Precision Chemistry最新文献

Given its high gravimetric energy density and status as a clean fuel when derived from renewables, hydrogen (H₂) is considered a premier candidate for energy storage; however, its low volumetric density limits its broader application. Chemical storage through the reversible incorporation of H₂ into chemical bonds offers a promising solution to its low volumetric density, circumventing subpar energy densities and substantial infrastructure investments associated with physical storage methods. Metal hydrides are promising candidates for chemical storage because of their high gravimetric capacity and tunability through nanostructuring and alloying. Moreover, metal hydride/H₂ interconversion may be interfaced with electrochemistry, which offers potential solutions to some of the challenges associated with traditional thermochemical platforms. In this Perspective, we describe anticipated challenges associated with electrochemically mediated metal hydride/H₂ interconversion, including thermodynamic efficiencies of metal hydride formation, sluggish kinetics, and electrode passivation. Additionally, we propose potential solutions to these problems through the design of molecular mediators that may control factors such as metal hydride solubility, particle morphology, and hydride affinity. Realization of an electrochemically mediated metal hydride/H₂ interconversion platform introduces new tools to address challenges associated with hydrogen storage platforms and contributes toward the development of room-temperature hydrogen storage platforms.

Given its high gravimetric energy density and status as a clean fuel when derived from renewables, hydrogen (H₂) is considered a premier candidate for energy storage; however, its low volumetric density limits its broader application. Chemical storage through the reversible incorporation of H₂ into chemical bonds offers a promising solution to its low volumetric density, circumventing subpar energy densities and substantial infrastructure investments associated with physical storage methods. Metal hydrides are promising candidates for chemical storage because of their high gravimetric capacity and tunability through nanostructuring and alloying. Moreover, metal hydride/H₂ interconversion may be interfaced with electrochemistry, which offers potential solutions to some of the challenges associated with traditional thermochemical platforms. In this Perspective, we describe anticipated challenges associated with electrochemically mediated metal hydride/H₂ interconversion, including thermodynamic efficiencies of metal hydride formation, sluggish kinetics, and electrode passivation. Additionally, we propose potential solutions to these problems through the design of molecular mediators that may control factors such as metal hydride solubility, particle morphology, and hydride affinity. Realization of an electrochemically mediated metal hydride/H₂ interconversion platform introduces new tools to address challenges associated with hydrogen storage platforms and contributes toward the development of room-temperature hydrogen storage platforms.

For nanochemistry, precise manipulation of nanoscale structures and the accompanying chemical properties at atomic precision is one of the greatest challenges today. The scientific community strives to develop and design customized nanomaterials, while molecular interactions often serve as key tools or probes for this atomically precise undertaking. In this Perspective, metal nanoclusters, especially gold nanoclusters, serve as a good platform for understanding such nanoscale interactions. These nanoclusters often have a core size of about 2 nm, a defined number of core metal atoms, and protecting ligands with known crystal structure. The atomically precise structure of metal nanoclusters allows us to discuss how the molecular interactions facilitate the systematic modification and functionalization of nanoclusters from their inner core, through the ligand shell, to the external assembly. Interestingly, the atomic packing structure of the nanocluster core can be affected by forces on the surface. After discussing the core structure, we examine various atomic-level strategies to enhance their photoluminescent quantum yield and improve nanoclusters' catalytic performance. Beyond the single cluster level, various attractive or repulsive molecular interactions have been employed to engineer the self-assembly behavior and thus packing morphology of metal nanoclusters. The methodological and fundamental insights systemized in this review should be useful for customizing the cluster structure and assembly patterns at the atomic level.

For nanochemistry, precise manipulation of nanoscale structures and the accompanying chemical properties at atomic precision is one of the greatest challenges today. The scientific community strives to develop and design customized nanomaterials, while molecular interactions often serve as key tools or probes for this atomically precise undertaking. In this Perspective, metal nanoclusters, especially gold nanoclusters, serve as a good platform for understanding such nanoscale interactions. These nanoclusters often have a core size of about 2 nm, a defined number of core metal atoms, and protecting ligands with known crystal structure. The atomically precise structure of metal nanoclusters allows us to discuss how the molecular interactions facilitate the systematic modification and functionalization of nanoclusters from their inner core, through the ligand shell, to the external assembly. Interestingly, the atomic packing structure of the nanocluster core can be affected by forces on the surface. After discussing the core structure, we examine various atomic-level strategies to enhance their photoluminescent quantum yield and improve nanoclusters’ catalytic performance. Beyond the single cluster level, various attractive or repulsive molecular interactions have been employed to engineer the self-assembly behavior and thus packing morphology of metal nanoclusters. The methodological and fundamental insights systemized in this review should be useful for customizing the cluster structure and assembly patterns at the atomic level.

Multiple helicenes display distinct aromatic cores characterized by highly twisted rings that are shared or fused with constituent helicene moieties. Diversifying these aromatic cores unlocks avenues for creating multiple helicenes with distinct properties and topologies. Herein we report the synthesis of a quadruple[6]helicene featuring pyrene as the aromatic core. The synthesis involved key steps of the annulative π-extension reaction and Scholl reaction. By extending multiple helicenes along the axial direction, the degree of contortion of the aromatic core can be controlled from nearly flat to highly twisted. Notably, quadruple[6]helicene exhibits a significant red-shift of 0.49 eV compared to quadruple[4]helicenes, of which the red-shift arises from both π-extension and augmented effective conjugation due to enhanced twisting. Quantum chemical calculations demonstrate that the degree of contortion in the pyrene core adeptly governs the energy levels of the HOMO and LUMO, which offers an alternative strategy beyond mere enlargement of the π backbone. An intriguing serendipitous finding reveals the formation of one-molecule-thick supramolecular homochiral nanosheets through self-interlocking interactions of enantiomers in single crystals, a rare packing motif for multiple helicenes.

Multiple helicenes display distinct aromatic cores characterized by highly twisted rings that are shared or fused with constituent helicene moieties. Diversifying these aromatic cores unlocks avenues for creating multiple helicenes with distinct properties and topologies. Herein we report the synthesis of a quadruple[6]helicene featuring pyrene as the aromatic core. The synthesis involved key steps of the annulative π-extension reaction and Scholl reaction. By extending multiple helicenes along the axial direction, the degree of contortion of the aromatic core can be controlled from nearly flat to highly twisted. Notably, quadruple[6]helicene exhibits a significant red-shift of 0.49 eV compared to quadruple[4]helicenes, of which the red-shift arises from both π-extension and augmented effective conjugation due to enhanced twisting. Quantum chemical calculations demonstrate that the degree of contortion in the pyrene core adeptly governs the energy levels of the HOMO and LUMO, which offers an alternative strategy beyond mere enlargement of the π backbone. An intriguing serendipitous finding reveals the formation of one-molecule-thick supramolecular homochiral nanosheets through self-interlocking interactions of enantiomers in single crystals, a rare packing motif for multiple helicenes.

Copper-doped Bi₂Se₃ (Cu _x Bi₂Se₃) is of considerable interest for tailoring its electronic properties and inducing exotic charge correlations while retaining the unique Dirac surface states. However, the copper dopants in Cu _x Bi₂Se₃ display complex electronic behaviors and may function as either electron donors or acceptors depending on their concentration and atomic sites within the Bi₂Se₃ crystal lattice. Thus, a precise understanding and control of the doping concentration and sites is of both fundamental and practical significance. Herein, we report a solution-based one-pot synthesis of Cu _x Bi₂Se₃ nanoplates with systematically tunable Cu doping concentrations and doping sites. Our studies reveal a gradual evolution from intercalative sites to substitutional sites with increasing Cu concentrations. The Cu atoms at intercalative sites function as electron donors while those at the substitutional sites function as electron acceptors, producing distinct effects on the electronic properties of the resulting materials. We further show that Cu_0.18Bi₂Se₃ exhibits superconducting behavior, which is not present in Bi₂Se₃, highlighting the essential role of Cu doping in tailoring exotic quantum properties. This study establishes an efficient methodology for precise synthesis of Cu _x Bi₂Se₃ with tailored doping concentrations, doping sites, and electronic properties.

Copper-doped Bi₂Se₃ (Cu_xBi₂Se₃) is of considerable interest for tailoring its electronic properties and inducing exotic charge correlations while retaining the unique Dirac surface states. However, the copper dopants in Cu_xBi₂Se₃ display complex electronic behaviors and may function as either electron donors or acceptors depending on their concentration and atomic sites within the Bi₂Se₃ crystal lattice. Thus, a precise understanding and control of the doping concentration and sites is of both fundamental and practical significance. Herein, we report a solution-based one-pot synthesis of Cu_xBi₂Se₃ nanoplates with systematically tunable Cu doping concentrations and doping sites. Our studies reveal a gradual evolution from intercalative sites to substitutional sites with increasing Cu concentrations. The Cu atoms at intercalative sites function as electron donors while those at the substitutional sites function as electron acceptors, producing distinct effects on the electronic properties of the resulting materials. We further show that Cu_0.18Bi₂Se₃ exhibits superconducting behavior, which is not present in Bi₂Se₃, highlighting the essential role of Cu doping in tailoring exotic quantum properties. This study establishes an efficient methodology for precise synthesis of Cu_xBi₂Se₃ with tailored doping concentrations, doping sites, and electronic properties.

Nonclassical C-glycosides, distinguished by their unique glycosidic bond connection mode, represent a promising avenue for the development of carbohydrate-based drugs. However, the accessibility of nonclassical C-glycosides hinders broader investigations into their structural features and modes of action. Herein, we present the first example of Pd-catalyzed stereospecific glycosylation of nonclassical anomeric stannanes with aryl or vinyl halides. This method furnishes desired nonclassical aryl and vinyl C-glycosides in good to excellent yields, while allowing for exclusive control of nonclassical anomeric configuration. Of significant note is the demonstration of the generality and practicality of this nonclassical C-glycosylation approach across more than 50 examples, encompassing various protected and unprotected saccharides, deoxy sugars, oligopeptides, and complex molecules. Furthermore, biological evaluation indicates that nonclassical C-glycosylation modifications of drug molecules can positively impact their biological activity. Additionally, extensive computational studies are conducted to elucidate the rationale behind differences in reaction reactivity, unveiling a transmetalation transition state containing silver (Ag) within a six-membered ring. Given its remarkable controllability, predictability, and consistently high chemical selectivity and stereospecificity regarding nonclassical anomeric carbon and Z/E configuration, the method outlined in this study offers a unique solution to the longstanding challenge of accessing nonclassical C-glycosides with exclusive stereocontrol.