Search Results (1,098)

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

Zeolites, both natural (e.g., clinoptilolite) and synthetic (e.g., FAU, ZSM-5), provide robust, tunable platforms for the removal of air pollutants and process-stream contaminants via adsorption and catalysis. This author-led article integrates experimental and theoretical insights on the adsorption of odorous compounds and ammonia (NH₃) and the catalytic abatement of nitrogen oxides (NOx) and nitrous oxide (N₂O), highlighting how topology, acidity, and metal speciation jointly control performance. Representative theoretical results show that adsorption on Brønsted acid sites is significantly more favorable (≈−1.1 eV for NH₃ and −0.37 eV for acetaldehyde) than on Na⁺ sites (≈0.02 eV and 1.22 eV, respectively), demonstrating the critical role of acid site distribution in adsorption selectivity. We dissect structure–function relationships encompassing pore size and connectivity, Si/Al ratio, Brønsted/Lewis site distribution, hydrophilicity/hydrophobicity, and the role of water, with emphasis on hierarchical porosity to alleviate transport limitations. Metal exchange and surface functionalization are discussed as levers to tailor adsorption strength and redox activity, supported by density functional theory (DFT) analyses and reaction pathways. We propose practical design descriptors (acid strength metrics, metal nuclearity, and confinement factors) that enable faster iteration of zeolite architecture for targeted separations and reactions. Sustainability considerations include the use of abundant natural zeolites, low-energy regeneration, stability under humid, mixed-stream conditions that minimize pressure drop and waste. The article closes with a forward look at data-guided optimization to accelerate “engineering zeolites” for durable, selective, and energy-efficient clean-air and process-intensification applications. Full article

Ferroptosis, an iron-dependent and lipid peroxidation-driven form of regulated cell death, has emerged as a “versatile player” in oncology. It exerts a dual, context-dependent role in cancer, acting as both a potent tumor suppressor and a facilitator of tumor progression and therapeutic resistance. This review systematically delineates the core molecular regulatory networks of ferroptosis, highlighting the intricate balance between its execution mechanisms—driven by polyunsaturated fatty acid (PUFA) oxidation, iron catalysis, and mitochondrial dysfunction—and the robust endogenous defense systems, including the GSH-GPX4, FSP1/DHODH-CoQ10, and GCH1-BH4 axes. We deeply explore the dichotomous nature of ferroptosis in tumorigenesis: while classical tumor suppressors like p53 and CDKN2A harness ferroptosis to halt tumor growth, cancer cells can hijack lipid metabolic reprogramming and specific enzymes (e.g., iPLA2β) to evade cell death and promote distant metastasis. Furthermore, we dissect the multidimensional crosstalk between ferroptosis and the tumor microenvironment (TME), emphasizing its bidirectional immunoregulatory effects. Although CD8+ T cell-derived IFN-γ can sensitize tumor cells to ferroptosis and amplify anti-tumor immunity, aberrant ferroptotic activation can paradoxically foster an immunosuppressive niche. Finally, we summarize the latest translational strategies using small-molecule inducers and synergistic combination therapies, emphasizing that biomarker-guided patient stratification remains the ultimate paradigm for overcoming resistance and realizing precision ferroptosis-targeted cancer therapy. Full article

Magnesium oxide (MgO) nanoparticles, recognized for their versatile applications from catalysis to biomedicine, require synthesis methods that offer precise control over their properties while ensuring safety and scalability. This study explores a safer, industrially viable adaptation of the polyacrylamide gel synthesis route by utilizing magnesium sulfate (MgSO₄) instead of conventional nitrates to mitigate explosion risks during calcination. A systematic study was conducted to evaluate the influence of key synthesis parameters, such as crosslinker ratio, initiator concentration, precursor loading, calcination conditions (including temperature, time, and heating rate), pH, and the use of chelating agents (EDTA and citric acid), on the purity, morphology, size distribution, and colloidal stability of the synthesized MgO nanoparticles. Characterization via X-ray spectroscopy XRF and XRD, acoustic spectroscopy, nitrogen physisorption (BET), electronic microscopy SEM and TEM and dispersion stability analysis revealed that polymeric cell volume (controlled by crosslinker and initiator) significantly influences size distribution, while chelating agents in alkaline environments drastically reduce particle size to ~20 nm and alter morphology to platelets (EDTA) or polygonal shapes (citric acid). Crucially, a low heating rate (2.5 °C/min) was found to yield smaller particles (~30 nm) and higher purity. This work provides a comprehensive blueprint for the tailored, safe, and scalable synthesis of MgO nanoparticles with targeted properties for specific technological applications. Full article

Poly(trimethylene ether) glycol (PO3G), a bio-based polyether polyol with excellent flexibility and superior hydrolytic stability, has emerged as a critical raw material for the preparation of high-performance polymer materials. This work optimized the sulfuric acid-catalyzed polymerization process and assessed the feasibility of using p-toluenesulfonic acid (PTSA) as an alternative catalyst. A parametric study was conducted to establish a reliable operating window for the sulfuric acid system. DFT calculations demonstrated that the driving force for chain growth decreases with increasing chain length, that recombination between chains of significantly different lengths is more favorable than between chains of equal length, and that the formation of disulfate esters is thermodynamically more favorable. Although PTSA required a higher catalyst loading, the resulting polymer had a markedly lower yellowness index. Prolonged reaction times lead to a molecular weight plateau, especially at high PTSA concentrations, while the yellowness index continues to increase after reaching the plateau. ¹H NMR analysis indicated the formation of benzenesulfonate monoester intermediates during PTSA catalysis, suggesting a potentially milder pathway and possibly fewer side reactions compared to the sulfuric acid system. This paper provides theoretical and experimental foundations for the green, efficient synthesis of PO3G and the catalyst optimization for analogous bio-based polyether polyols. Full article

Hydrothermal carbonization (HTC) of wet biomass faces a fundamental tradeoff between higher heating value (HHV) and energy recovery (ER), where conditions that enhance carbon densification often reduce solid-phase energy retention. This study investigates whether co-biomass selection combined with citric acid (CA) catalysis can overcome this tradeoff in HTC of water hyacinth (WH), an invasive aquatic feedstock. WH was co-processed with wheat straw (WS), rice husk (RH), and chicken manure (CM) at 240–270 °C, with CA-assisted experiments performed at 240 °C. Individual feedstock HTC confirmed the HHV–ER tradeoff, and co-HTC without catalysis failed to resolve it. CA addition improved carbon densification but reduced ER when applied to WH alone. The WH–CM–CA system uniquely achieved a concurrent HHV of 21.3 MJ kg⁻¹ and ER of 95.8%, with synergistic effects of 50.0% and 29.7%, respectively. FTIR and elemental analysis indicated that Maillard-type condensation between WH-derived sugars and CM-derived amino acids drove preferential solid-phase carbon retention. These findings demonstrate that resolving the HHV–ER tradeoff requires coupling CA catalysis with biochemical complementarity between carbohydrate-rich and protein-rich feedstocks. This approach provides a practical route for hydrochar production with high energy density and recovery for waste-to-energy applications, supporting circular and low-carbon valorization of invasive aquatic biomass and livestock waste streams. Full article

In this work, two-dimensional copper-based metal–organic frameworks (Cu-MOFs) nanozymes, including cuprous oxide-tetrakis (4-carboxyphenyl) porphyrin (Cu₂O-TCPP) and copper-cuprous oxide-tetrakis (4-carboxyphenyl) porphyrin (Cu-Cu₂O-TCPP), were synthesized, which exhibit dual ascorbate oxidase (AO) and peroxidase (POD)-like activities. The reductants, such as ascorbic acid (AA), can be oxidized by the cascade AO and POD catalysis on Cu-MOFs to oxidize p-phthalic acid (PTA) and generate fluorescence. Consequently, a fluorescence sensing platform for AA and other reducing substances was established. This platform offers potential for efficient and selective monitoring of reductive species and related antioxidant levels in food systems. The results showed that the two Cu-MOFs displayed favorable linear relationships (R² ≥ 0.99) for the detection of AA, glutathione (GSH) and L-cysteine (L-Cys). Their limits of detection (LOD) were 5.3 μM for Cu₂O-TCPP and 92.5 μM for Cu-Cu₂O-TCPP. Finally, by detecting real samples of vitamin C tablets and fruits, the accuracy of the two Cu-MOFs nanos enzymes was validated, with Cu₂O-TCPP showing higher accuracy. 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

The synthesis of n-bromobutane from n-butanol is a classic undergraduate organic chemistry experiment, primarily intended to illustrate the bimolecular nucleophilic substitution (S_N2) mechanism. However, this experiment is commonly plagued by low yields and the formation of byproducts (e.g., n-butene and di-n-butyl ether), which confuse students. To reveal the molecular origin of these competitive pathways, this study employs density functional theory (DFT) calculations to systematically investigate the reaction mechanism under acid catalysis. Four potential reaction pathways were explored: S_N2 substitution, E2 elimination, intermolecular etherification, and a high-energy E2 pathway. The computational results indicate that the S_N2 pathway to n-bromobutane is kinetically and thermodynamically favorable due to its low energy barrier. In contrast, the E2 elimination pathway possesses a higher energy barrier (18.8 kcal/mol vs. 13.5 kcal/mol for S_N2), explaining why elevated temperatures favor the formation of n-butene. Moreover, the etherification pathway was found to be the most energetically demanding, consistent with the trace amounts of di-n-butyl ether observed experimentally. These findings provide a quantitative molecular-level rationale for the strict temperature control and standardized reagent addition sequences in the laboratory protocol. By visualizing the potential energy surfaces, this computational approach bridges the gap between theoretical mechanism and practical operation, offering a valuable pedagogical tool for enhancing student understanding. Full article

Diphenylamine is an important organic chemical intermediate, and its industrial synthesis is mainly achieved through the continuous condensation of aniline. In this study, Hβ zeolite was modified with citric acid, and its catalytic performance in the aniline condensation reaction for diphenylamine synthesis was systematically investigated. The crystal structure, acidic characteristics, pore properties, and Si/Al composition of the catalysts were comprehensively characterized by means of XRD, SEM, BET, Py-IR, ICP, and ²⁷Al MAS NMR. The catalytic activities of Hβ zeolites modified with different concentrations of citric acid were evaluated in a micro fixed-bed reactor, and the structure–activity relationship was systematically discussed in combination with the characterization results. The results demonstrate that the Hβ zeolite modified with 1.5 mol/L citric acid achieves precise matching with the aniline condensation reaction in terms of crystal structure integrity, pore channel parameters, acid property distribution, and Si/Al ratio regulation. Compared with the unmodified catalyst, its catalytic activity is improved by approximately 28%, with a diphenylamine selectivity of 100%. This study proposes a modification mechanism of Hβ zeolite by citric acid. Full article

Making 1 $\mathrm{k}$$\mathrm{t}$ of cheese produces 9 $\mathrm{k}$$\mathrm{t}$ of cheese whey permeate, a waste with 5% lactose, which is either discarded or dried for animal feed. One pathway to add value to this waste is to convert it to lactic acid (LA), a monomer for polylactic acid, the largest bioplastic produced in the world. Lactose hydrolyses to glucose and galactose. While Brønsted acidity enhances lactose hydrolysis, Lewis acidity favours the formation of lactic acid. For the first time, we tested both industrial whey permeate and purified lactose as feedstocks for LA over a heterogeneous catalyst–Er₂O₃/Al₂O₃. LA Yield from whey permeate reached 14%, while the maximum yield with purified lactose was 22%. LA yield was invariant with respect to mixing speed while increasing temperature accelerates the time it takes to reach quasi-equilibrium. Yield was also independent of pressure with either air, He, N₂, or H₂ in the vapour space above the liquid phase in the autoclave. LA yield over spent catalyst with fresh lactose was only 11%, which indicates that the catalyst deactivates. Based on XRF analyses, the Er₂O₃ mass fraction dropped from 15% to 5%, with 6.4% leaching into the aqueous phase after the first step but only 0.8% after the second test. Full article

Considering the expanded interest in reducing organic solvents in synthesis, surfactants and surfactant-based catalysis have been used to carry out various organic transformations in water. In recent years, the integration of Lewis and Brønsted acid catalysis with micellar systems has gained considerable attention as a powerful approach to enhance reaction efficiency while minimizing the environmental impact of synthetic processes. In this article, we depict the most recent advances in the water-interceded synthesis of different organic systems by utilizing different surfactant-type catalysts, which are important structural motifs in pharmaceuticals, agrochemicals and functional materials. Further, these methods incorporate green reaction media, mild reaction conditions, and a great yield of product with high purity in a shorter interval of time. Understanding the scope and impact of this area, authors have made efforts to collect and compile the data that indicates many named reactions, such as Friedlander annulation, aldol condensation, the Biginelli reaction, the Mannich reaction, Suzuki–Miyaura cross-coupling, etc., now take place using surfactant-based catalysts. Full article

The combination of photochemistry with stereoselective catalysis has emerged as an effective strategy to achieve stereocontrol in light-driven transformations. Chiral phosphoric acids (CPAs) have recently attracted attention in this context due to their ability to activate substrates while providing a defined chiral environment. This minireview highlights recent developments in CPA-enabled asymmetric photochemical transformations, focusing on systems in which CPAs incorporate a chromophore on the chiral backbone or form light-absorbing CPA-substrate complexes that enable photoactivation without the presence of an external photocatalyst. The main catalytic strategies, mechanistic features, and current limitations are discussed. Full article

The transition to renewable carbon resources has positioned lignocellulosic biomass as a key feedstock for sustainable fuel and chemical production; however, its intrinsic recalcitrance limits efficient conversion. Dilute acid pretreatment functions as a homogeneous Brønsted acid catalytic system that selectively depolymerizes hemicellulose and disrupts lignin–carbohydrate complexes, while competing with consecutive sugar dehydration reactions, thereby enhancing downstream processing. This review presents a feedstock-specific analysis of acid catalyzed biomass deconstruction across agricultural residues, woody biomass, and energy crops, with xylose yield employed as a kinetically and mechanistically relevant descriptor of catalytic performance. By correlating proton activity, reaction severity, diffusion constraints, lignin chemistry, and mineral interference with observed conversion behavior, the work establishes a structure–reactivity–performance framework for biomass dependent hydrolysis. Particular attention is given to competing dehydration and condensation pathways that reduce pentose selectivity and generate fermentation inhibitors. The analysis identifies optimal severity windows for maximizing catalytic efficiency while suppressing degradation reactions and provides guidance for feedstock-tailored pretreatment and next-generation acid catalytic systems and reactor configurations in integrated biorefineries. Full article

Formic acid (FA) has emerged as a promising liquid hydrogen storage material, yet efficient photothermal dehydrogenation catalysts with high activity and H₂ selectivity remain challenging. Herein, a polymetallic synergistic PdCu/M-ZNC (where M represents the co-doped In, Sn and Mo species) is fabricated by molten-salt-assisted pyrolysis of ZIF-8 precursors followed by metal incorporation. The unique molten salt environment effectively preserves the porous architecture of ZIF-8, enabling the secure anchoring of PdCu alloy nanoparticles onto the carbonaceous matrix enriched with M-N_x coordination sites. Under light irradiation, the PdCu alloy sites kinetically accelerated the overall adsorption and activation of FA molecules. Based on empirical observations and corroborated by the established literature, this alloying effect was inferred to facilitate the C-H bond cleavage and HCOO* desorption processes. Concurrently, the M-N_x sites act as efficient electron transfer channels, facilitating the rapid coupling of photogenerated electrons with protons (H⁺) to evolve H₂. Consequently, the optimal catalyst exhibits an enhancement in gaseous product yield (404.46 mmol/g/h) and H₂ selectivity (67.49%) at 75 °C. This work offers a catalyst design that aligns with several principles of green chemistry: it maximizes the atom utilization of precious Pd, incorporates synergistic non-precious metals within MOF-derived frameworks to enhance stability, and leverages solar energy to drive hydrogen production under mild conditions, presenting a more sustainable pathway for hydrogen release from liquid carriers. Full article