Search Results (688)

Real-time detection of chemical warfare agents (CWAs) and toxic industrial chemicals underpins military protection, counter-terrorism, and emergency response. Yet field instruments usually fail for a reason unrelated to sensitivity: they cannot identify agents that are not already in their reference libraries, such as novel analogs, mixtures, and degradation products. We argue that this unknown-agent problem is a structural limitation of single-modality sensing, because any one class of information (molecular bonds, ion mobility, elemental composition, or chemical reactivity) is rarely sufficient to resolve an unfamiliar threat. We review the dominant field modalities, including FTIR, Raman/SERS, ion mobility and field-asymmetric ion mobility spectrometry, laser- and spark-induced plasma spectroscopy, metal-oxide sensor arrays, and portable mass spectrometry, and show that their weaknesses are largely complementary. We then set out the principle of orthogonal multimodal sensing, in which complementary information axes are combined by machine learning with anomaly and open-set detection so that unfamiliar agents are recognized as such rather than misidentified. Four hybrid architectures are critically compared, and we examine spark-induced decomposition diagnostics, consumable-free self-decontaminating field systems with edge AI, and the open challenges of standardized datasets, calibration transfer, and validation, before outlining a roadmap toward field-relevant recognition of unidentified chemical threats. Full article

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 Na[Co(η⁵-C₅H₅){P(O)(OMe)₂}₃] (NaL_OMe) salt containing the anionic tripodal Kläui ligand η⁵-cyclopentadienyltris(dimethylphosphonato)cobaltate(III), 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 with other 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 δ(³¹P) = 160.20 ppm (2) and 159.43 ppm (3) are diagnostic of cerium(III). Full article

Silver complexes are potential antimicrobial agents that trigger destructive processes in bacterial cells, leading to their death. Their ability to simultaneously stimulate tissue regenerative properties also makes them promising components in the development of medical materials. A common complication arising from the treatment of bone tissue damage is hospital-acquired infection, requiring repeated revision surgeries. The use of bone grafts with antibacterial properties can help solve this problem. New pyridine complexes of silver(I) with thiophenecarboxylic (Htph) and nitric acid anions have been synthesized: [Ag(tph)(py)₂]_n·nHtph (1, py—pyridine) and [Ag(bpy)]_n·nNO₃ (2, bpy—4,4′-bipyridine), the structures of which have been determined using X-ray analysis. Despite the fact that 2 is a known structure, we were able to obtain new cell parameters by conducting an X-ray diffraction analysis at a lower temperature of 100 K. According to X-ray diffraction data, both compounds are polymers in which the cationic part is formed by linear fragments (CN_Ag = 2) [Ag(py)₂]⁺ (1)/[Ag(bpy)₂]⁺ (2), and acid anions act as counterions. The presence of intermolecular and non-valent π-π interactions provides additional stabilization of supramolecular levels. Aqueous solutions 1 and 2 are stable for two weeks, according to UV-Vis data. Incubation of crosslinked resorbable polymer matrices functionalized separately with complex 1 or 2 in saline solution revealed a sustained, prolonged release of silver ions over 14 days. Evaluation of the antimicrobial potential of 1 and 2 against Gram-positive/Gram-negative species and fungi demonstrated moderate, controlled bacteriostatic growth inhibition broadly across tested strains, confirming the bifunctionality of the crosslinked hybrid matrix systems—moderate suppression of bacterial growth while simultaneously stimulating tissue regeneration. An increase in cell viability, expressed in their active proliferation under the influence of complexes 1 and 2 up to 156%, as well as calcium deposition, indicates the high cytocompatibility and pro-mineralization capacity of the new compounds. Full article

Cationic lanthanide luminophores remain underexplored compared with their neutral analogues, despite attractive features for solution-processed electroluminescent devices. Here we report the synthesis and characterization of five europium(III) cationic complexes of the type [Eu(L^{N,N})₂(L^{O,O})₂][PF₆], where L^{N,N} = 2,2′-bipyridine, 1,10-phenanthroline, or bathophenanthroline and L^{O,O} = acetylacetonate (acac) or hexafluoroacetylacetonate (hfac). These complexes are obtained in good yield via one-pot reactions from EuCl₃·6H₂O, β-diketonates, and diimine ligands, and are confirmed by FT-IR and RAMAN spectroscopies, elemental analysis, and single-crystal X-ray diffraction to possess well-defined EuO₄N₄ coordination spheres with PF₆ counterions. UV–Vis spectra show intense ligand-centered π–π* bands below ~300 nm and weak visible tails, consistent with efficient antenna sensitization and negligible direct Eu(III) f–f absorption. All complexes exhibit characteristic Eu(III) emission between ~575 and 725 nm, dominated by the ⁵D₀ → ⁷F₂ transition near 610–620 nm for all complexes and ⁵D₀ → ⁷F_3,4 transitions for 4 and 5, with similar line patterns but markedly different intensities. Replacing acac with hfac dramatically enhances performance with the quantum yields increasing from 15–18% to 85–93%, and excited-state lifetimes from 1.01–1.53 ms to 2.50–3.25 ms. These gains are attributed to improved ligand triplet to Eu(III) ⁵D₀ energy matching and reduced multiphonon relaxation, establishing these cationic Eu(III) complexes as promising emitters for solution-processable photonic devices. Full article

Wormlike micelles provide the structural basis for the viscoelasticity of clean fracturing fluids, yet the molecular mechanism by which calcium-containing brine regulates their growth remains insufficiently understood. In this work, all-atom molecular dynamics simulations were performed to investigate the calcium-regulated self-assembly of an EAHSB/EHAC/NaPts surfactant–counterion system. In the absence of Ca²⁺, dispersed surfactant and counterion molecules first formed small spherical aggregates, which subsequently fused into larger micelles, rod-like intermediates, and finally wormlike micelles. Increasing the local surfactant/counterion loading further promoted one-dimensional micellar growth and network-like association. When Ca²⁺ was introduced, the assembly process became slower and the final aggregate morphology shifted from elongated wormlike micelles to smaller spherical aggregates. Radial distribution functions and coordination-number analysis show that Ca²⁺ redistributes charged-group correlations within the mixed surfactant/counterion assemblies. Hydration analysis indicates enlarged polar hydration shells, whereas hydrophobic-tail hydration and gauche-defect probabilities reveal enhanced tail exposure and looser chain packing. These results demonstrate that Ca²⁺ suppresses wormlike micelle growth through coupled electrostatic redistribution, interfacial hydration, and hydrophobic-chain disorder, thereby favoring high-curvature spherical aggregates over extended wormlike networks. Full article

Infectious wounds are plagued by persistent infection, uncontrolled inflammation, and delayed repair, while traditional therapies suffer from the poor solubility of natural drugs, low bioavailability, and bacterial drug resistance. To address these issues, this study developed a photo-responsive chitosan composite hydrogel (BBR-AS@Ce6@Matrix) cross-linked by chitosan (CS) and oxidized sodium alginate (OSA), co-loaded with Berberine–Asiaticoside cocrystal (BBR-AS) and chlorin e6-loaded chitosan nanoparticles (Ce6@CS NPs). The BBR-AS co-crystal was prepared by solvent method and verified to significantly improve the solubility and dissolution of asiaticoside. The Ce6@CS NPs were fabricated via non-solvent-assisted counterion complexation, showing high encapsulation efficiency, uniform particle size, and efficient singlet oxygen generation under irradiation. The hydrogel exhibited a three-dimensional porous network, favorable rheology, high water content, pH-dependent swelling and erosion behaviors, and significantly promoted BBR/AS release in vitro. In vitro experiments demonstrated strong antibacterial activity against Escherichia coli and Staphylococcus aureus, good cytocompatibility, and enhanced migration of L929 and Hacat cells. In a rat infectious wound model, the hydrogel combined with light irradiation markedly accelerated wound closure, promoted collagen deposition and angiogenesis, upregulated VEGF/CD31, and downregulated TNF-α/IL-6. In conclusion, BBR-AS@Ce6@Matrix integrates co-crystal solubilization, nanoparticle-facilitated release, and photodynamic synergy to achieve antibacterial, anti-inflammatory, pro-angiogenic and tissue remodeling effects, providing a promising multifunctional platform for infectious wound repair. Full article

Understanding the absorption and desorption behavior of superabsorbent polymers (SAPs) in ionic environments is critical for their practical applications. Ion exchange between monovalent counterions within the SAP and multivalent cations (e.g., Ca²⁺) in solution not only induces macroscopic desorption but also generates non-uniform internal strain, creating a complex feedback loop with ion transport. This study establishes a phenomenological coupled model that integrates Fickian diffusion for ion transport with an elastic wave equation for SAP deformation. The coupling is realized through deformation-dependent diffusion coefficients and an ion-concentration-modulated elastic modulus, with the latter described by a first-order linear relationship over a limited range. Taking Ca²⁺ as a representative divalent cation, we systematically investigate the effects of solution concentration, SAP particle size, and ion dissociation degree. The model predicts several non-intuitive phenomena, including transient internal free Ca²⁺ concentrations exceeding the boundary concentration by up to ~15% and concentration gradient inversions for small SAP particles (radius 75 μm) at later times. Characteristic absorption time constants τ_a range from 98 s to 179 s depending on particle size and Ca²⁺ level. Simulated total Ca²⁺ uptake agrees with experimental data within an 8% mean relative error. The model is validated against macroscopic absorption/desorption curves and total Ca²⁺ uptake, while the predicted internal concentration and strain fields remain to be confirmed by spatially resolved experiments. These findings provide new mechanistic insights into the chemo-mechanical coupling in SAPs and offer guidance for their tailored design. Full article

To develop novel, green, and highly effective fungicides, a series of benzoxazinone-functionalized pyridylpyrazole derivatives (8a–8z) were designed and synthesized via a metal-catalyst-free route using a pyraziflumid intermediate. The synthetic procedure included diazotization, cyclization, hydrolysis, and methanesulfonyl chloride-mediated dehydrative cyclization. The optimal conditions (3.0 equiv pyridine in water, BF₄⁻ as the counterion, 25 °C, 3 h) afforded a maximum yield of 63.7%. Bioassays showed that 8p exhibited 92.0% inhibition against maize rust (Puccinia polysora) and 8q exhibited 90.5% inhibition against cucumber anthracnose (Colletotrichum orbiculare) at 50 mg/L. Substituents on the aromatic and pyridyl moieties jointly regulated fungicidal activity, with distinct pathogen-dependent selectivity. Docking results revealed that 8j bound to succinate dehydrogenase (SDHI) with a binding energy of −11.8 kcal/mol, and the polar interaction between its carbonyl group and Lys163 was key to enhancing binding affinity. This study provides a scientific basis for the green synthesis and rational design of pyridylpyrazole-based fungicides. Full article

Per- and polyfluoroalkyl substances (PFASs) are persistent environmental contaminants whose mobility in soil and groundwater is strongly controlled by adsorption and desorption processes. In saturated clay-rich soils, these processes are complex because PFASs interact with hydrated mineral surfaces, organic matter, metal oxides, exchangeable cations, and pore-water constituents. This review synthesizes the current literature on PFAS adsorption and desorption in saturated soils, with an emphasis on clay mineralogy, mineral–water interfaces, pore-water chemistry, and electrochemical double layer (EDL) effects. PFAS retention is influenced by molecular properties such as chain length, functional head group, and charge state, as well as soil properties such as organic carbon content, clay mineral type, surface charge, cation exchange capacity, and Fe/Al oxide content. Longer-chain PFASs and sulfonate-based compounds generally show stronger retention, while shorter-chain PFASs tend to remain more mobile. This review focuses particularly on how an EDL affects PFAS behavior in saturated clay systems. Unlike dry clay surfaces, saturated clay surfaces are covered by structured water, exchangeable ions, and diffuse counterion layers. These hydrated interfacial conditions influence how closely anionic PFASs can approach negatively charged clay surfaces, how dissolved cations reduce electrostatic repulsion or promote cation-mediated binding, and how effectively short-range interactions such as hydrophobic association, van der Waals forces, hydrogen bonding, and surface association contribute to adsorption. Desorption is also emphasized because adsorption does not necessarily represent permanent immobilization. Changes in pH, ionic strength, cation composition, dissolved organic matter, or competing solutes can weaken retention and promote PFAS release. Overall, PFAS mobility in saturated clay-rich soils should be interpreted as a coupled interfacial process rather than simple partitioning to soil solids. Future work should better connect molecular-scale mechanisms, EDL behavior, adsorption–desorption experiments, and saturated transport studies to improve predictions of PFAS retention and long-term groundwater release. Full article

Background/Objectives: Formulating antibiotics as active pharmaceutical ingredient ionic liquids (API-ILs) has been proposed as a strategy to help overcome antimicrobial resistance. However, the effects of API-ILs on bacterial mutation frequency, an increase of which is associated with a higher risk of resistance development, have not yet been assessed. Here, API-ILs based on the antibiotic ciprofloxacin were synthesized using five structurally different counter ions of varying biological activity - low ([Chol]⁺ and [EMMor]⁺), intermediate ([TMC₁₀A]⁺) and high ([TMC₁₆A]⁺ and [TC₈MA]⁺) - and investigated in terms of their antimicrobial activity and mutation frequency in Escherichia coli MG1655. Methods: API-ILs were synthesized according to the CBILS© route. Conductivities and antimicrobial activity (determined by minimal inhibitory concentrations (MICs) and disk diffusion (DD) assays) of API-ILs as well as of individual API and ILs were measured, followed by mutation frequency assays. Results: Five novel ciprofloxacin-based API-ILs were synthesized. Overall, a lower dissociation of API-ILs compared to the respective ILs was observed, indicating presence of stable ion pairs in aqueous solution. All API-ILs retained the antimicrobial activity of ciprofloxacin. A higher mutation frequency (2.6–6.99-fold increase) was observed for API-ILs than for ciprofloxacin alone (1.71-fold increase), when compared to no treatment control, while ILs alone had no or a moderate impact (0.62–1.65-fold increase). Conclusions: Although it is possible to synthesize novel stable API-IL compounds with a high antimicrobial activity using ciprofloxacin and ILs of different structural classes, this can result in increased bacterial mutation frequencies. It is therefore crucial to improve our understanding of how API-ILs can be designed in a safer way. Full article

DNA conformational transitions in aqueous environments are strongly influenced by electrostatic interactions with surrounding cations. This review/perspective article summarizes the experimental findings reported during the last decade on the competitive/cooperative effects of cations with different valencies on DNA conformational behavior. Recent experimental studies based on single DNA observations have shown that divalent cations, such as Mg(2+) and Ca(2+), can inhibit DNA compaction induced by the trivalent cation spermidine (SPD(3+)), revealing that the effects of coexisting cations are not simply additive. Such competitive behavior cannot be adequately explained within the conventional Debye–Hückel framework, which predicts always additive electrostatic screening contributions from cations of different valencies. To elucidate the underlying mechanism of competitive effects, a theoretical framework has been proposed by extending the framework of current counterion condensation theory, which incorporates changes in translational entropy arising from the ion-exchange process between monovalent counterions and divalent or trivalent cations interacting with DNA as a highly negatively charged polyelectrolyte. In the theoretical framework, the increase in translational entropy arises from the ion exchange process between monovalent counterions and trivalent cations in the absence of divalent cations, whereas the presence of divalent cations diminishes the entropic gain associated with this exchange. By interpreting the recent experimental findings through the aid of the development of theoretical modeling, this review/perspective article provides a coherent insight on how coexisting multiple cations regulate DNA conformation. Full article

We report the synthesis, characterisation and electronic modulation of three novel fused polyheterocyclic ligands—naphtho[1,2-b]furan-4,5-dione (1), furo[3′,2′:3,4]naphtho[1,2-d]imidazole (2), and benzo[a]furo[2,3-c]phenazine (3)—and their Cu(II), Zn(II) and Fe(II/III) complexes. Compound (1) was isolated at 96.5% yield using fulvic acid as a green organocatalyst. ⁵⁷Fe Mössbauer spectroscopy identified two high-spin Fe(III) environments in a 37:63 ratio (δ = 0.377 mm s⁻¹; Δ = 0.62 and 1.01 mm s⁻¹), with no evidence of magnetically ordered oxide phases. Six enantiomeric metal malate salts were synthesised at 86–93% yield for spectrophotometric titrations. The key finding is a striking Cu(II)-specific enantioselective molecular recognition: (3) binds (S)-(−)-malate Cu(II) with log K = 9.02, a factor of 2.5× higher than the (R)-(+)-malate complex (log K = 8.62), while Fe(II) and Zn(II) show no enantioselectivity. These results establish chiral counter-ion engineering combined with π-conjugated polyheterocyclic scaffolds as a powerful strategy for chiroptical sensing and asymmetric catalysis. Full article

Ten compounds have been prepared among them six different dioxido(pyridine-2,6-dicarboxylato)vanadate(V) compounds with piperazinium (H₂pip²⁺) (1·6H₂O), methylpiperazinium (H₂mepip²⁺) (2·5H₂O), ethylpiperazinium (H₂etpip²⁺) (3·3H₂O), isopropylpiperazinium (H₂isopip²⁺) (4·H₂O), phenylpiperazinium (Hphepip⁺) (5∙H₂O) and thiomorpholinium 1-oxide (HtmorO⁺) (6·2,6-H₂pydc·2H₂O) cations as counterions as well as methylpiperazinium (H₂mepip²⁺) salt of a mixed valence vanadium [VO(2,6-pydc)-(μ-O)-VO(H₂O)(2,6-pydc)]⁻ complex (7), thiomorpholin-4-ium vanadate (Htmor)VO₃ (8), hexa(thiomorpholin-4-ium) decavanadate hexahydrate (Htmor)₆[V₁₀O₂₈]·6H₂O (9·6H₂O) and organic salt cocrystal thiomorpholin-4-ium 6-carboxypicolinate pyridine-2,6-dicarboxylic acid (Htmor)⁺(2,6-Hpydc)⁻∙(2,6-H₂pydc)·2H₂O (10·2H₂O) via different pathways starting either from pyridine-2,6-dicarboxylic acid or its esters, and were structurally characterized by single-crystal X-ray diffraction. Extended hydrogen bonding interactions are present due to the presence of organic cations as well as due to the diverse roles of water molecules in the hydrogen bonding network. Centrosymmetric hydrogen bonding was found to be an important motif, and diverse supramolecular patterns were also observed due to a wide variety of C–H···O and π···π interactions stabilizing the crystal lattices. Full article

Volatile amphiphiles and surfactant mixtures have gained wide applications in diverse areas of industry, cosmetics, and medicine. The surface tension isotherms, measured at different solute ratios, and data processing, using appropriate theoretical models, provide quantitative information on their bulk and interfacial properties. Here, this approach is applied for mixtures of volatile amphiphile (benzyl acetate, linalool, geraniol, menthol, citronellol) and sodium dodecyl sulfate (SDS). All surface tension isotherms are described by the van der Waals model for a two-component adsorption layer, taking into account the counterion binding in the Stern layer, by varying only one adjustable parameter (interfacial pair interaction energy between adsorbed molecules). Knowing the parameters of the model, we computed various properties of the adsorption layers (adsorptions of different components, occupancy of the Stern layer, and interfacial electrostatic potential). The experimental aqueous solubilities of mixtures are fitted using the regular solution theory to obtain the pair bulk interaction parameter. The mixing of SDS and: (i) benzyl acetate and citronellol is antagonistic; (ii) linalool and geraniol is synergistic; and (iii) menthol is ideal. The reported properties of the volatile amphiphiles and SDS mixtures could be of interest for increasing the range of their applicability in practice. Full article

Highly polar M-mol-X (M = alkali metal, mol = molecule, X = halogen) insertion complexes have been predicted to offer potential practical applications, including molecular interactions with light, ion-pair induced isomerization, etc. In the present work, the insertion complexes of the seven-membered, fused bicyclic norcaradiene and its monocyclic isomer trapped in Li-I, Na-I, and K-I counterion pairs were investigated using ab initio methods. The structures, stability, polarities, and simulated infrared spectra are analyzed and the effects of the insertion on the norcaradiene to cycloheptatriene isomerization process are examined. Furthermore, an uncommon bond between iodine and a fully substituted carbon atom is reported upon and hypothesized to be catalyzed by the presence of the cation in the insertion complexes. Full article