Science China Chemistry最新文献

Single-atom catalyst has garnered widespread attention to mimic mature enzymes due to its well-defined atomic structure and coordination environments. However, since the carbon-carbon (C–C) coupling reactions require synergistic catalysis of multiple sites, single-atom catalysts suffer from insufficient active sites and unclear reaction mechanisms. Controlling the reaction intermediates in a precisely targeted pocket through careful metal-organic cage design is therefore crucial. Here, we prepare a tetrahedral [Cu₆L₄]-type boron–imidazolate cage integrating highly active Cu sites and optimized cavity, which exhibits enzyme like specific catalytic performance in electrochemical CO₂ reduction reaction (CO₂RR) to enhance the selectivity of C₂H₄. Electrochemical analyses and computational calculations suggest that the single Cu site together with neighboring boron-imidazolate ligands provides suitably synergistic effects that enable the energetically favorable formation of an *COCHO intermediate, a key step determining selectivity. As a result, the [Cu₆L₄]-type cage of BIC-145 achieves a Faradaic efficiency of 28% for C₂H₄ maintaining an average current density of −3.54 mA cm⁻² over a 5-hour electrolysis period. This work represents the first example for studying single-metal site catalysts with ultra-low coordination numbers through the rational design of metal-organic cages.

Tunable light–matter interactions are exhibited by organic low-dimensional crystals, making these crystals a promising platform for organic photonics. However, the precise synthesis of organic low-dimensional crystals remains challenging due to the stochastic nature of molecular nucleation processes. Herein, the directed nucleation process is driven by the introduction of metastable seed-crystals as the trunk, which ultimately leads to branched-array organic heterostructures. The successful formation of organic heterostructures with high-density branched arrays is attributed to the highest attachment energy (E_att(023) = −104.25 kcal mol⁻¹) of the exposed (023) crystal plane during the seed-crystal growth route. Significantly, these as-prepared heterostructures inherently have an ultralow lattice mismatch ratio η of 0.7% between trunk and branch, which contributes to the multi-channel photon transportation. Therefore, this work provides valuable insights into a versatile synthetic strategy for accessing low-dimensional heterostructures for integrated optoelectronics.

The development of an advanced phototheranostic platform that combines imaging and therapy in a single agent is an appealing yet challenging task. In this study, we successfully constructed three novel fluorescent probes by leveraging pharmaceutical chemistry and the design philosophy of the π-bridge effect. Through a systematic comparative analysis of their fluorescence properties, water solubility, molecular conformation, and electrostatic potential, we revealed the fundamental principles governing the optical behavior and biological selectivity of these probes. Notably, the probe TPhIQ-CNTh demonstrated extended fluorescence in the near-infrared region, a significant aggregation-induced emission (AIE) effect, and the ability to distinguish tumor cells from normal cells. Moreover, it efficiently generated reactive oxygen species (ROS) and specifically labeled lipid droplets, enabling the precise staining and killing of cancer cells. This study presents a practical strategy for designing precise tumor treatments that integrate efficient imaging-guided photodynamic therapy (PDT) by harnessing the unique properties of AIE materials.

This study concentrates on the development of high temperature polymer electrolyte membranes (HT-PEMs), which are essential components for HT-PEM fuel cells (HT-PEMFCs). Although the phosphoric acid (PA)-doped polybenzimidazole (PBI) has been regarded as the successful HT-PEM, this system still suffers from several challenges, including the use of carcinogenic monomers, complex synthesis procedures, and poor solubility in organic solvents. To develop more cost-effective, readily synthesized and high-performance alternatives, this study employs a simply superacid-catalyzed Friedel-Crafts reaction to synthesize a series of poly(triphenyl-co-dibenzo-18-crown-6 pyridine) copolymers, denoted as P(TP_x%-co-CE_y%), using p-triphenyl, dibenzo-18-crown-6 and 4-acetylpyridine as monomers. The copolymerized hydrophilic and bulky crown ether unites introduce large free volumes and multiple interaction sites with PA molecules, as elucidated by theoretical calculations. Meanwhile microphase separation structures are formed as confirmed by atomic force microscope (AFM), transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). Thus P(TP_x%-co-CE_y%) membranes exhibit excellent PA absorption and proton conduction abilities. For example, after immersing in 85 wt% PA at 30 °C, the P(TP_91%-co-CE_9%) membrane achieves a PA doping content of 205% and a high conductivity of 0.138 S cm⁻¹ at 180 °C, while maintaining a tensile strength of 7.5 MPa at room temperature. Without humidification and backpressure, the peak power density of an H₂-O₂ cell equipped with P(TP_91%-co-CE_9%)/205%PA reaches nearly 1200 mW cm⁻², representing one of the highest performances reported for PA-doped HT-PEMs to date. This work demonstrates the enormous potential of poly(triphenyl-co-crown ether pyridine) membranes in the HT-PEMFC applications.

Metabolic adaptation of cancer cells is a key tactic for maintaining their tumorigenicity and viability in the tumor immune microenvironment (TIME). Concurrent modulation on the metabolic pathway and immune system could change the living condition of cancer cells and potentiate the efficacy of anticancer drugs. A copper complex (DDCu) was designed to influence the energy metabolism of cancer cells and reshape the TIME. DDCu restrained the production and transportation of lactate by inhibiting the expression of lactate dehydrogenase and monocarboxylate transporter 4, thereby altering the metabolic pathway of cancer cells and improving the acidic tumor microenvironment. Meantime, DDCu was reduced to Cu⁺ by cellular glutathione to react with lipoylated proteins of the tricarboxylic acid cycle and destabilize the Fe–S cluster proteins, leading to the aggregation of dihydrolipoamide S-acetyltransferase and cuproptosis in cancer cells. Furthermore, DDCu promoted the polarization of macrophages from the M2 to M1 phenotype, activated CD4⁺ and CD8⁺ T cells, and reversed the immunosuppression. As a result, DDCu inhibited the tumor growth through a synergy between metabolic regulation and immunomodulation.

Tetra-coordinated fluoroboron compounds have garnered significant attention in organic light-emitting diodes (OLEDs) due to their remarkable optoelectronic properties and high chemical stability. However, the design of novel tetra-coordinated fluoroboron-based blue thermally activated delayed fluorescence (TADF) materials with excellent external quantum efficiency (EQE) remains crucial. In this study, a novel tetra-coordinated difluoroboron-based blue TADF material with 3,6-diphenylcarbazole donor and 2-(4-phenylpyridin-2-yl)phenolate difluoroboron acceptor molecular skeleton has been designed and synthesized. Benefiting from the larger dihedral angle (68.0°) between the donor and acceptor moieties, the compound m-PhCz-BF2 exhibited a smaller singlet-triplet energy splitting (ΔE_ST) value of 0.043 eV. As a result, a sky-blue emission with peak wavelengths of 491 and 487 nm and photoluminescence quantum yields (PLQY) of 93% and 99% were obtained in solution and doped film, respectively. Additionally, the m-PhCz-BF2 doped OLED demonstrated sky-blue electroluminescence (Commission Internationale de l’Éclairage, CIE_y ⩽ 0.33) and a high peak EQE of 27.4% with maximum brightness of 17,493 cd/m². Notably, these devices also achieved a high current efficiency of 62.5 cd/A and a power efficiency of 49.4 lm/W. These remarkable performances indicate that the m-PhCz-BF2 has the potential to function as a highly efficient TADF dopant for the fabrication of sky-blue OLEDs.