Latest ArticlesAchieving precise control over product selectivity in electrochemical alkene oxidation requires catalysts that can be programmed to favor specific bond-forming pathways. Here, we demonstrate that carbon dots (CDs) serve as programmable interfacial mediators to direct propylene electro oxidation exclusively toward the epoxy bond formation on Ag-graphene hybrids. The engineered Ag-6CDs/G catalyst exhibits a remarkable propylene oxide (PO) Faradaic efficiency of 39.71% and a production rate of 218.85 mmol g‒1 h‒1. We deconvolute the triple role of CDs in programming this selectivity: (1) As a structural mediator that dictates Ag nanoparticle size and spatial distribution, maximizing active site density; (2) as an electronic mediator that fine tunes the Ag d band center, thereby optimizing the adsorption strength ratio between propylene (C=C) and the crucial *OH intermediate to a value ideal for C–O coupling; and (3) as a local microenvironment mediator whose oxygenated surface facilitates water activation, ensuring an efficient supply of oxygen species. This multifunctional mediation is rigorously verified through in situ spectroscopy, electrochemical diagnostics, and density functional theory (DFT) calculations, which collectively map the reaction coordinate and identify the CD induced shifts in adsorption energetics as the origin of the selective pathway. Our work provides a generalizable blueprint for programming bond forming selectivity in electrocatalysis through rational interfacial design.
The copper-catalyzed enantioselective [4 + 1] annulation of yne-thienyl esters with 1,3-dicarbonyl compounds was realized through an elegant remote stereocontrol strategy. Greatly diverse spirocycles were obtained in moderate to good yields with excellent stereochemical control. Moreover, preliminary mechanistic studies suggest an remote substitution and Conia-ene cascade pathway on the remote stereochemical induction progress.
Bilayer nanographenes represent an emerging class of molecular carbon architectures that provide unique opportunities to explore interlayer electronic communication and chiroptical phenomena in confined π-systems. However, the development of well-defined chiral bilayer nanographenes capable of transferring chirality across extended π-surfaces and supramolecular assemblies remains challenging. Herein, we report the synthesis and structural characterization of a chiral bilayer spironanographene (spiro-NG) composed of two nanographene subunits connected through a rigid spirobifluorene core. Single-crystal X-ray diffraction reveals a folded bilayer geometry that enforces significant interlayer π-overlap while simultaneously generating intrinsic molecular chirality. Enantiomeric resolution affords configurationally stable P- and M-spiro-NG, which display pronounced circular dichroism (CD) and circularly polarized luminescence (CPL). Furthermore, the exposed π-surfaces of the bilayer scaffold enable π-surface recognition with coronene, leading to hetero-π stacked co-crystals that highlight the supramolecular adaptability of the nanographene framework. Notably, supramolecular co-assembly of spiro-NG with achiral fluorophores enables chirality transfer through Förster resonance energy transfer, resulting in induced CPL emission with tunable wavelengths. These findings establish bilayer spironanographene as a versatile chiral nanographene platform that integrates structural chirality, supramolecular recognition, and chiroptical functionality, offering new opportunities for the development of chiral carbon-based photonic materials.
Alkali metal batteries (AMBs) have emerged as promising candidates for next-generation high-energy-density energy storage systems due to their high theoretical specific capacity and high output voltage. However, further application of AMBs is hindered by severe dendritic growth and large volume expansion of alkali metal anodes (AMAs) during cycling, as well as their unstable interphases. In this context, carbon dot-based nanomaterials (CDNMs), with their superior specific surface area, tunable heteroatom doping, and abundant surface functional groups, have been extensively investigated to stabilize AMAs, demonstrating remarkable potential in addressing aforementioned issues. Considering the rapidly growing research enthusiasm in this topic in recent years, here, we comprehensively summarize recent progress in application of CDNMs in stable and dendrite-free AMAs. First, the critical challenges of alkali metal anodes and the corresponding modification strategies in alkali metal batteries are discussed. Furthermore, the structure and properties of carbon dots (CDs) are introduced, as well as the advantages, disadvantages, and research progress of various CDs preparation methods are summarized from both the top-down and bottom-up perspectives. In addition, the relationship between fabrication methods, micro/nanostructure, and electrochemical performance are systematically summarized and discussed. Finally, in light of the current research status, the challenges and opportunities of the application of CDNMs in AMBs are proposed.
Amphipathic TAP-dU and TAP-dC were designed with a distinctive donor-π-acceptor (D-π-A) electronic architecture, which the nucleoside function and TAP-moiety act as the electron donor and electron acceptor, respectively. The base-triggered charge transfer is influenced by protonation/deprotonation states and conformational twisting. Hydrogen-bonding interactions between the pyrimidine and ribose were thoroughly examined by nuclear magnetic resonance (1H NMR) spectroscopy, single-crystal X-ray crystallography, and density functional theory (DFT) calculations. Importantly, TAP-dU exhibits pH-dependent self-assembly and π-π stacking interactions, leading to an aggregated fluorescence multicolor shift from blue to green to yellow, with emission wavelengths reaching up to 545 nm. Unlike our previously reported nucleus-targeted TPE-dU/TPE-dC and mitochondria-targeted TPE-FdU, this study demonstrates that both nontoxic TAP-dC and TAP-dU effectively achieve endoplasmic reticulum (ER)-specific imaging in NIH-3T3 and HeLa cells. Additionally, due to its biocompatibility, TAP-dC also serves as a promising candidate for in vivo Ag+ detection in NIH-3T3 and zebrafish via bioimaging.
Zwitterionic hydrogels as a new generation of functional materials are widely used in many frontier fields. However, zwitterionic hydrogels usually contain a large amount of active water and are inevitably frozen at low temperatures, thus sacrificing their mechanical properties and conductivity, which greatly limits their application. Herein, a novel strategy, namely the unique anti-polyelectrolyte effect (APE) of zwitterions is proposed to reduce the freezing point of zwitterionic hydrogels. The regulation mechanism of this strategy is that the electrostatic associated zwitterionic groups are exposed, thus increasing hydration by allowing these groups to establish strong hydrogen bonding with water molecules during the volume expansion process of zwitterionic polymer in salt. The overall water activity is decreased in the hydrogels, thus reducing the freezing point of the hydrogels. Sulfonic-based 2-(methacryloyloxy)ethyl dimethyl(3-sulfopropyl)-ammonium hydroxide (SBMA) and carboxylic-based 2-carboxy-N,N-dimethyl-N-(2′-methacryloyloxyethyl)ethanaminium inner salt (CBMA) zwitterionic monomers are selected as a proof of concept. SBMA based hydrogels with strong APE have a higher bound water content and a lower free water content than CBMA based hydrogels with almost no APE. Benefitting from the strong APE, the freezing point of SBMA based hydrogel (−20.9 ℃) is significantly lower than that of CBMA based hydrogel (−12.4 ℃). This work offers a practical and meaningful guidance for the design of anti-freezing zwitterionic hydrogels and further promotes the application of zwitterionic hydrogels in low temperature environments.
How to break through the oxidation energy barrier of C(sp3)-H bonds with high dissociation energy and prevent excessive oxidation is a significant challenge. This study presents the atomic-level regulation of POMOF dimensions by inducing structural differentiation through hydroxide end-capping. Two homologous isomers, named as Co-W10 and OH-Co-W10 respectively, have formed three-dimensional (3D) and two-dimensional (2D) structures through varied metal coordination modes. The 2D structure of OH-Co-W10 demonstrates excellent electron delocalization and transfer channels over the 3D structure of Co-W10. OH-Co-W10 exhibits enhanced oxygen activation capacity compared to Co-W10. In the catalytic oxidation of toluene, OH-Co-W10 achieves an impressive conversion rate of 98.1%, and the selectivity of benzaldehyde is as high as 97.3% (6720.2 µmol/g), which is cleaner and more efficient than that of the latest photocatalysts and Co-W10 (4713.1 µmol/g). In this study, the hydroxide capping strategy is proposed for generation of homologous isomers, offering a new direction for catalytic oxidation of C(sp3)-H bonds by expounding differences in active sites through distinct structural features.
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