Hypoxia and the acidic microenvironment play a vital role in tumor metastasis and angiogenesis, generally compromising the chemotherapeutic efficacy. This provides a tantalizing angle for the design ...of platinum(IV) prodrugs for the effective and selective killing of solid tumors. Herein, two carbonic anhydrase IX (CAIX)‐targeting platinum(IV) prodrugs have been developed, named as CAIXplatins. Based on their strong affinity for and inhibition of CAIX, CAIXplatins can not only overcome hypoxia and the acidic microenvironment, but also inhibit metabolic pathways of hypoxic cancer cells, resulting in a significantly enhanced therapeutic effect on hypoxic MDA‐MB‐231 tumors both in vitro and in vivo compared with cisplatin/oxaliplatin, accompanied with excellent anti‐metastasis and anti‐angiogenesis activities. Furthermore, the cancer selectivity indexes of CAIXplatins are 70–90 times higher than those of cisplatin/oxaliplatin with effectively alleviated side‐effects.
Tumor microenvironment and metabolism regulation can be achieved by targeting carbonic anhydrase IX with platinum(IV) prodrugs, termed CAIXplatins. This strategy could be used to treat hypoxic and aggressive tumors. The advantages of CAIXplatins in comparison to cisplatin/oxaliplatin include the greatly increased cancer selectivity index, enhanced therapeutic efficiency, reduced level of side‐effects, as well as the excellent anti‐angiogenesis activity.
Abstract The current industrial ammonia synthesis relies on Haber–Bosch process that is initiated by the dissociative mechanism, in which the adsorbed N 2 dissociates directly, and thus is limited by ...Brønsted–Evans–Polanyi (BEP) relation. Here we propose a new strategy that an anchored Fe 3 cluster on the θ-Al 2 O 3 (010) surface as a heterogeneous catalyst for ammonia synthesis from first-principles theoretical study and microkinetic analysis. We have studied the whole catalytic mechanism for conversion of N 2 to NH 3 on Fe 3 /θ-Al 2 O 3 (010), and find that an associative mechanism, in which the adsorbed N 2 is first hydrogenated to NNH, dominates over the dissociative mechanism, which we attribute to the large spin polarization, low oxidation state of iron, and multi-step redox capability of Fe 3 cluster. The associative mechanism liberates the turnover frequency (TOF) for ammonia production from the limitation due to the BEP relation, and the calculated TOF on Fe 3 /θ-Al 2 O 3 (010) is comparable to Ru B5 site.
Platinum‐based catalysts occupy a pivotal position in diverse catalytic applications in hydrogen chemistry and electrochemistry, for instance, the hydrogen evolution reactions (HER). While adsorbed ...Pt atoms on supports often cause severe mismatching on electronic structures and HER behaviors from metallic Pt due to the different energy level distribution of electron orbitals. Here, the design of crystalline lattice‐confined atomic Pt in metal carbides using the Pt‐centered polyoxometalate frameworks with strong PtO‐metal covalent bonds is reported. Remarkably, the lattice‐confined atomic Pt in the tungsten carbides (Ptdoped@WCx, both Pt and W have atomic radii of 1.3 Å) exhibit near‐zero valence states and similar electronic structures as metallic Pt, thus delivering matched energy level distributions of the Pt 5dz2 and H 1s orbitals and similar acidic hydrogen evolution behaviors. In alkaline conditions, the Ptdoped@WCx exhibits 40 times greater mass activity (49.5 A mgPt−1 at η = 150 mV) than the Pt@C because of the favorable water dissociation and H* transport. These findings offer a universal pathway to construct urgently needed atomic‐scale catalysts for broad catalytic reactions.
Crystalline lattice‐confined atomic Pt in metal carbides with “real” matched properties as metallic platinum are developed using Pt‐centered polyoxometalate frameworks with strong PtOW/Mo covalent bonds. The WC lattice‐confined Pt atoms exhibit near‐zero valence states, similar electronic structures, and matched hydrogen evolution behaviors as Pt(111) surface; remarkably, they offer 40 times greater mass activity than Pt@C‐20% in alkaline conditions.
The generation of molecular chirality in the absence of any molecular chiral inductor is challenging and of fundamental interest for developing a better understanding of homochirality. Here, we show ...the manipulation of molecular chirality through control of the handedness of helical metal nanostructures (referred to as nanohelices) that are produced by glancing angle deposition onto a substrate that rotates in either a clockwise or counterclockwise direction. A prochiral molecule, 2-anthracenecarboxylic acid, is stereoselectively adsorbed on the metal nanohelices as enantiomorphous anti-head-to-head dimers. The dimers show either Si-Si or Re-Re facial stacking depending on the handedness of the nanohelices, which results in a specific enantiopreference during their photoinduced cyclodimerization: a left-handed nanohelix leads to the formation of (+)-cyclodimers, whereas a right-handed one gives (-)-cyclodimers. Density functional theory calculations, in good agreement with the experimental results, point to the enantioselectivity mainly arising from the selective spatial matching of either Si-Si or Re-Re facial stacking at the helical surface; it may also be influenced by chiroplasmonic effects.
Chinese traditional liquor, a major type of global distilled spirits, offers a unique flavor system acquired across thousands of years of development. Owing to the various raw brewing materials, ...types of koji, fermentation vessels, and processes used during liquor production, significant differences can occur in the content of flavor chemical components, such as esters, alcohols, aromatics, ketones, nitrogen compounds, acids, and aldehydes in the resulting liquor. Therefore, the liquor can be characterized on the basis of four basic flavors: sauce‐, strong‐, light‐, and rice‐aroma, and eight derivative flavors: feng‐, sesame‐, chi‐, te‐, mixed‐, laobaigan‐, herbal‐, and fuyu‐aroma. In this review, we describe the production and development process of Chinese traditional liquor in detail; summarize the flavor types, flavor chemical composition characteristics, and research progress related to this liquor; and discuss the influence of trace chemical components on liquor flavor, with the aim of laying a theoretical foundation for stabilizing the quality and increasing the yield of traditional liquor.
Different from isolated metal atoms and large metal nanoparticles (NPs), supported metal clusters (SMCs) possess distinct geometric and electronic structures and thus exhibit enhanced activity and ...designated selectivity in catalysis. So far, with the development in synthetic methodologies and characterization techniques, SMCs with fine structures could be constructed and well-defined at the atomic level. In addition, based on computational modeling of SMCs, theoretical calculations corroborated well with experimental results, providing in-depth insights into the structure–property relationship for SMCs in catalysis. In this Review, classic synthetic strategies and key characterization techniques of SMCs are summarized. Subsequently, the applications of SMCs in important catalytic reactions based on recent studies are discussed, including aerobic oxidation, hydrogenation, dehydrogenation, water–gas shift (WGS) reaction, and photocatalytic reactions. In particular, the importance of the cluster size-effect and metal–support interactions in determining the catalytic performance of SMCs is highlighted. Lastly, challenges and prospects in SMCs’ catalysis are illustrated.
Fundamental understanding of the dynamic behaviors at the electrochemical interface is crucial for electrocatalyst design and optimization. Here, we revisit the oxygen reduction reaction mechanism on ...a series of transition metal (M = Fe, Co, Ni, Cu) single atom sites embedded in N-doped nanocarbon by ab initio molecular dynamics simulations with explicit solvation. We have identified the dissociative pathways and the thereby emerged solvated hydroxide species for all the proton-coupled electron transfer (PCET) steps at the electrochemical interface. Such hydroxide species can be dynamically confined in a "pseudo-adsorption" state at a few water layers away from the active site and respond to the redox event at the catalytic center in a coupled manner within timescale less than 1 ps. In the PCET steps, the proton species (in form of hydronium in neutral/acidic media or water in alkaline medium) can protonate the pseudo-adsorbed hydroxide without needing to travel to the direct catalyst surface. This, therefore, expands the reactive region beyond the direct catalyst surface, boosting the reaction kinetics via alleviating mass transfer limits. Our work implies that in catalysis the reaction species may not necessarily bind to the catalyst surface but be confined in an active region.
We have constructed a general thermodynamic model of chemical potentials and applied ab initio electronic structure and molecular dynamics simulations, as well as kinetic Monte Carlo analysis, to ...probe the dynamical, reactive, and kinetic aspects of metal single-atom catalysts (SACs) on oxide support. We choose Au single atoms (SAs) supported on ceria as a typical example to demonstrate how our model can guide the rational design of highly stable and reactive SACs. It is shown that, under realistic conditions, various factors such as temperature, pressure, particle size, and the reducibility of the support can strongly affect both the stability and the reactivity of SACs by altering the relative chemical potentials between SAs and metal nanoparticles (NPs). The Au SAs at step sites of ceria support are rather stable, even at temperatures as high as 700 K, and exhibit around 10 orders of magnitude more reactivity for CO oxidation than the terrace sites. Remarkably, under reaction conditions, Au SAs can be dynamically created at the interface of small-size Au NPs on ceria support even without step sites, which accounts for the puzzling significant size effect in gold catalysis. Our work underscores an unrecognized critical role of Au SAs in gold nanocatalysis and provides a general methodology for designing the metal SACs on oxide supports.
Catalysis by gold supported on reducible oxides has been extensively studied, yet issues such as the nature of the catalytic site and the role of the reducible support remain fiercely debated topics. ...Here we present ab initio molecular dynamics simulations of an unprecedented dynamic single-atom catalytic mechanism for the oxidation of carbon monoxide by ceria-supported gold clusters. The reported dynamic single-atom catalytic mechanism results from the ability of the gold cation to strongly couple with the redox properties of the ceria in a synergistic manner, thereby lowering the energy of redox reactions. The gold cation can break away from the gold nanoparticle to catalyse carbon monoxide oxidation, adjacent to the metal/oxide interface and subsequently reintegrate back into the nanoparticle after the reaction is completed. Our study highlights the importance of the dynamic creation of active sites under reaction conditions and their essential role in catalysis.
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