Latest ArticlesDue to the high local concentration of substrates in confined space, porous solid Brønsted acids have been extensively explored for efficient acid-catalyzed reaction. However, the porous structures with strong Brønsted acids lack long-term stability due to chemical hydrolysis. Moreover, the products inhibition effect in confined rigid cavities severely obstructs subsequent catalysis. Here, tubular Brønsted acid catalyst with unique recognition of protons was presented by self-assembly of pH-responsive aromatic amphiphiles. The responsive assembly could mechanically transfer hydrogen ions from low-concentration acidic solution into tubular defined pores, thereby producing effective catalytic activity for Mannich reactions in mildly acidic solution. Notably, the tubular catalyst unfolded into flat sheets upon addition of triethylamine for efficient release of products, which could be recovered by subsequent acidification and the catalytic activity still remained. Therefore, the porous Brønsted acid with reversible assembly provides a new strategy for mass synthesis through increasing conversion times.
In this work, we have designed and synthesized a cyano-substituted p-phenylenevinylene derivative (PPTA), which can self-assemble into positively charged nanoparticles in an aqueous solution with a deep green fluorescence. An anionic polyelectrolyte material guar gum modified by carboxylic acid (GP5A) was chosen to build an artificial light-harvesting system (LHS) through self-assembly with PPTA, in which two acceptors Eosin Y (EY) and Nile red (NiR) were loaded into the PPTA-GP5A assemblies through electrostatic interaction and Van der Waals force. By adjusting the molar ratio of PPTA-GP5A/EY at 1:0.004, the one-step artificial LHS can exhibit high energy transfer efficiency (38.9%) and antenna effect (AE) (4.6). Subsequently, with the addition of NiR, the and AE of the two-step sequential artificial LHS were calculated to be 71.9% and 13.5, respectively. Moreover, the two-step artificial LHS constructed by the polyelectrolyte material GP5A can be used as a nanoreactor to photocatalyst alkylation of C-H bonds of phenyl vinyl sulfone (PVS) and tetrahydrofuran (THF) in water with a yield of 42%. Therefore, we have constructed an artificial LHS with two-step energy transfer based on polyelectrolytes through the electrostatic interaction to improve energy transfer efficiency, which can also be used as a nanoreactor for photocatalysis.
Photoresponsive supramolecular systems have merited extensive attention for their applications in materials science and life science. Here, we synthesized a water-soluble stiff-stilbene molecular photoswitch, exhibiting outstanding photoisomerization reaction between its (E)- and (Z)-configurations upon irradiation at distinct light. The photoswitch can assemble with cucurbit[7]uril (CB[7]) to form a superior fluorescent supramolecular complex (compared to the only guest) with excellent water solubility, which manifested dramatic photoluminescence enhancement caused by restriction of intramolecular rotation and remained good photochromic characteristics. Furthermore, introduction of CB[7] influence photoreaction quantum yield (Φ) of the stiff-stilbene, leading to reduction of ΦE→Z and increase of ΦZ→E of the stiff-stilbene. Importantly, the photoadjustable supramolecular assembly can act as a fluorescence switch, and the phototunable guest further selectively modulate G-quadruplex structure of Tel22 upon light irradiation or with addition of CB[7]. The study provides a new simple way for accurately regulating photochromic properties of molecular switches and developing smart materials with potential applications in controlled modulation of G-quadruplex, targeted biological imaging and so on.
Molecular oxygen within Polyoxometalates (POMs) based compounds are ideal oxidants with high atom economy and its use results in the production of water as the only byproduct. Significant progress has been made in the development of catalytic methods for aerobic alcohol oxidation to have aldehydes and ketones with POMs based compounds. They are alternative to the use of traditional hypervalent iodine catalyst systems which are with molecular oxygen as a terminal oxidant. Further, POMs based catalysts can be applied to catalytic reactions with different modes of energization such as thermocatalysis, photocatalysis and electrocatalysis. This review summarizes the frontier advances in polyoxometalates for catalytic alcohol selective oxidation in thermocatalytic, electrocatalytic, and photocatalytic applications. The three advantages of POM catalysts in terms of performance, economy, and environmental protection are highlighted. These include the use of sol-gel and electrostatic assembly methods to increase the reaction surface area, reduce the use of precious metals, and improve the stability of POMs catalysts. The field of selective alcohol oxidation is advanced. Finally, the challenges of preparing more efficient and "green" catalysts are presented.
Zinc-ion hybrid capacitors (ZICs) are considered as newly-emerging and competitive candidates for energy storage devices due to the integration of characteristic capacitor-level power and complementary battery-level energy. The practical application of rising ZICs still faces the specific capacity and dynamics mismatch between the two electrodes with different energy storage mechanisms, which cannot meet the ever-growing indicator demand for portable electronic displays and public traffic facilities. Focusing on these unresolved issues, this mini-review presents recent advances in ZICs referring to the hybrid energy storage mechanism, design strategies of both capacitor-type and battery-type electrode materials, and electrolyte research toward advanced performances (e.g., high operational potential, wide adaptive temperature). Finally, current challenges and future outlook have been proposed to guide further exploration of next-generation ZICs with a combination of high-power delivery, high-energy output and high-quality service durability.
Rechargeable aqueous zinc-ion batteries (AZIBs) are attracting tremendous attention because of their intrinsic merits such as high safety and low cost. Cathode plays a critical role in enhancing the electrochemical performance of AZIBs. However, it is difficult to design a robust and high-efficiency cathode material and further implement the commercialization of AZIBs. Metal-organic frameworks (MOFs) electroactive compounds are attractive to serve as the cathode of AZIBs due to their unique porosity and crystal structures, resource renewability and structural diversity. In this work, a calcium-pure terephthalates acid framework (Ca-PTA·3H2O) was synthesized by facile hydrolysis and cationic exchange method, then explored as a novel cathode for AZIBs. The results highlight a high specific capacity of 431 mAh/g (0.51 mAh/cm2) at a current density of 50 mA/g, and excellent cycle performance with capacity retention of ~90% after 2700 cycles at 500 mA/g. The following up characterizations investigate the reversible zinc storage mechanism in detail. This experiment made a specific contribution to the exploration of the new MOF as a competitive cathode for AZIBs.
Radiotherapy is widely used clinically, but the toxic and side effects of nonselective killing of high-energy radiation limit its application. Finding biocompatible materials to assemble radiotherapy sensitizers and studying their sensitization patterns are of great significance for the clinical application. Here, biocompatible zinc porphyrin was chosen as sub-unit to construct various dimensional coordination frameworks. By employing top-down approach, suitable nanoframeworks with various dimensional zinc porphyrin were synthesized as radiosensitizers. The experimental data showed that high-dimensional zinc porphyrin nanoframeworks exhibit higher X-ray response performance.
The performance of Li||Sb-Sn liquid metal batteries (LMBs) is hindered by the corrosion of the Sb-Sn cathode on its current collector. Herein, a uniform, dense, and low-oxidized W coating was prepared by plasma spraying, which can effectively resist the corrosion of the cathode and improve the cycle stability of the Li||Sb-Sn LMBs. For the first time, micro-CT nondestructive inspection is applied in the field of LMBs. The corrosion micromorphology and composition evolution of the SS304 matrix and Sb-Sn cathode with or without the plasma-sprayed W coating is obtained without disassembling the battery, which proves that the W coating can effectively protect the SS304 matrix. Our autonomous new LMB device for nondestructive inspection is universal and can be applied to different LMBs systems for advancing knowledge of corrosion mechanism and protection. This work guarantees the ability to directly visualize the inner critical positions in three dimensions and fills the knowledge gap in the field of LMB detection technology.
Materials with controllable luminescence colors are highly desirable for numerous promising applications, however, the preparation of such materials, particularly with color-controllable room-temperature phosphorescence (RTP), remains a formidable challenge. In this work, we reported on a facile strategy to prepare color-controllable RTP materials via the pyrolysis of a mixture containing 1-(2-hydroxyethyl)-urea (H-urea) and boric acid (BA). By controlling the pyrolysis temperatures, the as-prepared materials exhibited ultralong RTP with emission colors ranging from cyan, green, to yellow. Further studies revealed that multiple luminescent centers formed from H-urea, which were in-situ embedded in the B2O3 matrix (produced from BA) during the pyrolysis process. The contents of the different luminescent centers could be regulated by the pyrolysis temperatures, resulting in color-tunable RTP. Significantly, the luminescent center engineering and in-situ immobilization strategy not only provided a facile method for conveniently preparing color-controllable RTP materials, but also endowed the materials prepared at relatively lower temperatures with color-changeable RTP features under thermal stimulus. Considering their unique properties, the potential applications of the as-obtained materials for advanced anti-counterfeiting and information encryption were preliminarily demonstrated.
Ferroelastic materials with switchable spontaneous strain possess widely potential applications in the field of energy and information conversion. Recently, organic-inorganic hybrid halide double perovskites (OIHHDPs) have become a charming new platform for developing various functional materials, such as ferroelectrics, fluorescence and X-ray detection. Nevertheless, OIHHDP ferroelastic materials, especially high-temperature ones, are rare. Herein, we initially synthesized an OIHHDP ferroelastic, (2,2-difluoroethanamine)2[(NH4)InCl6] (1), which possesses a ferroelastic phase transition at 407 K. Moreover, thanks to the flexible B-site for OIHHDPs, we replaced the NH4+ ions within [(NH4)InCl6]n2n– formworks with K+ ions, which endows with coordination bonds between 2,2-difluoroethanamine organic cations and [KInCl6]n2n– formworks. Due to the existence of coordination bonds, the phase transition temperature of (2,2-difluoroethanamine)2[KInCl6] (2) can reach 458 K. As far as we know, this value is the highest reported in OIHHDP ferroelastics. This work offers inspiration for the design of high-temperature OIHHDP phase transition materials including ferroelectrics and ferroelastics.
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