Chemical record最新文献

The construction of complex chiral cyclic architectures, ubiquitous in bioactive natural products, represents a perennial pursuit in organic synthesis. Among the myriad of strategies, cycloaddition reactions are unparalleled in their ability to efficiently assemble such structures with high atom economy. While higher-order cycloadditions (involving more than 6π electrons) provide a powerful and intriguing pathway to elaborate polycyclic systems, their development has been historically hampered by challenges in periselectivity, regiocontrol, and particularly, the achievement of high enantioselectivity. This review comprehensively summarizes the recent remarkable progress in this field, which has been revitalized by the burgeoning application of organocatalysis. We systematically categorize and discuss the advances based on the key substrate types involved, including aromatic aldehydes/esters, fulvenes, and tropones. For each substrate class, we elucidate the distinct activation modes enabled by two predominant organocatalytic strategies: nucleophilic amine catalysis and N-heterocyclic carbene catalysis, detailing their mechanisms and the resultant reaction paradigms. This review aims to provide a clear overview of the current state of catalytic higher-order cycloadditions, highlighting the scope, selectivity, and mechanistic insights of these transformations. Finally, we outline the challenges and future opportunities in this fast-evolving field.

The synthesis of amide building blocks is crucial for producing diverse amide-containing compounds such as peptides, proteins, and amino acids. The demand for innovative methods of amide bond derivatives, considered as vital nonclassical bioisosteres, is steadily increasing because of its pivotal role in drug development. A highly cost-effective and efficient approach for generating amide functional groups involves the metal-catalyzed hydration of nitriles, offering profound implications for both academic and industrial sectors. This review explores the recent successful catalytic systems, encompassing both homogeneous and heterogeneous solid catalysts that enhance the catalytic transformation of nitriles into amides. Furthermore, theoretical studies employing density functional theory calculations to elucidate the cooperative mechanism between the catalyst and the carbon–nitrogen bond in nitriles are overviewed.

India generates over 500 million tonnes of agricultural waste annually, much of which is lignocellulosic biomass rich in silica, calcium, potassium, and carbon elements, which are favourable for catalytic applications. This study highlights the valorisation of abundant agro-wastes such as rice husk (up to 20% silica), coconut shell (74%–78% fixed carbon), sugarcane bagasse (45%–55% cellulose), and tamarind seed (rich in polysaccharides and carbon), as cost-effective and sustainable catalysts. Various preparation techniques, such as calcination (450°C–700°C), acid/base activation (e.g. H₂SO₄, KOH), and nanoparticle impregnation (e.g. CaO, ZnO, Fe₃O₄), are explored to enhance the surface area (up to 250 m²/g) and activate functional groups. Agro-waste-derived catalysts exhibit high performance, achieving over 90% conversion in transesterification, efficient alcohol oxidation under mild conditions, and up to 98% dye degradation (e.g. methylene blue) within 60–90 min. Economic evaluations estimate production costs at $30–50 per ton, positioning them as competitive alternatives to conventional catalysts. Comparative insights from African innovations reveal opportunities for regional scalability. The study further explores Artificial Intelligence (AI)-assisted catalyst design, with life-cycle assessments indicating a potential reduction of up to 40% in greenhouse gas emissions, and integration prospects within decentralised biorefineries, supporting the transition to a circular, low-carbon chemical economy.

The use of pincer complexes based on platinum group metals is undoubtedly one of the most widely applied strategies today for the design of homogeneous catalysts in various chemical transformations, owing to their high stability and facile functionalization. This review aims to cover the advances achieved so far in homogeneous catalytic reactions using pincer complexes with platinum group metals (Ru, Os, Rh, Ir, Pd, and Pt), specifically in acceptorless dehydrogenation, hydrogenation, hydrogen storage, and cross-coupling reactions. Moreover, this review seeks to highlight the ligand–metal synergy and cooperation present in these systems, and how this enables the development of innovative, versatile, and efficient homogeneous catalysts that outperform known compounds, thereby contributing to greener chemical processes.

Eight-membered ring skeletons are central to numerous pharmaceutical molecules and biologically active substances. Recent years have witnessed remarkable progress in the construction of these challenging ring systems. Among the various synthetic strategies, transition metal catalysis, particularly palladium-catalyzed cycloaddition reactions, has emerged as an efficient and reliable methodology for generating diverse eight-membered ring frameworks. This review provides a detailed classification and comprehensive summary of palladium-catalyzed cycloaddition modes for constructing eight-membered ring compounds, specifically focusing on the [4 + 4], [5 + 3], and [6 + 2] cycloaddition strategies. This article aims to highlight the latest advancements in the synthesis of eight-membered ring compounds via palladium-catalyzed cycloaddition reactions, thereby stimulating and promoting further exploration of innovative synthetic approaches in this field.

Due to its zero carbon emissions, hydrogen has emerged as a promising clean energy source. By utilizing water electrolysis for hydrogen production, carbon neutralization can be advanced technologically and practically. Developing durable, cost-effective electrocatalysts with low overpotentials is essential for electrochemical water splitting. In order to produce hydrogen efficiently, it is important to choose materials that are most suitable for converting energy into hydrogen. Due to their tunable structure, expansive surface area, and outstanding electrocatalytic properties, carbon nanomaterials are becoming increasingly important in this field. Furthermore, their high conductivity and catalytic potential make them promising hydrogen energy candidates. As a precursor material, biochar can be used to produce carbon nanomaterials in an innovative manner. Carbon nanomaterials have been synthesized from biochar in a variety of ways, each producing a different structure. This review discusses biochar production and biochar nanostructures derived from biochar, including carbon dots, carbon tubes, nanofibers, nanosheets, and nanoflakes, along with their energy conversion efficiency and structural tunability. Furthermore, this review investigates recent advances in electrochemical water splitting. It places a particular emphasis on carbon nanomaterials derived from biochar as catalysts. Its objective is to provide valuable insight into the advancement of sustainable hydrogen energy solutions.

The cover illustrates G-quadruplex-forming aptamers as therapeutic oligonucleotides for neurodegenerative diseases. Their unique secondary structures confer high target specificity, while clay-based nanocarriers, including halloysite nanotubes and montmorillonite, are depicted as stabilizing and delivery platforms. This combination provides exciting opportunities to enhance nuclease resistance, bioavailability, and targeted transport across biological barriers. More details can be found in the Review by Bruno Pagano and co-workers (DOI: 10.1002/tcr.202500126).

Molybdenum oxide (MoO₃) is a promising material for gas sensing due to its unique physicochemical properties, including multiple chemical valence states, high thermal stability, and suitable bandgap. Oxygen vacancies, as critical structural defects, significantly enhance the gas sensing performance of MoO₃ by modifying its electronic structure and surface chemistry. This review discusses the formation mechanism of oxygen vacancies and their role in improving sensing performance, such as introducing energy levels within the bandgap, altering surface atomic configurations, and promoting gas adsorption and reactions. Experimental and theoretical studies demonstrate that oxygen vacancies enhance sensitivity and selectivity for gases like NH₃, NO₂, H₂S, TEA, and ethanol. Strategies to optimize oxygen vacancy (OV) concentration, including doping with metal/rare earth elements and microstructure design, are also explored. Future research directions include in-depth studies on OV formation mechanisms, performance under complex conditions, and advanced sensor development, supported by theoretical calculations to better understand their effects on MoO₃'s electronic and adsorption properties.

The value of caricatures for the understanding of the history of sciences, particularly chemistry, has long been recognized by general historians. The most striking and rare contemporary and ancient caricatures of some famous chemists whose names have entered the annals of chemistry have been collected in this manuscript. The purpose of this article is to show that a caricature can not only make you smile, but also throw light on the substantive content of scientific concepts, hypotheses, and discussions on the most important problems and challenges of different periods.

By mimicking artificial photosynthesis, utilizing abundant solar energy to directly convert CO₂ into renewable fuels or high-value chemicals offers a promising approach to tackle energy scarcity and global warming. Porphyrins and their derivatives, renowned for their unique conjugated structures and adaptable metal active sites, facilitate the reversible transformation of light, electrical, and chemical energy. This review provides a comprehensive overview of recent advancements in porphyrin-based materials, from molecular structures to framework systems, emphasizing strategies to enhance photocatalytic CO₂ conversion. Initially, the principles and distinctive attributes of porphyrin-based photocatalysis for CO₂ reduction are outlined, highlighting recent innovations in porphyrin molecular engineering to boost light absorption, charge separation, and catalytic efficiency. Then, porphyrin-based molecular heterogeneous photocatalytic systems are explored, which merge the advantages of homogeneous and heterogeneous catalysts for CO₂ reduction, including porphyrin-based covalent organic frameworks, metal–organic frameworks, and covalent organic polymers. Finally, future research directions, emphasizing the optimization of porphyrin structures, the exploration of new photocatalytic mechanisms, and the integration of porphyrin-based materials into practical devices for efficient CO₂ conversion are discussed. This review aims to offer fresh perspectives on the application of porphyrin-based materials in photocatalytic CO₂ reduction, inspiring innovative strategies in energy conversion.