Catalytic Effects of Ammonium and Sulfonium Salts and External Electric Fields on Aza-Diels–Alder Reactions

2019 ◽  
Vol 85 (4) ◽  
pp. 2618-2625 ◽  
Author(s):  
Cyndi Qixin He ◽  
Ching Ching Lam ◽  
Peiyuan Yu ◽  
Zhihui Song ◽  
Maggie Chen ◽  
...  
Keyword(s):  
Electric Fields ◽  
Diels Alder ◽  
Sulfonium Salts ◽  
External Electric Fields ◽  
Catalytic Effects

scholarly journals Heterogeneous Intramolecular Electric Field as a Descriptor of Diels-Alder Reactivity

2020 ◽  
Author(s):  
Matthew Hennefarth ◽  
Anastassia N. Alexandrova
Keyword(s):  
Electric Field ◽  
Electron Density ◽  
Electric Fields ◽  
Alder Reaction ◽  
Diels Alder ◽  
Charge Movement ◽  
External Electric Fields ◽  
Topological Features ◽  
Diels Alder Reaction ◽  
Kinetics Of

<div> <div> <div> <p>External electric fields have proven to be an effective tool in catalysis, on par with pressure and temperature, affecting the thermodynamics and kinetics of a reaction. However, fields in molecules are complicated heterogeneous vector objects, and there is no universal recipe for grasping the exact features of these fields that implicate reactivity. Herein, we demonstrate that topological features of the heterogeneous electric field within the reactant state, as well as of the quantum mechanical electron density – a scalar reporter on the field experienced by the system – can be identified as rigorous descriptors of the reactivity to follow. We scrutinize specifically the Diels-Alder reaction. Its 3-D nature and the lack of a singular directionality of charge movement upon barrier crossing makes the effect of the electric field not obvious. We show that the electric field topology around the dienophile double bond, and the associated changes in the topology of the electron density in this bond are predictors of the reaction barrier. They are also the metrics by which to rationalize and predict how the external field would inhibit or enhance the reaction. The findings pave the way toward designing external fields for catalysis, as well as reading the reactivity without an explicit mechanistic interrogation, for a variety of reactions. </p> </div> </div> </div>

scholarly journals Heterogeneous Intramolecular Electric Field as a Descriptor of Diels-Alder Reactivity

2020 ◽  
Author(s):  
Matthew Hennefarth ◽  
Anastassia N. Alexandrova
Keyword(s):  
Electric Field ◽  
Electron Density ◽  
Electric Fields ◽  
Alder Reaction ◽  
Diels Alder ◽  
Charge Movement ◽  
External Electric Fields ◽  
Topological Features ◽  
Diels Alder Reaction ◽  
Kinetics Of

<div> <div> <div> <p>External electric fields have proven to be an effective tool in catalysis, on par with pressure and temperature, affecting the thermodynamics and kinetics of a reaction. However, fields in molecules are complicated heterogeneous vector objects, and there is no universal recipe for grasping the exact features of these fields that implicate reactivity. Herein, we demonstrate that topological features of the heterogeneous electric field within the reactant state, as well as of the quantum mechanical electron density – a scalar reporter on the field experienced by the system – can be identified as rigorous descriptors of the reactivity to follow. We scrutinize specifically the Diels-Alder reaction. Its 3-D nature and the lack of a singular directionality of charge movement upon barrier crossing makes the effect of the electric field not obvious. We show that the electric field topology around the dienophile double bond, and the associated changes in the topology of the electron density in this bond are predictors of the reaction barrier. They are also the metrics by which to rationalize and predict how the external field would inhibit or enhance the reaction. The findings pave the way toward designing external fields for catalysis, as well as reading the reactivity without an explicit mechanistic interrogation, for a variety of reactions. </p> </div> </div> </div>

Directional Diels–Alder cycloadditions of isoelectronic graphene and hexagonal boron nitride in oriented external electric fields: reaction axis rule vs. polarization axis rule

Nanoscale ◽  
2020 ◽  
Vol 12 (28) ◽  
pp. 15364-15370 ◽  
Author(s):  
Wei-Wei Wang ◽  
Chang-Wei Wang ◽  
Jia-Jia Zheng ◽  
Fu-Lin Shang ◽  
Jing-Shuang Dang ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Boron Nitride ◽  
Electric Fields ◽  
Hexagonal Boron Nitride ◽  
Diels Alder ◽  
External Electric Fields ◽  
Polarization Axis ◽  
Catalytic Mechanisms

We introduced the distinct catalytic mechanisms of the oriented-external-electric-fields-promoted DA reactions of graphene and hexagonal boron nitride. The different responses to fields can be elucidated from the different charge transfer characters.

scholarly journals Emulsions in external electric fields

2021 ◽  
pp. 102455
Author(s):  
Johan Sjöblom ◽  
Sameer Mhatre ◽  
Sébastien Simon ◽  
Roar Skartlien ◽  
Geir Sørland
Keyword(s):  
Electric Fields ◽  
External Electric Fields

scholarly journals Vacancy tuned thermoelectric properties and high spin filtering performance in graphene/silicene heterostructures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zainab Gholami ◽  
Farhad Khoeini
Keyword(s):  
Electric Fields ◽  
High Spin ◽  
High Efficiency ◽  
Practical Applications ◽  
External Electric Fields ◽  
Ferromagnetic Exchange ◽  
High Spin Polarization ◽  
Filtering Effect ◽  
Spin Switching ◽  
Spin Filtering

AbstractThe main contribution of this paper is to study the spin caloritronic effects in defected graphene/silicene nanoribbon (GSNR) junctions. Each step-like GSNR is subjected to the ferromagnetic exchange and local external electric fields, and their responses are determined using the nonequilibrium Green’s function (NEGF) approach. To further study the thermoelectric (TE) properties of the GSNRs, three defect arrangements of divacancies (DVs) are also considered for a larger system, and their responses are re-evaluated. The results demonstrate that the defected GSNRs with the DVs can provide an almost perfect thermal spin filtering effect (SFE), and spin switching. A negative differential thermoelectric resistance (NDTR) effect and high spin polarization efficiency (SPE) larger than 99.99% are obtained. The system with the DV defects can show a large spin-dependent Seebeck coefficient, equal to Ss ⁓ 1.2 mV/K, which is relatively large and acceptable. Appropriate thermal and electronic properties of the GSNRs can also be obtained by tuning up the DV orientation in the device region. Accordingly, the step-like GSNRs can be employed to produce high efficiency spin caloritronic devices with various features in practical applications.

scholarly journals Cisplatin under oriented external electric fields: A deeper insight into electrochemotherapy at the molecular level

2020 ◽  
Author(s):  
Li Zhang ◽  
Ya‐Ling Ye ◽  
Xiao‐Ling Zhang ◽  
Xiang‐Hui Li ◽  
Qiao‐Hong Chen ◽  
...  
Keyword(s):  
Electric Fields ◽  
Molecular Level ◽  
External Electric Fields ◽  
Insight Into

An experimental and simulation study on the self-assembly of colloidal cubes in external electric fields

Soft Matter ◽  
2014 ◽  
Vol 10 (45) ◽  
pp. 9110-9119 ◽  
Author(s):  
Hanumantha Rao Vutukuri ◽  
Frank Smallenburg ◽  
Stéphane Badaire ◽  
Arnout Imhof ◽  
Marjolein Dijkstra ◽  
...  
Keyword(s):  
Electric Fields ◽  
Simulation Study ◽  
Self Assembly ◽  
The Self ◽  
External Electric Fields
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