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121.
Wang YN Bohle DS Bonifant CL Chmurny GN Collins JR Davies KM Deschamps J Flippen-Anderson JL Keefer LK Klose JR Saavedra JE Waterhouse DJ Ivanic J 《Journal of the American Chemical Society》2005,127(15):5388-5395
Here, we explore the chemistry of the previously undocumented E form of diazeniumdiolates having the structure R(1)R(2)NN(O)=NOR(3). Reported crystallographic studies have uniformly revealed the Z configuration, and our attempts to observe a Z --> E conversion through thermal equilibration or photochemical means have, until now, consistently failed to reveal a significant amount of a second conformer. As a typical example, the NMR spectrum of trimethyl derivative Me(2)NN(O)=NOMe revealed no evidence for a second configuration. Electronic structure calculations attribute this finding to a prohibitively high interconversion barrier of approximately 40 kcal/mol. A similar result was obtained when we considered the case of R(1) = Me = R(3) and R(2) = H at the same levels of theory. However, when MeHNN(O)=NOMe was ionized by dissociating the N-H bond, the barrier was calculated to be lower by approximately 20 kcal/mol, with the E form of the anion being favored over Z. This circumstance suggested that an E isomer might be isolable if a Z anion were formed and given sufficient time to assume the E configuration, then quenched by reaction with an electrophile to trap and neutralize the E form and restore the putatively high interconversion barrier. Consistent with this prediction, basifying iPrHNN(O)=NOCH(2)CH(2)Br rapidly led to a six-membered heterocycle that was crystallographically characterized as containing the -N(O)=NO- functional group in the E configuration. The results suggest an approach for generating pairs of Z and E diazeniumdiolates for systematic comparison of the rates at which the individual isomers release bioactive NO and of other physicochemical determinants of their biomedical utility. 相似文献
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W. C. Waterhouse 《Archiv der Mathematik》1986,47(3):229-231
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William C. Waterhouse 《Letters in Mathematical Physics》1994,30(3):187-188
The linear operators from a finite-dimensional Clifford algebra to itself are computed in terms of suitable two-sided multiplications and operations on the center. 相似文献
129.
A. Paul Krapcho David J. Waterhouse Abdelhakim Hammach Roberto Di Domenico Ernesto Menta Ambrogio Oliva 《合成通讯》2013,43(5):781-794
Benzylic zinc reagents add with high regioselectivity to 1-(phenoxycarbonyl) salts of methyl nicotinate to yield methyl-1-(phenoxylcarbonyl)-4-benzyl-1,4-dihydronicotinates. The dihydronicotinates on heating with sulfur in decalin afford methyl 4-benzylnicotinates. 相似文献
130.
Jiaqi Zhao Ya Bai Zhenhua Li Dr. Jinjia Liu Dr. Wei Wang Pu Wang Dr. Bei Yang Dr. Run Shi Prof. Geoffrey I. N. Waterhouse Prof. Xiao-Dong Wen Prof. Qing Dai Prof. Tierui Zhang 《Angewandte Chemie (International ed. in English)》2023,62(13):e202219299
The activation of water molecules in thermal catalysis typically requires high temperatures, representing an obstacle to catalyst development for the low-temperature water-gas shift reaction (WGSR). Plasmonic photocatalysis allows activation of water at low temperatures through the generation of light-induced hot electrons. Herein, we report a layered double hydroxide-derived copper catalyst (LD-Cu) with outstanding performance for the low-temperature photo-driven WGSR. LD-Cu offered a lower activation energy for WGSR to H2 under UV/Vis irradiation (1.4 W cm−2) compared to under dark conditions. Detailed experimental studies revealed that highly dispersed Cu nanoparticles created an abundance of hot electrons during light absorption, which promoted *H2O dissociation and *H combination via a carboxyl pathway, leading to the efficient production of H2. Results demonstrate the benefits of exploiting plasmonic phenomena in the development of photo-driven low-temperature WGSR catalysts. 相似文献