2 research outputs found
Linker Engineering for Reactive Oxygen Species Generation Efficiency in Ultra-Stable Nickel-Based Metal–Organic Frameworks
Interfacial charge transfer on the surface of heterogeneous
photocatalysts
dictates the efficiency of reactive oxygen species (ROS) generation
and therefore the efficiency of aerobic oxidation reactions. Reticular
chemistry in metal–organic frameworks (MOFs) allows for the
rational design of donor–acceptor pairs to optimize interfacial
charge-transfer kinetics. Herein, we report a series of isostructural fcu-topology Ni8-MOFs (termed JNU-212, JNU-213, JNU-214, and JNU-215) with linearly bridged bipyrazoles as organic linkers. These crystalline
Ni8-MOFs can maintain their structural integrity in 7 M
NaOH at 100 °C for 24 h. Experimental studies reveal that linker
engineering by tuning the electron-accepting capacity of the pyrazole-bridging
units renders these Ni8-MOFs with significantly improved
charge separation and transfer efficiency under visible-light irradiation.
Among them, the one containing a benzoselenadiazole unit (JNU-214) exhibits the best photocatalytic performance in the aerobic oxidation
of benzylamines with a conversion rate of 99% in 24 h. Recycling experiments
were carried out to confirm the stability and reusability of JNU-214 as a robust heterogeneous catalyst. Significantly,
the systematic modulation of the electron-accepting capacity of the
bridging units in donor–acceptor–donor MOFs provides
a new pathway to develop viable noble-metal-free heterogeneous photocatalysts
for aerobic oxidation reactions
Nototronesides A–C, Three Triterpene Saponins with a 6/6/9 Fused Tricyclic Tetranordammarane Carbon Skeleton from the Leaves of <i>Panax notoginseng</i>
Three triterpene
saponins, nototronesides A–C (<b>1</b>–<b>3</b>), possessing an unprecedented 6/6/9 fused
tricyclic tetranordammarane core, were isolated from the leaves of <i>Panax notoginseng</i>. Their structures were elucidated on the
basis of spectroscopic data, and the structure of sapogenin (<b>1a</b>) was further confirmed by X-ray crystallography. The existence
of <b>1</b>–<b>3</b> adds a new dimension to the
diversity of the triterpene family. Moreover, compound <b>2</b> showed a moderate neuroprotective effect on serum deficiency-induced
cellular damage in PC12 cells