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This study reports a green and sustainable protocol for synthesizing polyfunctionalized indole derivatives. It involves the use of the gelatinous pulp of Dillenia indica fruit as the catalyst. The gelatinous component from fresh and mature fruit of Dillenia indica is directly used as the catalyst. The mixture of the reactants along with the catalyst is magnetically stirred at 60°C in water. After equilibrium is achieved, the product is extracted with ethyl acetate, followed by recrystallization using an ethanol/diethyl ether mixture. Syntheses of twelve compounds in moderate to high yields have been reported. The catalyst can be reused up to the third cycle without compromising yield. The catalytic activity of Dillenia indica fruit gel has been compared with previously reported bio-based catalysts. The data clearly indicate that the newly discovered catalyst surpasses other catalysts in several aspects, including energy efficiency, shorter reaction time, catalyst complexity, and the use of green solvents. Without the catalyst, the yield is limited to about 30%, but the catalyst helps to afford yields well over 80%. The catalyst does not work in organic solvents. The catalytic activity of the gel from the fruit of Dillenia indica has been established beyond doubt. The catalyst is inexpensive and reusable. By harnessing the unique catalytic activity of this bio-based catalyst, a sustainable protocol for the synthesis of highly functionalized heterocycles has been developed. The substrate scope of the protocol is broad.

Transformations of olefins into valuable feedstocks and their end products are among the most versatile chemical processes in modern science and technology. Among these reactions, olefin oligomerization and polymerization are instrumental in producing a wide range of products, including fuels, plasticizers, lubricants, surfactants, detergents, co-monomers, and plastics. Over the past century, homogeneous late-transition-metal catalysts have successfully facilitated olefin oligomerization reactions, but not without major drawbacks, such as a lack of catalyst recyclability and reusability. On the other hand, while heterogeneous catalysts are recyclable, they suffer from poor selectivity, thus limiting their application in the production of fine and specialty chemicals. This has necessitated the evolution of a third generation of catalysts in the form of supported single-site ("hybrid") catalysts that bridge both the advantages of homogeneous and heterogeneous catalysts of high selectivity and recovery, respectively. Therefore, in this review, we present the use of inorganic, organic, and polymer supports to immobilize molecular catalysts reported to date in the literature. The review covers the immobilization strategies, types of inorganic and polymer supports, and the application of these supported catalysts in ethylene oligomerization and polymerization reactions. It further presents a comparative analysis of the different classes of supports, a critical evaluation of the immobilization strategies, and their influence on the performance of the resultant immobilized catalysts. The major findings and critical analyses of the literature data, together with future perspectives, are also summarized.

Understanding electrochemical hydrogen evolution reaction (HER) mechanisms requires precise identification of key intermediates (H*, OH*, and H2O*). While in situ single-crystal studies have provided foundational mechanistic insights into interfacial dynamics and intermediate behavior during the HER, extending these findings to structurally complex nano-catalysts remains challenging. Recent advances in in situ characterization techniques have enabled real-time observation of reaction intermediates, yet a systematic understanding across diverse catalyst architectures remains incomplete. This review assesses HER intermediate research, bridging the gap from model single-crystals to nano-catalysts by: (i) discussing methods for intermediate identification and their roles in elucidating HER mechanisms, (ii) summarizing single-crystal surface modification strategies bridging single-crystal model and nano-catalyst studies, and (iii) highlighting current challenges and proposing future directions for catalyst design and intermediate characterization, offering valuable perspectives for developing advanced HER electrocatalysts.

A detailed kinetic, mechanism, and operando speciation study on the controlled, catalytic, cascade-like dehydropolymerization of H3B·NMeH2 to form N-methyl polyaminoborane [H2BNMeH]n (Me-PAB) using Ir(tBu-POCOP)H2 as a precatalyst is reported. Catalyst speciation, as monitored using online FlowNMR, shows the formation of a borohydride complex Ir(tBu-POCOP)(H)(BH4) during an induction period, that rapidly speciates to Ir(tBu-POCOP)H4 during productive turnover. Kinetic studies in the roles of NMeH2, trace water, and [H3B·NMeH2] on the induction period, productive catalysis and speciation reveal a complex set of processes that provide a framework for numerical and computational (DFT) modeling. Collectively these combine to support a mechanism for the dehydrogenation of H3B·NMeH2 to form the actual monomer, H2B═NMeH, that involves concerted B-H/N-H activation. By understanding the factors that control the maximum rate of dehydrogenation [ν(max)] and catalyst speciation, and deploying temperature variation and amine additives, a wide-range of Me-PAB molecular weights (Mn = 35,000-191,200 g·mol-1) can be achieved; in addition to low catalyst loadings (21 ppm), multigram scales (16 g) and water/air tolerance. The development of such systems which operate to selectively produce Me-PAB, using as-supplied substrates and simple catalysts, that also work on a scale useful for materials testing, promotes the wider exploitation of Me-PAB as a general preceramic precursor to hex-boron nitride.

Copper-catalyzed Ullmann-type amination has emerged as a cost-effective and sustainable alternative to palladium-based C-N coupling, yet its broader adoption is often limited by high catalyst loadings. These high loadings arise in part from catalyst deactivation pathways that are still not fully understood. In this study, we examine the mechanism and stability of a homogeneous copper-oxalamide catalytic system for the coupling of aryl bromides with primary amines. As well as revealing mechanistic insight into the catalytic process, these kinetic studies show that under these conditions (EtOH solvent and KOH base) the copper centre is remarkably robust, but the oxalamide ligand undergoes rapid base-mediated hydrolysis, thus establishing ligand decomposition as a key limitation to catalyst longevity. By compensating for this ligand instability through controlled excess, we are able to achieve exceptionally low copper loadings of 5-50 ppm, delivering turnover numbers in copper of up to 7 × 104 for aryl bromides and 2 × 105 for aryl iodides. These findings further highlight copper's potential as a greener alternative to palladium in pharmaceutical and agrochemical synthesis and provide a foundation for further ligand design taking into account both catalyst stability and activity.

The development of sustainable and efficient catalytic systems remains a critical challenge in organic synthesis, particularly for the preparation of β-amino ketones, which are valuable intermediates in pharmaceuticals and fine chemicals. Conventional synthesis methods often rely on toxic reagents, harsh conditions, or non-recyclable catalysts, limiting their green and practical applicability. To address these challenges, we report a one-pot green synthesis of β-amino ketones using indium-doped ZnO nanomaterials as an efficient heterogeneous catalyst under mild, room-temperature conditions in ethanol. The catalyst was prepared via a simple and time-efficient sol-gel auto-combustion technique, where DMF acted simultaneously as the solvent and fuel, eliminating the need for distilled water. Comprehensive characterisation, including XRD, UV-vis, FTIR, and TEM analyses, confirmed the successful incorporation of indium into the ZnO lattice, accompanied by a red shift in the band gap and a structural transition from hexagonal wurtzite to spherical morphologies. These nanostructure modifications significantly enhanced catalytic activity, enabling the effective activation of carbonyl groups and promoting the synthesis of β-amino ketones in high yields. Beyond efficiency, the process is environmentally benign, cost-effective, and the catalyst is readily recyclable, making it a promising alternative to conventional homogeneous and metal-catalysed methods. This work highlights the potential of indium-doped ZnO nanostructures as green catalysts for scalable and sustainable organic transformations.

This study presents a novel P-doped V-Cr composite oxide catalyst for the ammoxidation of 2,6-dichlorotoluene. P-doped V-Cr composite oxides, which crystallized in the hexagonal CrVO3 structure, were synthesized by the solvothermal method with H3PO4 addition. The V-Cr composite oxide particles were composed of numerous nanorods (∼10 nm wide, 100-200 nm long), which assembled into compact microspheres (0.5-1 µm in diameter). The addition of H3PO4 led to the formation of loosely packed irregular and porous nanoparticles with increased specific surface area and pore sizes. Elemental mapping revealed a homogeneous surface distribution of V, Cr, and P. As the molar ratio of V, Cr, and P was set as 1 : 1 : 0.1 in the solvothermal reaction system, the resulting VCrP0.10-N600 product exhibited a maximum specific surface area of 38.7 m2 g-1 and an average pore size of 7.8 nm. In contrast to the P-free VCr-N600, medium-strong acid sites predominated on the VCrP0.10-N600 product, with their concentration exceeding those of weak and strong sites by over an order of magnitude. The catalytic performance of P-doped V-Cr composite oxides was evaluated for the ammoxidation of 2,6-dichlorotoluene to 2,6-dichlorobenzonitrile. The VCrP0.10-N600 catalyst, featuring the optimal P content, achieved a conversion of 92.7%, a molar yield of 78.7% and a selectivity of 82.7%. These values represented improvements of 5.5%, 7.5% and 4.8%, respectively, compared with the P-free VCr-N600 catalyst. First principles methods calculations confirmed that P doping broadened the density of states (DOS) near the Fermi level, thereby increasing the yield, while the introduction of highly localized empty states enhanced selectivity. These theoretical findings were consistent with our experimental results.

Novel ruthenium complexes for olefin metathesis incorporating unsymmetrical, backbone-substituted N-heterocyclic carbenes (uNHCs) were synthesised and fully characterised. The effect of NHC backbone configuration (syn or anti), in combination with a pendant N-benzyl substituent and increasingly sterically demanding N'-aryl groups, was systematically evaluated in representative metathesis reactions and in transformations targeting the valorisation of renewable substrates into industrially relevant products. The NHC substitution pattern significantly affected both the stability and catalytic behaviour of the resulting complexes. In comparison to the commercial benchmark Hoveyda-Grubbs second-generation catalyst (HGII), which remains generally superior in standard metathesis reactions, the newly developed complexes proved to be more efficient in selected sustainable processes such as the self-metathesis of eugenol acetate and the ethenolysis of ethyl oleate. Notably, the N-benzyl, N'-2,6-diisopropylphenyl catalyst featuring an anti NHC backbone achieved more than 90% selectivity towards the desired terminal olefins and a TON up to 12 900 in the ethenolysis reaction. Moreover, in the synthesis of degradable polymers via alternating ring-opening metathesis polymerisation of bio-based monomers (an exo-norbornene derivative and a cyclic enol ether), the analogous catalyst bearing a syn NHC backbone displayed higher Z-selectivity compared to HGII (Z double bond content 78% vs. 21%).

The green and efficient synthesis of amino acids is of great importance to both life science and the chemical industry. Electrocatalytic C─N coupling, driven by renewable electricity under mild conditions, offers a sustainable route for converting simple feedstocks into value-added nitrogen-containing compounds and thus provides a promising strategy for glycine production. Bismuth-based catalysts are commonly used in the electrosynthesis of amino acids. Herein, we report a Bi2S3 nanosheet-based catalyst for glycine electrosynthesis under acidic conditions, achieving 67.5% Faradaic efficiency (FE) and a yield rate of 0.51 mmol h-1 cm-2 at 200 mA cm-2. Operando Raman and attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) identify catalyst reconstruction and a tandem mechanism mediated by NH2OH and oxime intermediates. Combined with the control sulfurization experiment on Bi, we found that sulfur incorporation can modulate the product selectivity, possibly by influencing the subsequent hydrogenation of the oxime intermediate to glycine.

Understanding and tailoring catalyst surface species is crucial for controlling reaction pathways and product selectivity. Herein, we demonstrate that triply bridging hydroxyl (tOH) on ceria oxide surfaces profoundly alter the CO2 hydrogenation pathway, shifting the major product from CO to CH4. Steam treatment of CeO2 supported rhenium catalyst generates abundant t-OH species, leading to a tenfold increase in the CH4 formation rate and ∼90% selectivity at 340°C and 30 bar. The operando spectroscopy combined with isotope-labeling experiments provide direct evidences for the involvement of t-OH in CH4 formation. Density functional theory calculations reveal that t-OH acts as a reactive proton donor, facilitating the hydrogenation of *HCOO to *HCOOH and thereby suppressing the decomposition of *HCOO to CO. Kinetic analysis further indicates that the presence of t-OH lowers the apparent activation energy from 118.8 kJ mol-1 to 73.2 kJ mol-1, enabling a more efficient methanation pathway. This phenomenon is also discovered to be universal on other oxide-supported Ni, Ru, and Rh catalysts. This work highlights the pivotal role of surface hydroxyls in CO2 hydrogenation reaction and offers fundamental insights into engineering surface-species to modulate product selectivity.

Single-atom catalysts (SACs) offer near-unity atomic utilization and uniform active sites, yet their aqueous-phase performance is constrained by competitive water adsorption, parasitic side reactions, and mass transfer limitations. This review systematically examines hydrophobic microenvironment engineering as a strategy to overcome these challenges, proposing a unified framework integrating wettability regulation with reaction-transport coupling. We comprehensively discuss construction strategies including surface modification, intrinsically hydrophobic supports, and biomimetic hierarchical structures, establishing a complete synthetic-to-wettability framework. Mechanistically, we elucidate how hydrophobic microenvironments optimize catalysis through mass transport regulation, active site protection, and electronic modulation, revealing multi-scale coupling from macroscopic contact angles to atomic dynamics. Drawing on advances in organic synthesis, energy conversion, and environmental catalysis, we outline core design principles such as moderate hydrophobicity and outline future directions, including stimuli-responsive catalysts. This framework guides the rational design and industrial translation of hydrophobic SACs.

NiFe layered double hydroxide nanoarray catalysts were loaded onto a Ni metal substrate with micro-scale curvature, which showed improved interfacial reaction kinetics and achieved a low OER overpotential of 257 mV at 400 mA cm-2, outstanding among the best-performing OER electrodes reported to date.

Trace kanamycin (KAN) residues in animal-derived foods pose a significant threat to public health. A multiplex self-enhanced electrochemiluminescence (ECL) sensor was constructed based on gadolinium-based metal-organic framework (Gd-MOF) with restricted aggregation-caused quenching (ACQ) effect, synergistically integrated with actively catalytic platinum‑nitrogen‑carbon single-atom catalyst (Pt-N-C SAC), enabling specific detection of KAN. Gd-MOF was synthesized via the eight-coordinate assembly between Gd3+ and 9,10-di(p-carboxyphenyl)anthracene (DPA). The rigid framework of Gd-MOF inhibited the π-π stacking of DPA through steric hindrance, thereby restricting the ACQ effect. Meanwhile, the coordination interaction with Gd3+ ions and the spatial confinement within the Gd-MOF framework effectively restricted the intramolecular motion of DPA, leading to reduced non-radiative energy dissipation. Owing to the dual effects, the ECL efficiency of the Gd-MOF was significantly enhanced. Atomically dispersed Pt active sites exhibited remarkable catalytic activity by lowering the activation energy barrier of the OO bond in PDS, thereby accelerating the generation of highly reactive SO4-• radicals. Gd-MOF and Pt-N-C SAC were combined through electrostatic self-assembly, resulting in intimate interfacial coupling that increased the loading capacity of Gd-MOF and improved the conductivity of Pt-N-C SAC@Gd-MOF. This synergistic integration enabled self-enhanced ECL through combining multiple enhancing effects of Pt-N-C SAC. Combined with molecularly imprinted polymer (MIP) with high binding affinity and selective target recognition capability, the fabricated MIP-ECL sensor exhibited wide linear detection range of 1-10,000 nM and low limit of detection of 0.71 nM. This multiple self-enhanced modulation strategy provided novel approach for ECL sensing detection of KAN in food and the environment.

Contact-electrification (CE) is a ubiquitous effect that would render two contact surfaces being reversely charged. These charged surfaces would induce an electric field in space, but polarization caused by this CE-derived electric field has long been ignored. Here, we propose an electrostatic polarization strategy to improve the performance of single-atom catalysts (SACs) based on this CE-derived electric field. Exemplified by Ru1/SiO2, its hydrogen yield could be enhanced by 7.62 times after improving the CE ability of the SiO2 substrate by fluorination. Such enhancement should mainly be ascribed to the expedited CE effect on fluorinated SiO2 substrates, which not only facilitates the water dissociation process but also establishes a strong electric field for improving the reduction activity of Ru SAs and the electrostatic attraction of protons. In addition, this strategy is feasible for SACs based on carbon substrates, further suggesting its generalizability. The practicability of Ru1/F-SiO2 was demonstrated through hydrogen evolution from real seawater, achieving a yield of 1.01 mmol·g-1·h-1 over 200 h. We expect this electrostatic polarization-based strategy to form a universal route for enhancing the activity of SACs.

The oxygen evolution reaction (OER) is limited by the difficulty of achieving complete oxidation of transition metals to higher valence states, restricting the utilization of their intrinsic activity. Conventional direct-current polarization typically produces mixed-valence surfaces with only partial enrichment of Ni3+ and Co3+. Here, we report a symmetric-waveform alternating-current activation strategy that induces dynamic surface reconstruction, enabling full conversion of Ni2+ into Ni3+ and partial oxidation of Co2+ into Co3+. Experimental characterization confirms the enrichment of high-valence species, while density functional theory calculations reveal that a fully trivalent Ni surface shifts the rate-determining step from *OH adsorption to *OOH adsorption with a reduced barrier. Projected density of states analysis shows Ni d-band centers approaching the Fermi level, facilitating stronger orbital interactions with oxygen intermediates. Charge distribution analyses further indicate enhanced conductivity and electron redistribution. These synergistic effects lower the overpotential at 10 mA cm-2 by 63.6 mV and increase catalytic activity by 12.5%. This work establishes dynamic valence-state engineering via alternating-current activation as a pathway for designing noble-metal-free, high-performance OER catalysts for sustainable hydrogen production.

Electron microscopy provides direct real-space access to the structural heterogeneity of catalysts across multiple length scales. However, its application to practical catalytic systems is often constrained by imaging artifacts, low signal-to-noise ratios, narrow fields of view, and the difficulty of extracting statistically representative information from large and complex data sets. Recent advances in artificial intelligence (AI), particularly deep learning, are transforming electron microscopy into a quantitative, high-throughput, and increasingly standardized analytical platform. This review highlights how AI enables large-scale, statistically grounded analysis of electron microscopy data, making it possible to extract structurally meaningful descriptors from catalytic materials across atomic, nanoscale, and dynamic regimes and to connect these descriptors more rigorously with structure-performance relationships. Current challenges, including data scarcity, model transferability, interpretability, and integration with spectroscopy, theory, and autonomous microscopy, are also discussed.

Why do even closely-related bacteria differ in their capacity to evolve antibiotic resistance? Drawing on evidence from experimental evolution, pathogen genomics, and molecular microbiology, this Essay argues that the evolution of antibiotic resistance in bacterial genomes is frequently catalyzed by the presence of 'resistance potentiators': genes, elements, or pathways that accelerate evolution in a trait-specific manner. Epidemiological evidence suggests that resistance potentiators that modulate phenotypes have been particularly important in successful pathogen lineages. Furthermore, experimental models show that combining antibiotics with inhibitors of resistance potentiators can restrict the evolution of resistance, suggesting that they could be future drug targets or otherwise lead to more evolution-informed antibiotic therapy.