- Electrochemical C-N coupling with perovskite hybrids toward efficient urea synthesis
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Electrocatalytic C-N coupling reaction by co-activation of both N2 and CO2 molecules under ambient conditions to synthesize valuable urea opens a new avenue for sustainable development, while the actual catalytic activity is limited by poor adsorption and coupling capability of gas molecules on the catalyst surface. Herein, theoretical calculation predicts that the well-developed built-in electric field in perovskite hetero-structured BiFeO3/BiVO4 hybrids can accelerate the local charge redistribution and thus promote the targeted adsorption and activation of inert N2 and CO2 molecules on the generated local electrophilic and nucleophilic regions. Thus, a BiFeO3/BiVO4 heterojunction is designed and synthesized, which delivers a urea yield rate of 4.94 mmol h-1 g-1 with a faradaic efficiency of 17.18% at -0.4 V vs. RHE in 0.1 M KHCO3, outperforming the highest values reported as far. The comprehensive analysis further confirms that the local charge redistribution in the heterojunction effectively suppresses CO poisoning and the formation of the endothermic ?NNH intermediate, which thus guarantees the exothermic coupling of ?NN? intermediates with the generated CO via C-N coupling reactions to form the urea precursor ?NCON? intermediate. This work opens a new avenue for effective electrocatalytic C-N coupling under ambient conditions.
- Yuan, Menglei,Chen, Junwu,Bai, Yiling,Liu, Zhanjun,Zhang, Jingxian,Zhao, Tongkun,Shi, Qiaona,Li, Shuwei,Wang, Xi,Zhang, Guangjin
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p. 6048 - 6058
(2021/05/14)
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- Short Total Synthesis of [15N5]-Cylindrospermopsins from 15NH4Cl Enables Precise Quantification of Freshwater Cyanobacterial Contamination
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Fresh water cyanobacterial algal blooms represent a major health risk because these organisms produce cylindrospermopsin, a toxic, structurally complex, zwitterionic uracil-guanidine alkaloid recognized by the EPA as a dangerous drinking water contaminant. At present, the ability to detect and quantify the presence of cylindrospermospin in water samples is severely hampered by the lack of an isotopically labeled standard for analytical mass spectrometry. Herein, we present a concise, scaled total synthesis of 15N cylindrospermosin from 15N ammonium chloride, which leverages a unique stereoselective intramolecular double conjugate addition step to assemble the tricyclic guanidine core. In addition to providing the first pure isotopically labeled probe for precise quantification of this potent biotoxin in fresh water sources, our results demonstrate how unique constraints associated with isotope incorporation compel novel solutions to synthesis design.
- Mailyan, Artur K.,Chen, Joanna L.,Li, Weiwei,Keller, Arturo A.,Sternisha, Shawn M.,Miller, Brian G.,Zakarian, Armen
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supporting information
p. 6027 - 6032
(2018/05/05)
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