Search

A series of stable N-doped porous carbon encapsulated Ni nanoparticles (Ni@CN) were prepared via direct pyrolysis of Ni-MOF-74(N) and utilized for the catalytic transfer hydrogenation (CTH) of phenol to cyclohexanol with isopropanol as a hydrogen donor. The prepared catalysts were characterized by means of TG, XRD, BET, SEM, TEM and XPS. The effects of preparation and reaction conditions on the CTH performance were investigated. The results showed that the Ni particles of Ni@CN were smaller than that of Ni@C, which reflected that the doping of nitrogen could improve the dispersion of Ni nanoparticles. Moreover, electrons can be redistributed with N-doping. These two factors contribute to better catalytic activity. The Ni@CN-450 catalyst exhibited 99.3% phenol conversion with 100% cyclohexanol selectivity. Moreover, the catalysts could be recycled and reused easily with the help of a magnet and its catalytic performance did not decrease obviously even after five successive cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] The fabrication of stable and efficient catalysts for green and economic catalytic transformation is significant. Here, highly stable covalent triazine frameworks (CTF-1) were used as the supporting material for anchoring ultrafine Pd nanoparticles (NPs) via a facile impregnation process and a one-pot calcination-reduction strategy. The widespread dispersion of ultrafine Pd NPs was a result of the abundant high nitrogen-content triazine groups of CTF-1 that endowed the catalyst Pd@CTF-1 with high catalytic activity. The catalytic performance of Pd@CTF-1 was demonstrated by the one-pot N -alkylation of benzaldehyde with aniline (or nitrobenzene) under mild reaction conditions, and Pd@CTF-1 exhibited a wide range of general applicability for N -alkylation reactions. The reaction mechanism for the N -alkylation reaction was also studied in detail. In addition, the Pd@CTF-1 catalyst exhibited high thermal and chemical stability, maintaining good catalytic efficiency after multiple reaction cycles. This study provides new insights for the fabrication of organic supporting materials with highly dispersed active catalytic sites that can lead to excellent catalytic performance for efficient, economical, and green reactions. [ABSTRACT FROM AUTHOR]

Abnormal expression of hydrogen peroxide (H 2 O 2) elucidates cell dysfunctions and might induce the occurrence and deterioration of various diseases. However, limited by its ultralow level under pathophysiological conditions, intracellular and extracellular H 2 O 2 was difficult to be detected accurately. Herein, a colorimetric and homogeneous electrochemical dual-mode biosensing platform was constructed for intracellular/extracellular H 2 O 2 detection based on FeS x /SiO 2 nanoparticles (FeS x /SiO 2 NPs) with high peroxidase-like activity. In this design, FeS x /SiO 2 NPs were synthesized with excellent catalytic activity and stability compared to natural enzymes, which improved the sensitivity and stability of sensing strategy. 3,3′,5,5′-Tetramethylbenzidine (TMB), as a multifunctional indicator, was oxidized in the presence of H 2 O 2 , generated color changes and realized visual analysis. In this process, the characteristic peak current of TMB decreased, which could realize the ultrasensitive detection of H 2 O 2 by homogeneous electrochemistry. Accordingly, by integrating visual analysis ability of colorimetry and the high sensitivity of homogeneous electrochemistry, the dual-mode biosensing platform exhibited high accuracy, sensitivity and reliability. The detection limits of H 2 O 2 were 0.2 μM (S/N = 3) for the colorimetric method and 2.5 nM (S/N = 3) for the homogeneous electrochemistry assay. Therefore, the dual-mode biosensing platform provided a new opportunity for highly accurate and sensitive detection of intracellular/extracellular H 2 O 2. [Display omitted] • A CM-EC dual-mode biosensing platform was constructed. • FeS x /SiO 2 nanoparticles with high peroxidase-like activity were synthesized. • The intracellular/extracellular H 2 O 2 detection was realized. • This method can be applied in cell samples without any pretreatment. [ABSTRACT FROM AUTHOR]

To improve the catalytic activity and reduce the dosage of noble metal catalysts has attracted much more attention for organic synthetic chemists. We facilely fabricated multilayer films of PEI-(PdCl 2 / 1 ) n through layer-by-layer (LBL) self-assembly method (PEI = polyethylenmine, 1 = 2,2′,7,7′-tetra(4-pyridyl)-9,9′-spirobifluorene, psf). UV–vis spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to monitor the growth of multilayer films. X-ray photoelectron spectroscopy (XPS) proved the palladium and ligand 1 were deposited on the film. The PEI-(PdCl 2 / 1 ) n multilayer films were used as the cisterns of catalysts to gradually discharge high active catalytic moieties in the Suzuki–Miyaura, Heck and Sonogashira cross-coupling reactions. The Pd-loading was as low as 12.1 × 10 −6 mol% measured by inductively coupled plasma OES spectrometer (ICP), and gave high yields in the typical reactions of bromobenzenes with phenylboronic acids. The LbL catalyst featured the simplicity of fabrication, high efficiency, reusability, convenient control and no sensitive to air in the reactions. [ABSTRACT FROM AUTHOR]