 40.222 μF cm−2. The selective degradation of MB dye using the Gd2O3–La2O3 composite achieved an acceptable degradation efficiency of 84.80 % compared to other pollutants under UV-light irradiation for 120 min, and the specified pH condition is 9 for the degradation of MB dye, and it follows the first-order kinetics model. Notably, post-OER and photocatalytic results exhibited good stability and reusability characteristics. Therefore, the Gd2O3–La2O3 catalyst can be used for real-time water oxidation and MB dye removal from polluted water.

Evaluation of homogeneous and heterogeneous catalytic strategies for furfural production from sugar-derived biomass in a solvent-free green pressurized reaction media (subcritical water-CO2)

A green organic, solvent-free, subcritical water-CO2 (subW-CO2) system was proposed for the production of furfural from the main hemicellulose's sugar, xylose. Despite subW itself showed potential for furfural generation due to its catalytic properties under subcritical conditions; when CO2 was added into the system as pressurization agent, higher yields were reached due to its effect as a Brønsted acid when dissolved in water. Furthermore, its combination with different Lewis acidic catalysts showed a synergistic effect, further improving furfural yield. In a batch configuration, five homogeneous and four heterogeneous catalysts were tested at 180 °C and 5.5 MPa and compared for the first time in a subW-CO2 reaction medium. Different furfural production paths were determined for the two catalysts types, with higher xylose isomerization rates to xylulose when homogeneous trivalent metal catalysts were used. CrCl3 and Nafion NR50 resin were selected as best catalysts from each of the groups due to higher furfural production rates (51.9 ± 0.9 % yield/h) and higher furfural selectivity (60.9 %), respectively. Furthermore, Nafion NR50 catalytic activity remained unchanged after 10 runs at 180 °C. The green subW-CO2 system furfural yields were comparable to water-organic solvent biphasic ones, proving to be a promising green alternative.

High-Pressure oC16-YBr3 Polymorph Recoverable to Ambient Conditions: From 3D Framework to Layered Material.

Exfoliation of graphite and the discovery of the unique properties of graphene─graphite's single layer─have raised significant attention to layered compounds as potential precursors to 2D materials with applications in optoelectronics, spintronics, sensors, and solar cells. In this work, a new orthorhombic polymorph of yttrium bromide, oC16-YBr3 was synthesized from yttrium and CBr4 in a laser-heated diamond anvil cell at 45 GPa and 3000 K. The structure of oC16-YBr3 was solved and refined using in situ synchrotron single-crystal X-ray diffraction. At high pressure, it can be described as a 3D framework of YBr9 polyhedra, but upon decompression below 15 GPa, the structure motif changes to layered, with layers comprising edge-sharing YBr8 polyhedra weakly bonded by van der Waals interactions. The layered oC16-YBr3 material can be recovered to ambient conditions, and according to Perdew-Burke-Ernzerhof-density functional theory calculations, it exhibits semiconductor properties with a band gap that is highly sensitive to pressure. This polymorph possesses a low exfoliation energy of 0.30 J/m2. Our results expand the list of layered trivalent rare-earth metal halides and provide insights into how high pressure alters their structural motifs and physical properties.

Copper Foil Substrate Enables Planar Indium Plating for Ultrahigh‐Efficiency and Long‐Lifespan Aqueous Trivalent Metal Batteries

AbstractAqueous trivalent metal batteries represent a compelling candidate for energy storage due to the intriguing three‐electron transfer reaction and the distinct properties of trivalent cations. However, little research progress has been achieved with trivalent batteries due to the inappropriate redox potentials and drastic ion hydrolysis side reactions. Herein, the appealing yet underrepresented trivalent indium is selected as an advanced metal choice and the crucial effect of substrate on its plating mechanism is revealed. When copper foil is used, an indiophilic indium‐copper alloy interface can be formed in situ upon plating, exhibiting favorable binding energies and low diffusion energy barriers for indium atoms. Consequently, a planar, smooth, and dense indium metal layer is uniformly deposited on the copper substrate, leading to outstanding plating efficiency (99.8–99.9%) and an exceedingly long lifespan (6.4–7.4 months). The plated indium anode is further paired with a high‐mass‐loading Prussian blue cathode (2 mAh cm−2), and the full cell (negative/positive electrode capacity, N/P = 2.5) delivers an excellent cycling life of 1000 cycles with 72% retention. This work represents a significant advancement in the development of high‐performance trivalent metal batteries.

Elucidating the role of Ag+, Cu2+, and Fe3+ in tuning the electrical characteristics of polyaniline prepared through post-doping method

Abstract Conducting polymers possess inherent electrical conductivity, attracting significant attention in engineering applications, including dye-sensitized solar cells, gas sensors, and energy storage electrodes. Of various conducting polymers, Polyaniline has gained much attention due to its low cost of monomer, ease of bulk synthesis, high flexibility, and good environmental stability. Nevertheless, the conductivity of polyaniline is rather low when it is prepared under an un-doped state. Despite that, there is no clear information regarding how the valency of a metal dopant and its concentration can affect the electrical characteristics and other physicochemical properties of doped polyaniline. This study aims to fill this research gap by elucidating the changes in the electrical characteristics of polyaniline through metal doping. Polyaniline was synthesized through chemical oxidative polymerization in an HCl medium, followed by a post-doping to produce metal-codoped polyaniline. Three dopant materials, namely AgNO3, Cu(NO3)2, and Fe(NO3)3, were used in this synthesis, representing mono-, di-, and tri-valent metal ions, respectively. Results showed that bare PANI (which was doped with HCl only) exhibited a higher electrical conductance value of 8.44 x 10-7 S, while 1 M of Ag-codoped polyaniline, 1 M of Cu-codoped polyaniline, and 1 M of Fe-codoped polyaniline exhibited electrical conductance values of 1.73 x 10-7 S, 4.27 x 10-8 S, and 2.33 x 10-6 S, respectively. Apparently, the trivalent metal dopant was able to improve the conductivity of polyaniline; however, a detrimental effect resulted when the concentration of Fe3+ was increased to 1.5 M (overdose), resulting in a drop in electrical conductance to 4.66 x 10-8 S. In terms of morphological property, Ag-doped polyaniline exhibited a mixture of plate-like and globule-like structures, while both Cu-doped polyaniline and Fe-doped polyaniline predominantly displayed tiny globule-like structures, likely attributed to the stronger acidity of the Cu(NO3)2 and Fe(NO3)3 solutions. Meanwhile, the presence of several common bands of polyaniline such as N-H, C=N, C-H aromatic, quinoid and benzoid units are detected in the produced samples. The project outcomes are expected to guide tailored development of metal-doped polyaniline for specific electrical applications.

Mineral chemistry and garnet U-Pb dating in the Bizmişen iron skarn deposit, Erzincan, East-Central Türkiye

In Bizmişen area, Middle Eocene (46.3–42.0 Ma) plutonic rocks (quartz diorite) were intruded into Triassic-Cretaceous limestones and Upper Cretaceous ophiolites and caused to skarn zones containing prograde (garnet, clinopyroxene) and retrograde (amphibole, epidote, calcite, magnetite, phlogopite, serpentinite and chlorite) minerals. Due to contact relationships of quartz diorites with both serpentinized ultramafic rocks and limestone blocks, the mineralogical associations represent calcic (grossular/andradite, amphibole, chlorite and epidote) as well as magnesian (diopside, serpentine, phlogopite, talc) skarns. During the skarnization process, garnet, diopside, epidote, scapolite and amphibole minerals developed in the endoskarn zone within quartz-diorite, and diopside, tremolite, serpentine, phlogopite, talc, Mg-chlorite and calcite minerals developed in the exoskarn zones in ophiolites (serpantinite and listwaenite) and limestones. Skarn and magmatic clinopyroxenes in serpentinized ultramafic hosted exoskarn zone have a compositional range of Wo45-53En35-53Fs0–15 and Wo24-51En38-76Fs0–11, and classified as diopside and augite, respectively. The end members of garnets are Adr46–54Grs43–50Prp1–2Sps1.1–5 in amphibole-epidote-calcite-garnet skarn in endoskarn zone, whereas Adr40–93Grs4–57Prp0.2–2.3Sps0.9–2 in epidote-calcite-garnet skarn in exoskarn zone, and classified as andradite-rich grandite garnets. FeO, MnO and partially MgO contents gradually increase from the edges to the center in zoned garnet grains. Amphibole compositions represent to calcic (Ca >1 atoms per formula unit) group (pargasite) and indicate the high oxygen fugacity conditions which caused the increase in the rate of magnetite crystallization. Al2O3 and FeO contents of epidotes range 23.68–27.63 and 9.10–14.45 wt%, respectively, correspond to composition of epidote and clinozoisite. The iron oxide contents (FeO, wt%) of magnetites change from 91.72 to 98.36 correspond to structural Fe3+1.88–1.97 and Fe2+0.91–1.0 values. The contents of Ti, divalent and trivalent metal cations correspond to ulvospinel-magnetite compositional line at the magnetite end-member. The mineral chemistry of skarn minerals shows similarities to those of most iron skarn deposits. Garnet U-Pb ages (46.95–45.63 Ma) are consistent with the cooling ages of the Bizmişen pluton. The prograde stage of skarn should be occurred syn-intrusion, whereas retrograde stage should be developed later than youngest garnet age (45.6 Ma) and before the oldest late stage argillic alteration (37.5 Ma).

Unveiling the impact of Fe-doping concentration on the local structure and morphological evolution of Cr2O3 nanoparticles

A series of Cr2−xFexO3 (0.0 ≤ x ≤ 0.3) nanoparticles were successfully synthesized using a sol-gel-based method. Analysis through XRD and SAED of both pure and Fe-doped Cr2O3 nanoparticles revealed a rhombohedral structure belonging to the R3‾cD3d6 space group, without the formation of secondary phases or Fe clusters. Fe ions were well integrated, as indicated by fluctuations in lattice parameters, and lattice strain. The crystallite size decreased from 38.42 to 27.54 nm with increasing doping concentration. HRTEM images depicted evenly distributed nanoparticles. At lower dopant concentrations (x = 0.1), smaller and more heterogeneous nanorod-like structures emerged, with average sizes and lengths of 36.56 and 39 nm, respectively. Increasing the doping content to x = 0.2 resulted in a morphological shift towards semi-spherical and ellipsoidal shapes, with average dimensions of 22.84 and 31 nm, respectively. At higher doping levels (x = 0.3), nanoparticles grew to 66.5 nm in size and exhibited a spherical morphology. Raman and Fourier transform infrared spectra showed red-shifting of absorption bands with increasing Fe content, attributed to variations in bond length and Cr/Fe–O–Cr/Fe structural perturbation. XPS and Mössbauer spectroscopy analyses confirmed the oxidation states of Fe3+ and ionized oxygen vacancies in the crystal lattice of Cr2O3 nanoparticles. Higher values of quadrupolar splitting Δ indicated greater structural disorder induced by Fe3+ in octahedral positions and in an oxygen-deficient environment. Atomistic simulations confirmed that Fe3+ dopants can induce the presence of vacancy-complexes, forming a stable double-defect configuration with vacant Cr sites along the c-axis, proximal to oxygen vacancies with a single positive charge. These findings offer both experimental and theoretical insights into the dynamics of structural defects in trivalent transition metal doping of Cr2O3 nanoparticles, which holds significant implications for spintronics research.

Thermodynamic Study of Adsorption behaviors of Trivalent Metal Ions onto Chelating Resin: Comparison between Scandium(III) and Other Metal Ions

Thermodynamic Study of Adsorption behaviors of Trivalent Metal Ions onto Chelating Resin: Comparison between Scandium(III) and Other Metal Ions

TEMPLATE-ENGINEERED TRIVALENT IRON AND CHROMIUM CONTAINING MACROCYCLIC COMPLEXES: CHARACTERIZATION AND IN VITRO STUDIES

A novel series of tetraaza macrocyclic complexes of biological importance was synthesized by “in situ” template reaction between triethylenetetramine and dibenzoylmethane in the presence of trivalent Fe and Cr metal salts in 1:1:1 molar ratio. These complexes are represented by molecular formula [M(C[Formula: see text]H[Formula: see text]N[Formula: see text]X]X2; [Formula: see text](III) and Cr(III); [Formula: see text], NO[Formula: see text], −OAc; C[Formula: see text]H[Formula: see text]N[Formula: see text] ligand. The reported complexes were characterized by using various physicochemical and spectroscopic techniques including elemental analyses, molar conductance, thermo-gravimetric analysis, FTIR, UV–Visible and mass spectral studies. The results obtained from analytical techniques and spectroscopic techniques together suggested the complexes have a square pyramidal geometry. Various computational studies were performed including molecular docking and modeling. Further, macrocyclic complexes were also screened for their “in vitro” antimicrobial activity against selected bacterial and fungal strains. The antioxidant activity of these complexes was also evaluated. Some of the complexes were found to possess remarkable antimicrobial activity and antioxidant activity. However, complex [Fe(C[Formula: see text]H[Formula: see text]N[Formula: see text](NO[Formula: see text]](NO[Formula: see text] was found to be most potent against selected bacterial and fungal strains. On the other hand, complex [Cr(C[Formula: see text]H[Formula: see text]N[Formula: see text](NO[Formula: see text]](NO[Formula: see text] was found to show best antioxidant activity with lowest value of IC[Formula: see text].