Latest ArticlesComputational tools on top of first principle calculations have played an indispensable role in revealing the molecular details, thermodynamics, and kinetics in catalytic reactions. Here we proposed a highly efficient dynamic strategy for the calculation of thermodynamic and kinetic properties in heterogeneous catalysis on the basis of efficient potential energy surface (PES) and MD simulations. Taking CO adsorbate on Ru(0001) surface as the illustrative model system, we demonstrated the PES-based MD can efficiently generate reliable two-dimensional potential-of-mean-force (PMF) surfaces in a wide range of temperatures, and thus temperature-dependent thermodynamic properties can be obtained in a comprehensive investigation on the whole PMF surface. Moreover, MD offers an effective way to describe the surface kinetics such as adsorbate on-surface movement, which goes beyond the most popular static approach based on free energy barrier and transition state theory (TST). We further revealed that the dynamic strategy significantly improves the predictions of both thermodynamic and kinetic properties as compared to the popular ideal statistic mechanics approaches such as harmonic analysis and TST. It is expected that this accurate yet efficient dynamic strategy can be powerful in understanding mechanisms and reactivity of a catalytic surface system, and further guides the rational design of heterogeneous catalysts.
In recent years, the direct introduction of sulfonyl and sulfenyl groups into unsaturated substrates by using thiosulfonates as unique dual functional reagents has inarguably provided chemists a new platform for the diverse synthesis of important S-containing derivatives. These 1,n-thiosulfonylation reactions usually feature simple procedures, 100% atom economy, and high regioselectivity. This review focuses on the recent advancements in the transformations of thiosulfonates through 1,n-thiosulfonylation involving the formation of two distinct C-S bonds under transition-metal-catalyzed or metal-free conditions, where thiosulfonates act as both a sulfonyl and a sulfenyl component.
Recent advances in epoxy resins have been forward to achieving high mechanical performance, thermal stability, and flame retardancy. However, seeking sustainable bio-based epoxy precursors and avoiding introduction of additional flame-retardant agents are still of increasing demand. Here we report the synthesis of p-hydroxycinnamic acid-derived epoxy monomer (HCA-EP) via a simple one-step reaction, and the HCA-EP can be cured with 4, 4′-diaminodiphenylmethane (DDM) to prepare epoxy resins. Compared with the typical petroleum-based epoxy resin, bisphenol A epoxy resin, the HCA-EP-DDM shows a relatively high glass transition temperature (192.9 ℃) and impressive mechanical properties (tensile strength of 98.3 MPa and flexural strength of 158.9 MPa). Furthermore, the HCA-EP-DDM passes the V-1 flammability rating in UL-94 test and presents the limiting oxygen index of 32.6%. Notably, its char yield is as high as 31.6% under N2, and the peak heat rate release is 60% lower than that of bisphenol A epoxy resin. Such findings provide a simple way of using p-hydroxycinnamic acid instead of bisphenol A to construct high-performance bio-based thermosets.
Traditional synthesis of sulfonylureas largely depends on nucleophilic addition of arylsulfonamides to pre-synthesized isocyanates. Now we report a new access to alkylsulfonylureas with good yields and broad substrate scope. With the insertion of commercialized chlorosulfonyl isocyanate under photoredox catalysis, alkylsulfonylureas are synthesized in one-pot from the corresponding anilines and silyl enolates. A reaction mechanism is proposed showing the transformation undergoes a radical process, and the practicality of this methodology is proven via application to bioactive molecules. Additionally, the anti-cancer and anti-virus screening of these compounds is evaluated.
Real-time exploring the cellular endocytic pathway of viral capsid proteins (VCPs) functionalized nanocargos at the single-particle level can provide deep insight into the kinetic information involved in virus infection. In this work, porcine circovirus type 2 (PCV2) VCPs with different functions are modified onto the surface of upconversion nanoparticles (VCPs-UCNPs) to investigate the cellular internalization process in real-time. Clathrin-mediated endocytosis is found to be the essential uptake mechanism for these VCPs-UCNPs. Besides, it is verified that P1-UCNPs (PCV2 VCPs with nuclear localization signal, namely P1) can be easily assembled close to the perinuclear area, which is different from that of P2-UCNPs (PCV2 VCPs without nuclear localization signal, namely P2). Interestingly, multistep entry processes are observed. Particularly, confined diffusion is observed during the transmembrane process. The intracellular transport of VCPs-UCNPs is dependent on microtubules toward the cell interior. During this process, P1-UCNPs display increased velocities with active transport, while diffusion much faster around the perinuclear area. But for P2-UCNPs, there are only two phases involved in their endocytosis process. This study presents distinct dynamic mechanisms for the nanocargos with different functions, which would make a useful contribution to the development of robust drug delivery systems.
Peroxide ligation of aqueous metal–oxo clusters provides rich speciation and structural diversity. Here, three novel transition-metal derivatives of polyoxometalate anions, [Ni2(H2O)10{P4Ta6(O2)6O24}]6– (1a), [Zn(H2O)4{P4Ta6(O2)6O24}]8– (2a) and [Cd(H2O)4{P4Ta6(O2)6O24}]8– (3a), have been successfully synthesized by adopting a one-pot reaction strategy. All of these hexatantalates are built from a new-type phosphorus-incorporated hexatantalates. We investigated the solution behaviors, and the peak assignments of the MS spectra indicated some degree of stability of them in water. Furthermore, the proton-conducting ability of compound 1a was also explored and it has shown well conductivity at high relative humidities, with conductivity achieved 1.22 × 103 S/cm (85 ℃, 90%RH).
Semiconductor photocatalysis holds great promise for breaking the inert chemical bonds under mild condition; however, the photoexcitation-induced modulation mechanism has not been well understood at the atomic level. Herein, by performing the DFT+U calculations, we quantitatively compare H2 activation on rutile TiO2(110) under thermo- versus photo-catalytic condition. It is found that H2 dissociation prefers to occur via the heterolytic cleavage mode in thermocatalysis, but changes to the homolytic cleavage mode and gets evidently promoted in the presence of photoexcited hole (h+). The origin can be ascribed to the generation of highly oxidative lattice O-radical (Obr·-) with a localized unoccupied O-2p state. More importantly, we identify that this photo-induced promotion effect can be practicable to another kind of important chemical bond, i.e., C–H bond in light hydrocarbons including alkane, alkene and aromatics; an exception is the C(sp1)-H in alkyne (HC≡CH), which encounters inhibition effect from photoexcitation. By quantitative analysis, the origins behind these results are attributed to the interplay between two factors: C-H bond energy (Ebond) and the acidity. Owing to the relatively high Ebond and acidity, it favors the C(sp1)-H bond to proceed with the heterolytic cleavage mode in both thermo- and photo-catalysis, and the photoexcited Obr·- is adverse to receiving the transferred proton. By contrast, for the other hydrocarbons with moderate/low Ebond, the Obr·- would enable to change their activation mode to a more favored homolytic one and evidently decrease the C–H activation barrier. This work may provide a general picture for understanding the photocatalytic R–H (R = H, C) bond activation over the semiconductor catalyst.
Inflammatory bowel disease (IBD) is a chronic and recurrent disease of the gastrointestinal tract, mainly including Crohn's disease (CD) and ulcerative colitis (UC). However, current approaches against IBD do not precisely deliver drugs to the inflammatory site, which leads to life-long medication and serious side effects that can adversely impact patients' adherence. It is necessary to construct optimal drug delivery systems (DDSs) that can target drugs to the region of inflammation, thereby improve therapeutic efficacy and reduce side effects. With the burgeoning development of nanotechnology-based nanomedicines (NMs) and prodrug strategy, remarkable progresses in the treatment of IBD have been made in recent years. Herein, the latest advances are outlined at the intersection of IBD treatment and nanotherapeutics as well as prodrug therapy. First, the pathophysiological microenvironment of inflammatory sites of IBD is introduced in order to rationally design potential NMs and prodrugs. Second, the necessity of NMs for the IBD therapy is elaborated, and the representative nanotherapeutics via passive targeted and active targeted NMs developed to treat the IBD are overviewed. Furthermore, the emerging prodrug-based therapeutics are summarized, including 5-aminosalicylic acid-, amino acid-, and carbohydrate-conjugated prodrugs. Finally, the design considerations and perspectives of these NMs and prodrugs-driven IBD therapeutics in the clinical translation are spotlighted.
Electrochemical nitrogen reduction reaction (NRR) has been considered as an appealing and sustainable method to produce ammonia from N2 under ambient conditions, attracting increasing interest. Limited by low solubility of N2 in water and high stability of NN triple bond, developing NRR electrocatalysts with both strong N2 adsorption/activation and high electrical conductivity remain challenging. Here, we demonstrate an efficient strategy to develop NRR electrocatalyst with synergistically enhanced N2 adsorption/activation and electrical conductivity by heteroatom doping. Combining computational and experimental study, the DFT-designed Ti-doped SnO2 exhibits significantly enhanced NRR performance with ammonia yield rate of 13.09 µg h−1 mg−1 at −0.2 V vs. RHE. Particularly, the Faradaic efficiency reaches up to 42.6%, outperforming most of Sn-based electrocatalysts. The fundamental mechanism for improving NRR performance of SnO2 by Ti doping is also revealed. Our work highlights a powerful strategy for developing high-activity electrocatalysts for NRR and beyond.
The applications of fluorescence resonance energy transfer (FRET) are coming to be one of the simplest and most accessible strategy with super-resolved optical measurements. Meanwhile, nanomaterials have become ideal for constructing FRET-based system, due to their unique advantages of tunable emission, broad absorption, and long fluorescence (FL) lifetime. The limitations of traditional FRET-based detections, such as the intrinsic FL, auto-FL, as well as the short FL lifetime, could be overcome with nanomaterials. Consequently, numbers of FRET-based nanomaterials have been constructed for precise, sensitive and selective detections in biological systems. They could act as both energy donors and/or acceptors in the optical energy transfer process for biological detections. Some other nanomaterials would not participate in the energy transfer process, but act as the excellent matrix for modifications. The review will be roughly classified into nanomaterial-involved and uninvolved ones. Different detection targets, such as nucleic acids, pathogenic microorganisms, proteins, heavy metal ions, and other applications will be reviewed. Finally, the other biological applications, including environmental evaluation and mechanism studies would also be summarized.
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