Search Results (904)

The efficient capture of carbon dioxide (CO₂) using polymer, supported ionic liquids (ILs) remains challenging due to limited understanding of atomic-scale interaction mechanisms. Here, a polystyrene (PS) oligomer supported by an amidinium chloride-based IL is proposed as a CO₂-absorbing material. Density functional theory (DFT) calculations were employed to investigate the structural, electronic, and intermolecular interaction energy characteristics of the PS oligomer, amidinium chloride ILs, CO₂, and their binary and ternary complexes. Molecular electrostatic potential maps (MEPs), reduced density gradient (RDG) plots with non-covalent interaction (NCI) snapshots, quantum theory of atoms in molecules critical point (CP) analysis, and electron localization function (ELF) analysis reveal pronounced hydrogen bonding and dispersion interactions between PS and IL that modulate the electronic environment of the IL anion, which is the primary CO₂ binding site. Interaction energy calculations show that the ternary PS–IL–CO₂ complex exhibits a significantly enhanced binding energy compared to the isolated IL–CO₂ complex, providing quantitative evidence for the cooperative role of the PS support. The results indicate enhanced CO₂ binding in the presence of PS supported by ILs, driven by cooperative electrostatic and dispersion interactions. These findings provide molecular-level insights into CO₂ capture mechanisms in polymer–IL hybrid systems. Full article

Cellulose is the most promising abundant renewable polymer material with the highest potential for the future low-carbon biorefineries. However, its utilization in industry is limited by the structural recalcitrance as a result of organization of crystalline domains, fibrillar architecture hierarchy and intramolecular and intermolecular hydrogen bonding which is responsible for access restriction for the catalysts and consequent cleavage of the glycosidic bonds. Therefore, efficient depolymerization of cellulose is of paramount importance as a step in biomass conversion into the low molecular products. In this review, the recent advances in cellulose depolymerization are discussed. The chemical, enzymatic, thermal, thermochemical, mechanochemical, oxidative and hybrid catalytic method is thoroughly discussed. Attention is paid to the mechanism of the depolymerization reaction steps as glycosidic bond activation as hydrolytic, radical mediated, and energy assisted pathways. Selectivity and conversion efficiency based on substrate morphology, solvent system and catalyst design are also discussed. Further, there is a comparison of key performance metrics which are relevant for the industrial process as product yield, carbon efficiency, energy demand, stability of the catalyst, solvent recyclability and impact to the environmental lifecycle. The pros and cons of the various methods are also represented. Processes based on mineral acids enable rapid conversion. However, they suffer from corrosion, waste handling issues and degradation by-products. On the other hand, enzymatic depolymerization processes offer relatively high selectivity but they are limited in terms of feedstock sensitivity and slow reaction kinetics. The downstream valorization mechanisms are also described with the result being that no single available technology is capable of satisfying all industrial requirements. Thus, future progress expects integrated circular processes where advanced catalysis, process intensification and digital optimization strategies take place. Full article

This study investigated an efficient approach for extracting saponins from Panax japonicus using deep eutectic solvents (DES) coupled with ultrasound-assisted (UA) extraction, and compared its performance with the methanol extraction method. Twenty-six DES were screened, and choline chloride–urea was selected as the optimal solvent. The total extraction yield was evaluated based on the sum of the yields of chikusetsusaponin IVa (CS-IVa) and ginsenoside Ro (G-Ro). The extraction process was optimized using single-factor experiments combined with an orthogonal array design. Molecular dynamics (MD) simulation was applied to reveal the extraction mechanism at the molecular level. The results showed that the optimal conditions were as follows: a choline chloride-to-urea molar ratio of 1:3, a solid-to-liquid ratio of 1:50, a water content of 60%, an ultrasonic temperature of 40 °C, and an ultrasonic time of 60 min. Under these conditions, the total extraction yield of Panax japonicus saponins reached 7.4%, which was 13% higher than that obtained with the pharmacopeia methanol extraction method. MD simulation demonstrated that DES weakens intermolecular interactions among saponins through hydrogen bonds and van der Waals forces, promoting the dispersion of saponin aggregates and enabling efficient dissolution. Compared with CS-IVa, G-Ro displayed a more pronounced solvation effect, which was likely attributed to the difference in the number of polar sites in their molecular structures. The UA-DES extraction method established herein is green and efficient. It provides a practical reference for the industrial extraction of Panax japonicus saponins and a theoretical foundation for mechanistic studies on natural product extraction using DES. Full article

Wastewater from street food activities is a major pollution source. In this study, sewage sludge (SS) from a treatment plant in Thailand was converted into a porous adsorbent via NaOH activation and calcination (SS-B-C600), while SS-C600 was used as a control. Characterization revealed that both samples were composed of SiO₂ with minor kaolinite. FTIR confirmed Si–O–Si vibrations in both samples, while SS-B-C600 showed enhanced –OH (Si–OH) groups, indicating improved surface hydroxylation. Activation significantly enhanced the adsorption performance for methylene blue (MB) in laboratory-scale experiments. The equilibrium data were best fitted by the Langmuir isotherm model, indicating monolayer adsorption, with maximum capacities of 3.11 mg/g (SS-C600) and 7.56 mg/g (SS-B-C600). The kinetic results were well described by the pseudo-second-order model, suggesting that the adsorption mechanism is governed by a combination of porosity and surface interactions through physisorption. DFT calculations revealed that intermolecular hydrogen bonds between MB and aluminosilicate play a key role in the formation of the complex, while the calculated interaction energy (ΔE = −304.27 kJ/mol) further confirmed the presence of strong intermolecular interactions. Moreover, SS-B-C600 showed stable performance over three reuse cycles, highlighting its potential as a cost-effective and sustainable adsorbent. Full article

In this study, polyvinyl alcohol (PVA) and chitosan (CS) were used as the base materials, and ethyl lauroyl arginate (LAE) as the antibacterial agent to prepare biodegradable bilayer composite films (P/C-L), whose properties compared with those of the monolayer films (P-C-L) of identical composition. Scanning electron microscopy (SEM) results revealed that the P/C-L films formed a compact microstructure with tight interlayer adhesion. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of intermolecular hydrogen bonds within the P/C-L films without the formation of new chemical bonds, and X-ray diffraction (XRD) indicates that the crystallinity of the P/C-L films was dominated by that of PVA. P/C-L films exhibited a dual-surface structure with a hydrophobic CS layer and a hydrophilic PVA layer, broadening their potential application range. The P/C-L films demonstrated superior water resistance and light transmittance to the P-C-L films. When the LAE content increased from 0% to 10%, the P/C-L films displayed a more stable range of variation concerning visible light transmittance, water contact angle (CS layers), and moisture absorption than that of the P-C-L films, with the corresponding changing values being 86.86% to 62.09%, 96.79°to 72.46°, and 8.35% to 19.78%, respectively. Regarding antibacterial properties, the P/C-L films exhibited significantly enhanced activity across all LAE concentrations. Notably, P/C-L films at 2% LAE already outperformed P-C-L films at 4% LAE. At an LAE content of 10%, the inhibition zone diameters of the P/C-L films against E. coli and S. aureus reached 39.42 mm and 42.15 mm, which were 12.71 mm and 13.10 mm larger than those of the P-C-L films, corresponding to increases of 47.58% and 45.09%, respectively. In addition, both the P/C-L bilayer films and the P-C-L films could achieve complete biodegradation within 30 days under laboratory soil burial conditions. These findings suggest that P/C-L films show advantageous overall characteristics, highlighting their strong potential in the field of sustainable active food packaging. Full article

Attenuated total reflection time-domain spectroscopy (ATR-TDS) in the terahertz regime was employed to investigate the dielectric response of water–acetone mixtures over the full molar concentration range. The ATR configuration enabled stable measurements in a controlled and nearly closed environment, minimizing acetone evaporation and allowing reliable characterization of this highly volatile binary system. The complex dielectric function, retrieved in the 0.4–1.6 THz range, was analyzed by means of a double Cole–Cole model, which provided a more consistent description of the mixtures than a simple Debye-based approach. A strongly nonlinear dependence on composition was observed, with the highest sensitivity in the water-rich region, where even small amounts of acetone produced a marked change in both the real and imaginary parts of the dielectric function. The extracted parameters indicate that acetone primarily suppresses the slow, cooperative relaxation channel associated with the hydrogen-bond network of water, whereas the faster channel remains comparatively less affected, consistent with its more local intermolecular origin. The evolution of the Kirkwood–Fröhlich correlation factors and of the broadening parameters further supports a progressive transition from a highly correlated hydrogen-bonded liquid to a structurally heterogeneous and weakly cooperative dipolar environment. These results demonstrate that THz ATR-TDS is a sensitive tool for probing intermolecular reorganization in aqueous binary mixtures, providing a physically grounded framework for the detection of acetone and other volatile hydrogen-bond-active species in water-based systems. Full article

Phosvitin (PV) is a highly phosphorylated protein with strong metal-chelating capacity and bioactivity, but its application is hindered by poor environmental stability. In this study, fructooligosaccharides (FOS) were introduced to form a PV–FOS composite system. The interaction mechanism and structural–functional changes were assessed via thermal and pH stability tests, molecular docking, FTIR, circular dichroism (CD), particle size, zeta potential and changes in turbidity. SDS-PAGE and changes in solubility confirmed the coexistence of PV and FOS in the composite system. Molecular docking revealed that FOS with varying degrees of polymerization can bind to PV through non-covalent interactions to form a complex. FTIR showed characteristic peaks of both components, with shifts and intensity changes at 3200–3500 cm⁻¹, ~1650 cm⁻¹, and 1200–900 cm⁻¹, indicating that non-covalent interactions, intermolecular forces that may be hydrogen bonds, occur between amide, carbonyl, and phosphate groups of PV and hydroxyl groups of FOS. CD demonstrated slight secondary structure rearrangement of PV without significant denaturation. Compared with PV alone, the PV-FOS complex showed an increased particle size and a weakly negative surface charge, which could be attributed to the presence of FOS. These changes may enhance the anti-aggregation capacity of the complex. Consistently, turbidity measurements further demonstrated that the PV-FOS complex exhibited better turbidity stability. Functionally, FOS incorporation significantly improved PV’s solubility, metal-chelating capacity, and lipid antioxidant activity under various temperature and pH conditions. In summary, FOS effectively complexes with PV via non-covalent interactions, thereby enhancing structural stability and functionality. Full article

Probiotics can promote gut health, but their efficacy is often limited by low viability and metabolic activity in the gastrointestinal (GI) tract. This study aimed to develop protective hydrogels for encapsulating Lactiplantibacillus plantarum CJLP 133 using a composite matrix of sodium alginate (SA) and cellulose nanofibers (CNFs). L. plantarum CJLP 133-loaded hydrogel beads were fabricated via the ionic gelation technique using an optimized formulation of SA and CNF. Scanning electron microscopy revealed that CNF integration improved spherical morphology with reduced surface cracking. Fourier transform infrared spectroscopy confirmed the formation of intermolecular hydrogen bonds between SA and CNF. CNF integration also reduced gumminess and chewiness, resulting in a softer texture. The survival rate of L. plantarum CJLP 133 remained high following thermal exposure and freeze-drying. The in vitro GI delivery system demonstrated a protective swelling profile in stimulated gastric fluid and a targeted, highly efficient release profile in stimulated intestinal fluid. Finally, the 3% SA + 0.5% CNF hydrogel with L. plantarum CJLP 133 exhibited significant synbiotic effects, enhancing probiotic growth, intestinal adhesion, and butyrate and succinate production. These results suggest that the SA/CNF-based hydrogel is an effective delivery system that ensures the targeted release of probiotics within the GI tract. Full article

The long-term application of immobilized quorum quenching (QQ) bacteria requires carrier materials with sufficient mechanical stability and durability across various operating conditions. This study aims to enhance the durability and stability of polyvinyl alcohol (PVA) beads and to evaluate their performance for long-term operation. The beads were synthesized using two PVA brands with different molecular weights (MWs), and the effect of cross-linking conditions and reagent purity on bead stability was also investigated. Primarily, their physical strength was evaluated under centrifugal forces. Additionally, polyvinyl alcohol and sodium alginate (PVA-SA) beads were incorporated with cellulose to enhance their strength. The structural and chemical characteristics of the beads were examined using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The results showed that PVA 100 kDa beads withstood centrifugal forces up to 11,000 rpm without breakage, whereas lower MW (PVA 85 kDa) beads failed at 5000 rpm. Bead quality was critically sensitive to calcium chloride purity, as impurities and reduced Ca²⁺ availability caused poor crosslinking and structural collapse. The results revealed that PVA 100 kDa increases the number of polymer chain entanglements and intermolecular interactions, which enhance the structural integrity. Bead quality is strongly influenced by the purity of calcium chloride in the crosslinking solution, as well as by the solution pH. SEM analysis showed that cellulose-incorporating beads exhibited a denser and more uniform pore structure, with median equivalent pore diameters reduced from 50 µm (PVA-SA) to 22.4 µm upon cellulose incorporation, while maintaining sufficient porosity for nutrient diffusion. Similarly, FTIR analysis confirmed that cellulose was successfully integrated, with increased hydroxyl interactions and modified C–O vibrational characteristics, indicating strong hydrogen bonding within the composite matrix. Principal component analysis (PCA) confirmed that hydroxyl interactions and C–O vibrational modes are the main contributors to spectral variation, indicating that cellulose acts as a structural modifier in the PVA-SA network. These results demonstrate the effectiveness of this strategy in designing durable PVA-SA-cellulose based composite beads for long-term QQ applications. Full article

Hydrogen energy systems rely extensively on polymeric materials for storage, sealing, transport, and tribological applications; however, their long-term reliability is strongly influenced by hydrogen–polymer interactions. This review presents a comparative analysis of polymers with and without hydrogen bonding, focusing on how molecular architecture governs hydrogen compatibility, transport behavior, and degradation mechanisms under high-pressure environments. Hydrogen-bonded polymers, such as polyamides, polyurethanes (PU), and polyimides, exhibit high mechanical strength and thermal stability due to strong intermolecular interactions but are susceptible to hydrogen-assisted chemical degradation and embrittlement. In contrast, non-hydrogen-bonded polymers, including polyethylene, polypropylene (PP), polytetrafluoroethylene (PTFE), and Polyether ether ketone (PEEK), demonstrate excellent chemical inertness and low hydrogen reactivity, yet experience diffusion-driven damage such as blistering and fatigue softening. This study establishes a unified framework linking molecular structure, hydrogen transport, and failure mechanisms, revealing a fundamental trade-off between mechanical integrity and chemical stability. Advanced strategies, including polymer blending, nanofiller reinforcement, and multilayer composites, are proposed to optimize durability, permeability, and overall hydrogen compatibility. Full article

The high pressure response and structural stability of crystalline racemic (RS) ibuprofen up to 7 GPa are explored by Raman spectroscopy, employing diamond anvil cells for the pressure application and glycerol as the pressure transmitting medium. Two independent high pressure experiments were performed with practically identical results. Both intermolecular vibrations (associated with weak van der Waals interactions and hydrogen bonding between ibuprofen molecules) and intramolecular vibrations (associated with strong covalent bonding within the ibuprofen molecule) are monitored as a function of pressure, with the former being far more susceptible to volume contraction. The pressure dependence of the Raman peak frequencies undergoes two distinct changes at ~2 and ~6 GPa, indicating the occurrence of pressure-induced structural modifications of ibuprofen. Based on the high pressure Raman data for the intermolecular vibrations of the RS ibuprofen below 2 GPa, a zero pressure value for the bulk modulus of ~7.5 GPa is also extracted. Full article

In this work, three 3-carboxamidecoumarin derivatives (3b, 3c, and 4) were synthesized and characterized by NMR, IR, and single-crystal X-ray. All compounds maintain an essentially planar coumarin scaffold stabilized by an intramolecular N–H⋯O hydrogen bond (S(6) motif), though compound 4 exhibits a more complex bifurcated S₃²(11)[S(6)S(6)S(5)] network that enhances its conformational rigidity. The crystal packing analysis reveals that while all derivatives form one-dimensional (1D) supramolecular tapes through C–H⋯O interactions, their 3D architectures differ significantly: 3b and 3c rely on a diverse combination of π⋯π stacking and lone pair⋯π contacts, whereas 4 is governed by highly directional stacking between the pyran and pyridine rings. Hirshfeld surface analysis and CE-B3LYP energy framework calculations quantified the balance between intermolecular forces, showing that 3b is dispersion-dominated (H⋯H, 43.5%), while 3c achieves a balanced electrostatic–dispersion regime due to the nitro group, which increases O⋯H/H⋯O contacts to 37.1% and yields the highest stabilization energy (−69.1 kJ/mol). These results demonstrate that the electronic nature of the substituents at the 3- and 6-positions drastically modulates the hierarchy of non-covalent interactions, providing key insights for the crystal engineering of coumarin-based supramolecular systems. Full article

A comprehensive thermodynamic and molecular-level investigation of adsorption on MgY and NH₄Y zeolites is presented using inverse gas chromatography at infinite dilution (IGC-ID), combined with a Hamaker-based formalism and an extended five-parameter Lewis acid–base model. The study introduces a unified framework that integrates dispersive, polar, and donor–acceptor interactions while explicitly accounting for temperature-dependent intermolecular geometry. The results demonstrate that the London dispersive free energy exhibits a highly linear temperature dependence (R² > 0.999), while the corresponding surface energy decreases linearly with temperature (e.g., ${\gamma }_s^d\left(T\right)=-0.297T+189.48$ mJ·m⁻² for MgY), reflecting the progressive weakening of dispersion forces. Simultaneously, the intermolecular separation distance follows a linear relation $r\left(T\right)=r_0+{\alpha }_{\mathrm{eff}}T$, with ${\alpha }_{\mathrm{eff}}$ values on the order of (2–3) × 10⁻³ Å·K⁻¹ for MgY, enabling the determination of intrinsic contact distances $r_0$ at 0 K, varying between 4.00 Å and 6.60 Å. A major finding is that the molecular surface area of adsorbed probes is not constant but follows a quadratic temperature dependence with excellent accuracy (R² > 0.999), establishing adsorption cross-section as a thermodynamic variable. The comparison between MgY and NH₄Y reveals two distinct adsorption regimes: MgY exhibits a structured and strongly dispersive interaction field associated with Mg²⁺ cations, whereas NH₄Y displays enhanced polarity, stronger specific interactions, and greater molecular flexibility driven by hydrogen bonding and protonic effects. Thermodynamic analysis of Lewis acid–base interactions shows that classical linear models are insufficient. Statistical evaluation (R² ≈ 0.986, minimum AIC/BIC, lowest RMSE) demonstrates that the five-parameter Hamieh model provides the most accurate and physically meaningful description, capturing nonlinear donor–acceptor interactions and amphoteric coupling effects. Overall, this work establishes a novel thermodynamic methodology that quantitatively links macroscopic surface energetics to microscopic interaction parameters, providing new insight into adsorption mechanisms and a robust framework for the rational design of porous materials in catalysis, separation, and energy applications. Full article

In this study, we systematically investigated the concentration-dependent effects of peptides derived from sour jujube kernel peptide (SJKP) on the multiscale structure, physicochemical properties, in vitro digestibility, and antioxidant activity of a complex formed between pea starch (PS) and SJKP. At an optimal SJKP content of 7.5% (w/w, based on starch dry basis), the slowly digestible starch (SDS) and resistant starch (RS) increased by 23.00% and 49.80%, respectively. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT–IR) verified the formation of complexes and enhanced the short-range structural order of starch. Thermal analysis showed that the gelatinization enthalpy increased to 11.73 J/g, accompanied by an elevated gelatinization temperature and improved thermal stability. Conversely, at 15% SJKP content, RDS rebounded to 58.3% due to phase separation and structural collapse of the starch matrix. Intermolecular force analysis revealed that hydrogen bonding dominated at SJKP concentrations ≤ 7.5%, while hydrophobic interactions prevailed at concentrations ≥ 10%. SJKP incorporation also endowed the complexes with antioxidant capacity. These findings illustrate that SJKP interacts with pea starch via non-covalent bonds, forming a mixed gel network. Moderate SJKP levels can effectively modulate starch digestibility and functionality via regulating intermolecular interactions and multi-scale structure, offering promising potential for developing low-glycemic index (LGI) functional foods, including baked snacks, nutritional beverages, and diabetic-specific staple foods. Full article

Intermolecular interactions play an important role in the formation and stability of co-crystals. In this study, the interaction behaviour of theophylline in co-crystal structures was systematically analysed using data from the Cambridge Structural Database. A total of fifty-three theophylline co-crystal structures were investigated and classified according to their intermolecular interaction motifs. A structured interaction scheme was developed to describe the accessible interaction sites of theophylline, including classical and non-classical hydrogen bonds, as well as halogen bonds and π∙∙∙π interactions. The study revealed theophylline’s high versatility in forming intermolecular interactions, resulting in twenty interaction patterns. Three dominant motifs were identified as occurring most frequently. The results indicate that steric effects influence the accessibility of specific interaction sites, particularly limiting interactions at the carbonyl group located between the two methyl groups. Hirshfeld surface analysis revealed that O∙∙∙H and H∙∙∙H interactions contribute most significantly to the intermolecular interactions in the analysed structures. Full article