Accounts of Chemical Research最新文献

Numerous metal artifacts of exceptional historical and artistic value from the Moche civilization (ca. 450 AD) were unearthed in the tomb of the Lady of Cao (El Brujo, Peru). The tomb yielded the tattooed, mummified remains of a young woman, who was approximately 25 years old at the time of her demise. The rich array of artifacts and insignia of power found within the tomb provides compelling evidence of her elevated status in the hierarchical Moche society. Among the artifacts, the gilded objects and intriguing apparently bimetallic nose ornaments, featuring adjacent gold and silver surfaces, are particularly noteworthy. These artifacts reveal the sophisticated craftsmanship of Moche metalworkers, who expertly produced and worked on Cu- and Ag-based alloys. Moche metalworkers, once they worked and shaped the alloys to a thickness of approximately 100–150 μm, in some artifacts meticulously formed localized, uniform, and thin (roughly 3–5 μm thick) gold- and silver-enriched surface layers by employing etching agents. This process involved the selective depletion of copper from Cu-based alloys and, in some regions, the removal of both copper and silver from a Ag–Cu–Au ternary alloy. The presence of epitaxially grown micrometric silver wires, which resemble the elongated architecture of naturally occurring silver curls, supports the hypothesis of a subtractive surface treatment. These findings demonstrate a pioneering, though empirical, capacity to produce specific Cu- and Ag-based alloys and to select suitable materials for surface manipulation. This capability led to the tailored chemical modification of the outermost layers, resulting in a fascinating monometallic or bimetallic appearance likely imbued with religious, symbolic, or shamanic values. It is noteworthy that the creation of such enthralling artistic masterpieces was uniquely enabled by this ability to manipulate matter at the micro- and nanoscale, combined with the goldsmiths’ artistic creativity.

The global plastic waste crisis, driven by exponential growth in plastic production, has necessitated the development of innovative approaches for recycling and upcycling. Poly(ethylene terephthalate) (PET), one of the most widely used polyesters, poses significant environmental challenges due to its chemical stability and non-degradable nature. While existing methodologies have made significant contributions to the recycling of PET waste through mechanical or chemical processes, an emerging strategy of upcycling PET into high-value products may offer greater potential to present significant advantages in economic feasibility and long-term sustainability. Over the past ten years, hundreds of publications have explored the upcycling of PET in the laboratory through catalytic reactions with various co-reactants, primarily water, hydroxides, alcohols, and amines. In this Account, we summarize our contributions on the design of novel catalytic strategies for the upcycling of PET along with other problematic wastes and H₂. For instance, we explored the co-upcycling of PET with other plastics such as poly(vinyl chloride) (PVC) and polyoxymethylene (POM), demonstrating how the chlorine from PVC could be utilized to depolymerize PET into terephthalic acid (TPA) and 1,2-dichloroethane (EDC) and how the formaldehyde derived from POM could be converted into 1,3-dioxolane through the condensation reaction with ethylene glycol (EG) derived from PET. We also developed a one-pot catalytic system that simultaneously hydrogenated PET and CO₂ into high-value chemicals, leveraging a dual-promotion effect on both CO₂ hydrogenation and PET methanolysis and achieving high yields of EG, dimethyl cyclohexanedicarboxylate (DMCD) and p-xylene (PX). A H₂-free, one-pot, two-step catalytic process was further presented to upcycle PET with CO₂, yielding formic acid (FA) and TPA. Moreover, we demonstrated a direct hydrogenation strategy to convert PET into a degradable polyester, poly(ethylene terephthalate)–poly(ethylene-1,4-cyclohexanedicarboxylate) (PET–PECHD), through controlled hydrogenation of its aromatic rings, which preserved the polymer’s mechanical and thermal properties while introducing degradability, offering a sustainable alternative for packaging materials.

Our research highlights the importance of catalyst design, reaction engineering, and process optimization in achieving efficient and scalable PET upcycling processes. By integrating multiple catalytic steps and leveraging waste-derived resources, we outline a roadmap for the near future of PET upcycling, aiming to enable breakthroughs in real-life plastic upcycling.

The conversion of CO₂ into high-value-added chemicals represents an effective strategy for CO₂ utilization. However, due to the inherent thermodynamic stability of CO₂, its conversion primarily relies on harsh conditions, such as high temperatures and pressures, along with the involvement of noble-metal catalysts. The effective transformation of CO₂ under mild conditions remains a significant challenge. Therefore, the development of efficient catalysts is of critical importance. Metal–organic frameworks (MOFs) are a class of porous crystalline materials formed by the self-assembly of metal ions with multidentate organic ligands through coordination bonds. Its precise and customizable structure, combined with high surface area and the ease of functional modification, makes it an ideal platform for catalytic applications. These advantages facilitate the design of catalysts with high activity, selectivity, and stability through rational structural modulation, significantly enhancing CO₂ conversion into value-added products under mild conditions. Moreover, this enables a deep understanding of the relationship between catalyst structure and performance. Therefore, summarizing research in this field and providing in-depth insight into the application of MOF-based catalysts for CO₂ conversion is crucial for advancing future developments.

In this Account, we will summarize and discuss recent advances on the structural design of non-noble metal MOFs and the mechanics in the catalytic conversion of CO₂, especially emphasizing how to enhance the catalytic activity and selectivity by modulating Lewis acid and/or base sites. This Account begins by outlining the challenges associated with CO₂ conversion. Subsequently, illustrating why MOFs are promising catalysts for CO₂ utilization. Next, we present several specific strategies for constructing highly efficient MOF-based catalysts utilized in CO₂ conversion: (1) To overcome the stability challenges associated with MOFs in CO₂ conversion, we designed and synthesized a series of cluster-based MOFs. The high connectivity of the metal clusters imparts exceptional structural stability. (2) We highlighted a new strategy involving multiple Lewis acid sites to synergistically catalyze the highly efficient conversion of CO₂ under mild conditions without the need for noble metals. (3) To obtain selective conversion of different reactions, we simultaneously introduced both Lewis acid and Lewis base active sites into the MOF structure. This approach significantly enhances catalytic efficiency while enabling a “switch-on/off” effect for different CO₂ reactions. (4) Through the nanoconfinement effect, we achieved substrate size selectivity and reaction pathway modulation, significantly improving the efficiency of multicomponent CO₂ reactions and reducing the for

Thioureas represent an important class of molecular frameworks, distinguished by their hydrogen-bonding capabilities. This feature has enabled the development of a variety of synthetic anion receptors and advanced molecular technologies with applications in analysis, catalysis, and therapeutics. Over the past three decades, our lab has focused on establishing N-acylamino acid amidothiourea platforms to revolutionize the thiourea-based supramolecular functionality, particularly in anion recognition, chirality transfer, spontaneous resolution, and macrocyclization synthesis. This Account highlights representative studies from our lab and describes our exploration of the relationship between N-acylamino acid amidothiourea conformation, folding, and emerging material properties.

The design of thiourea-based anion receptors usually involves enhancing the hydrogen-bonding propensity of the thioureido −NH proton(s). Conventional strategies employ electron-withdrawing groups to increase the acidity of −NH(s), although this risks deprotonation of −NH when they are too acidic or encounter highly basic anions. Our lab developed an alternative strategy for this goal that circumvents this limitation. By incorporating electron-donating amide groups to generate N-amidothioureas and exploiting molecular allostery to drive intramolecular charge transfer (ICT), we achieved a dramatic enhancement in anion binding affinity by orders of magnitude. The N-amidothioureas also serve as dynamic regulators of intramolecular chirality transfer via N–N bond conformational switching from twisted to planar states. Notably, N-acylamino acid amidothioureas exhibit a pronounced template effect due to the folded β-turn structure, enabling efficient macrocyclization syntheses that were previously unattainable. This breakthrough has facilitated the construction of macrocycle-based nanopores for transmembrane transport. Furthermore, by integrating intermolecular binding sites, we achieved helicity propagation of the helical β-turn structure through self-assembly, yielding supramolecular double helices with a linear CD-ee dependence. It presents a critical step toward spontaneous resolution for practical applications.

Given the expanding interest in thiourea and its derivatives, our chiral helical building blocks provide a versatile platform for advancing functional thiourea-based materials.

What does the word antioxidant mean? Antioxidants are supposed to be nontoxic, versatile molecules capable of counteracting the damaging effects of oxidative stress (OS). Thus, when evaluating a candidate molecule as an antioxidant, several aspects should be considered. Antioxidants are more than free radical scavengers. Other routes may contribute to their protection against OS, including modulation of the redox enzymatic system, preventing free radical formation, and repairing oxidized biomolecules. However, molecules intended as antioxidants can also exhibit pro-oxidant or toxic effects. Thus, understanding the full complexity of their chemistry is crucial for making reliable predictions about their activity.

This Account focuses on computational tools that can assist in addressing such a challenging task. Some key aspects to consider when evaluating the potential antioxidant activity (AOX) of a molecule using these tools are (i) its absorption, distribution, metabolism, and excretion (ADME) properties; (ii) the effects of solvent and pH on its speciation and reactivity; and (iii) the toxicity of the molecule, its metabolites, and the products of the reactions it may undergo in vivo. While computational tools offer unique insights into the chemoprotective effects of antioxidants, care must be taken when assessing the data they produce. For example, reactivity descriptors alone are seldom enough to make reliable predictions on AOX. The thermodynamics and kinetics of the reaction pathways contributing to it frequently rule the antioxidant performance. The selected method of calculation should be reliable for the task at hand, since it influences the numerical outcome. Using some references for comparison allows adding context to the calculated data.

We have developed two protocols that can be combined to include those aspects into computational studies of antioxidants: the Quantum Mechanics-Based Test for Overall Free Radical Scavenging Activity (QM-ORSA) and the Computer-Assisted Design of Multifunctional Antioxidants Based on Chemical Properties (CADMA-Chem). Some examples of the application of these protocols are discussed herein. They illustrate the diversity of reaction mechanisms and environmental conditions that modulate AOX, considering potential benefits and risks. These protocols provide a theoretical framework for investigating AOX that allows straightforward comparison with experimental results. They can be applied to known antioxidants for gaining insight into observed behavior as well as in the development of new antioxidants intended as potential drug candidates for the treatment of OS-related diseases.

This work aims to promote comprehensive investigations into antioxidant chemistry, contribute to the interpretation of the results obtained from calculations, and encourage the development of safe, efficacious molecules that ameliorate the harmful effects of OS on human health.

Hydroaminoalkylation, the catalytic addition of amines to alkenes, has evolved as a powerful tool in modern synthetic chemistry, offering an atom-economic and green approach to the construction of C–C bonds. This reaction enables the direct amine functionalization of alkenes and alkynes without the need for protecting groups, directing groups, or prefunctionalization, thereby eliminating stoichiometric waste and minimizing synthetic steps. Over the past two decades, significant advances in catalyst development and mechanistic understanding have expanded the scope of hydroaminoalkylation, allowing for control over regio-, diastereo-, and enantioselectivity. In this Account, we provide a comprehensive overview of our contributions to this field, from fundamental mechanistic insights into early transition metal catalysis to the rational design of hydroaminoalkylation catalysts for small molecule and polymer functionalization. We discuss key breakthroughs, including the development of N,O-chelated early transition metal catalysts, and the use of hydroaminoalkylation in synthesis by providing direct access to valuable α- and β-alkylated amines that serve as key building blocks in pharmaceuticals, agrochemicals, and fine chemicals. The practical applications of hydroaminoalkylation extend beyond small molecule synthesis to the field of polymer chemistry, where it enables both pre- and postpolymerization amination strategies. These advances have unlocked new applications in materials science, particularly in the design of self-healing polymers, adhesives, antibacterial coatings, and polymeric binders for energy storage applications. Additionally, we demonstrate the compatibility of hydroaminoalkylation with other catalytic methods in both small molecule synthesis and polymer chemistry. Finally, we highlight remaining challenges and future opportunities, such as the development of earth-abundant metal catalysts, enantioselective hydroaminoalkylation strategies, and advanced polymer applications. By bridging the gap between small molecule synthesis and polymer chemistry, hydroaminoalkylation shows much promise as a transformative strategy for modern catalysis.