Journal of Chemical Sciences最新文献

CeO₂/chitosan/expanded graphite (CeO₂/CS/EG) was prepared by hydrothermal synthesis and used for the heterogeneous catalytic ozonation of 4-chlorophenol (4-CP) in wastewater. The catalysts were characterized by XRD, SEM, EDS, BET, XPS and FT-IR. In order to study the catalytic activity of CeO₂/CS/EG, the catalytic performance of CeO₂/CS/EG/O₃ system was compared with other reaction systems, and the effects of catalyst dosage, pH, initial 4-CP concentration, O₃ concentration and co-existing ions on the degradation of 4-CP in this system were investigated. The results showed that CeO₂/CS/EG/O₃ system showed high catalytic activity for 4-CP degradation. Under the optimal conditions (pH > 6.5, catalyst dosage 1.0 g L^–1, initial concentration of 4-CP 100 mg L^–1, ozone concentration 2.5 mg L^–1, reaction time 30 min), the removal rate and mineralization rate of 4-CP reached 99.4% and 70.2%, respectively. This degradation process conformed to first-order reaction kinetics. After five consecutive catalytic cycles, the removal rate of 4-CP was still above 97%, showing the excellent stability and reusability of CeO₂/CS/EG. The ·OH was identified as the main reactive species causing 4-CP degradation through free radical scavenging experiments. According to the main intermediates measured by the HPLC-MS technique, five possible degradation processes of 4-CP catalytic ozonation were deduced.

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CeO₂/chitosan/expanded graphite (CeO₂/CS/EG) were prepared by hydrothermal synthesis and used for heterogeneous catalytic ozonation of 4-chlorophenol (4-CP) in wastewater. The results showed that the removal efficiency of 4-CP and total organic carbon (TOC, a key parameter representing the total carbon content in organic compounds that indicates mineralization degree) reached 99.4 and 70.2% under optimal conditions. Besides, OH^⋅ was identified as the main substance causing 4-CP degradation.

Developing dual-state emission fluorogens (DSEgens) with highly efficient emission in both solution and solid state is an emerging research topic in the optical field. Especially, DSEgens with deep-red emission are particularly scarce. In this work, two donor–acceptor–donor (D-A-D) type triphenylamine derivatives (TBT-2CN and TBT-4CN) were designed, synthesized and characterized. The compounds possess highly efficient emission in both solution and aggregation states. The fluorescence of TBT-2CN and TBT-4CN solid emit deep-red fluorescence at 620 and 770 nm, respectively. Meanwhile, TBT-2CN and TBT-4CN exhibited reversible mechanochromism properties, in which the fluorescence spectra of the compounds were red-shifted by 9 and 67 nm after grinding. Moreover, the spectra reverted to the initial state after being fumed by dichloromethane for a few minutes. In addition, the compounds were sensitive to H₂S. The solutions and paper-based devices of the molecules could detect the H₂S in both solution and solid states.

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Two novel triphenylamine derivatives with deep-red dual-state emission were designed and synthesized for reversible mechanochromism and H₂S detection.

Enzyme immobilization on a biocompatible, robust, reusable solid support is an effective strategy to augment the catalytic performance of free/native enzyme. Herein, a hybrid polymeric blend made up of biocompatible chitosan (CHI) and polyvinyl alcohol (PVA) carrier was successfully used to immobilize Pseudomonas cepacia lipase (PCL). The biocatalyst (PVA:CHI:PCL) was investigated for the kinetic resolution (KR) of racemic secondary alcohol 1-phenylethanol. Results showed that the developed biocatalyst offered significant biocatalytic activity for the kinetic resolution of 1-phenylethanol with conversion of 49% to the respective acetate of one isomer and excellent enantiomeric excess of substrate (ee_s:96%) as well as enantiomeric excess of product (ee_p:99%) and enantioselectivity (E). Further, synthesized binary blend biocatalyst offered excellent reusability up to six consecutive cycles with 41% conversion, 72% ee_s, and 98% ee_p at sixth recycle. Interestingly, immobilized biocatalyst displayed exceptionally enhanced biocatalytic activity as compared to free lipase PCL. Further study is extended to evaluate the green metrics involving determination of E-factor, atom efficiency, atom utilization and mass intensity. Results showed that use of the immobilized biocatalyst offered two-fold higher conversion than free lipase and better greener metrics as compared to that of free lipase.

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Lipase PCL immobilized on PVA:CHI support was applied as a biocatalyst for kinetic resolution of (±)1-phenylethanol to offer 49% conversion with excellent enantiomeric excess of substrate (ee_s:96%), product (ee_p:99%) and enantioselectivity. The developed biocatalyst offered two-fold higher conversion, recyclability and better greener metrics in terms of E-factor, mass-intensity, and atom-efficiency than free lipase.

In this research, TiO₂ and copper-modified TiO₂ were investigated in the process of isopropanol photocatalytic removal from the air. Modification of TiO₂ with copper was carried out using two methods: impregnation and chemical reduction. XRD, XPS, FESEM, EDAX, PL and UV–Vis DRS were used to study the chemical and physical characteristics of TiO₂ and copper-modified TiO₂. UV–Vis DRS and PL results indicated that copper loading on TiO₂ increases absorption in the visible range and significantly reduces the recombination of photoelectron and hole pairs. XRD and XPS analyses showed that both copper species i.e., Cu₂O and CuO exist in the Cu_xO/TiO₂(RE) photocatalyst. According to photocatalytic tests, copper-modified TiO₂ exhibited enhanced photocatalytic activity compared to pure TiO₂, and the optimal photocatalyst (Cu_xO(1%)/TiO₂(RE)) decomposed 100% isopropanol under visible light radiation.

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Isoproterenol (ISO) is a sympathomimetic amine, an analog of epinephrine (E) and norepinephrine (NE), characterized by the N-alkyl substitution. The crystallographic structure was optimized by several common functionals (B3LYP, CAM-B3LYP, B3PW91, M05-2X, M06-2X) in conjunction with the 6-311++G(d,p) basis set. The appropriate level of theory was determined by comparing the experimental and theoretical bond lengths and angles. Different isomers of ISO were examined, and their stability interactions were quantified by the Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) approaches. The experimental spectra (infrared, Raman, NMR, and UV-Vis) were simulated and assigned after the optimization at the M05-2X/6-311++G(d,p) level of theory. The antiradical activity was determined towards two model (DPPH^• and ABTS^•+) and two biologically relevant (HO^• and Asc^•) radical species and compared to the activity of E and NE. The structural features governing activity and preferred mechanism were elucidated by the quantum chemical methods. The Sequential Proton Loss Electron Transfer (SPLET) mechanism was a dominant one both thermodynamically and kinetically. The protein binding affinity towards Bovine Serum Albumin (BSA) was investigated by spectrofluorimetric titration and molecular docking simulations. The most important interactions were outlined. The importance of N-alkyl substitution proved substantial for the interactions with amino acids, but it did not affect the antiradical activity.

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Structure, spectra, intramolecular interactions, protein binding affinity and antioxidant capacity of isoproterenol, a sympathomimetic amine, were examined by a combination of experimental and theoretical methods and compared to those of epinephrine and norepinephrine. The importance of ending groups attached to amino nitrogen atoms and the radical scavenging mechanism were discussed.

Hydroxyl-terminated polybutadiene (HTPB) resin is the most widely used material for producing polyurethane elastomers due to its ability to maintain elastomeric properties at very low temperatures. Moreover, its high solid-loading capacity makes it an ideal binder for composite manufacturing. Replacing this resin with a self-healing HTPB resin, in addition to the aforementioned properties, can increase the service life of components and reduce potential damage to parts fabricated with this resin. In this study, thermal and mechanical properties of self-healing HTPB resin are compared with those of conventional HTPB resin. Low-temperature differential scanning calorimetry (DSC) analysis indicates that the elastomeric properties of the resin have not changed significantly, and glass transition temperature (T_g) increased only about 5°C. Additionally, both resins exhibit similar and predictable thermal behaviour in thermogravimetric analysis (TGA). Tensile testing reveals a 45% increase in tensile strength and a 75% increase in Young’s modulus, while elongation at break decreases by 64%. Viscosity changes show a three-fold increase compared to the original resin, and finally, the quantitative self-healing efficiency obtained through tapered double cantilever beam (TDCB) testing is ~96% after 24 h.

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Self-healing hydroxyl-terminated polybutadiene (HTPB) resin, in addition to exhibiting excellent elastomeric properties and high solid loading, possesses the ability to repair cracks and scratches that may form within its structure. Intrinsic self-healing process commences immediately upon crack initiation, and over time, the resin gradually reverts to its original state, with up to 96% of the damage being repaired within 24 h.

Atom-precise metal nanoclusters have emerged as a class of materials with unique structural and electronic properties, driven by quantum size effects and precise atomic arrangements. This review delves into recent advancements in the field, focusing on key aspects, such as ligand exchange reactions, structural characterization and catalytic properties of copper nanoclusters (NCs), development of silver cluster-assembled materials with enhanced stability and properties, and stabilization of NCs in metal–organic frameworks (MOFs). Synthesis of specific clusters for desired applications can be attained through ligand exchange transformation reaction. Among the coinage metal ions, the research on copper NCs is less explored due to low redox potential. Still, there are some reports with unique structural architecture that exhibit catalytic properties. Stability and properties of clusters can be enhanced by linking the cluster to higher dimensional or embedded into the porous MOF structures.

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This review discusses some of the recent advancements achieved in the field of nanoclusters and their assemblies, ranging from fundamental studies to structure-property correlation and applications.

Aroylhydrazones are compounds characterized by a double bond between carbon and nitrogen atoms. They are notable in coordination chemistry for their versatile coordination modes and a wide range of applications. These compounds are synthesized by condensing hydrazides with aromatic aldehydes or ketones, forming stable imine linkages. Their coordination diversity comes from their ability to act as multidentate ligands, coordinating through nitrogen, oxygen, and sometimes sulfur atoms, resulting in various metal complexes with different geometries and properties. Factors like pH, solvent, and the nature of the metal ions influence this diversity. Aroylhydrazones are crucial in medicinal chemistry, material science, and catalysis, serving as antimicrobial agents, anti-inflammatory drugs, and sensors, and in developing organic-inorganic hybrid materials. In catalysis, they stabilize transition states and facilitate organic transformations, proving valuable in both industrial and synthetic organic chemistry. Aroylhydrazone-based complexes have shown efficiency in reactions such as oxidation, epoxidation, alkylation, and nitro-aldol condensation. Their structural versatility and catalytic efficiency make them valuable for developing new catalytic systems and materials. This review article provides an overview of the coordination diversity and significant catalytic applications of metal complexes derived from aroylhydrazone compounds.

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Aroylhydrazones exhibit significant importance due to their versatile coordination diversity, enabling the formation of various metal complexes. These complexes demonstrate notable catalytic applications in organic transformations, highlighting their potential in industrial and pharmaceutical process. The multifaceted nature of aroylhydrazones underscores their value in advancing catalysis and coordination chemistry.

In recent years, nanoparticles have found widespread use in several fields ranging from pharmaceuticals, mechanical devices and electronics. Their uses for therapeutic purposes originate from their uniform size that can be fabricated or engineered to be tuned to a specific requirement. Biomaterials like proteins/peptides are an excellent medium to design structural materials to act as carrier systems for small molecules. Nanoparticles possess the ability to encapsulate various types of small molecules, including therapeutic and imaging agents for disease treatment and diagnosis. However, due to the presence of nonspecific intermolecular interactions, the release of the associated small molecules from nanoparticles poses a challenge. In this article, we demonstrate the preparation of protein nanoparticles from an inexpensive source, rich in proteinaceous material. The nanoparticles thus prepared are capable of encapsulation of multifunctional small molecules and regulation of sustained release under specific stimuli is possible.

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Synopsis Our study presents a cost-effective source for preparing protein nanoparticles from discarded cataractous eye lens proteins. These nanoparticles efficiently encapsulate curcumin and enable its sustained release under physiological stimuli. The biocompatible system shows potential as a novel vehicle for delivering hydrophobic drugs, with implications for targeted therapeutic applications.