Latest ArticlesA method for the generation of alkyl radicals from inert alkyl C-O bonds has been developed via an iron/borane reagent/alkoxide catalytic system, which can be employed for the synthesis of amines from nitroarenes with excellent efficiency. Preliminary mechanistic studies reveal that the amine synthesis may be involving a single electron transfer pathway to form alkyl radicals, and the low-valent iron species may be the active intermediates.
Carbon dots (CDs) have attracted considerable attention as a new type of fluorescent carbon nanomaterial because of their excellent optical properties, biocompatibility, and high electrical conductivity. Research on CDs has been conducted for nearly two decades and has focused on numerous precursors, various synthesis conditions and properties and applications of CDs. Biomass is critical in the green development of CDs because of its low cost, environmental friendliness, and sustainable properties. This review focuses on the advantages and applications of biomass-derived CDs. In addition, the challenges of photobleaching, toxicity, and stability of biomass-based CDs are discussed in detail. Lastly, the prospects and challenges of biomass-derived CDs are highlighted.
We have synthesized two copper nanoclusters (NCs) with a protection of the same ligand diphenylphosphino-2-pyridine (C17H14NP, dppy for short), formulated as Cu4(dppy)4Cl2 and Cu21(dppy)10, respectively. The former one bears a distorted tetrahedron Cu4 core with its six edges fully protected by chlorine and dppy ligands, while the latter presents a symmetric Cu21 core on which ten dppy molecules function as monolayer protection via well-organized monodentate or bidentate coordination. Interestingly, the Cu4(dppy)4Cl2 cluster exhibits a strong yellow emission at ~577 nm, while Cu21(dppy)10 displays dual emissions in purple (~368 nm) and green (~516 nm) regions respectively. In combination with TD-DFT calculations, we demonstrate the origin of altered emissions and unique stability of the two copper nanoclusters pertaining to the ligand coordination and metallic superatomic states.
Lithium (Li)–CO2 battery is rising as an attractive energy-storage system with the competence of CO2 conversion/fixation. However, its practical development is seriously hindered by the high overpotential. Herein, a rational design on a highly catalytic Li–CO2 battery electrode built by graphdiyne powder as a multi-functional laminar scaffold with anchored highly dispersed Ru nanoparticles is explored. The strong interaction between the abundant acetylenic bond sites of graphdiyne scaffold and Ru nanoparticles can effectively promote the electrochemical progress and reduce the voltage polarization. The unique channels architecture of the cathodic catalyst with enough space not only accelerates CO2 diffusion and electrons/Li+ transport, but also allows a large amount of accommodation for discharged product (Li2CO3) to assure an advanced capacity. The corresponding Li–CO2 battery displays an advanced discharged capacity of 15,030 mAh/g at 500 mA/g, great capacity retention of 8873 mAh/g at 2 A/g, high coulombic efficiency of 97.6% at 500 mA/g and superior life span for 120 cycles with voltage gap of 1.67 V under a restricted capacity of 1000 mAh/g at 500 mA/g. Ex/in-situ studies prove that synergy between Ru nanoparticles and acetylene bonds of GDY can boost the round-trip CO2RR and CO2ER kinetics.
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.
Fluorescent silicon quantum dots (Si QDs) were hydrothermally synthesized from a mixture of 3(2-aminoethylamino) propyl (dimethoxymethylsilane) (AEAPDMMS) and poly(vinylpyrrolidine) (PVP). The resulting Si QDs exhibited good water solubility and high stability. Under the optimized conditions, the probe revealed an excellent linear fluorescence quenching effect on Co2+ ranging from 1 µmol/L to 120 µmol/L with a limit of detection of 0.37 µmol/L (based on 3 s/k). The quenching mechanism was studied, showing that static quenching (SQE) causes the main effect. Furthermore, the test paper based on Si QDs was prepared, which is cost-effective, high sensitivity, good selectivity, easy to use and show excellent anti-interference capability. This method was applied to analyze the content of Co2+ in environmental water samples with satisfying results.
Photocatalytic activation of peroxymonosulfate (PMS) has garnered a lot of interest in the field of wastewater treatment. Herein, a plasmonic Ag nanoparticles decorated MIL-101(Fe) hybrid was synthesized through a photodeposition process. Upon light irradiation, the Ag/MIL-101(Fe) exhibit reinforced photocatalytic activities for elimination of bisphenol A (BPA) with PMS. The optimized 2.0% Ag/MIL-101(Fe) composite presented the highest photocatalytic activity with kinetic constant k of 0.102 min−1, which was about 10-fold of the pristine MIL-101(Fe). Loading of plasmonic Ag into MIL-101(Fe) boosts photoinduced carrier separation and accelerates PMS activation to generate strong oxidative radicals. Photoelectrochemical tests and multiple spectroscopic studies confirmed the promoted charge carrier separation and transfer capability of Ag/MIL-101(Fe). Combining the results of radical trapping experiments and electron spin resonance (ESR), the formed SO4•−, •OH, •O2− and 1O2 had a significant role in the photocatalytic process. According to intermediate study, the degradation pathway was studied, and the possible mechanism was proposed.
Herein, two antimony sulfates, named RbSb(SO4)2 (1) and CsSb(SO4)2 (2), have been successfully synthesized with the introduction of Sb3+ cation with stereochemically active lone pairs (SCALP) into sulfates by the conventional hydrothermal method. Both two compounds endow short ultraviolet (UV) absorption edges (281 nm and 278 nm, respectively) and large birefringence (0.171@546 nm and 0.174@546 nm, respectively), which means that they are promising short-wave UV optical materials. Interestingly, though both of the two compounds exhibit similar 1D chained structures, and possess the same functional moieties including SbO4 seesaws and SO4 tetrahedral groups, they exhibit significantly opposite macroscopic symmetries, i.e., compound 1 crystallizes in a centrosymmetric (CS) manner (P21/n) and compound 2 in a noncentrosymmetric (NCS) manner (P212121), due to the size of cations [r(Rb+) = 1.56 Å, r(Cs+) = 1.67 Å] affects the orientation of SCALP of the adjacent Sb3+.
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.
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.
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