Polyoxometalates (POMs) biological and biomedical applications have attracted increasing attention over the past decades. Polyoxometalates are inorganic transition metal oxygen clusters characterized by having multiple structures and tunable electronic properties that are well-known to be effective inhibitors of many enzymes, such as ATPases. Herein, a new hybrid POM of the Keggin type, Vanadium-substituted Keggin polyoxotungstate, namely (C₆H₁₅N)₄(C₆H₁₆N)₆(VW₁₂O₄₀)₂·4H₂O, was synthesized via wet-chemical methods in aqueous solution. Its purity was confirmed, and the compound was fully characterized by single-crystal X-ray diffraction, infrared spectroscopy, UV-visible spectroscopy, and thermogravimetric analysis. The Keggin-type compound exhibited a half maximal inhibitory concentration (IC50) value of 8.25 μM toward calcium adenosine triphosphatase (Ca2+-ATPase) inhibition, as measured spectrophotometrically using a coupled pyruvate kinase/lactate dehydrogenase enzyme assay. Hirshfeld surface analysis was employed to investigate intermolecular interactions within the crystal structure, revealing differences in hydrogen bonding and oxygen-based contacts. These structural features may suggest a possible relationship with the observed biological activity; however, no direct correlation with Ca2+-ATPase inhibition can be firmly established from the present data. Therefore, the observed relationships should be considered preliminary and structural in nature, rather than mechanistic. Further computational and biological studies are required to clarify the role of these interactions in enzyme inhibition.

Abstract Although iron has emerged as an earth-abundant alternative for 1,3-diene coordinative polymerization, stereoselective iron systems remain uncommon and are often associated with limited catalytic activity. Here, we report three iron(II) complexes supported by 1,1-diaryl-N-(quinolin-8-yl)methanimine ligands, which upon activation with Al(iBu)3/[CPh3][B(C6F5)4] or methylaluminoxane (MAO), promote trans-1,4-selective polymerization of isoprene and β-myrcene with high activity (TOF up to 5700 h–1 at room temperature) and trans-1,4 contents of up to 95 and 99%, respectively. These systems operate under mild conditions and afford polymers with tunable molar masses by varying the monomer-to-Fe ratio. Beyond homopolymers, the catalyst platform allows the synthesis of poly(isoprene-block-myrcene) through sequential copolymerization, yielding trans-1,4-stereoregular materials. Density functional theory (DFT) calculations provide mechanistic insights into the origin of the trans-1,4 selectivity, rationalizing the experimentally observed selectivity. This work demonstrates that well-defined iron catalysts can efficiently mediate trans-selective 1,3-diene polymerization with high activity, highlighting the potential of iron for the development of precision polymerization catalysts.

The reaction of ZrO2 with K2S2O7 has been performed at different temperatures between 400 and 450 °C in order to identify the formation of potential products and investigate their reactivity and their thermal and dissolution behavior. The products formed during the reaction were fully characterized by chemical and thermal analyses as well as X-ray diffraction. The solid state reaction with a 2 ZrO2 : 5 K2S2O7 molar ratio at 440 °C leads to new compound K10Zr2(SO4)9, never identified before, which further decomposed into K2SO4 and ZrO2 at 950 °C. The crystal structure of K10Zr2(SO4)9 was refined from single-crystal XRD data in noncentrosymmetric monoclinic space group Cc and characterized by infrared and Raman spectroscopies and SHG analysis. Finally, it was found to be soluble in water with a minimal solubility of 11.8 g/L at 18 °C. Because of the chemical similarities between Zr and Hf, isotype phase K10Hf2(SO4)9 was also identified and synthesized as a pure phase.

A series of alkyl 2-oxo-1,2-dihydroquinoline-4-carboxylate derivatives (4A-4M) was synthesized under phase-transfer catalysis conditions starting from 2-oxo-1,2-dihydroquinoline-4-carboxylic acid. The structures of all compounds were confirmed by 1H and 13C NMR, MALDI MS, FT-IR, and UV-Vis spectroscopy. Single-crystal Xray diffraction analyses of derivatives 4G, 4H and 4K provided detailed insight into their molecular geometry and solid-state organization. Density Functional Theory (DFT) calculations at the B3LYP/6-311++G(d,p) level were performed to optimize molecular geometries and evaluate electronic properties, including frontier molecular orbitals and molecular electrostatic potential distributions. Hirshfeld surface analysis, complemented by fingerprint plots and shape index mapping, enabled quantitative assessment of intermolecular contacts, highlighting the role of hydrogen bonding and pi-pi interactions in crystal packing. The antibacterial activity of selected compounds was evaluated using the broth microdilution method, revealing moderate activity for several derivatives. Molecular docking simulations against the LasR-OC12-HSL complex (PDB: 3IX3) were conducted to explore potential binding interactions, providing a theoretical framework for interpreting structure-interaction relationships.The combined crystallographic, computational, and biological data provide a comprehensive structural and physicochemical characterization of these quinoline-4-carboxylate derivatives.

In this work, trialkylamine-functionalized ionic liquids were assessed for their dual role as solvents and ligands in the biphasic reductive hydroformylation of methyl 10-undecenoate (MU), a renewable substrate derived from castor oil. Systematic tuning of the aminated ionic liquids through cation and anion variation identified 1-(2-piperid-1-yl-ethyl)-3-ethanolimidazolium hexafluorophosphate, [PEEtOHim][PF6] combined with dodecane as the most effective biphasic couple, enabling efficient rhodium reductive hydroformylation with a turnover frequency in alcohols of 33 h-1 while limiting rhodium leaching in the apolar phase to as little as 1.5% of its initial loading. Under optimized conditions, the system was recycled for at least nine consecutive runs with constant selectivity in alcohols, highlighting the robustness of the catalytically active species stabilized within the ionic liquid phase. A cumulative total turnover number in alcohols of 1282 was achieved through this atom-economical tandem process, further demonstrating the potential of aminated ionic liquids in biphasic catalytic systems. This work underscores the relevance of ionic liquid-based strategies for sustainable catalysis and the valorization of renewable feedstocks, bridging high-performance chemistry with the principles of green chemistry.

In this work, a V-substituted Lindqvist polyoxotungstate, (C₇H₁₁N₂)₄[V₂.₁₂W₃.₈₈O₁₉]•4 H₂O (1), was synthesized via a solution-based synthetic methodology and comprehensively characterized. The identification of the characteristic functional groups was achieved through infrared spectroscopy, revealing distinct vibrational absorption bands representative of the hybrid polyoxometalate structure. UV-visible absorption spectroscopy was employed to investigate the optical properties of the material. Furthermore, computational studies were conducted to assess the stability of the compound. The binding stability is enhanced by strong hydrogen bonding, van der Waals forces, and electrostatic interactions occurring within the three-dimensional (3D) supramolecular network formed between the vanadotungstate polyanion and the organic moieties, as demonstrated by single-crystal X-ray diffraction and Hirshfeld surface analysis. In addition, density functional theory (DFT) calculations were performed to gain further insights into the electronic structure and stability of the compound.

Abstract A family of iron complexes bearing iminopyridine (ImPy) ligands with systematic variations on the N ‐aryl and pyridine moieties was evaluated as pre‐catalysts for the coordinative polymerization of β‐myrcene and butadiene. Upon activation with Al i Bu 3 and trityl borate, these complexes were further assessed under coordinative chain transfer polymerization (CCTP) conditions using ZnEt 2 as chain transfer agent (CTA). Several complexes exhibited high activities in both polymerization regimes, with regioselectivities strongly dependent on the monomer nature. Polymyrcenes with moderately to highly 1,4‐regular microstructures were obtained, whereas butadiene polymerization generally led to 1,2 units with variable 1,4 incorporations, except for Fe1 which yielded significant 1,4‐polybutadiene. The addition of 10 equivalents of ZnEt 2 as CTA uncovered pronounced differences in catalyst performance arising from their steric and electronic characteristics. Non‐fluorinated complexes (Fe1–Fe4) exhibited clear CCTP signatures, including substantial reductions of M n and narrower dispersities, while fluorinated analogues (Fe5–Fe8) were essentially unaffected. A second series of iron complexes supported by ImPy derivative ligands (Fe9–Fe12) further emphasized the critical role of steric hindrance near the pyridine nitrogen and of chelate ring size. Finally, statistical copolymerization of butadiene/myrcene and under chain transfer conditions proceeded efficiently with Fe2–Fe4. © 2026 Society of Chemical Industry.

Nickel allyl activation for ethylene oligomerization is enhanced via Lewis acid driven hapticity change.

Two copper(II) coordination polymers bridged by dicyanamido (N(CN)(2)(-))- and azido (N-3(-)) ligands, [CuLN(CN)(2)](n) (1) and [{CuLN3}(2)(H2O)](n) (2) (L- = N-(2-pyridylmethyl)-L-alaninato) have been synthesized and thoroughly studied using structural and spectroscopic methods. Both complexes crystallize in the chiral orthorhombic P2(1)2(1)2(1) space group. Complex 1 features 1D zigzag chains through the two terminal nitrogen nitrile groups of the mu(1,5)-bridging N(CN)(2)(-) ligand. These chains are assembled via intermolecular N-H center dot center dot center dot O hydrogen bonding interactions, forming a 3D supramolecular network. Complex 2 is a dissymmetric dimer with the Cu1 center being in a distorted square pyramidal geometry environment, while the Cu2 center is in a distorted octahedral geometry. In complex 2, an infinite 3D supramolecular structure is achieved via Cu1-O2(i) bonds, O2(i) being the oxygen atom of a carboxylate group from the L- ligand of an adjacent dimer. Intermolecular hydrogen bonding interactions of the type N-H center dot center dot center dot O in 1 and N-H center dot center dot center dot O and O-H center dot center dot center dot O in 2 contribute to stabilizing the threedimensional frameworks. The three-dimensional Hirshfeld surface (3D-HS) analysis and the two-dimensional fingerprint (2D-FP) plots reveal that the two structures are dominated by the H center dot center dot center dot H and N center dot center dot center dot H/H center dot center dot center dot N contacts. Upon excitation at 315 nm, maximum emissions centered at 498 nm and 805 nm for 1 and at 497 nm and 805 nm for 2 are exhibited. These luminescence behaviors are attributed to charge transition between the L- ligand and the Cu2+ ions.

The title compound, C19H14N2O3, features competition and interplay of a range of weak interactions, which actualize under the absence of conventional hydrogen-bond donors. Two kinds of stacking interactions, namely slipped antiparallel interactions of cyanophenyl groups as well as quinoline and carboxy groups, are primarily important. In combination with relatively short tetrel OCH3...N[triple-bond]C bonds [C...N = 3.146 (3) Å] they are responsible for the generation of the layers, while the interlayer bonding occurs via C—H...O and C—H...N weak hydrogen bonds. These findings are consistent with the results of Hirshfeld surface analysis and calculated interaction energies. Contributions of the C...C, C...N/N...C and C...O/O...C contacts originating in the stacking interactions account for 17.0% to the surface area. The largest interactions energies are associated with the two kinds of stacks (−45.8 and −24.3 kJ mol−1) and they are superior to the energies of weak hydrogen bond and tetrel interactions (−12.4 to −22.4 kJ mol−1). Evaluation of the electrostatic, dispersion and total energy frameworks indicate that the consolidation is dominated via the dispersion energy contributions.

The title compound, C19H14N2O3, features competition and inter-play of a range of weak inter-actions, which actualize under the absence of conventional hydrogen-bond donors. Two kinds of stacking inter-actions, namely slipped anti-parallel inter-actions of cyano-phenyl groups as well as quinoline and carb-oxy groups, are primarily important. In combination with relatively short tetrel OCH3⋯N≡C bonds [C⋯N = 3.146 (3) Å] they are responsible for the generation of the layers, while the inter-layer bonding occurs via C-H⋯O and C-H⋯N weak hydrogen bonds. These findings are consistent with the results of Hirshfeld surface analysis and calculated inter-action energies. Contributions of the C⋯C, C⋯N/N⋯C and C⋯O/O⋯C contacts originating in the stacking inter-actions account for 17.0% to the surface area. The largest inter-actions energies are associated with the two kinds of stacks (-45.8 and -24.3 kJ mol-1) and they are superior to the energies of weak hydrogen bond and tetrel inter-actions (-12.4 to -22.4 kJ mol-1). Evaluation of the electrostatic, dispersion and total energy frameworks indicate that the consolidation is dominated via the dispersion energy contributions.

The reaction of FeCl2 with the iminopyridine ligand containing fluorinated N-aryl groups {2-[(Ar)N = C(R)]C5H4N, where Ar = 3,5-(CF3)2C6H3 and R = H (L1) or CH3 (L3); Ar = C6F5 and R = H (L2) or CH3 (L4); and iminoquinoline 2-[(3,5-(CF3)2(C6H3)N = CH)]C9H6N (L5)} resulted in distinct iron coordination complexes whose structures were determined by single-crystal X-ray diffraction. Ligands L1 and L2 yielded mononuclear bis-ligated iron dichlorides (L1 or L2)2FeCl2 (complexes 1 and 2), while L3 and L5 formed dinuclear complexes (L3 or L5)2Fe(μ-Cl2)FeCl2 (complexes 3 and 5). Ligand L4 produced an unprecedented tetranuclear dimer [(L4)2FeCl(μ-Cl2)FeCl2]2 (complex 4). Mössbauer spectroscopy revealed single quadrupole doublets for mononuclear complex 2 and two sets of doublets for dinuclear complexes 3 and 5 and tetranuclear complex 4, confirming Fe(II) in high-spin states. Magnetic susceptibility and Curie-Weiss analyses elucidated magnetic interactions, showing reduced effective magnetic moments correlated with increasing Fe-(μ-Cl)-Fe bridges. DFT calculations and NBO analyses supported these findings, highlighting lower charge density on bridging compared to terminal chlorides. Activated by AliBu3/[CPh3][B(C6F5)4], complexes 1 and 2 showed lower activities (TOF = 1,000-1,200 h-1) than complexes 3 and 5 (TOF = 90,000 h-1) for isoprene polymerization, producing polymers with enriched cis-1,4-alt-3,4 microstructures.

A practical strategy in synthetic organic chemistry for shutting down temporarily the nucleophilicity of thiols is to exploit their redox properties by converting them into disulfides. The stability of such a thiol protection in reductive medium can be sensitive to microenvironmental changes, including chemical modifications occurring nearby. Although difficult to achieve, large shifts in disulfide stability might provide a practical mean for bringing selectivity in a reacting system comprising multiple thiol functionalities. Here we report that the stability of a cyclic disulfide increases dramatically upon acylation of an amino group placed in the vicinity of the S─S bond. The gain in stability is so pronounced that the amide bond formation acts as a redox lock. We describe the application of such a redox switch to the chemoselective assembly of polypeptides by thiol-based peptide ligation chemistries.

The crystal structure of new quinoline-4-carboxyl­ate derivative exhibits a range of weak inter­actions, which were assessed using Hirshfeld surface analysis and inter­action energy calculations to support the dominant significance of the dispersion forces.

The newly discovered series of layered monophosphate tungsten bronzes (L-MPTB) [Ba(PO4)2]WmO3m-3 consist of m-layer-thick slabs of WO6 octahedra separated by barium-phosphate spacers. They display a 2D metallic behavior confined in the central part of the perovskite slabs. Here, we report the missing m = 2 member of this series, containing the rather uncommon W5+ oxidation state. We have analyzed its structure-property relationships in relation to the other members of the L-MPTB family. In particular, we have determined its crystal structure by means of single-crystal X-ray and electron diffraction and investigated its physical properties from resistivity, Seebeck-coefficient and heat-capacity measurements combined with first-principles calculations. All the L-MPTB compounds show metallic behavior down to 1.8 K without any clear charge-density-wave (CDW) order. The m = 2 member, however, displays an increased influence of the spacer that translates into anisotropic negative thermal expansion, reversed thermopower and reversed crystal-field splitting of the tungsten t2g orbitals. Our analysis of the full [Ba(PO4)2]WmO3m-3 series reveals a systematic and significant W off-centering in their octahedral coordination. We identify the resulting anti-polar character of these W displacements as the crucial aspect behind the 2D metallicity of these systems: It leads to the presence of bound charges whose screening determines the distribution of mobile charges, tending to accumulate at the center of the [WmO3-m] block. We argue that this mechanism is analogous to enhanced conductivity observed for charged domain walls in ferroelectrics, thus providing a general design rule to promote 2D metallicity in layered systems.

The synthesis of 2-pyridinemethanamido borohydride complexes of yttrium and neodymium was achieved through the in situ deprotonation of the protio-ligand 2-pyridinemethanamine C5H3R1N-C(CH3)R2-NH(2,6-iPr2C6H3), denoted as PyAH (with PyAH1: R1 = R2 = H; PyAH2: R1 = CH3, R2 = H; PyAH3: R1 = C(CH3) 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N-(2,6-iPr2C6H3), R2 = CH3), in the presence of trisborohydride RE(BH4)3(THF)3 (RE = Y and Nd) as a precursor and a base. The isolation of various molecular structures, nine of which were structurally characterized by X-ray diffraction analysis, was achieved and revealed to depend not only on (i) the nature of the 2-pyridinemethanamido ligand and (ii) the rare-earth element but also on (iii) the reaction conditions, notably the type of base used. These include seven mono-substituted species, eventually also comprising the cation derived from the base reagent, such as [(PyA1)Y(BH4)3]2[Mg(THF)6] (1Y), [(PyA1)Nd(BH4)3Mg(PyA1)](THF)4 (1Nd), (PyA1)Nd(BH4)2(THF)2 (1 ' Nd), [(PyA1)Nd(THF)(BH4)(mu-BH4)]2 (1 '' Nd), [(PyA2)Nd(BH4)3]2[Mg(THF)6] (3Nd), (PyA2)Nd(BH4)2(THF)2 (3 ' Nd) and (PyA3)Nd(BH4)2 (4Nd), as well as two bis-substituted complexes (PyA1)2Y(BH4) (2Y) and (PyA1)2Nd(BH4) (2Nd). On the other hand, the unexpected amido/ene-amido derivative [(PyA(EA))Y(BH4)2][Li(THF)4] (5Y) (PyA(EA): R1 = CCH2-N(2,6-iPr2C6H3), R2 = CH3), where the PyAH3 protio-ligand underwent double deprotonation, was recovered from the reaction carried out with nBuLi in the yttrium series. In some cases, the synthesis led to the isolation of borohydride 2-pyridinemethanamido-supported magnesium complexes (PyA2)Mg(BH4)(THF) and (PyA3)Mg(BH4)(THF). In parallel, the PyAH2 pro-ligand could be structurally analyzed, and an unprecedented adduct of the type [KN(SiMe3)2PyAH1]2 was isolated and characterized by X-ray diffraction analysis. Preliminary investigations of the ring-opening polymerization of l-lactide and epsilon-caprolactone with some of the complexes synthesized are finally presented, demonstrating moderate to high catalytic activities.

A Co(II) oxalate coordination polymer, (C7H11N2)(2)[Co(C2O4)(2)]center dot 5H(2)O (1) (C7H11N2+ = 2-amino-4,6-dimethylpyridinium cation), has been synthesized and characterized by elemental and thermal analyses, FT-IR and UV/Vis spectroscopies, powder X-ray diffraction (PXRD), single-crystal X-ray diffraction and variable temperature magnetic susceptibility measurements. Compound 1 is a polymerized organic-inorganic hybrid salt, the asymmetric unit of which consists of one Co(II) ion, one bidentate C2O42- ligand, two halves of bidentate C2O42- ligands, two 2-amino-4,6-dimethylpyridinium C7H11N2+ cations and five crystal water molecules. Each CoII center is six-coordinated in a distorted octahedral geometry fulfilled by six oxygen atoms from three chelating C2O42- ligands. The [Co(C2O4)(2)](2-) ions act as complex ligands and efficiently bridge neighboring Co2+ ions, forming chains of complex anions linked by hydrogen bonded water molecules. Hydrogen bonding interactions of the type O-H center dot center dot center dot O and N-H center dot center dot center dot O along with pi-pi stacking interactions between pyridine rings contribute to the stabilization of the 3D supramolecular framework. Temperature-dependence magnetic moment (mu) collected under zero-field cooled (ZFC) and field-cooled (FC) conditions revealed weak antiferromagnetic ordering at low temperatures.

A novel Co(II) oxalate hybrid salt, (C7H11N2)2[Co(C2O4)2]·5H2O (1) (C7H11N2+ = 2-amino-4,6-dimethylpyridinium cation) has been synthesized and characterized by elemental and thermogravimetric analyses, FT-IR and UV/Vis spectroscopies, single-crystal X-ray diffraction and SQUID magnetometry. The structure of salt 1 consists of zig-zag chains of the [Co(C2O4)2]2- anionic complexes, with the Co(II) centers located in a distorted (2 + 2 + 2) octahedral environment of six oxygen atoms from three chelating oxalato(2-) ligands. These chains delineate voids encapsulating pyridinium cations and crystal water molecules. Another striking feature of this structure is the presence of five-membered water clusters. Hydrogen bonding interactions of the type O–H∙∙∙O and N–H∙∙∙O along with π–π stacking interactions between pyridine rings contribute to the stabilization of the 3-D supramolecular framework in 1. Temperature-dependence magnetic moment (µ) collected under zero-field cooled (ZFC) and field-cooled (FC) conditions revealed an antiferromagnetic ordering at low temperatures in 1.

Two organic-inorganic hybrid salts, (C6H9N2)(2)[Co(C2O4)(2)]center dot H2O (1) and (C5H7N2)(2)[Co(C2O4)(2)(H2O)(2)] (2) (C6H9N2+ = 2-amino-3-methylpyridinium; C5H7N2+ = 4-aminopyridinium) have been obtained. Salt 1 is characterized by the formation of one-dimensional chains of the anionic complexes [Co(C2O4)(2)](2-), with the Co(II) centers located in a distorted (2 + 2 + 2) octahedral environment of six oxygen atoms from three chelating oxalato(2 -) ligands. By contrast, salt 2 features discrete anionic complexes [Co(C2O4)(2)(H2O)(2)](2-) with distorted (4 + 2) octahedral CoO6 coordination sphere formed by two bidentate O,O-donor oxalato(2 -) ligands in the equatorial plane and two aqua ligands in the axial positions. Hydrogen bonding interactions of the type O-H center dot center dot center dot O and N-H center dot center dot center dot O along with pi-pi stacking interactions between pyridine rings contribute to the stabilization of the 3-D supramolecular frameworks in 1 and 2. Temperature-dependence magnetic moment (mu) collected under zero-field cooled (ZFC) and field-cooled (FC) conditions revealed strong antiferromagnetic ordering below T-N = 25 K for 1, a behavior which is confirmed by the negative Weiss constant, theta = 27.6 K. By contrast, in 2, the Weiss constant, theta = 0 K is in line with a paramagnetic behavior. The three-dimensional Hirshfeld surface (3D-HS) analysis and the two-dimensional fingerprint plots (2D-FP) revealed that in 2, the structure is dominated by H center dot center dot center dot O/ H center dot center dot center dot O and H center dot center dot center dot H contacts.