Latest ArticlesPillararenes are a new type of supramolecular hosts, and they have been widely applied in drug delivery, catalysis, separation process, and sensors. However, they have rarely been used to produce hydrogen. Here, we report that pillararenes were used as functional molecules to explore photocatalysts and efficiently promoted hydrogen production from water. The most common and easily synthesized p-dimethoxy pillar[5]arene (PI-OMe) was employed to form an organic-inorganic hybrid material with titanium dioxide (TiO2), denoted as PI-OMe-TiO2, using a convenient sol-gel method. When the material was loaded with Pt nanoparticles, the resulting Pt/PI-OMe-TiO2 had a good activity and stability in catalyzing water splitting to produce hydrogen under visible light. The optimized catalyst Pt/PI-OMe-TiO2(5.2 wt%) had a photocatalytic hydrogen production rate of 1736 µmol g−1 h−1 under visible light (λ > 420 nm) irradiation. The catalyst with a Pt loading of 0.5 wt% and a PI-OMe content of 5.2 wt% also showed good long-term durability after 10 cycles of 50 h testing. The total amount of hydrogen produced was 65.01 mmol/g, and the corresponding turnover number (TON) value was 2084. Our findings suggest that pillararene derivatives are promising functional molecules to make efficient and stable hybrid photocatalysts with TiO2 and open a new door to hydrogen production using visible light.
A three-dimensional flexible organic framework FOF-1 has been synthesized from the condensation of a tetratopic acylhydrazine and a rigid 4,4′-diphenyl-4,4′-bipyridinium dialdehyde in water through the quantitative formation of hydrazone bond. FOF-1 is further applied to construct a polycatenane framework FOF-pc-1 through the quantitative cucurbit[7]uril encapsulation for the diphenylbipyridinium subunits of the framework by making use of the dynamic nature of the hydrazone bond in water. The bipyridinium subunits in both frameworks can be reduced their radical cation counterparts to produce conjugated radical cation-linked dynamic organic frameworks rc-FOF-1 or rc-FOF-pc-1. Polycatenation is revealed to enhance the stability of the dynamic frameworks in water, whereas depolycatenation can be reached for both FOF-pc-1 and rc-FOF-pc-1 by using a ferrocene guest to form a more stable complex with CB[7].
Solvent-free luminescent molecular liquids (LMLs), which exhibit nonvolatile fluidic nature and active optoelectronic properties, were widely used. For further development, we introduced siloxane units into AIE molecules, designed and synthesized TPE derivatives with siloxane side chains via facile Piers-Rubinsztajn reaction. The obtained AIE molecular liquids exhibit unique photophysical properties. Compared with the obtained alkyl TPE-solids, siloxane TPE show liquid state, which proves that the siloxane units have stronger liquefaction effect than alkyl. Viscosity test shows that siloxane TPE-liquids has far more lower viscosity and better fluidity than the long-chain alkyl molecular liquids in previous research. All those properties are attributed to the weak interaction between flexible molecular chains of siloxane. Besides, fluorescence test shows temperature responsiveness of siloxane TPE-liquids. We developed this low-viscosity nonvolatile AIE molecular liquid as green fluorescent ink.
An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist of inexpensive rose bengal as photocatalyst to prepare a series of alkyl substituted oxazolines in moderate to excellent yields. High regioselectivity, operational safety, mild conditions and excellent substrate generality give this protocol broad application prospects.
The modification and functionalization of peptides is of great significance in modern biotechnology and drug development. Here we report a highly reactive Michael-type warhead for the covalently modification of cysteine on peptide and protein. By installing a vinyl group onto a methionine residue of peptide, the produced vinyl sulfonium can be efficiently nucleophilic added by appropriate cysteine residue of this peptide, and thus yield a cyclized peptide. This peptide cyclization strategy was proven to exhibit improved cell penetration and good stability. Moreover, a peptide ligand bearing vinyl sulfonium could covalently bind to the cysteine in the target protein, indicating the potential of vinyl sulfonium as a novel warhead for developing covalent peptide inhibitor.
A novel method for metal-free C-H borylation of 2-(N-methylanilino)-5-fluoropyridines and 2-benzyl-5-fluoropyridines has been reported. The 5-fluoropyridine directed borylation reaction exhibited high efficiency and site exclusivity. The useful protocol could be executed on a gram-scale easily and the borylated products showed good derivatization applications. Moreover, the practicality of the strategy was expanded by the fact that the directing group could be removed in an acceptable yield.
Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science. The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H2O in the reaction mixture.
The development of innovative strategies and methods to provide natural product-like macrocycles not accessible by biosynthesis, but endowed with novel bioactivities and simplified structure, is highly desirable. Inspired by the key scaffolds of rapamycin and FR252921, herein, we report a Rh(Ⅲ)-catalyzed C-H alkylation macrocyclization, which enables access to CF3-substituted macrolides. DFT calculations reveal that the chemoselectivity between C-H alkylation and olefination macrocyclization was highly controllable. Moreover, the unique CF3-substituted macrolides showed potent anti-inflammation activities against TNF-α, IL-6 and CCL2 mRNA expression.
Noble metal aerogels (NMAs), belonging to the porous material, have exhibited excellent catalytic performance. Although the synthesis method continues to improve, it still exists some problems which hindered the experimental process, such as high concentration of noble metal precursors, long synthesis cycle, expensive production cost, and uncontrollable ligament length. In this work, ultrasonic wave and reducing agent NaBH4 were simultaneously applied to gelation process. With the cavitation of ultrasound, it can generate huge energy with heating and stirring, thus gelation reaction proceeded quickly, and even completed the process in only a few seconds, that is much faster than the recorded. A wide concentration range was successfully expanded from 0.02 mmol/L to 62.5 mmol/L. Further, we extended this method to a variety of noble metal elements (Au, Ru, Rh, Ag, Pt, Pd), and this method is adaptive for the synthesis of single metal aerogels (Au, Ag, Ru, Rh, Pd), bimetal and trimetal aerogels (Au-Ag, Au-Rh, Au-Ru, Au-Pt, Au-Pd, Au-Pt-Pd). In addition, the ligament size of alloy aerogels are 10 nm or less. Moreover, their brilliant properties were demonstrated in hydrogen evolution reaction (HER) and ethanol oxidation reaction (EOR).
Artificial membrane transporters that either use chalcogen bonds to facilitate transmembrane flux of anions or show high selectivity toward perchlorate anions are rare. In this work, we report on one such novel monopeptide-based transporter system, featuring both chalcogen bonds for highly efficient anion transport and high transport selectivity toward ClO4- anions. Structurally, these monopeptide molecules associate with each other via H-bonds to produce H-bonded 1D stack that not only one dimensionally but also directionally aligns the terminal bicyclic thiophene motifs to the same side. Functionally, these well-aligned thiophenes create a sulfur-rich transmembrane pathway, combinatorially fine-tunable to enable anions to efficiently cross the membrane in the increasing activity of Cl- < Br- < NO3- < ClO4- via chalcogen bonds, with EC50 values of 0.75, 0.40, 0.37 and 0.093 μmol/L (0.3 mol% relative to lipid molecules), respectively.
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