5 research outputs found
Highly <i>trans-</i>Stereoselective Synthesis of Bicyclic Isoxazolidines via Copper-Catalyzed Triple Cascade Catalysis
A triple
cascade was developed using a simple copper catalyst to <i>trans</i>-selectively access bicyclic isoxazolidines in a one-pot
synthesis. This strategy features the in situ generation of nitrones
and subsequent trapping by [3 + 2] cycloaddition. In this method,
copper serves three catalytic functions: as a Lewis acid for the ene
reaction, as an organometallic for aerobic oxidation, and as a Lewis
acid for an <i>endo</i>-selective [3 + 2] cycloaddition.
The successful merging of aerobic oxidation and Lewis acid catalysis
demonstrated efficient cascade synergy
Highly <i>trans-</i>Stereoselective Synthesis of Bicyclic Isoxazolidines via Copper-Catalyzed Triple Cascade Catalysis
A triple
cascade was developed using a simple copper catalyst to <i>trans</i>-selectively access bicyclic isoxazolidines in a one-pot
synthesis. This strategy features the in situ generation of nitrones
and subsequent trapping by [3 + 2] cycloaddition. In this method,
copper serves three catalytic functions: as a Lewis acid for the ene
reaction, as an organometallic for aerobic oxidation, and as a Lewis
acid for an <i>endo</i>-selective [3 + 2] cycloaddition.
The successful merging of aerobic oxidation and Lewis acid catalysis
demonstrated efficient cascade synergy
Highly <i>trans-</i>Stereoselective Synthesis of Bicyclic Isoxazolidines via Copper-Catalyzed Triple Cascade Catalysis
A triple
cascade was developed using a simple copper catalyst to <i>trans</i>-selectively access bicyclic isoxazolidines in a one-pot
synthesis. This strategy features the in situ generation of nitrones
and subsequent trapping by [3 + 2] cycloaddition. In this method,
copper serves three catalytic functions: as a Lewis acid for the ene
reaction, as an organometallic for aerobic oxidation, and as a Lewis
acid for an <i>endo</i>-selective [3 + 2] cycloaddition.
The successful merging of aerobic oxidation and Lewis acid catalysis
demonstrated efficient cascade synergy
Gated Water Transport through Graphene Nanochannels: From Ionic Coulomb Blockade to Electroosmotic Pump
Understanding
and controlling water or ion transport in nanochannels
plays an important role in further unravelling the transport mechanism
of biological membrane channels and designing functional nanofluidic
devices. Molecular dynamics simulations were conducted to investigate
water and ion transport in graphene nanochannels. Similar to electron
coulomb blockade phenomenon observed in quantum dots, we discovered
an ionic coulomb blockade phenomenon in our graphene nanochannels,
and another two ion transport modes were also proposed to rationalize
the observed phenomena under different electric-field intensities.
Furthermore, on the basis of this blockade phenomenon we found that
the Open and Closed states of the graphene nanochannels for water
transport could be switched according to external electric-field intensities,
and electroosmotic flow could further enhance the water transport.
These findings might have potential applications in designing and
fabricating controllable valves in lab-on-chip nanodevices
Double-Edged Role of VOCs Reduction in Nitrate Formation: Insights from Observations during the China International Import Expo 2018
Aerosol nitrate (NO3β) constitutes
a significant component of fine particles in China. Prioritizing the
control of volatile organic compounds (VOCs) is a crucial step toward
achieving clean air, yet its impact on NO3β pollution remains inadequately understood. Here, we examined the
role of VOCs in NO3β formation by combining
comprehensive field measurements conducted during the China International
Import Expo (CIIE) in Shanghai (from 10 October to 22 November 2018)
and multiphase chemical modeling. Despite a decline in primary pollutants
during the CIIE, NO3β levels increased
compared to pre-CIIE and post-CIIENO3β concentrations decreased in the daytime (by β10 and β26%)
while increasing in the nighttime (by 8 and 30%). Analysis of the
observations and backward trajectory indicates that the diurnal variation
in NO3β was mainly attributed to local
chemistry rather than meteorological conditions. Decreasing VOCs lowered
the daytime NO3β production by reducing
the hydroxyl radical level, whereas the greater VOCs reduction at
night than that in the daytime increased the nitrate radical level,
thereby promoting the nocturnal NO3β production.
These results reveal the double-edged role of VOCs in NO3β formation, underscoring the need for transferring
large VOC-emitting enterprises from the daytime to the nighttime,
which should be considered in formulating corresponding policies