Frontiers in Chemistry最新文献

The ability to achieve a series of solid-state [2 + 2] cycloaddition reactions within related hydrogen-bonded co-crystals is reported. These multicomponent molecular solids contain either trans-1,2-bis(3-pyridyl)ethylene (3,3-BPE) or trans-1,2-bis(2-pyridyl)ethylene (2,2-BPE) as the reactant, along with one of two chlorinated anilines that behave as a template, namely 2,3,5,6-tetrachloroaniline (C ₆ H ₃ Cl ₄ N) or 2,4,6-trichloroaniline (C ₆ H ₄ Cl ₃ N). For each of the four unique organic solids, the co-crystallization process yields a three-component hydrogen-bonded assembly with a formula of either 2(C ₆ H ₃ Cl ₄ N)·(3,3-BPE), 2(C ₆ H ₄ Cl ₃ N)·(3,3-BPE), 2(C ₆ H ₃ Cl ₄ N)·(2,2-BPE), or 2(C ₆ H ₄ Cl ₃ N)·(2,2-BPE). In all co-crystals, these anilines template up to a quantitative yield for the photoreaction since they are able to engage in both N-H···N hydrogen bonds and homogeneous face-to-face π-π stacking interactions, which position the ethylene groups within the different reactant molecules in a suitable location to photoreact. These results complete the series for the remaining symmetric bipyridine-based reactants to undergo a solid-state [2 + 2] cycloaddition reaction utilizing these chlorinated anilines. This work expands and illustrates the potential for these chlorinated anilines to serve as reliable molecular templates that crystal engineers can utilize to control the organic solid state and achieve photoreactions.

A sustainable production of ammonia using waste biomass is a new milestone to a low-carbon bioeconomy that is circular. This paper defines an integrated Aspen Plus model which integrates the steam gasification of paper mill sludge and municipal solid waste and the Haber-Bosch process to generate carbon-neutral green ammonia. The synthesis of thermochemical conversion and catalytic synthesis was optimized systematically by altering paper mill sludge feed ratio (20:80, 60:40, and 40:60 wt%), steam toward municipal solid waste ratio and pressures in the synthesis. The highest hydrogen yield (H₂ = 0.4572) and heating value (7.82 MJ/Nm³) was obtained in the 60:40 blend at 800 °C and S/B = 0.025, whereas the highest NH₃ mole fraction in the solution (0.9493) was obtained under 40:60 blend at 500 °C and 250 bar. The addition of cryogenic CO₂ removal and water gas shift optimization greatly improved the purification of hydrogen and total carbon capture. The innovation of the work consists in the combined modelling structure that converts heterogeneous waste flows into a closed-loop, low-emission system of ammonia production, which has two advantages in the value of waste and the synthesis of renewable fertilizers. The results present an upscale able and ecologically friendly pathway to next-generation production of ammonia, between circular waste management and green chemical production.

Sulfur-bearing molecules are central to interstellar chemistry, yet their observed abundances in the gas phase remain far below cosmic expectations in dense interstellar regions. Mixed N-S-O species such as thionylimide (HNSO) are particularly relevant, as they incorporate three key biogenic elements. The cis conformer of HNSO has recently been detected in the Galactic Center cloud G+0.693-0.027, but no high-resolution data for the higher energy conformer (trans-HNSO) had been available until now. We report the first laboratory detection and rotational spectroscopic characterization of trans-HNSO. Spectra were recorded with the Center for Astrochemical Studies Absorption Cell (CASAC) free-space spectrometer employing a hollow-cathode discharge source, yielding 104 assigned transitions between 200 and 530 GHz. A Watson S-reduced Hamiltonian fit reproduced the data with an rms of 40 kHz, providing accurate rotational and centrifugal distortion constants in excellent agreement with CCSD(T) predictions. Although trans-HNSO lies only a few kcal/mol above the cis form, it has larger dipole components, making its lines particularly intense (more than 5 times brighter, assuming equal abundances) and a very promising candidate for future astronomical detection. The new measurements enable reliable frequency predictions for astronomical searches and will be added to public databases. Combined with recent evidence for tunneling-driven trans-to-cis isomerization at cryogenic temperatures, these results open the way to test directly whether quantum tunneling governs the interstellar distribution of HNSO isomers.

Analysis and identification of gunshot residue (GSR) are considered critical forensic evidence in shooting incident investigations. This study comparatively analyzed gunshot residue from Fiocchi non-toxic ammunition (NTA), ADCOM, and NATO ammunitions, all commonly utilized by Dubai Police, using Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM/EDS) following the American Society for Testing and Materials (ASTM) E1588-20 standards. The elemental compositions of ammunition components, including cartridge cases, bullets, gunpowder, and primers, were thoroughly characterized. Primer residue revealed significant elemental differences, with Fiocchi NTA ammunition unexpectedly containing detectable lead particles, although at lower levels compared to ADCOM and NATO ammunition. Across all ammunition types, GSR particles predominantly measured below 3 μm, effectively differentiating them from common environmental contaminants. GSR particle deposition was consistently higher on shooters' dominant right hands due to firearm mechanics and hand dominance. Particle counts generally decreased over time post-discharge but were influenced significantly by shooter activities rather than elapsed time alone. Notably, limitations within the ASTM E1588-20 classification scheme resulted in no identifiable Heavy-Metal-Free (HMF) GSR particles for Fiocchi NTA, emphasizing the need for updated and expanded classification criteria. Future research is recommended to enhance forensic methods and classification frameworks to accommodate evolving ammunition formulations.

The transition toward a circular bioeconomy demands innovative, sustainable, and efficient technologies for biomass valorization and pulping. Green chemistry strategies, particularly organosolvent pulping pretreatment, are emerging as pivotal solutions to unlock the full potential of lignocellulosic feedstocks. Organosolvent processes employ environmentally benign solvents to selectively fractionate biomass components, enabling the recovery of high-purity cellulose, hemicelluloses, and lignin with minimal environmental footprint. These technologies advance the principles of green chemistry by minimizing hazardous reagents, reducing energy consumption, and promoting waste valorization. Recent developments demonstrate their capacity not only to improve pulping efficiency but also to produce value-added chemicals, biomaterials, and biofuels, thereby closing resource loops and reducing reliance on fossil-based systems. This review uniquely integrates advances in organosolvent pulping pretreatment within the framework of green chemistry and circular bioeconomy. This work systematically compares multiple green solvent systems including ionic liquids, deep eutectic solvents, and bio-derived organosolvent methods alongside catalytic, biocatalytic, and process intensification techniques. It also synthesizes recent industrial case studies, bridging the gap between laboratory research and pilot-to-commercial scale deployment. By highlighting the synergistic role of these technologies in achieving high-purity biomass fractionation with minimal environmental footprint, the review provides actionable insights for researchers, policymakers, and industry stakeholders aiming to accelerate the transition to a regenerative, circular bioeconomy.

Perovskite solar cells (PSCs) are regarded as a promising candidate for next-generation photovoltaics. Facet engineering for the controlled growth of perovskite crystals has emerged as a breakthrough strategy to address the efficiency-stability trade-off in PSC devices. Among various crystallographic orientations, (111)-oriented perovskite films have garnered significant attention due to their unique advantages in defect tolerance, ion migration suppression, and environmental adaptability. This review systematically summarizes the structural, electronic, and stability characteristics of the (111) facet. By analyzing key engineering strategies such as additive-regulated growth, ligand-assisted crystallization, and substrate-template induction, the roles of these methods in suppressing competitive facet orientations and promoting preferential (111) alignment are revealed. Experimental evidence demonstrates that (111)-dominated orientations exhibit superior stability in perovskite films across different bandgaps, making them ideal for both single-junction perovskites and tandem devices. Despite notable progress, challenges remain in scaling up (111)-predominant films with homogeneous morphology and reconciling growth kinetics with thermodynamic stability. Emerging solutions, such as machine learning-guided additive design and in situ characterization of facet-dependent degradation, are highlighted as critical pathways to unlock commercial viability. By bridging fundamental crystallography and device performance, this review provides a roadmap for leveraging (111) facet engineering to unleash the full potential of PSCs.

β-Cyclodextrin (β-CD) is a cyclic heptasaccharide, part of the family of molecules which are widely used in several biological applications. The unique cone-shape of cyclodextrins with multiple binding sites make them a well-suited building block for constructing porous crystalline solids, such as metal-organic frameworks (MOFs). However, owing to the symmetry constraints, progress in the coordination chemistry of β-CD with alkali and alkaline earth metal cations has been limited and there is less understanding of this chemistry compared to its analogues of α-CD and γ-CD. In this work, synthetic conditions were optimised to obtain two MOF structures with β-CD as the organic linker, one each with Na⁺ and K⁺ cations. As well as structural determination, detailed solid-state characterization is reported for both the MOFs. The structure analysis helps shed light on the binding tendencies of β-CD and these structures will further facilitate the deployment of biocompatible building blocks for the development of reticular solid materials.

The JAK2 pseudokinase domain (JH2) is an important therapeutic target in hematologic and oncologic diseases, motivating the search for selective allosteric inhibitors. In this study, a multilayer perceptron (MLP) deep learning model was trained on 1,200 JAK2-targeting compounds and validated internally and externally, while a BREED-based fragment hybridization strategy generated 6,210 new molecules that were screened using MLP scoring, pharmacokinetic filters, and molecular docking. Three compounds-BRD1, BRD2, and BRD3-emerged as promising inhibitors, with BRD1 showing the strongest binding affinity, highest conformational stability, and best selectivity for key JH2 residues, surpassing the reference ligand 36H; MD and ADMET analyses further supported its stability and favorable safety profile. Overall, BRD1 is identified as a strong computational candidate for selective allosteric inhibition of JAK2-JH2, warranting future experimental validation, and all models and code are openly available.

Introduction: The simultaneous quantification of Brimonidine Tartrate and Timolol Maleate in ophthalmic formulations is essential for ensuring product quality, efficacy, and stability. However, few methods provide adequate selectivity, sensitivity, and environmental sustainability. This study aimed to develop and validate a robust, rapid, and reproducible reversed-phase high-performance liquid chromatography (RP-HPLC) method with stability-indicating and green chemistry attributes.

Methods: Chromatographic separation was performed on a Supelco Discovery C18 column (25 cm × 4.6 mm, 5 μm) using isocratic elution with phase A (30 mM triethylamine buffer, pH 7.0) and phase B (acetonitrile) in a ratio of 80:20. The flow rate was 1.0 mL/min, and analytes were detected at 245 nm and 295 nm using a diode array detector. Method validation followed ICH Q2 (R1), USP, and FDA guidelines, evaluating linearity, accuracy, precision, specificity, robustness, and sensitivity. Forced degradation under acid, base, oxidative, thermal, and photolytic conditions was conducted to assess stability-indicating capability. Green analytical chemistry (GAC) metrics were calculated using Eco-Scale, GAPI, and AGREE tools.

Results: The method exhibited excellent linearity over 100-500 ppm for Brimonidine Tartrate and 250-1,250 ppm for Timolol Maleate. Accuracy ranged from 99.42% to 99.82% for Brimonidine Tartrate and 98.71% to 101.10% for Timolol Maleate. Precision, specificity, and robustness results showed relative standard deviations below 2%. The LODs were 0.08 ppm for Brimonidine Tartrate and 0.20 ppm for Timolol Maleate, while LOQs were 0.24 ppm and 0.60 ppm, respectively. Forced degradation confirmed the method's ability to separate both drugs from their degradation products. Brimonidine Tartrate remained stable under all stress conditions, whereas Timolol Maleate was susceptible to hydrolytic and oxidative degradation. The method demonstrated moderate greenness with an Eco-Scale score of _~75, a GAPI pictogram with mixed green/yellow zones, and an AGREE score of 0.57.

Discussion: The validated RP-HPLC method proved accurate, precise, sensitive, and stability-indicating for the simultaneous determination of Brimonidine Tartrate and Timolol Maleate. Its moderate GAC performance supports a balance between analytical rigor and sustainability. These findings establish the method as suitable for routine quality control and stability testing of ophthalmic formulations containing both drugs.

In this study, novel 2D/1D graphene/silver-silver sulfide (Ag-Ag₂S) hybrid nanocomposites were successfully synthesized and characterized using X-ray Diffraction (XRD), Ultraviolet-Visible (UV-Vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). The structural-optical properties and dye-photodegradation performance of Ag nanowires (NWs), Ag-Ag₂S core-shell NWs, and a 2D/1D graphene/Ag-Ag₂S hybrid nanocatalyst were examined. SEM confirms uniform, non-agglomerated Ag NWs and a layered graphene morphology; after sulfidation, Ag₂S (and incidental Ag₂O) forms on Ag NW surfaces, while Ag-Ag₂S NWs are randomly distributed across graphene sheets. XRD results confirm the presence of crystalline phases corresponding to Ag, Ag₂S, and silver oxide (Ag₂O), indicating successful hybridization and partial oxidation during synthesis. UV-Vis spectra show the two Ag localized surface plasmon resonances (LSPR) (∼350/380 nm) collapsing into a broadened band upon Ag₂S shelling, consistent with higher dielectric loss and interfacial damping; graphene/Ag-Ag₂S is dominated by a π-π* transition near 200-250 nm. Tauc analysis yields, E.g., ≈ 2.9 eV (Ag NWs), and after hybridization, approximately 2.5 eV (Ag₂S), 3.8 eV (Ag), and 4.6 eV (Ag₂O); the composite (graphene/Ag-Ag₂S) exhibits two optical gaps (∼3.28 and 4.72 eV), reflecting its multiphase nature and graphene-induced states. Methylene blue (MB) degradation follows pseudo-first-order kinetics with the strongest linearity for graphene/Ag-Ag₂S (R² ≈ 0.89-0.92). At pH 3, the hybrid achieves the highest removal efficiency (89.55% at 5 h) and the largest rate constant (k_obs = 0.5349 h^-1). The synergy arises from assisted carrier generation in Ag, heterojunction-driven separation in Ag-Ag₂S, and rapid electron transport/π-π adsorption on graphene, which together maximize radical formation and suppress recombination under acidic conditions.