Search Results (205)

Metal ions, including Mg(II), Ca(II), Sr(II), Co(II), Ni(II), Cu(II), Nd(III), Eu(III), and Tb(III), were investigated in binary systems alongside ampicillin at molar ratios of 1:1 and 1:2. These investigations were carried out in aqueous solutions, and the formation of complexes was verified through meticulous computational analysis. Detailed stability constants for the formed complexes and equilibrium constants for the involved reactions were meticulously determined. Furthermore, a comprehensive examination of the impact of ligand concentration on the configuration of the central metal atom’s coordination sphere was conducted. This investigation was complemented by spectroscopic measurements, which effectively confirmed the observed changes in the coordination sphere of the metal ions. Full article

This study presents the synthesis and physicochemical characterization of coordination compounds formed between chrysin, a natural flavonoid, and transition metal ions: Mn(II), Co(II), and Zn(II). The complexes were obtained under mildly basic conditions and analyzed using elemental analysis, thermogravimetric analysis (TGA), silver-assisted laser desorption/ionization mass spectrometry (SALDI-MS), FT-IR spectroscopy, and ¹H NMR. The spectroscopic data confirm that chrysin coordinates as a bidentate ligand through the 5-hydroxyl and 4-carbonyl groups, with structural differences depending on the metal ion involved. The mass spectrometry results revealed distinct stoichiometries: 1:2 metal-to-ligand ratios for Mn(II) and Co(II), and 1:1 for Zn(II), with additional hydroxide coordination. Biological assays demonstrated that Co(II) and Mn(II) complexes exhibit enhanced antibacterial and anti-biofilm activity compared to free chrysin, particularly against drug-resistant Staphylococcus epidermidis, whereas the Zn(II) complex showed negligible biological activity. Full article

Polymethyl methacrylate nanoparticles functionalized with three different compounds, acrylic acid (AA), curcumin (CUR), and fumaramide (FA), were tested in a two-step solid–liquid extraction process (extraction and stripping) for yttrium recovery. In both stages, the best conditions were determined: pH, solid–liquid ratio and the compound with the highest affinity for yttrium recovery, obtaining 90% of efficiency for both stages in a single work cycle. The results obtained by SEM ruled out the growing of nanoparticles by swelling and confirmed the formation of structural arrangements by the addition of the metal to the system. In addition, there is evidence that the recovery process can be selective considering the mixing of rare earth elements through changes in pH. Using isothermal titration calorimetry (ITC), the thermodynamic properties of the extraction process were calculated, understanding the system as the union of a macromolecule and a ligand. The results showed that the extraction process was spontaneous and highly entropic. Full article

Searching for new and efficient transfer hydrogenation catalysts, a series of new organometallic ruthenium(II)-arene complexes of the formulae [Ru(η⁶-p-cymene)(L)Cl][PF₆] (1–8) and [Ru(η⁶-p-cymene)(L)Cl][Ru(η⁶-p-cymene)Cl₃] (9–11) were synthesized and fully characterized. These were prepared from the reaction of pyridine–quinoline and biquinoline-based ligands (L) with [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂, in 1:2 and 1:1, metal (M) to ligand (L) molar ratios. Characterization includes a combination of spectroscopic methods (FT-IR, UV-Vis, multi nuclear NMR), elemental analysis and single-crystal X-ray crystallography. The pyridine–quinoline organic entities encountered, were prepared in high yield either via the thermal decarboxylation of the carboxylic acid congeners, namely 2,2′-pyridyl-quinoline-4-carboxylic acid (pqca), 8-methyl-2,2′-pyridyl-quinoline-4-carboxylic acid (8-Mepqca), 6′-methyl-2,2′-pyridyl-quinoline-4-carboxylic acid (6′-Mepqca) and 8,6′-dimethyl-2,2′-pyridyl-quinoline-4-carboxylic acid (8,6′-Me₂pqca), affording the desired ligands pq, 8-Mepq, 6′-Mepq and 8,6′-Me₂pq, or by the classical Friedländer condensation, to yield 4,6′-dimethyl-2,2′-pyridyl-quinoline (4,6′-Me₂pq) and 4-methyl-2,2′-pyridyl-quinoline (4-Mepq), respectively. The solid-state structures of complexes 1–4, 6, 8 and 9 were determined showing a distorted octahedral coordination geometry. The unit cell of 3 contains two independent molecules (Ru-3), (Ru′-3) in a 1:1 ratio, due to a slight rotation of the arene ring. All complexes catalyze the transfer hydrogenation of acetophenone, using 2-propanol as a hydrogen donor in the presence of KOiPr. Among them, complexes 1 and 5 bearing methyl groups at the 8 and 4 position of the quinoline moiety, convert acetophenone to 1-phenylethanol quantitatively, within approximately 10 min with final TOFs of 1600 h⁻¹. The catalytic performance of complexes 1–11, towards the transfer hydrogenation of p-substituted acetophenone derivatives and benzophenone, ranges from moderate to excellent. An inner-sphere mechanism has been suggested based on the detection of ruthenium(II) hydride species. Full article

Every year, millions of people worldwide suffer from bone tissue damage caused by bone trauma and surgical operations, as well as diseases such as osteoporosis, osteoarthritis, osteomyelitis, and periodontitis. Bone defect repair is one of the major challenges in the field of regenerative medicine. Although bone grafts are the gold standard for treating bone defects, factors such as donor sources and immune responses limit their application. Functionalized nanomaterials have become an effective means of treating bone diseases due to their good biocompatibility and osteoinductivity, anti-inflammatory, and antibacterial properties. Metal–organic frameworks (MOFs) are porous coordination polymers composed of metal ions and organic ligands, featuring unique physical properties, including a high surface area–volume ratio and porosity. In regenerative medicine, MOFs function as the functions of drug carriers, metal ion donors, nanozymes, and photosensitizers. When combined with other functional materials, they regulate cellular reactive oxygen species, macrophage phenotypic transformation, bone resorption, osteogenesis, and mineralization, providing a new paradigm for bone tissue engineering. This study reviews the classification of functionalized MOF composites in biomedicine and the application of their synthesis techniques in bone diseases. The unique in vivo and in vitro applications of MOFs in bone diseases, including osteoarthritis, osteoporosis, bone tumors, osteomyelitis, and periodontitis, are explored. Their properties include excellent drug loading and sustained release abilities, high antibacterial activity, and bone induction abilities. This review enables readers to better understand the cutting-edge progress of MOFs in bone regeneration applications, which is crucial for the design of and functional research on MOF-related nanomaterials. Full article

In this study, the structure of the synthesized Zn(II) complex with homovanillic acid (HVA) was investigated using the FT-IR, UV/Vis, and NMR spectroscopic methods, as well as elemental and thermal (TG, DTG, and DSC) analysis. The stoichiometric molar ratio of metal:ligand for the solid form of the complex was established as 1:2, with coordination through the carboxylate group and aromatic ring substituents. The theoretical structural and electronic parameters were calculated by the use of the B3LYP/6-311++G(d,p) method. Antioxidant properties were examined using spectroscopic tests: DPPH (1,1-diphenyl-2-picrylhydrazyl radical), FRAP (ferric reducing antioxidant activity), and ABTS (2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (diammonium salt radical cation). The Zn(II) complex with HVA showed similar or lower antioxidant properties compared to the ligand, depending on the antioxidant assay. The antimicrobial activity of acid and its complex with Zn(II) against Escherichia coli, Bacillus subtilis, and Candida albicans were also investigated by evaluation of the minimum inhibitory concentration (MIC). The Zn(II) complex shows higher antibacterial and antifungal activity compared to HVA. Full article

This study explores the use of a deep eutectic solvent (DES) composed of choline chloride and pyrogallol (1:1 molar ratio) for the recovery of lithium, cobalt, and nickel from spent lithium-ion battery cathodes based on LiNi_0.33Co_0.33Mn_0.33O₂ (NMC111). The DES exhibits moderate viscosity, intrinsic redox activity, and strong complexation ability, enabling efficient metal dissolution under mild conditions. The effects of both temperature (50–80 °C) and time (up to 12 h) on leaching efficiency were systematically investigated. Optimal leaching parameters—80 °C, 8 h, and a liquid-to-solid ratio of 50—yielded extraction efficiencies of 92% for Li, 85% for Co, and 88% for Ni. Kinetic modeling indicated pseudo-first-order behavior with activation energies of 26.6, 22.1, and 25.2 kJ/mol for Li, Co, and Ni, respectively. Mechanistic analysis confirmed the dual role of pyrogallol as both reducing agent (facilitating Co³⁺ to Co²⁺ conversion) and chelating ligand. Full article

As the need for energy is constantly increasing and in the long term fossil fuels are not an option because of global overheating due to the greenhouse effect, alternative energy production concepts such as photovoltaics, wind energy, IR energy harvesters etc., have been developed. The problem is that renewable energy sources are stochastic, and therefore there is a need for electrical energy storage either in rechargeable batteries or in high-performance supercapacitors. In this respect, novel materials are needed to meet the challenges that are related to these technologies. Metal–organic frameworks (MOFs) represent highly promising materials for energy storage applications in supercapacitors (SCs) and thus in recent years have become essential for clean and efficient energy conversion and storage. Metal–organic frameworks (MOFs) present numerous benefits as electrocatalysts, electrolyte membranes, and fuel storage materials; they exhibit exceptional design versatility, extensive surface-to-volume ratios, and permit functionalization with multivalent ligands and metal centers. Here we present an overview of MOF-based materials for electrical energy storage using high-performance supercapacitors. This review deals with recent advances in MOF-based materials for supercapacitors. Finally, an outlook on the future use and restrictions of MOFs in electrochemical applications, with focus on supercapacitors, is given. Full article

The development of drug carriers with efficient absorption and controlled delivery properties is crucial for advancing medical treatments. Metal–organic frameworks (MOFs) with tunable porosity and a large surface area represent a promising class of materials for this application. Among them, NUIG4 stands out as a biocompatible MOF that exhibits exceptionally high doxorubicin (Dox) absorption (1995 mg dox/g NUIG4) and pH-controlled release properties. In this study, we report the synthesis and characterisation of multivariate MOFs (MV-NUIG4), which are analogues of NUIG4 that maintain the same topology while incorporating different functional groups within their framework. Eight new MV-NUIG4 MOFs have been synthesised through in situ reactions of the corresponding 4-aminobenzoic acid derivative with 4-formylbenzoic acid. The compounds were thoroughly characterised using a range of techniques, including powder X-ray diffraction, infrared spectroscopy, ¹H-NMR, and single-crystal X-ray crystallography. The experimental ratio of the reagents and ligand precursors for the synthesis of MV-NUIG4 MOFs matched the ratio of the linkers in the final products. These structures incorporate additional functional groups, such as methyl and hydroxyl, in varying ratios. Computational modelling was used to provide further insight into the crystal structure of the MOFs, revealing a random distribution of the functional groups in the framework. The Dox absorption and release capacity of all analogues were studied, and the results revealed that all analogues displayed high drug absorption in the range of 1234–1995 mg Dox/g MOF. Furthermore, the absorption and release rates of the drug are modulated by the ratio of functional groups, providing a promising approach for controlling drug delivery properties in MOFs. Full article

To address the challenges of environmental adaptability and passivation in nanoscale zero-valent iron (nFe⁰) systems, we developed oxalate-modified nFe⁰ (nFe_oxa) through a coordination-driven synthesis strategy, aiming to achieve high-efficiency Cr(VI) removal with improved stability and reusability. Structural characterization (STEM and FT-IR) confirmed the formation of a FeC₂O₄/nFe⁰ heterostructure, where oxalate coordinated with Fe(II) to construct a semiconductor interface that effectively inhibits anoxic passivation while enabling continuous electron supply, achieving 100% Cr(VI) removal efficiency within 20 min at an optimal oxalate/Fe molar ratio of 1/29. Mechanistic studies revealed that the oxalate ligand accelerates electron transfer from the Fe⁰ core to the surface via the FeC₂O₄-mediated pathway, as evidenced by EIS and LSV test analyses. This process dynamically regenerates surface Fe(II) active sites rather than relying on static-free Fe(II) adsorption. XPS and STEM further demonstrated that Cr(VI) was reduced to Cr(III) and uniformly co-precipitated with Fe(II/III)-oxalate complexes, effectively immobilizing chromium. The synergy between the protective semiconductor layer and the ligand-enhanced electron transfer endows nFe_oxa with superior reactivity. This work provides a ligand-engineering strategy to design robust nFe⁰-based materials for sustainable remediation of metal oxyanion-contaminated water. Full article

UiO-type Zr-BDC MOFs have garnered the interest of the scientific community due to their exceptional diversity in composition, structure, and chemical environment, as well as their high thermal and chemical stabilities. This work demonstrates the sustainable synthesis of a series of nanocrystalline/semicrystalline UiO-66(Zr) metal–organic frameworks (MOFs) under facile conditions—specifically at room temperature, in water, with high yield, and without the use of modulators or toxic byproducts. The synthesis involves either deprotonating the linker or utilizing various ratios of water and DMF as solvents. The as-prepared materials obtained from both synthesis strategies share key structural features with conventional UiO-66(Zr) in their short- and medium-range physicochemical properties, while exhibiting significant differences in crystallinity and textural properties. Nonetheless, the materials generally lack long-range order (semicrystalline), in particular these synthesized following the deprotonation strategy. However, the materials prepared using mixed solvent strategy seem to exhibit characteristics of nanocrystalline UiO-66(Zr). Overall, both approaches successfully addressed various synthesis challenges related to the highly sought-after Zr-based metal–organic frameworks (MOFs). Some of these MOF materials were tested for the photodegradation of rhodamine B (RhB) under mercury light irradiation, evidencing high photocatalytic efficiency of up to 75 ± 0.078% within 120 min under the pseudo-first-order model. This suggests an interaction between the photocatalyst and the RhB dye, involving electron injection from RhB and the ability for ligand-to-metal charge transfer (LMCT), which enhances the efficient photocatalytic degradation of RhB. The trapping experiments indicated that superoxide radicals (•O₂⁻) and photogenerated holes (h⁺) are crucial in the photodegradation of RhB. Moreover, the materials showed good recyclability across five tested cycles. A plausible photocatalytic reaction mechanism has been proposed to explain these findings. Full article

The complexation behavior of lanthanide(III) ions with terephthalic acid (1,4-benzene-dicarboxylic acid) in 0.01 M KNO₃ aqueous solutions was studied across a broad pH range and at two metal-to-ligand ratios using potentiometric titration combined with photoluminescence spectroscopy. Chemometric analysis of titration curves enabled the determination of relative molar fractions, stability constants, and probable stoichiometry of the formed complexes. In solutions with a 1:2 metal-to-ligand ratio, bis-complexes (two terephthalate ligands per lanthanide ion) predominated, while ligand-rich conditions favored the formation of tetra-complexes (four ligands per metal ion). In alkaline media, bis-complexes transform into mixed hydroxy-terephthalate species. Meanwhile, for the tetra-complexes, the addition of NaOH results in the formation of lanthanide ion hydroxo complexes without organic ligands. The structural diversity of these complexes, driven by the terephthalate ligand’s tendency to maximize denticity, suggested dimeric or oligomeric configurations. The stability constants and structural features of complexes in solution were found to align with those of known solid-state lanthanide–terephthalate polymers, highlighting their potential as models for polymeric structures. Full article

Metal halide perovskite nanorods hold great promise for optoelectronic applications. However, they tend to undergo phase transitions due to the instability of the crystal phase under environmental conditions, leading to a rapid decline in the fluorescence efficiency. Here, we report a method in which trioctylphosphine (TOP) directly serves as both the surface ligand and solvent to synthesize highly stable α-CsPbI₃ nanorods (NRs). This approach produces monodisperse α-phase NRs with controlled sizes (1 μm and 150 nm in length, and an aspect ratio of 10:1), as confirmed by high-resolution transmission electron microscopy (TEM) and X-ray diffraction. The optimized NRs exhibit a high photoluminescence quantum yield of around 80%, as well as excellent environmental stability; after 15 days of storage, the photoluminescence quantum yield (PLQY) retention is 90%. Transient absorption spectroscopy shows that the carrier lifetime is extended to 23.95 ns and 27.86 ns, attributed to the dual role of TOP in defect passivation and hydrolysis suppression. This work provides a scalable paradigm for stabilizing metastable perovskite nanostructures through rational ligand selection, paving the way for durable perovskite-based optoelectronics. Full article

It is known that designer polymers can be used for the synthesis and stabilization of metallic nanoparticle systems, providing new, tailorable properties. In this work, we demonstrate the trifold utility of a designer polymer, trimethoxysilylpropyl-(polyethylenimine) (TMSP-PEI), providing reduction, stabilization, and protection in a single step. Our facile and unique synthesis affords gold nanoparticles with varying sizes and morphologies in a range of solvents without the need for additional reducing agents. The use of this substituted polymer was manipulated in terms of the metal-to-ligand ratio to induce changes in the nanoparticle nucleation and growth. Upon further experimental analysis, it was discovered that adjustments to not only the metal–ligand ratio but also the solvent environment produced nanoparticles with different shape and size distributions. In addition, the synthesized gold nanoparticles were investigated for their catalytic ability to reduce Eosin Y in the presence of sodium borohydride without degradation. Full article

The application of metal–organic frameworks (MOFs) has attracted increasing attention in organic synthesis. The modification of MOFs can efficiently tailor the structure and improve the property for meeting ongoing demand in various applications, such as the alteration of gas adsorption and separation, catalytic activity, stability, and sustainability or reusability. In this study, carboxyethylsilanetriol (CEST) disodium salt was used as a dual-functional ligand for modified Al-MIL-53 to fabricate CEST-functionalized Al-MIL-53 samples through a hydrothermal reaction of aluminum nitrate, terephthalic acid, and CEST disodium salt by varying the molar ratio of CEST to terephthalic acid and keeping a constant molar ratio of Al³⁺/-COOH of 1:1. The structure, composition, morphology, pore feature, and stability were characterized by XRD, different spectroscopies, electron microscopy, N₂ physisorption, and thermogravimetric analysis. With increasing CEST content, CEST-Al-MIL-53 still preserves an Al-MIL-53-like structure, but the microstructure changed compared with pure Al-MIL-53 due to the integration of CEST. Such a CEST-Al-MIL-53 was used as the support to load Pd particles and afford a catalyst Pd/CEST-Al-MIL-53 for Suzuki–Miyaura C-C cross-coupling reaction of aryl halides and phenylboronic acid under basic conditions. The resulting Pd/CEST-Al-MIL-53 showed a high catalytic activity compared with Pd/Al-MIL-53, due to the nanofibrous structure of silicon species-integrated CEST-Al-MIL-53. The nanofiber microstructure undergoes a remarkable transformation into intricate 3D cross-networks during catalytic reaction, which enables the leachable Pd particles to orientally redeposit and inlay into these networks as the monodisperse spheres and thereby effectively preventing Pd particles from aggregation and leaching, therefore demonstrating a high catalytic performance, long-term stability, and enhanced reusability. Obviously, the integration of CEST into MOFs can effectively prevent the leaching of active Pd species and ensure the re-deposition during catalysis. Moreover, catalytic performance strongly depended on catalyst dosage, temperature, time, solvent, and the type of the substituted group on benzene ring. This work further extends the catalytic application of hybrid metal–organic frameworks. Full article