Latest ArticlesFour pillar[5]arene-based bicyclic compounds, so-called molecular universal joint (MUJ), were synthesized by incorporating a bisamide ring containing N, O, or S-heteroatom groups, which served as stimuli-responsive chiroptical molecular devices. The structure of MUJ was confirmed by 1H NMR spectra and single-crystal X-ray diffraction analysis, and their planar-chiral enantiomers were successfully separated. Chiroptical inversion behaviors from in to out configurations triggered by temperature, solvent, and guest complexation were investigated by circular dichroism spectra. Chiroptical inversion could be realized in the presence of adiponitrile in certain solvents due to the solvation effects on the side ring and the threading of the guest into the pillar[5]arene cavity. However, the stronger self-included interactions between the cavity and the inside ring of certain MUJs led to inhibition of the switching.
Metastable molybdenum carbide (α-MoC), as a catalyst and an excellent support for metal catalysts, has been widely used in thermo/electro-catalytic reactions. However, the selective synthesis of α-MoC remains a great challenge. Herein, a simple one-pot synthetic strategy for the selective preparation of metastable α-MoC is proposed by electrochemical co-reduction of CO2 and MoO3 in a low-temperature eutectic molten carbonate. The synthesized α-MoC shows a reed flower-like morphology. By controlling the electrolysis time and monitoring the phase and morphology of the obtained products, the growth process of α-MoC is revealed, where the carbon matrix is deposited first followed by the growth of α-MoC from the carbon matrix. Moreover, by analyzing the composition of the electrolytic products, the formation mechanism for α-MoC is proposed. In addition, through this one-pot synthetic strategy, S-doped α-MoC is successfully synthesized. Density functional theory (DFT) calculations reveal that S doping enhanced the HER performance of α-MoC by facilitating water absorption and dissociation and weakening the bond energy of Mo-H to accelerate H desorption. The present work not only highlights the valuable utilization of CO2 but also offers a new perspective on the design and controllable synthesis of metal carbides and their derivatives.
Radiation damage can cause a series of gastrointestinal (GI) tract diseases. The development of safe and effective GI tract radioprotectants still remains a great challenge clinically. Here, we firstly report an oral radioprotectant Gel@GYY that integrates a porous gelatin-based (Gel) hydrogel and a pH-responsive hydrogen sulfide (H2S) donor GYY4137 (morpholin-4-ium 4 methoxyphenyl(morpholino) phosphinodithioate). Gel@GYY has a remarkable adhesion ability and long retention time, which not only enables responsive release of low-dose H2S in stomach and subsequently sustained release of H2S in the whole intestinal tract especially in the colon, but also ensures a close contact between H2S and GI tract. The released H2S can effectively scavenge free radicals induced by X-ray radiation, reduce lipid peroxidation level, repair DNA damage and recover vital superoxide dismutase and glutathione peroxidase activities. Meanwhile, the released H2S inhibits radiation-induced activation of nuclear factor κB (NF-κB), thus reducing inflammatory cytokines levels in GI tract. After treatment, Gel@GYY displays efficient excretion from mice body due to its biodegradability. This work provides a new insight for therapeutic application of intelligent H2S-releasing oral delivery system and potential alternative to clinical GI physical damage protectant.
The development of molecular probes or systems with the ability of multiple orthogonal responses is an effective approach to precisely detect biomolecules with similar chemical structures. Herein, we report the synthesis of a water-soluble TPE-based octacationic cage (1) with the compressed TPE-containing bilayer, which endows it with good fluorescence properties and potential conformation chirality. As a result, 1 exhibits molecular recognition for anionic nucleotides within its two “claw”-like cavities to form 1:2 host-guest complexes in water, companying with selective turn-off fluorescence and turn-on CD responses to G/GTP over other nucleotides.
Carbon aerogels prepared from renewable nano building blocks are rising-star materials and hold great promise in many fields. However, various defects formed during carbonization at high temperature disfavor the stress transfer and thus the fabrication of flexible carbon aerogel from renewable nano building blocks. Herein, a structural defect-reducing strategy is proposed by altering the pyrolysis route of cellulose nanofiber. Inorganic salt that inhibits the generation of tar volatilization during pyrolysis can prevent the formation of various structural defects. Microstructure with fewer defects can reduce stress concentration and remarkably enhance the compressibility of carbon aerogel, thus increasing the maximum stress retention of carbon aerogel. The carbon aerogel also has high stress sensor sensitivity and excellent temperature coefficient of resistance. The structural defect-reducing strategy will pave a new way to fabricate high-strength carbon materials for various fields.
The A2A adenosine receptor (A2AAR) has attracted attention as an emerging immunotherapeutic target with several antagonists being evaluated in clinical trials. However, A2AAR antagonists show limited efficacy as monotherapies. Herein, we communicate our design and synthesis of a novel series of A2AAR/histone deacetylase (HDAC) bifunctional inhibitors, based on the core structure of the A2AAR antagonist PBF-509. The new compounds were designed using a pharmacophore-merging strategy and features a tri-substituted pyrimidine core. The binding affinity for A2AAR and inhibitory activity against HDACs of all the new compounds were tested. A number of compounds exhibited nanomolar or subnanomolar activity against both targets and some showed equally potent antiproliferative activity against MC38, CT26 and HCT116 colon cancer lines compared to HDAC inhibitors SAHA and MGCD-0103 in vitro. The binding poses of compound 5a in both A2AAR and HDAC1 were predicted by molecular docking studies. Collectively, these results suggest these tri-substituted pyrimidine derivatives are promising leads for developing A2AAR/HDAC dual-acting compounds as novel antitumor agents.
To achieve a lower detection limit has always been a goal of analytical chemists. Herein, we demonstrate the first picomolar level detection capability for Fe3+ ion via luminescence detection technology. The results of structural analysis and theoretical calculation show that Fe3+ ions are adsorbed on the central node of Eu-DBM (DBM = dibenzoylmethane) sensor in the form of single ion at ultralow concentration. Subsequently, the pathways of photo-induced charge and energy transfer of the obtained Eu-DBM@Fe3+ material have been changed, from the initial DBM-to-Eu3+ before Fe3+ adsorption to the ultimate DBM-to-Fe3+ after adsorption process, which quenches the luminescence of Eu3+ ion. This work not only obtains the highly sensitive luminescence detection ability, but also innovatively proposes the single-ion adsorption mechanism, both of which have important scientific and application values for the development of more efficient detection agents in the future.
A H4SiW12O40-catalyzed three-component tandem reaction of 2-acylbenzoic acids, primary amines and phosphine oxides to form 3,3-disubstituted isoindolinones was developed. By employing H4SiW12O40 as the catalyst and dimethyl carbonate (DMC) as the solvent, a diverse range of 2-acylbenzoic acid derivatives and primary amines worked well to give the C3-phosphinoyl-functionalized 3,3-disubstituted isoindolinones with the yield range of 61%-87%. Advantages of this transformation include green catalyst and solvent, available starting materials, broad substrate scope, high efficiency and operational simplicity with water as the sole by-product. The strategy achieved an efficient and green molecular fragment assembly to access isoindolinones, which would provide opportunities for the synthesis of potential biologically active molecules in a green manner.
Methicillin-resistant Staphylococcus aureus (MRSA), the most common pathogen in hospital and community environments, can cause serious and even fatal infections. The antibiotics currently used for clinical treatment of MRSA have developed resistance, and there is an urgent need to develop new antimicrobials to treat infections caused by MRSA strains. Quinoline analogues play an important role in the development of antimicrobials. Herein, we discussed the current development of antibacterial activities of quinoline analogues, mainly for anti-MRSA activity, and their structure–activity relationships (SARs) from the perspective of using the quinoline nucleus to search for novel potential anti-MRSA candidates. Additionally, the mechanisms of some representative quinoline analogues against MRSA were clarified. Altogether, this review could provide further insights for the rational development of quinoline-based antibacterial drugs, especially against MRSA.
While nickel(Ⅱ) complexes have been widely used as catalysts for carbon-carbon coupling reactions, the exploration of their photophysical and photochemical properties is still in the infancy. Here, a series of square-planar Ni(Ⅱ) complexes [(diNHC)NiX2] bearing chelating benzimidazole-based bis(N-heterocyclic carbene) ligands and varying anionic coligands (1, X = Cl; 2, X = Br; 3, X = I) are synthesized and structurally characterized. In solid state, both 1 and 2 exhibit orange-red photoluminescence under ambient conditions. The photophysical and electrochemical measurements along with density functional theory (DFT) calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer (LLCT) character. This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(Ⅱ) complexes.
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