Solvent-Responsive Reversible and Controllable Conversion between a Polyimine Membrane and an Organic Molecule Cage.

Adaptive bionic self-correcting behavior offers an attractive property for chemical systems. Here, based on the dynamic feature of imine formation, we propose a solvent-responsive strategy for smart switching between an amorphous ionic polyimine membrane and a crystalline organic molecule cage without the addition of other building blocks. To adapt to solvent environmental constraints, the aldehyde and amine components undergo self-correction to form a polymer network or a molecular cage. Studies have shown that the amorphous film can be switched in acetonitrile to generate a discrete cage with bright birefringence under polarized light. Conversely, the membrane from the cage crystal conversion can be regained in ethanol. Such a membrane-cage interconversion can be cycled continuously at least 5 times by switching the two solvents. This work builds a bridge between the polymer network and crystalline molecules and offers prospects for smart dynamic materials.

Boost of Gas Adsorption Kinetics of Covalent Organic Frameworks via Ionic Liquid Solution Process.

Adsorption, storage, and conversion of gases (e.g., carbon dioxide, hydrogen, and iodine) are the three critical topics in the field of clean energy and environmental mediation. Exploring new methods to prepare high-performance materials to improve gas adsorption is one of the most concerning topics in recent years. In this work, an ionic liquid solution process (ILSP), which can greatly improve the adsorption kinetic performance of covalent organic framework (COF) materials for gaseous iodine, is explored. Anionic COF TpPaSO3 H is modified by amino-triazolium cation through the ILSP method, which successfully makes the iodine adsorption kinetic performance (K80% rate) of ionic liquid (IL) modified COF AC4 tirmTpPaSO3 quintuple compared with the original COF. A series of experimental characterization and theoretical calculation results show that the improvement of adsorption kinetics is benefited from the increased weak interaction between the COF and iodine, due to the local charge separation of the COF skeleton caused by the substitution of protons by the bulky cations of ILs. This ILSP strategy has competitive help for COF materials in the field of gas adsorption, separation, or conversion, and is expected to expand and improve the application of COF materials in energy and environmental science.

Anomalous Melting Point of Multicharge Ionic Liquids: Structural, Electrostatic, and Orbital Properties of [Ln(NO3)6]3- (Ln = Ce, Pr) Anions.

Salts composed of multicharged cations/anions usually exhibit a large lattice energy and strong Coulomb force, which results in high melting points. However, an increasing number of highly charged ionic liquids exceed expectations based on conventional experience; even their melting points are much lower than those found for simple ionic liquids composed of monovalent ions. To further study this phenomenon, we studied a group of stable ionic liquids containing tricharged [Ce(NO3)6]3- and [Pr(NO3)6]3- anions. The structures for [C6mim]3[Ce(NO3)6] and [C6mim]3[Pr(NO3)6] were determined by single-crystal X-ray diffraction with triclinic and P1̅ space groups. The electrostatic potential density per unit ion surface and volume was proposed and calculated. Additionally, theoretical analysis based on Hirshfeld surface and charge decomposition was carried out to explore the intermolecular interaction and electronic structure of the lanthanide anions. The electrostatic and orbital properties were found to be more useful for understanding the melting points of highly charged salts compared with the sole use of lattice energy. The electrostatic potential density per unit ion surface and volume showed a linear relationship with the melting point of ionic liquids composed of monovalent to trivalent ions. These structure-melting point relationships will be beneficial for expounding new low-melting-point ionic liquids with a wide liquidus range.

The Proton Dissociation of Bio-Protic Ionic Liquids: [AAE]X Amino Acid Ionic Liquids.

[AAE]X composed of amino acid ester cations is a sort of typically "bio-based" protic ionic liquids (PILs). They possess potential Brønsted acidity due to the active hydrogens on their cations. The Brønsted acidity of [AAE]X PILs in green solvents (water and ethanol) at room temperature was systematically studied. Various frameworks of amino acid ester cations and four anions were investigated in this work from the viewpoint of structure-property relationship. Four different ways were used to study the acidity. Acid dissociation constants (pKa) of [AAE]X determined by the OIM (overlapping indicator method) were from 7.10 to 7.73 in water and from 8.54 to 9.05 in ethanol. The pKa values determined by the PTM (potential titration method) were from 7.12 to 7.82 in water. Their Hammett acidity function (H0) values (0.05 mol·L-1) were about 4.6 in water. In addition, the pKa values obtained by the DFT (proton-transfer reactions) were from 7.11 to 7.83 in water and from 8.54 to 9.34 in ethanol, respectively. The data revealed that the cationic structures of [AAE]X had little effect and the anions had no effect on the acidity of [AAE]X. At the same time, the OIM, PTM, Hammett method and DFT method were reliable for determining the acidic strength of [AAE]X in this study.

Bio-based ionic liquid filter with enhanced electrostatic attraction for outside filtration and inside collection of viral aerosols.

Hazardous biological pathogens in the air pose a significant public environmental health concern as infected individuals emit virus-laden aerosols (VLAs) during routine respiratory activities. Mask-wearing is a key preventive measure, but conventional filtration methods face challenges, particularly in high humidity conditions, where electrostatic charge decline increases the risk of infection. This study introduces a bio-based air filter comprising glycine ionic liquids (GILs) and malleable polymer composite (GILP) with high polarity and functional group density, which are wrapped around a melamine-formaldehyde (MF) resin skeleton, forming a conductive, porous GIL functionized ionic network air filter (GILP@MF). When subjected to low voltage, the GILP@MF composite efficiently captures VLAs including nanoscale virus particles through the enhanced electrostatic attraction, especially in facing high humidity bioaerosols exhaled by human body. The filtration/collection efficiency and quality factor can reach 98.3% and 0.264 Pa-1 at 0.1 m s-1, respectively. This innovative filter provides effective VLA protection and offers potential for non-invasive respiratory virus sampling, advancing medical diagnosis efforts.

On-site portable detection of gaseous methyl iodide using an electrochemical method.

We report an electrochemical device for portable on-site detection of gaseous CH3I based on PVIm-F for the first time. The device achieves detection of gaseous CH3I with a significant selectivity and a low detection limit (0.474 ppb) in 20 min at 50 °C and 50% relative humidity, which is of great significance for achieving real-time on-site monitoring of radioactive hazardous environments.

Low-melting multicharge ionic liquids with [Ln(NO3)5]2- (Ln = Ho-Lu): structural, electrostatic, thermochemical, and fluorescence properties.

A series of green and safe heavy-rare-earth ionic liquids were obtained using a straightforward method. The stable structures of these ionic liquids, characterized by high-coordinating anions, were confirmed by nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, and single crystal X-ray diffraction (XRD). These ionic liquids exhibited wide liquid phase intervals and excellent thermal stability. The bidentate nitrato ligands occupied a sufficient number of coordination sites on the lanthanide ions, resulting in the formation of water-free 10-coordination structures. To explain the anomalous melting points observed in these multi-charged ionic liquids, a combination of experimental data and theoretical studies was employed to investigate the relationship between the electrostatic properties and the melting point. The electrostatic potential density per unit ion surface and volume were proposed and utilized for melting point prediction, demonstrating good linearity. Furthermore, the coordinating spheres of the lanthanide ions in these ionic liquids were devoid of luminescence quenchers such as O-H and N-H groups. Notably, the ionic liquids containing Ho3+, Er3+, and Tm3+ exhibited long lifetime near-infrared (NIR) and blue emissions, respectively. The UV-vis-NIR spectra revealed numerous electronic transitions of the lanthanide ions, which were attributed to their unique optical properties.

Hydrogen-bonding and π-π interaction promoted solution-processable covalent organic frameworks.

Covalent organic frameworks show great potential in gas adsorption/separation, biomedicine, device, sensing, and printing arenas. However, covalent organic frameworks are generally not dispersible in common solvents resulting in the poor processability, which severely obstruct their application in practice. In this study, we develop a convenient top-down process for fabricating solution-processable covalent organic frameworks by introducing intermolecular hydrogen bonding and π-π interactions from ionic liquids. The bulk powders of imine-linked, azine-linked, and ß-ketoenamine linked covalent organic frameworks can be dispersed homogeneously in optimal ionic liquid 1-methyl-3-octylimidazolium bromide after heat treatment. The resulting high-concentration colloids are utilized to create the covalent organic framework inks that can be directly printed onto the surface. Molecular dynamics simulations and the quantum mechanical calculations suggest that C‒H···π and π-π interaction between ionic liquid cations and covalent organic frameworks may promote the formation of colloidal solution. These findings offer a roadmap for preparing solution-processable covalent organic frameworks, enabling their practical applications.

Ultralow-cost portable device for cesium detection via perovskite fluorescence.

Public anxiety and concern from cesium pollution in oceans have been back on the agenda since tons of nuclear waste water were announced to be poured into oceans. Cesium ion can easily enter organisms and bioaccumulate in animals and plants, thus its harm is chronic to humans through food chains. Here we showed a kind of hybrid ionic liquid membrane (HILM) for detection of cesium ion in seawater through CsPbBr3 perovskite fluorescence. With sustainability in mind, HILM was built frugally. The lowest cost of HILM is below 3 cents per piece. The HILM can detect cesium ion quickly with eye-readable fluorescence signal. Ultracheap, portable, easy-to-use on-site detection device could offer benefit for personal security and applications in environment science and ecology in the future decades.

Hydrogen-bonding and "π-π" interaction promoted solution-processable mixed matrix membranes for aromatic amines detection.

Detection of hazardous compounds can alleviate risk to human health. However, it remains a challenge to develop easy-to-use testing tools for carcinogenic aromatic amines. Herein, we presented a conjugated molecule-based aniline detector, mixed matrix membranes (MMMs), through the solution-processable strategy. The pentacene-based dispersed phase is achieved using the state-of-the-art ionic liquids (ILs) as the continuous phase, based on which MMMs are easily manufactured by a solution process. Moreover, molecular dynamics (MD) simulations and quantum mechanical calculations suggested that hydrogen bonding and π-π interaction between ILs cations and pentacene could promote the dissolution. These prepared MMMs can offer easy-operation and on-site detection of carcinogenic primary aromatic amines with eye-readable fluorescence signal. This work provides a paradigm for the design of a portable testing device for various hazardous compounds.

Online discovery of the molecular mechanism for directionally detoxification of Fuzi using real-time extractive electrospray ionization mass spectrometry.

ETHNOPHARMACOLOGICAL RELEVANCE: Aconitum carmichaelii Debeaux, a famous traditional medicinal herb for collapse, rheumatic fever, and painful joints, always raises global concerns about its fatal toxicity from toxic alkaloids when improperly processed. Therefore, it is urgent to clarify the internal molecular mechanism of processing detoxification on Aconitum and develop simple and reliable approaches for clinical application, which is also of great significance to the rational medicinal use of Aconitum. AIM OF THE STUDY: The study aimed at developing a complete molecular mechanism exploration strategy in complex medicinal herb decocting system, clarifying the internal molecular mechanism of processing detoxification on Aconitum, and exploring valid approaches for detoxification. MATERIALS AND METHODS: Aconiti Lateralis Radix Praeparata (Fuzi) was selected as the model for exploring the complex Aconitum detoxification mechanism using an advanced online real-time platform based on extractive electrospray ionization mass spectrometry. The methods realized the sensitive capture of dynamic trace intermediates, accurate qualitative and quantitative analysis, and real-time and long-term monitoring of multi-components with satisfactory accuracy and resistance to complex matrices. RESULTS: Components in the complex Aconitum decocting system were real-timely characterized and fat meat was discovered and verified to directionally detoxify Aconitum while reserving the therapy effect. More importantly, the dynamic detoxification mechanism in the chemically complex Aconitum decoction was molecularly profiled. A novel reaction pathway based on nucleophilic substitution reaction mechanism was proposed. As confirmed by the theoretic calculations at DFT B3LYP/6-31G (d) levels, fatty acids (e.g., palmitic acid) acted as a green, cheap, and high-performance catalyst and promote the decomposition of toxic diester alkaloids to non-toxic and active benzoyl-monoester alkaloids through the discovered mechanism. CONCLUSION: The study exposed a novel detoxification molecular mechanism of Aconitum and provided an effective method for the safe use of Aconitum, which could effectively guide the development of traditional processing technology and compatibility regulation of the toxic herb and had great value to the modernization and standardization development of traditional medicine.

Designing high-performance hypergolic propellants based on materials genome.

A new generation of rocket propellants for deep space exploration, ionic liquid propellants, with long endurance and high stability, is attracting more and more attention. However, a major defect of ionic liquid propellants that restricts their application is the inadequate hypergolic reactivity between the fuel and the oxidant, and this defect results in local burnout and accidental explosions during the launch process. We propose a visualization model to show the features of structure, density, thermal stability, and hypergolic activity for estimating propellant performances and their application abilities. This propellant materials genome and visualization model greatly improves the efficiency and quality of developing high-performance propellants, which benefits the discovery of new advanced functional molecules in the field of energetic materials.

High-performance particulate matter including nanoscale particle removal by a self-powered air filter.

Particulate matter (PM) pollutants, including nanoscale particles (NPs), have been considered serious threats to public health. In this work, a self-powered air filter that can be used in high-efficiency removal of PM, including NPs, is presented. An ionic liquid-polymer (ILP) composite is irregularly distributed onto a sponge network to form an ILP@MF filter. Enabled by its unique electrochemical properties, the ILP@MF filter can remove PM2.5 and PM10 with high efficiencies of 99.59% and 99.75%, respectively, after applying a low voltage. More importantly, the charged ILP@MF filter realizes a superior removal for NPs with an efficiency of 93.77%. A micro-button lithium cell or silicon-based solar panel is employed as a power supply platform to fabricate a portable and self-powered face mask, which exhibits excellent efficacy in particulate removal compared to commercial masks. This work shows a great promise for high-performance purification devices and facile mask production to remove particulate pollutants.

Handy fluorescent paper device based on a curcumin derivative for ultrafast detection of peroxide-based explosives.

We report a handy, simple and inexpensive paper device for extremely sensitive detection of peroxide-based explosives. The sensing device fabricated using a curcumin derivative was capable of ultrafast sensing of triacetone triperoxide. The detection time was below 5 s. Moreover, the sensor retained full function under storage at ambient temperature for at least 120 days.

Tunneling Atomic Layer-Deposited Aluminum Oxide: a Correlated Structural/Electrical Performance Study for the Surface Passivation of Silicon Junctions.

Passivation is a key process for the optimization of silicon p-n junctions. Among the different technologies used to passivate the surface and contact interfaces, alumina is widely used. One key parameter is the thickness of the passivation layer that is commonly deposited using atomic layer deposition (ALD) technique. This paper aims at presenting correlated structural/electrical studies for the passivation effect of alumina on Si junctions to obtain optimal thickness of alumina passivation layer. High-resolution transmission electron microscope (HRTEM) observations coupled with energy dispersive X-ray (EDX) measurements are used to determine the thickness of alumina at atomic scale. The correlated electrical parameters are measured with both solar simulator and Sinton's Suns-Voc measurements. Finally, an optimum alumina thickness of 1.2 nm is thus evidenced.

Hydrogen bonding behaviors of binary systems containing the ionic liquid 1-butyl-3-methylimidazolium trifluoroacetate and water/methanol.

The hydrogen-bonding properties of binary systems consisting of a representative Brønsted acidic hydrophilic ionic liquid (IL) 1-butyl-3-methylimidazolium trifluoroacetate ([Bmim][CF(3)CO(2)]) and a cosolvent, water or methanol, over the entire concentration range have been investigated by methods of attenuated total reflectance infrared spectroscopy, (1)H NMR spectroscopy, and quantum chemical calculations. It has been found that the hydrogen-bonding interactions between the anion [CF(3)CO(2)](-), rather than the cation, and the cosolvent molecules are dominant at low concentration of cosolvent. The H-bond interaction site between the IL anion and water/methanol is the O atom in the -COO group, while the -CF(3) group makes a positive contribution by donating electron to the carboxylic group, forming a cooperative hydrogen-bonding system. For the cation [Bmim](+), although the C2-H is the favorable proton donor in H-bonding interactions, the water/methanol molecules form H-bonds with the alkyl C-H at low water/methanol concentration due to the stronger interaction between C2-H and [CF(3)CO(2)](-). Interestingly, we found that the interaction between methanol and the IL is stronger than that between water and the IL because the methyl group in methanol has a positive contribution to the formation of H-bonds. The following sequential order of interaction strength is established: [Bmim](+)-methanol-[CF(3)CO(2)](-) > [Bmim](+)-water-[CF(3)CO(2)](-) > [Bmim](+)-[CF(3)CO(2)](-) > [CF(3)CO(2)](-)-methanol > [CF(3)CO(2)] (-)-water > [Bmim](+)-methanol > [Bmim] (+)-water.