Latest ArticlesA convenient photocatalytic multi-component reaction of alkenes, quinoxalin-2(1H)-ones, and diazo compounds has been developed in the presence of water. A number of ester-containing quinoxalin-2(1H)-ones could be efficiently obtained in moderate to good yields at room temperature. This metal-free visible-light-driven tandem reaction was conducted through proton-coupled electron transfer (PCET) process using water as the hydrogen donor and 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) as the photocatalyst.
Selective catalytic transfer hydrogenation (CTH) of carbonyl compounds to obtain specific alcohols holds significant importance across various fields. Achieving multiple selectivity in CTH is particularly crucial, but full of great challenge. Herein, a cationic In-captured Zr-porphyrin framework (1) with nanosized pores/cages was successfully constructed and showed high structure stability. Catalytic investigations revealed that 1 displayed highly multi-selective CTH of aldehydes and ketones containing both chemo- and size selectivity for the first time. The CTH of aldehydes and ketones exhibited remarkable reductive selectivity of 99% towards CO bonds into CHOH in the presence of -NO2, -CN and CC groups. Through tuning the reaction conditions, 1 also exhibited highly selective reduction of 97% for -CHO groups in the simultaneous presence of -CHO and -COCH3 groups in intra- and intermolecular settings. Remarkably, reductive selectivity towards -CHO group remained prominent among five concurrent unsaturated groups mentioned above. Additionally, the definite pore size of 1 facilitated volume control of substrates, enabling size selectivity. 1 as a heterogeneous catalyst was further confirmed by leaching tests, and maintained high activity even after being used for at least six cycles. Mechanistic studies have revealed that Zr6O8 clusters served as the catalytic centers and the observed chemoselectivity mainly results from the synergistic effect of distinct metal sites within 1. The heightened selectivity towards -CHO over -COCH3 can be attributed to the easier realization of transfer hydrogenation processes for -CHO compared to -COCH3.
Supramolecular luminescent materials (SLMs) exhibit exceptional luminescence properties and the ability to be intelligently regulated through diverse assembly approaches, making them highly attractive in the field of luminescent materials. In recent years, the novel macrocyclic arenes characterized by unique electron-rich structures, ease of derivatization, tunable conformations and even inherent luminescence properties afford much opportunities to create such dynamic smart luminescent materials. The incorporation of macrocyclic arenes into SLMs leads to simple preparation process, diverse photophysical phenomena and sophisticated regulatory mechanisms, which is also currently one of the most frontier and hot topics in macrocyclic and supramolecular chemistry and even luminescent materials. In this review, the research advances in construction and applications of SLMs based on macrocyclic arenes in the last several years will be presented from the different assembly strategies, including host-guest complexes, supramolecular polymers, nanoparticles, and other assemblies. Moreover, some insights into future directions for this research area will also be offered.
Boron-doped diamond (BDD) is a well-known anode material with a high pollutant degradation ability for electrochemical oxidation wastewater treatment. Nevertheless, the cost of production and mechanical strength of BDD membranes remain unsatisfactory. Magnetic BDD particles derived from industrial waste may represent a promising alternative to BDD membranes, although the challenge remains in assembling these particles into a usable electrode. In this study, magnetic BDD particles were attracted to a Ti/RuO2-IrO2 electrode using a magnet, thus constituting a novel 2.5-dimensional (2.5D) electrode. To ascertain the structure-activity relationship of the novel electrode, essential characterizations, multi-physics simulations, pollutant degradation and electrosynthesis experiments were conducted. The results indicate that an appropriate quantity of BDD particles (0.1 g/cm2) can enhance the number of active sites by approximately 20%. A strong synergistic effect was observed between the Ti/RuO2-IrO2 and BDD particles in the degradation of various pollutants, including azo dye, p-benzoquinone, succinic acid and four kinds of real wastewaters, as well as glycerol conversion. The joint active sites on the interface between Ti/RuO2-IrO2 and BDD particles, as well as the inner active sites on BDD particles, have been identified as crucial in the mineralization of pollutants and the generation of value-added products. The optimal amount of BDD particles (0.1 g/cm2) is sufficient to preserve the joint active sites and to maintain an adequate polarization on the BDD particles. Nevertheless, the hybrid feature of the 2.5D electrode is diminished when a greater quantity of BDD particles (0.3 g/cm2) is loaded.
Lithium metal has emerged as a highly promising anode material for enhancing the energy density of secondary batteries, attributed to its high theoretical specific capacity and low electrochemical potential. However, safety concerns related to lithium dendrite-induced short circuits and suboptimal electrochemical performance have impeded the commercial viability of lithium metal batteries. Current research efforts primarily focus on altering the solvated structure of Li+ by modifying the current collector or introducing electrolyte additives to lower the nucleation barrier, expedite the desolvation process, and suppress the growth of lithium dendrites. Nevertheless, an integrated approach that combines the advantages of these two strategies remains elusive. In this study, we successfully employed metal-organic salt additives with lithophilic properties to accelerate the desolvation process, reduce the nucleation barrier of Li+, and modulate its solvated structure. This approach enhanced the inorganic compound content in the solid electrolyte interphase (SEI) on lithium foil surfaces, leading to stable Li+ deposition and stripping. Specifically, LiCu cells demonstrated excellent cycle life and Coulombic efficiency (97.28% and 98.59%, respectively) at 0.5 mA/cm2@0.5 mAh/cm2 and 1 mA/cm2@1 mAh/cm2 for 410 and 240 cycles, respectively. LiLi symmetrical cells showed no short circuit at 1 mA/cm2@1 mAh/cm2 for 1150 h, and LiLFP full cells retained 68.9% of their capacity (104.6 mAh/g) after 250 cycles at N/P (1.1:1.0) with a current density of 1 C.
Although supramolecular transformations have been emerged as a potent strategy for transitioning between various topologies, post-modification induced topological transformations have never been explored in the context of [2]catenane topologies. In this study, we present a novel supramolecular transformation between a Hopf link and a macrocycle, induced by the Diels–Alder click reaction. By strategically selecting the half-sandwich ruthenium binuclear fragment B as a rigid capping agent, we successfully integrated tetrazine moieties into the metalla[2]catenane structure. We demonstrated that the introduction of 2,5-norbornadiene (NBD) as an external stimulus allows for the transformation of the novel metalla[2]catenane, featuring reactive tetrazine sites, into the corresponding monomeric ring through post-modification for the first time. The synthetic results are corroborated by single-crystal X-ray diffraction analysis, ESI-TOF/MS, elemental analysis, and detailed solution-state NMR techniques.
Aryl-ether bonds are facile to attack by oxidizing radicals, thus stimulating the exploitation of ether-free polymers as proton exchange membranes (PEMs) for the long-lasting operation of fuel cells. In this study, a novel class of PEMs derived from all-carbon fluorinated backbone polymers containing sulfide-linked alkyl sulfonic acid side chains have been developed through a straightforward and effective synthetic procedure. The sulfide-linked alkyl sulfonate groups were tethered to the poly(triphenylene pentafluorophenyl) backbone through a quantified and site-specific para-fluoro-thiol click reaction. Owing to the existence of obvious phase separation morphology between hydrophobic main chain and hydrophilic sulfonate groups in the side chains, resulting PEMs demonstrated favorable proton conductivity of 142.5 mS/cm at 80 ℃, while maintaining excellent dimensional stability with an in-plane swelling ratio of <17% as well as a through-plane swelling ratio of <25%. They also exhibit elevated thermal decomposition temperatures (Td5% exceeding 300 ℃) alongside high tensile strength (>50 MPa). Furthermore, the ether-free full-carbon fluorinated main chain and the -S- group in the side chain, which serves as an effective free-radical scavenger, providing good chemical stability during Fenton's test. The PEMs achieved a maximum power density of 407 mW/cm2 in a single H2/air fuel cell, and an open-circuit voltage decline rate of 0.275 mV/h in a durability test at 30% RH and 80 ℃. Concurrently, the hydrogen crossover current density is only 1/3 of that of Nafion 212. These findings reveal that the resulted PEMs display considerable antioxidative properties along with commendable performance, with prospective applications in proton exchange membrane fuel cells.
Quantum dots (QDs), a type of nanoscale semiconductor material with unique optical and electrical properties like adjustable emission and high photoluminescence quantum yields, are suitable for applications in optoelectronics. However, QDs are typically degraded under humid and high-temperature circumstances, greatly limiting their practical value. Coating the QD surface with an inorganic silica layer is a feasible method for improving stability and endurance in a variety of applications. This paper comprehensively reviews silica coating methodologies on QD surfaces and explores their applications in optoelectronic domains. Firstly, the paper provides mainstream silica coating approaches, which can be divided into two categories: in-situ hydrolysis of silylating reagents on QD surfaces and template techniques for encapsulation QDs. Subsequently, the recent applications of the silica-coated QDs on optoelectronic fields including light-emitting diodes, solar cells, photodetectors were discussed. Finally, it reviews recent advances in silica-coated QD technology and prospects for future applications.
Single-molecule junctions are building blocks for constructing molecular devices. However, intermolecular interactions like winding bring additional interference among the surrounding molecules, which inhibits the intrinsic coherent transport through single-molecule junctions. Here, we employed a nanocavity (dimethoxypillar[5]arene, DMP[5]), which is analogous to electric cables, to confine the conformation of flexible chains (1,8-diaminooctane, DAO) via host-guest interaction. Single-molecule conductance measurements indicate that the conductance of DAO encapsulated with DMP[5] is as high as that of pure DAO, as reproduced by theoretical simulations. Intriguingly, the molecular lengths of the DAO encapsulated with DMP[5] increase from 1.13 nm to 1.46 nm compared with the pure DAO, indicating that DMP[5] keeps DAO upright-standing via the confinement effect. This work provides a new strategy to decouple the intermolecular interaction by employing an insulating sheath, enabling the high-density integration of single-molecule devices.
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