Chemistry and Materials Science

Abstract: Five new crystalline phases from coordination compounds containing copper(II) ethylenediamine and iodine (F1-F5) were obtained and identified by Single Crystal X-Ray Diffraction (SCXRD). The compounds present a coordination environment where the four nitrogen atoms are located in a square planar geometry and two apical positions complete an octahedron with different degrees of distortion from the ideal geometry. These two opposite vertices are occupied by one iodide and one water molecule in F1 or two iodide ligands in F2-F5. The compounds can easily be synthesized and undergo several transformations that were monitored and studied. A comparative study of the crystal packing was performed to understand the stability of the different phases.

Abstract: Objective: This study aimed to evaluate the feasibility of producing suspension NPK fertilizers from wet-process phosphoric acid (WPA), sunflower ash, and ammonium nitrate, characterize the elemental composition of the starting materials, and estimate raw material requirements for formulations with different nutrient compositions. Methods: Wet-process phosphoric acid and two ash samples were characterized using X-ray fluorescence (XRF) spectroscopy. Five suspension NPK fertilizer samples were analyzed for their main nutrient components following sample mineralization, using photometric methods. Elemental phosphorus and potassium concentrations were converted into their corresponding P₂O₅ and K₂O equivalents. Theoretical raw material requirements were estimated using nutrient-based mass balance equations. Results: The potassium contents of the two sunflower ash samples were 29.30% and 26.10%, corresponding to K₂O equivalents of 35.29% and 31.44%, respectively. The elemental phosphorus content of WPA was 8.82%, equivalent to 20.21% P₂O₅. The five NPK suspension samples exhibited reported N–P₂O₅–K₂O compositions of 9–12–4, 11–11–11, 10–9–4, 8–7–5, and 7–7–6, respectively. Among the investigated formulations, NPK-2 had the highest reported combined nutrient content of 33%. For a target formulation of 100 g of NPK 11–11–11 fertilizer, theoretical nutrient-balance calculations indicated approximate requirements of 53.25 g of WPA, 34.91 g of sunflower ash, and 32.35 g of ammonium nitrate. However, the calculated total input mass exceeded the target product mass, indicating the need for experimental validation of the overall mass balance. Conclusions: The findings indicate the potential of sunflower ash as an alternative potassium source for suspension NPK fertilizer formulations in combination with wet-process phosphoric acid and ammonium nitrate. Nutrient-based calculations provide a preliminary basis for estimating raw material requirements. Further investigations are needed to verify the actual mass balance, confirm the total nitrogen content, and evaluate suspension stability and agrochemical properties before establishing a validated production formulation.

Abstract: The efficient capture of both I₂ and CH₃I is of critical importance for environmental remediation due to their high toxicity and environmental mobility. In this study, an imidazole and bismuth co-loaded silicalite-1 zeolite (Im@Bi-TSL-1) was synthesized by a combined hydrothermal reduction and solid-phase adsorption method. Based on the dual function strategy, Im@Bi-TSL-1 exhibited a maximum adsorption capacity of 2494.5 mg/g for I₂ and 568.6 mg/g for CH₃I, with BiI₃ and BiOI identified as the final adsorption products resulting from the synergistic methylation reaction and metal-based reaction. Moreover, the Im@Bi-TSL-1 after CH₃I adsorption (Im@Bi-TSL-1-CH₃I) exhibited a maximum iodide leaching rate of 39.2% in pure water at 72 h, surpassing that of commercial Ag-loaded zeolite (AgZ). The TSL-1-based composite delivered superior performance across multiple evaluation metrics, underscoring its potential for iodine capture. This study provides a design reference for the development of high-performance radioactive iodine adsorbents, aiming to achieve efficient removal and immobilization of iodine gaseous species.

Abstract: Coordination of organic biradicals to transition metals is a promising route to multifunctional materials, but controlling the metal oxidation state during complexation remains challenging. Here we attempted to prepare a ruthenium(III) complex with the 2,6-bis(1-oxyl-4,4,5,5-tetramethyl-4,5-dihydro-1-H-imidazol-2-yl)pyridine (bisimpy), tridentate imino-nitroxide, from [RuCl3(PhCN)3]. Instead, redox processes between the ligand and the ruthenium precursor in solution yielded the ruthenium(II) complex [Ru(bisimpy)(PhCN)Cl2]. The product was characterized by single-crystal X-ray diffraction and UV-vis absorption in solution supported by TD-DFT and BS-DFT calculations. Structural analysis confirms the tridentate coordination of bisimpy to a centrosymmetric Ru(II) ion, rendering the two iminonitroxide fragments equivalent. UV-vis spectra show intense ligand-centered bands in the UV region and MLCT transitions in the near-IR region absent in the free biradical. TD-DFT computation reproduces the experimental spectra assigning the features to metal-to-ligand, and mixed ligand–ligand/metal–ligand transitions. Notably, BS-DFT computation predicts a dramatic change in the intramolecular exchange between the two radical centers: whereas the free biradical is weakly ferromagnetic, coordination to the diamagnetic Ru(II) center switches the coupling to strongly antiferromagnetic through a metal-mediated superexchange pathway. These results show that the imino-nitroxide biradical directs the reaction toward Ru(II) rather than the targeted Ru(III) species and demonstrate that a formally diamagnetic d⁶ metal can actively modulate radical–radical magnetic communication. In the Ru(II) complex, the diamagnetic low-spin 4d⁶ center (S = 0) does not participate in direct magnetic exchange with the radicals, but it mediates a strong antiferromagnetic coupling between the two radical centers through superexchange involving the 4d metal orbitals.

Abstract: Vapor-responsive phosphorescent materials are desirable for sensing, yet reversible switching in Cu(I) complexes remains challenging. Here, a series of ionic and neutral Cu(I)–Imphen–diphosphine complexes were designed and synthesized to enable reversible phosphorescence switching upon exposure to NH₃ and HCl vapors. The complexes were characterized by IR, NMR, X-ray single-crystal diffraction, and ESI-MS. Photophysical studies revealed that absorption and emission are governed by both ligand deprotonation and solvent effects: in dichloromethane, ionic and neutral complexes show markedly different spectral profiles, whereas in DMSO, strong solvation and hydrogen-bond acceptance smooth the spectral differences between ionic and neutral complexes. Notably, when deposited on silica gel TLC plates, complexes 1a and 1b display reversible, visually detectable phosphorescence switching upon alternating exposure to NH₃ and HCl vapors. This response is attributed to reversible protonation/deprotonation, which modulates high-frequency vibrational quenching channels and the extent of π-conjugation, with additional influence from the confined silica gel microenvironment and heat-assisted volatilization of DMSO-d₆ during fuming. This work provides a robust foundation for developing Cu(I)-based materials for reversible acid–base vapor phosphorescent sensing.

Abstract: The aim of this paper is to obtain and verify the structures and the biological activity of novel metal complexes derived from 5-carboxy-2-thiouracil. The paper outlines a synthesis method and assesses the antimicrobial activity of newly formed Cu(II), Ni(II) and Co(II) complexes. Several syntheses were carried out with and without NaOH. The structural were verified by melting point analysis, ICP-OES for Cu, Ni and Co, UV-Vis, ATR, solid state and solution 1H NMR, 13C NMR spectroscopy. In addition, the antimi-crobial activity of these complexes and the free ligand are assessed against both Gram-positive and Gram-negative bacteria, as well as yeasts. For the cytotoxic assay we were used the HCT-116 colorectal cell line (ATCC). Only two Ni(II) complexes show reduction in the number of viable tumor cells. All the other compounds did not lead to a significant reduction in the number of viable cells as determined by one-way ANOVA statistical analysis.

Abstract:

Upon metal coordination, the upper rim modification of the Schiff base ligand 2-methoxy-6-((methylimino)methyl)phenol gives rise to a new family of [M(II)₇] (M = Co, Ni, Zn) pseudo metallocalix[6]arenes in the form of [Co(II)₇(OMe)₆(L₃)₆](NO₃)₂^.H₂O^.3MeOH (1), [Ni(II)₇(OMe)₆(L₃)₆](NO₃)₂^.2H₂O (4), [Zn(II)₇(OH)₂(OMe)₄(L₃)₆](NO₃)₂^.4MeOH^.10H₂O (5) and [Zn(II)₇(OMe)₆(L₄)₆](NO₃)₂^.10MeOH^.13H₂O (6), where L₃H = 2-methoxy-4-phenyl-6-[(methylimino)methyl]phenol and L₄H = 2-methoxy-4-tolyl-6-[(methylimino)methyl]phenol). The upper rim functionalisation provides this family with extensions to their molecular cavity walls when compared to their previously reported siblings. Attempts at encapsulating guest moieties (e.g. C₆₀) unexpectedly give rise to the monometallic complex [Co(II)Co(III)(L₃)₃(NO₃)₂]^.H₂O (3).

Abstract: Two diastereoisomers of bis(mepirizole)bis(isothiocyanato-K,N)cobalt(II) (1 and 2) have been isolated from the reaction of cobalt(II) thiocyanate and meperizole depending on the crystallisation solvent (ethanol, 1; acetonitrile, 2). In both crystal structures, the Co(II) ions exhibit distorted octahedral [CoN₄N’₂] environment. The analysis of the packing frameworks shows a cooperative relationship between non-classical Hbonds C(sp³)H···X (X = N, O, S, pi) and pi-hole bonds, which control the arrangement of the supramolecular 3D networks. The values of the shortest intermolecular metal-metal separation are 8.584(2) in 1 and 8.249(1) in 2. Both diatereoisomers exhibit magnetic behavior typical of mononuclear Co(II) systems with significant zero-field splitting (ZFS) values, D being 75.8(1) and 52.9(2) cm-1 for 1 and 2, respectively. Q-band EPR studies confirm the positive value for the D parameters for both compounds. Alternating current dynamic susceptibility measurements show that 1 and 2 exhibit field-induced slow relaxation of the magnetization, which is reminiscent of single-ion magnet (SIM) behavior.

Abstract: The phase-pure syntheses of Fe(dca)₂ and Fe(dca)₂(NH₃)₂ have enabled comprehensive investigation of their structural and magnetic properties. Fe(dca)₂ crystallizes in the orthorhombic space group Pnnm, with Fe²⁺ ions octahedrally coordinated by six dca ligands, forming a rutile-like 3D network. Temperature-dependent structural analysis reveals minor distortions and a slight unit cell volume contraction (~2.5 ų) from 300 K to 25 K. Fe(dca)₂(NH₃)₂ crystallizes in the monoclinic space group P2₁/c, featuring two axial ammonia ligands and dca-bridged Fe²⁺ ions forming layers. Magnetic susceptibility measurements of Fe(dca)₂ reveal a ferrimagnetic transition at T_C = 19.1 K, con-firmed by SQUID data, Mößbauer spectroscopic measurements and low-temperature neutron diffraction. A magnetic hysteresis at 5 K indicates long-range cooperative magnetic ordering. ATR-IR spectroscopic measurements support the structural models and confirm the chemical composition of both compounds. TGA shows the thermal decomposition of Fe(dca)₂.

Abstract: The 17-e anion, [Fe(CO)₄]^- , was first characterised in 1981 by Breeze et al. We subsequently challenged their interpretation, suggesting that they had produced [Fe(CO)₃]^-. In the light of new calculations here, we withdraw that view. We confirm that [Fe(CO)₄]^- has the C_3v structure (as previously reported) and we have calculated the following, new, energy-factored force constants: k₁ = 1437.2 k₂ = 1456.2 k₁₁ = 48.6 k₁₂ = 47.7 where k₁ refers to the three chemically identical equatorial CO groups and k₂ refers to the sole axial CO group ( k₁₁ and k₁₂ are the CO,CO interaction constants). This force field is significantly different from that originally proposed.

Abstract: The treatment of Ce(OH)₄ in thionyl chloride and dimethoxyethane (DME) resulted in the formation of a highly unstable red Ce(IV) complex with the composition [CeCl₄(DME)₂] (1). From the reaction of 1 with the tripodal Kläui ligand η⁵-cyclopentadienyltris(dimethylphosphonato)cobaltate(III), [Co(η⁵-C₅H₅){P(O)(OMe)₂}₃]– (L_OMe), the two new cerium(III) complexes [Ce(L_OMe)₂(H₂O)₂]Cl·2.5H₂O (2), 1D-[Ce(μ-Cl)(L_OMe)(H₂O)₃]Cl (3) and the cerium(IV) complex [CeCl₂(L_OMe)₂]·acetone (4) were obtained and structurally characterized. The complexes 3 and 4 are the first cerium complexes featuring the L_OMe ligand together with chlorido ligands. Due to the potential exchange of the chloride counterions and ligands in 2 - 4, these complexes could serve as precursors in molecular cerium coordination chemistry. The assigned cerium oxidation states are supported by the bond valence sum (BVS) method. The ³¹P-NMR spectra with d(³¹P) = 160.20 ppm (2) and 159.43 ppm (3) are diagnostic of cerium(III).

Abstract: Pure and glycine-doped strontium formate dihydrate [Sr(HCOO)₂·2H₂O] single crystals were grown by slow evaporation using glycine concentrations of 0.005 – 0.1 M. The influence of glycine incorporation on structural, vibrational, electronic, and antimicrobial properties was studied experimentally and using DFT (B3LYP/6-311G**). The HOMO – LUMO gap (7.111 eV) indicates stability, while the hyperpolarizability (6973.787 a.u.) suggests potential nonlinear optical behavior. FT-IR and FT-Raman analyses show characteristic modes with slight shifts due to glycine–lattice interactions. Doped crystals exhibit enhanced antimicrobial activity, with a maximum inhibition zone of 36 mm against Escherichia coli at 0.1 M concentration. Results indicate that glycine affects the electronic and biological properties of strontium formate dihydrate, suggesting potential optical and antimicrobial applications.

Abstract: The amide macrocyclic complexes of zinc (ZnMc1, ZnMc2, and ZnMc3) were synthesized through template condensation of oxalic acid with different diamines (p-phenylenediamine, ethylenediamine, and propylenediamine). These zinc complexes were characterized using FT-IR, UV-Vis, conductance measurements, and DFT analysis, then tested for in vitro antibacterial and anticancer activities against Bacillus subtilis and HCT-15 cell lines, respectively. The results suggest that the complexes have promising antimicrobial and anticancer properties. The molecular structures of these zinc (II) complexes were also optimized theoretically, and their electronic and thermodynamic properties were determined with density functional theory (DFT). Finally, molecular docking studies using AutoDock evaluated the biological relevance of the synthesized complexes, identifying the most effective binding modes between the complexes and the receptor protein's active site. Two protein receptors, 6COX and 7AHL, were used to dock the macrocyclic complexes. The binding energies provide insights into their pharmaceutical potential. SwissADME and pkCSM were used to predict pharmacokinetic properties and toxicity. The ADMET profile of these macrocyclic architectures revealed their oral bioavailability and drug-like properties. Zinc complexes are known for their medicinal applications. So, these complexes were synthesized and studied as promising drug candidates for the future, though further research is needed to develop potent inhibitors.

Abstract: The removal of thorium from contaminated water sources is crucial for environmental protection and nuclear waste management. Herein, we present a dual-strategy design of a thiophene-integrated porphyrin covalent organic framework (TAPP-BTD-COF) that combines rigid macrocyclic scaffolds with flexible thiophene linkages, incorporating complementary N and S donor sites. This tailored COF achieves efficient and selective capture of Th(IV) from acidic aqueous solutions. By leveraging the topological arrangement of the porphyrin core to modulate the conformation of thiophene-based connectors, a coordination environment with N–S synergistic sites is created, which significantly enhances Th(IV) selectivity over competing ions. At pH 4.5, the synthesized TAPP-BTD-COF exhibits a high adsorption capacity of 437.18 mg g-1 and reaches equilibrium within 20 minutes. It demonstrates exceptional selectivity for Th(IV), with a separation factor exceeding 2.6×10³ relative to common interfering ions, and retains over 90% adsorption capacity after three consecutive cycles. Mechanistic studies confirm that the high performance originates from N–Th / S–Th dual-dentate coordination. This work provides a strategic design of functional COFs for thorium recovery and represents a highly efficient adsorbent system for Th(IV) removal from aqueous streams.

Abstract: Reactive oxygen species (ROS)-mediated cancer therapy has attracted extensive attention due to its high spatiotemporal selectivity and minimum side-effects. Herein, we report a nonanuclear Pd-based coordination cage of Pd6-TMPP(Ni), constructed from Ni-chelated TMPP(Ni) as the metalloligand and Pd2+ ions (H2TMPP = meso-tetrakis (6-methylpyridin-3-yl) porphyrin). Pd6-TMPP(Ni) integrates dual ROS-generation for cancer therapy, viz., hydroxyl radical (•OH) production and photoinduced singlet oxygen (1O2) generation. In vitro cytotoxicity assays against cancer cell lines NCI-H82 (lung cancer), A549 (lung cancer), KYSE-510 (esophageal cancer), and Te-1 (esophageal cancer), reveal its potent dark toxicity (IC₅₀: 1.867–2.107 μmol L−1) and phototoxicity (IC₅₀: 0.835–1.528 μmol L−1), which is attributed to enhanced intracellular ROS accumulation. This work develops a versatile therapeutic platform that harnesses Ni-induced •OH for chemodynamic therapy (CDT) and porphyrin-generated ¹O₂ for photodynamic therapy (PDT), thereby mitigating the oxygen dependence of conventional PDT.

Abstract: In this work, the activity of vanadium-doped and undoped phosphomolybdic acids, H3+n PMo12-nVnO40 (n = 0, 1, 2 and 3), was evaluated in the acetalization reaction of furfural with alkyl alcohols. The main focus was to verify how vanadium charge impact catalytic activity of phosphomolybdic acid, and to try to link these effects to changes in their structural properties. The main reaction parameters such as catalyst charge, catalyst concentration, temperature, time, type of alcohol, type of aldehyde, vanadium charge, and H+ ion charge were studied. Various Brønsted acids (sulfuric, p-toluenesulfonic, undoped and doped phosphomolybdic acids) were evaluated in condensation reactions of furfural with methyl alcohol. Notably, H4PMo11V1O40 was the most active and selective catalyst toward the formation of methyl acetal furfural. The water has a leveling effect over the strength of these acids. Nonetheless, under reaction conditions, the presence vanadium impacted the strength of phosphomolybdic acids, allowing distinguish what is the strongest; vanadium monosubstituted phosphomolybdic acid. The superior performance of H4PMo11V1O40 was attributed to its additional acidity, resulting from the presence of very strong (H+) and Lewis and Brønsted acid sites, due to the substitution of Mo6+ by V5+ in its structure.

Abstract: Well-defined, small-molecule, platinum-centered coordination compounds are of continued interest in both basic and applied research, particularly in medicinal chemistry and pharmaceuticals (i.e., cisplatin). Organoplatinum(IV) complexes have been reported to exhibit substantial in vitro cytotoxicity across a range of cancer cell lines. Compared with coordinatively unsaturated platinum(II) species, electronically and coordinatively saturated platinum(IV) complexes are generally more inert, reducing undesirable side reactions in plasma and cellular environments and potentially improving their safety profiles as chemotherapeutic agents. In addition, the presence of organic ligands can enhance lipophilicity, facilitating passive diffusion across cell membranes. Here, we report the synthesis, structural characterization, and in vitro anticancer activity of a series of organoplatinum(IV) complexes of the general formula Pt(CH₃)₂I₂{n,n′-dimethyl-2,2′-bipyridine} (n,n′ = 4,4′; 5,5′; 6,6′). The 5,5′- and 6,6′-dimethyl isomers were characterized by single-crystal X-ray diffraction. All three dimethyl-substituted complexes, along with the parent compound Pt(CH₃)₂I₂{2,2′-bipyridine}, were evaluated for cytotoxic activity against a panel of 60 human cancer cell lines. Whereas Pt(CH₃)₂I₂{2,2′-bipyridine} and the 4,4′- and 5,5′-dimethyl derivatives displayed limited cytotoxicity, the 6,6′-dimethyl isomer exhibited notable activity, particularly against the colon cancer cell line HCT-116 (LC₅₀ = 8.17 M) and the ovarian cancer cell line OVCAR-3 (LC₅₀ = 7.34 M). The enhanced cytotoxicity of the 6,6′-dimethyl derivative is attributed, at least in part, to the relatively facile dissociation of the 6,6′-dimethyl-2,2′-bipyridine ligand from the platinum(IV) center, suggesting that sterically induced ligand lability plays an important role in modulating biological activity in this particular compound, giving new structural activity impetus for potential drug molecules.

Abstract: This work investigates the potential of wollastonite-based brushite cement (WBC) for the stabilization and solidification of radioactive waste contaminated by ⁹⁰Sr. This phosphate binder was formed by the reaction of wollastonite (CaSiO₃) with a phosphoric acid solution containing borax and metallic cations (Al³⁺, Zn²⁺). Two cement pastes were investigated: a commercial binder (WBC-C) and an optimized formulation (WBC-O), produced using a zinc-free mixing solution with a higher aluminum content than that of WBC-C. Both materials mainly contained amorphous hydrated silica and calcium aluminophosphate, along with crystalline brushite, residual wollastonite, and quartz. The stability of WBC-C under γ-irradiation was evaluated up to a dose of 1 MGy. The only observable effect was water radiolysis, leading to dihydrogen production at yields comparable to Portland cement matrices and geopolymers. Strontium leaching, assessed using the ANSI/ANS-16.1 procedure, followed a two-stage release mechanism combining surface wash-off and diffusion. The apparent diffusion coefficient D_a of Sr in WBC-C was three orders of magnitude lower than typical values reported for Portland cement matrices. WBC-O showed enhanced Sr retention due to its higher aluminum content, which refines mesopores and reduces diffusion pathways accessible to Sr. WBC binders therefore appear to be promising candidates for strontium immobilization.

Abstract: Ammonium N-ethyloxamate (AmEtOxam) was synthesized, fully characterized by microanalytical and spectroscopic means, and assayed as a precursor of calcium oxalate, acting as a protecting agent for white Carrara marble. The monohydrate form of AmEtOxam shows a water solubility of 1.5 mol·L–1 (~23% w/w), significantly higher than that of common calcium oxalate precursors (CaOx), such as ammonium oxalate (0.4 mol·L–1, ~5% w/w). While AmEtOxam is stable in water solution and in the solid state in its monohydrate form, , during the application on carbonate stone it undergoes a complete hydrolysis resulting in the formation of an uniform weddellite layer (CaC2O4·2H2O) on carbonate stone surfaces. Application of 5% w/w aqueous solutions by spraying, brushing, and immersion resulted in different effects. Spraying yielded the most balanced performance, improving mechanical strength, reducing water absorption, recovering superficial tension, and limiting chromatic alteration. Brushing achieved significant gain in surface hardness with minimal aesthetic impact. Immersion most effectively reduced porosity and increased surface tension. These results, coupled with the negligible chromatic changes induced in all cases, make AmEtOxam a promising candidate for the conservation of stone cultural heritage.

Abstract: In this work, a CdS–MoS₂–rGO thin-film photocathode was fabricated on FTO substrates via a single-ink drop–spin-coating method followed by annealing under N₂ atmosphere. Among the studied compositions, the film containing 86:9:5 wt% of CdS, MoS₂, and rGO exhibited the best photoelectrochemical performance. Under visible-light illumination from a 50 W halogen lamp (~0.25 sun) in neutral electrolyte, the optimized photocathode achieved a photocurrent density of 0.83 mA cm⁻² at −0.75 V vs Ag/AgCl and retained approximately 96% of its initial current during 60 min of chopped-light operation. Electrochemical impedance spectroscopy revealed a reduced charge-transfer resistance (~120 Ω·cm²), while the Tafel slope decreased to ~85 mV dec⁻¹, indicating enhanced charge transfer and hydrogen evolution kinetics. Hydrogen production was confirmed by gas chromatography, with an evolution rate of ~58.6 μmol h⁻¹. The improved performance is attributed to the synergistic roles of CdS as the light absorber, rGO as an electron-transport network, and MoS₂ as a cocatalyst. These results demonstrate the potential of the CdS–MoS₂–rGO architecture for photoelectrochemical hydrogen evolution under neutral conditions.