Latest ArticlesHerein, we report the first visible-light photoredox-catalyzed carboxylation of aryl epoxides with CO2 to synthesize hydroxy acid derivatives. A variety of valuable β-, γ-, δ-, ε-hydroxy acid derivatives are obtained in moderate to high yields under mild conditions. This protocol shows noteworthy functional-group compatibility, high chemo- and regioselectivities under transition-metal-free conditions with an inexpensive organo-dye as photosensitizer. Mechanistic studies indicate that the benzylic carbanion is generated as an intermediate via the sequential single electron transfer (SSET) process.
The stable coordinated metallo-complexes based on 2,2′:6′,2″-terpyridine (tpy) and its derivatives have been widely researched for various wide-ranging applications in photoelectronics, catalysis, sensor, photoluminescence, and so on. However, the most reported studies ignored the comprehensive comparison between structures modified by different positions and photoluminescence. Herein, we design a series of metallo-complexes which were assembled with tpy substituted triphenylamine (TPA) at different positions and metal ions and explored their photophysical properties. In the solution state, MLE2 based on the 5,5″-positions modification showed the highest PLQYs and PL intensity. With the increase of solvent polarity, MLB2 exhibit the largest redshift. In the solid state, from MLA2 to MLE2, the emission colours are gradually red-shifted from yellow to red. The findings in this work may pave a new way to design functional metallo-complexes, not just for PL properties.
Here, we designed asymmetric (mDS) and symmetrical (dDS) chiral V-shaped molecules by linking one or two dansyl groups to trans-1,2-cyclohexane diamine and investigated the solvent-regulated structural transformation and inversed circularly polarized luminescence (CPL) in the self-assemblies. Upon increasing water volume fraction (fw) in the mixed solvent of water/acetonitrile, asymmetric mDS selfassembled into hollow nanospheres and microtubes, while solid nanospheres and solid microplates were corresponding to symmetric dDS. During this transformation process, the emission of mDS and dDS was changed from yellow-green to blue and cyan color, which was ascribed to twisted intramolecular charge transfer (TICT) and locally excited (LE) fluorescence of V-shaped DS molecules. The conformation of N,N-dimethyl groups with respect to naphthalene ring also led to the transformation of structures. These tubular and platelike structures had stronger and reversed CPL signals in comparison with spheroidal structures. The chiral information of DS assembly could be effective transferred to achiral Nile red via co-assembly strategy, which endowed Nile red exhibiting inversed induced CPL signal regulated by water fraction. This work provides a method for achieving a variety of self-assembled structures with adjustable chiroptical properties.
Hydrogen evolution electrocatalysts derived from metal-organic crystalline frameworks can inherit the merits of ordered and adjustable structures with high surface area. In this paper, organic-octamolybdate crystalline superstructures (OOCS) with a fixed stoichiometric ratio of Mo8(L)2 and high Mo content (> 40 wt%) were synthesized using flexible ligands with controllable lengths (named as OOCS-1–3). Then, molybdenum carbides coated with carbon layers as electrocatalysts (Mo2C@C-1–3) can be obtained directly from a one-step high-temperature carbonization process using OOCS-1–3 as precursors. As a typical example, Mo2C@C-3 exhibits satisfactory hydrogen evolution activity with a low overpotential of 151 mV (1.0 mol/L KOH) at 10 mA/cm2 and stability for 24 h. The electrocatalytic activity is mainly from the synergistic interactions between the carbon layers and molybdenum carbide species. Furthermore, compared with the initial content of C, N, Mo in OOCS and Mo2C@C, the catalytic activity increases with the N amount. This work makes organic-octamolybdate crystalline superstructures used as general precursors to product high Mo content electrocatalysts applied in energy storage and conversion fields.
Nowadays, lithium-ion batteries (LIBs) play a crucial role in modern society in the aspect of portable electronic devices and large-scale smart grids. However, the current performance of lithium-ion batteries has been unable to meet the growing expectations of society and scientific community. Herein, we have synthetically investigated availability of 2D Ni-TABQ monolayer as anode based on DFT for LIBs applications. Our findings have demonstrated that 2D Ni-TABQ monolayer is a semiconductor with a small band gap of 0.2 eV, which suggest that the electronic property of 2D Ni-TABQ monolayer would take place an evident shift from semiconductor property to metallic property after Li adsorption. Furthermore, we checked the stability of 2D Ni-TABQ monolayer and investigated the viability of exfoliation from bulk multilayer Ni-TABQ to form 2D Ni-TABQ monolayer in the light of exfoliation energy and binding energy. We continuously studied electrochemical properties of 2D Ni-TABQ monolayer with respect of theoretical specific capacity, Li-ion diffusion barriers and open-circuit voltage. During the charging process, 2D Ni-TABQ monolayer can achieve a high specific capacity of 722 mAh/g with an open-circuit voltage range from 1.12 V to 0.22 V. These aforementioned results make the 2D Ni-TABQ monolayer a promising anode for LIBs.
Local delivery of nanoparticles holds promise for colorectal cancer (CRC) therapy. However, the presence of the mucus layer on the epithelium poses a significant challenge to drug delivery, thereby adversely affecting treatment efficiency. It is crucial to develop efficient drug delivery carriers that can effectively overcome mucus barriers to treat colorectal cancer. Herein, we utilized poly(1,4-butadiene)-b-poly(ethylene oxide) polymers to prepare four distinct geometries of polymeric micelles, namely linear micelles (LMs), worm-like micelles (WLMs), large spherical micelles (LSMs), and small spherical micelles (SSMs) to investigate the influence of shape effects on overcoming colonic mucosal barrier. We found that the carriers exhibited diverse shapes while maintaining comparable physicochemical properties. Of these, WLMs had an aspect ratio similar to segmented filamentous bacteria, which exhibited superior mucus penetration ability, leading to prolonged drug release kinetics and faster entry into epithelial cells compared to LSMs. Furthermore, rectally administrated 10-hydroxycamptothecin-loaded WLMs traversed the colorectal mucus in orthotopic CRC nude mice model, penetrated and accumulated within tumor tissue, and effectively aggregated within cancer cells, thereby inducing significantly robust antitumor outcomes in vivo. These findings underscore the significance of shape design in overcoming colonic mucosal absorption barriers, offering a novel approach for the development of drug delivery carriers tailored for effective tumor therapy.
FeS2 shows significant potential as cathode material for all-solid-state lithium batteries (ASSLBs) due to its high theoretical specific capacity, low cost, and environmental friendliness. However, the poor ion/electron conductivity and large volume variation effect of FeS2 inhibit its practical applications. Here, the influence of particle size of FeS2 on the corresponding sulfide-based solid-state batteries is carefully investigated by tuning FeS2 size. Moreover, low operating temperature is chosen to mitigate the large volume changes during cycling in the battery. S-FeS2 with smaller particle sizes delivers superior electrochemical performances than that of the larger L-FeS2 in Li5.5PS4.5Cl1.5-based ASSLBs under different operating temperatures. S-FeS2 shows stable discharge capacities during 50 cycles with a current density of 0.1 mA/cm2 under -20 ℃. When the current density rises to 1.0 mA/cm2, it delivers an initial discharge capacity of 146.9 mAh/g and maintains 63% of the capacity after 100 cycles. This work contributes to constructing ASSLBs enables excellent electrochemical performances under extreme operating temperatures.
Surface modification of microporous bone scaffolds using nanoparticles has been broadly studied in bone tissue engineering. Aiming at improving vascularized bone regeneration (VBR), zeolitic imidazolate framework-8 (ZIF-8) was encapsulated with dimethyloxallyl glycine (DMOG) and the drug-carrying nanoparticles (D@Z) could be uniformly coated onto the surface of the bone scaffold. The osteogenic and angiogenic actions of D@Z are closely correlated with the amount of slowly released DMOG, and in general, exhibited a favorable association. Then, the D7.5@Z group, which showed the greatest capacity to induce in vitro osteogenesis–angiogenesis coupling, was utilized for surface modification of the bone scaffold. Biological processes including phosphate-containing compound metabolic process, cell differentiation, cell proliferation and cell motility might contribute to enhanced ability to induce VBR by the coated scaffold and signaling pathways such as Rap1, Ras, phosphatidylinositol 3-kinase/protein kinase B (PI3K-AKT) and vascular endothelial growth factor (VEGF) signaling pathways participated in these processes. Finally, as depicted by in vitro real time-polymerase chain reaction (RT-PCR), Western blot (WB) and in vivo cranial bone defect model, the microporous scaffold coated with nano-D7.5@Z greatly promoted VBR. To conclude, nano-D@Z has significant promise for practical application in modification of microporous bone scaffolds to enhance VBR, and DMOG loading quantity has a beneficial influence on D@Z to improve osteogenesis–angiogenesis coupling.
A new aggregation-induced emission (AIE)-based fluorescence sensor, TPEPy-SS-C14, for simultaneous recognition of adenosine triphosphate (ATP) and hydrogen sulfide (H2S) has been reported via the aggregation-disaggregation mechanism. The probe self-assembles nano-structure aggregations in aqueous solution. It shows fluorescence turn-on response toward ATP for the complexation-enhanced aggregation, but leads to fluorescence quenching of H2S for cleavage the aggregations.
C-Oligosaccharides are rare in nature and possess diverse bioactivities. However, their chemical synthesis faces many challenges. In this work, enzymatic introduction of C-linked sugar chains to target aglycones was successfully achieved by multi-enzymatic cascade reactions. A C-glycosyltransferase from Aloe barbadensis was employed to introduce the first C-linked glucose and then a cyclomaltodextrin glucanotransferase from Bacillus licheniformis was used to extend the sugar chain. A total of twenty C-oligosaccharides with 2–6 sugars were synthesized from scale-up reactions and exhibited good water solubility and sodium-dependent glucose transporter 2 (SGLT2) inhibitory activity. Furthermore, a glucoamylase was used to control the length of the sugar chain and the C-maltosides were efficiently synthesized. These findings not only expanded the structural diversity of C-oligosaccharides, but also provided a strategy for the modification of C-glycoside drugs to improve the druggability.
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