Science China Chemistry最新文献

Herein, we perform a topological transformation by guest induction, converting [2]catenane Rh-1 into the Rh-3 molecular figure-of-eight. The transformation involves the interaction of longer π-acceptor half-sandwich Rh^III bimetallic building block B1 [(Cp*Rh)₂(TPPHZ)](OTf)₄ and π-donor bipyridyl ligands 4,4′-bis((pyridin-4-ylthio)methyl)-1,1′-biphenyl with four molecules of pyrene under ambient temperature in high yields. Intriguingly, despite the involvement of a single pyrene molecule in modifying [2]catenane Rh-2 by transitioning B1 to B2, the underlying skeleton of Rh-2 remains unaltered. Furthermore, we explored the application of these substances before and after the reaction for near-infrared (NIR) photothermal conversion. Through meticulous structural analysis, the π–π stacking interactions play a pivotal role in stabilizing the abovementioned structures, enhancing the nonradiative transitions and initiating photothermal conversion in solution. Based on the results, the introduction of pyrene significantly intensified the π–π stacking interactions but diminished the electron density between the adjacent NDI units, leading to a decrease in the NIR photothermal conversion efficiency (from 58.29% to 51.60%). In this study, an innovative approach is introduced for fabricating valuable half-sandwich-structured NIR photothermal conversion materials, and this research has promising prospects for enhancing the field of materials science with potential candidates for future development.

Rare earth metal-organic frameworks (RE-MOFs) have drawn wide attention owing to diverse network structures and various application prospects. However, due to the unpredictable formation of the nodes, it is still challenging to design novel RE-MOFs. A novel versatile strategy was developed employing a RE-acetate complex (RE₂(CH₃COO)₆·4H₂O) as a precursor to construct RE-MOFs. 2D RE-MOFs (RE-DBP) and 3D RE-MOFs (RE-TCPP) could be obtained by using dicarboxylic porphyrin ligands H₂DBP and tetracarboxylic porphyrin ligands H₂TCPP, respectively. Ten RE-MOFs were further synthesized to verify the universality of the methodology. Highly crystalline RE-MOFs could also be prepared at room temperature via the developed strategy, which could significantly promote large-scale preparation and practical application of RE-MOFs. As proof of the concept, the performance of porphyrin-based RE-MOFs was investigated in the photocatalytic cycloaddition of CO₂ with epoxides. Among the RE-DBP(Co) MOFs, Tb-DBP(Co) exhibited the best photocatalytic performance, which was also greater than that of the corresponding 3D MOF Tb-TCPP(Co) due to the optimal 2D structure and thus the accelerated photogenerated charge separation and transfer process. This work not only provides a novel versatile strategy to design and develop RE-MOFs, but also proposes a promising approach for the potential bulk production of RE-MOFs at room temperature.

Electrochemical CO₂ reduction reaction (CO₂RR) has been regarded as one of the most promising solutions to achieving “zero carbon emission”. In most of the CO₂RR-related studies, high-purity CO₂ has been employed as the feed gas; however, in practice, CO₂ is generally emitted in low concentrations, so it is of great significance to realize high-selectivity electroreduction of low-concentration CO₂ with large concentration fluctuation. In this work, we constructed a dual-active-site catalyst and successfully achieved CO₂ local enrichment and conversion for low-concentration CO₂. Operando experiments reveal that the catalyst has one type of site for activating CO₂ and one type of site for binding the reaction intermediates. The dual-active-site catalyst displays a selectivity for formic acid consistently above 97% over a broad potential window (from −0.9 to −1.6 V vs. RHE). Even when fed with a low-concentration CO₂ stream (volume ratio from 50% down to 10%), the dual-active-site catalyst could display high activity and selectivity (>91%). In particular, the selectivity is still above 85% when the CO₂ volume ratio is as low as 5%. This work offers a feasible route for converting low-concentration CO₂ via a synergistic effect for dual-active-site catalysts.

Lipid nanoparticles (LNPs) are non-viral nucleic acid delivery systems that show great potential in vaccine development and disease treatment. Although LNPs are particularly advantageous for in vivo delivery, the wide application of LNPs is impeded as their systemic delivery of nucleic acid drugs to extrahepatic tissues remains highly challenging. To address this issue, we developed lung-targeted polyzwitterionic LNPs with zwitterionic polymer poly(2-methyacryloyloxyethyl phosphorylcholine) (PMPC) modified 1,2-dimyristoyl-sn-glycerol lipid for the delivery of small interfering RNA (siRNA). Three libraries with 90 PMPC-LNPs@siRNA were established. The polyzwitterionic PMPC-LNPs had high siRNA encapsulation efficiency of about 90%. The findings revealed that polyzwitterionic PMPC-LNPs@siRNA absorbed protein corona with the main component of Vitronectin, mediating lung-targeted delivery of siRNA. With good cellular uptake and endo/lysosomal escape ability, in vitro and in vivo studies demonstrated that polyzwitterionic PMPC-LNPs with siRNA against tumor necrosis factor-α (TNF-α) could significantly down-regulate the TNF-α in mRNA and protein levels, and improved the pathological features of lung inflammation. Polyzwitterionic PMPC-LNPs@siRNA achieved safe and efficient treatment of lung inflammation. Therefore, this work offered a promising siRNA therapeutic approach for lung diseases.

The development of near-infrared (NIR) photosensitizers with aggregation-induced emission (AIE) properties, switchable luminescence colors, and satisfactory photodynamic therapy (PDT) effects on the treatment of fungal infection is of great importance but very challenging. Herein, two ionic organic luminogens are constructed by employing diphenylamine, diphenylacrylonitrile/1,2-diphenylethene, and methylated quinoline cation as building blocks. It is found that the resulting compounds TCQF and TQF show apparent AIE properties and produce intense fluorescence with high photoluminescence quantum yields of up to 31.2% in the solid state. In the meantime, their emission colors can be switched between red and NIR and in the NIR region by mechanical force and solvent vapor, respectively, thereby enabling remarkable and reversible mechanochromism with emission variations of up to 104 nm. More excitingly, TCQF and TQF can efficiently generate ROS under the illumination of white light and show excellent antimicrobial activities and satisfactory PDT capabilities. Inspired by the unique anti-fungus properties, TCQF is employed as a biocompatible NIR photosensitizer for treating wound infection with C. albicans, and apparent PDT effects are achieved. This work provides a new direction for the development of multifunctional NIR materials with AIE properties.

Lead halide perovskite quantum dots (LHP QDs) have been revealed to possess great potential in photocatalytic applications including CO₂ reduction, which however suffer from poor stability. Herein, a high crystalline hydrazine-linked three-dimensional (3D) covalent organic framework, USTB-17, was fabricated from the reaction between 12-connected building block and 4-connected 3,5,7-tetrakis(4-aldophenyl)-adamantane. Post-modification with Ni²⁺ affords the metallic framework USTB-17(Ni) followed by sequential deposition of the CH₃NH₂PbI₃ (MAPbI₃) perovskite QDs into its pores, generating the USTB-17(Ni)@MAPbI₃ composite. Powder X-ray diffraction analysis together with theoretical simulations and transmission electron microscopy discloses the crystalline nature of USTB-17, USTB-17(Ni), and USTB-17(Ni)@MAPbI₃ with an unprecedented non-interpenetrated hpt topology. The close contact of QDs inside the COF pores with the Ni catalytic site locating at the pore surface of COF allows a rapid transfer of the photogenerated electrons in QDs to the Ni catalytic sites, enhancing the photocatalytic activity for CO₂ reduction. This endows USTB-17(Ni)@MAPbI₃ with efficient photocatalysis performance for photocatalytic CO₂ reduction with CO generation rate of 365 µmol g⁻¹ h⁻¹ and CO selectivity up to 96% under visible-light irradiation, 7 times higher than that of USTB-17(Ni). After four cycles of reactions, the photocatalytic CO generation rate remains almost unchanged, demonstrating its excellent cycle stability.

The conventional method of fabricating hydrogels constantly confronts the conflict between elasticity and toughness, limiting their repetitive application. Achieving the desired elasticity through a simple and low-cost approach is a significant challenge for hydrogels, particularly through rational molecular design. Here, low-hysteresis and high-toughness hydrogels are developed from the design of a new feature monomer, N-acryloylethylsemicarbazide (NACE). Based on a concept of “asymmetric H-bonding design”, the unique double and triple H-bonding of NACE can result in a novel asymmetric crosslinking polymer with alternating strong and weak H-bonding regions. The NACE is copolymerized with acrylamide (AM) to regulate the mechanical properties of hydrogel via H-bonding density. The P(NACE-AM) ionic hydrogels are obtained simply and rapidly via one-step photopolymerization without a chemical cross-linking agent. The P(NACE-AM) hydrogels combine superb mechanical elasticity and toughness, and excellent ionic conductivity, showing great potential as durable ionic conductive devices for wearable utilization.

Large-area flexible organic photovoltaic (OPV) modules are challenging to achieve high power conversion efficiency (PCE). Electrical shunts or shortages generally occur in large-area OPV modules due to the ultrathin (100–200 nm) and soft active layers. Improving the surface smoothness of bottom transparent electrode will be able to suppress the shunts and shortages. In this work, we report a method to fabricate smooth and flexible transparent electrodes based on thin silver film, and further to fabricate efficient large-area flexible OPV modules. The fabricated thin silver transparent electrodes simultaneously have high conductivity, high optical transmittance, good mechanical flexibility and low surface roughness. Humidity exposure (h.e.) treatment on MoO₃ effectively facilitates the continuous growth of the thin transparent silver electrode. 6 nm silver film on MoO₃ (h.e.) on plastic substrate shows a transmittance up to 89%, a sheet resistance of 15 Ω/sq, and a low surface roughness with a root-mean-square value of 0.276 nm. Furthermore, 52-cm² flexible organic solar modules (15 subcells) showed a certified PCE of 12.66%. Furthermore, a 1350 cm² flexible component assembled by 25 pieces of 52–55 cm² modules showed certified PCE of 12.10% with an open-circuit voltage of 62.85 V.

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.

Immobilizing highly dispersed Au nanoparticles onto titanium silicalite-1 (TS-1) by a simple impregnation method under light is still a challenging task. In this work, a high photostable Au precursor protected by thiol ligands was firstly synthesized, and the as-prepared Au precursor displayed excellent stability under light for over 30 days, while the Au precursor without thiol ligands formed precipitates after just 2 h under light. Subsequently, the Au precursor protected by thiol ligands was immobilized on the external surface of uncalcined TS-1 (i.e., TS-1-B) by the incipient wetness impregnation method (IWI method) to prepare Au/TS-1-B catalyst. The activity of as-prepared Au/TS-1-B catalyst in the hydro-oxidation of propane to acetone was 1.4 times higher than that of the catalyst prepared by the deposition-precipitation urea method (DPU method). The structures of the Au/TS-1-B catalysts prepared by different methods were analyzed by multiple characterizations. Compared to the Au/TS-1-B catalyst prepared by the DPU method, the Au/TS-1-B catalyst synthesized by the IWI method exhibited a narrower size distribution of Au nanoparticles and had more small Au particles (<2 nm), which is the main reason for its superior activity. Additionally, the effects of gold loadings, reaction temperature and Si/Ti molar ratio on the catalytic performance of the Au/TS-1-B catalyst prepared by the IWI method were also investigated. In addition, the Au/TS-1-B catalyst prepared by the IWI method also exhibited excellent stability for over 140 h.