Latest ArticlesVitamin B12 (macrocyclic cobalamin) has been recently reported to be capable of electrochemically catalyzing water oxidation in a neutral phosphate buffer solution. In this work, density functional calculations were employed to elucidate the water oxidation mechanism catalyzed by vitamin B12. The calculations showed that the catalytic cycle starts from the L•-CoII-OH2 complex 1. A proton-coupled electron transfer process then leads to the formation of a L•-CoIII-OH complex 2, followed by another proton-coupled electron transfer event to afford a corrin ligand radical cation intermediate 3 (L•-CoIII-O•). The redox non-innocent nature of the corrin ligand plays an essential role in the oxidation process. 3 is capable of triggering the O-O bond formation via a water nucleophilic attack mechanism, in which a hydrophosphate dianion functions as a base to accept a proton from the water nucleophile. A dioxygen molecule is released after the oxidation of the CoIII-OOH intermediate. The rate-determining step was calculated to be the O-O bond formation with a total barrier of 16.5 kcal/mol. While the use of water molecules as the proton acceptor was found to be less feasible for the O-O bond formation, with a barrier of 31.2 kcal/mol, further highlighting the crucial of phosphate in water oxidation.
Room temperature phosphorescent (RTP) materials have a variety of applications ranging from bio-imaging, optoelectronic devices to information security protection. However, the preparation procedures for these materials are always tedious and time-consuming. Here, we report a micro-wave approach to prepare RTP carbon dots (CDs) in only 8 min. The micro-wave promoted the carbon and boron bond formation using natural compounds glucose and boric acids. This result has been confirmed using TEM, FTIR, XPS and XRD measurements. The C-B hetero atomized material presented a long afterglow property. With the irradiation with UV light, we observed an eight-second RTP by naked eyes after the lamp was turned off, and the phosphorescence lifetime was 487 ms. This excellent performance was mainly due to the formation of B-C bonds that promoted the intersystem crossings (ISC) and non-radiation transition of triplet states. Moreover, the glass state of the materials also helped to stabilize the triplet states of B-CDs and made its non-irradiation inactivated, which resulted in the characteristics of yellow green RTP. These results have demonstrated that micro-wave is a convenient and effective strategy to make hetero atomized RTP material, providing new possibilities for their industrial productions.
In recent years, porphyrins with a similar structure to chlorophyll are often used as photosensitizers or reaction centers to improve the light absorption capacity or catalytic selectivity of existing photocatalytic systems. However, photocatalytic reactions include photoelectric conversion, photocarrier transport, and surface reaction, which requires the overall design of porphyrin-based photocatalysts. In this paper, the research work of porphyrin molecular design in heterogeneous photocatalysis in recent years is reviewed. Besides, the application of interface control and spatial confinement effect in porphyrin-based hybrid photocatalyst is introduced. Finally, the future development direction of porphyrin-based photocatalysts is prospected and the main challenges in the research of porphyrin-based photocatalysts are given.
Catalytic hydrodeoxygenation (HDO) is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons. Herein, an efficient bimetallic catalyst Pt1Ni4/MgO was prepared and applied in the HDO of dibenzofuran (DBF). High yield (95%) of the desired product bicyclohexane (BCH) was achieved at 240 ℃ and 1.2 MPa of H2. Superior catalytic performance could be ascribed to the "relay catalysis" of Pt sites and Ni sites, and the reaction pathway is proposed as well. Scale-up experiment and recyclability test were also performed, which demonstrated the recyclability and promising potential application of Pt1Ni4/MgO.
Combined theoretical and experimental studies have explained the mechanism of Pd-catalyzed δ-C(sp3)−H arylation of primary amines. Instead of the monomeric Pd mechanism, our research unveils that all steps including C-H activation, oxidative addition, and reductive elimination take place via the heterodimeric Pd-Ag intermediates and transition states. Experimentally, the active heterodimeric Pd-Ag species were detected by mass spectrometry, which further confirms the proposed heterodimeric mechanism. Insight gained through this study reveals the synergistic manner of palladium catalysis and silver(I) additives in native NH2-directed C‒H activation and C-C coupling reactions.
The integration of luminescence and chirality in carbon dots (CDs) encourages candidates to explore novel functions and applications of CDs, however, the preparation of chiral CDs is very limited. Herein, we report a hydrothermal method to fabricate chiral CDs by utilizing amino acid enantiomers as the precursors. LGln-CDs or DGln-CDs with uniform size of 3–4 nm show excitation-dependent blue fluorescence in solutions. Circular dichroism measurement confirms the opposite optical rotation of chiral CDs in the region from 200 nm to 300 nm, and the signals can be regulated by concentrations of CDs solution. Time-dependent density functional calculation reveals that polypeptides may exist on the surface of CDs due to the polycondensation of L/DGln at high temperature, and the optical activity of CDs originates from the stacking of neighboring carbonyl groups. The facile synthetic methodology proposed will provide potential opportunities for the preparation and application of chiral and chiroptical CDs-based materials.
P-doping is an effective way to modulate the electronic structure and improve the Na+ diffusion kinetics of TiO2, enabling enhanced electrochemical performance. However, it is a challenge to prepare TiO2 with a high P-doping concentration starting from TiO2 in a crystalline state. In this work, we design a novel two-step route for constructing a carbon-coated anatase P-doping TiO2 nanospheres (denote as (P-AnTSS)@NC) with high P-doping concentration, by utilizing amorphous TiO2 nanospheres with the ultra-high specific area as P-doping precursor firstly, and followed by carbon coating treatment. Experimental results demonstrate that P is successfully doped into the crystal lattice and carbon layer is well coated on the surface of TiO2, with P-doping and carbon-coating contents of ~13.5 wt% and 10.4 wt%, respectively, which results in the enhanced pseudocapacitive behavior as well as favorable Na+ and electron transferring kinetics. The (P-AnTSS)@NC sample shows excellent rate and cycle performance, exhibiting specific capacities of 177 and 115 mAh/g at 0.1 and 1.0 A/g after 150 and 2000 cycles, respectively.
A variety of nano-engineered photosensitizers have been developed for photodynamic therapy (PDT) of cancer diseases. However, traditional nano-engineering methods usually cannot avoid drug leakage and premature release, and have disadvantages such as low drug load and inaccurate release. The self-assembly strategy based on amphiphilic peptides has been considered to be more attractive nano-engineering method. Here we developed novel acid-activatable self-assembled nanophotosensitizers based on an amphiphilic peptide derivative. The peptide derivative was synthesized from a fluorescein molecule with thermally activated delayed fluorescence (TADF). The self-assembled nanophotosensitizers can specifically enter the tumor cells and disassemble inside lysosomes companied with "turn-on" fluorescence and photodynamic therapy effect. Such smart nanophotosensitizers will open new opportunities for cancer theranostics.
Series tunneling across peptides composed of various amino acids is one of the main charge transport mechanisms for realizing the function of protein. Histidine, more frequently found in redox active proteins, has been proved to be efficient tunneling mediator. While how it exactly modulates charge transport in a long peptide sequence remains poorly explored. In this work, we studied charge transport of a model peptide junction, where oligo-alanine peptide was doped by histidine at different position, and the series of peptides were self-assembled into a monolayer on gold electrode with soft EGaIn as top electrode to form molecular junction. It was found that histidine increased the overall conductance of the peptide, meanwhile, its position modulated the conductance as well. Quantitative analysis by transport model and ultraviolet photoelectron spectroscopy (UPS) indicated a sequence dependent energy landscape of the tunneling barrier of the junction. Density-functional theory (DFT) calculation on the electronic structure of histidine doped oligo-alanine peptides revealed localized highest occupied molecular orbital (HOMO) on imidazole group of the histidine, which decreased charge transport barrier.
As one of the most promising fluorescent nanomaterials, carbon dots (CDs) have been extensively studied for their fluorescent properties in solution. However, research on the synthesis of multicolor solid-state fluorescence (SSF) CDs (from blue to red) is rarely reported. Herein, we used o-phenylenediamine, m-phenylenediamine and p-phenylenediamine with dithiosalicylic acid (DTSA) in the solvothermal reaction using acetic acid as a solvent to obtain aggregation-induced emissive (AIE) CDs of red (620 nm), green (520 nm), and blue (478 nm), respectively. XPS spectra and TEM image show that with the red-shift of luminescence, the particle size and content of C=O of the CDs gradually increases. Finally, based on the non-matrix solid-state multicolor luminescence characteristics of CDs, the application of white light LED devices is realized. Besides, based on the fat-soluble properties of CDs, fingerprint detection applications are realized.
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62199257
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
