scholarly journals Experimental and Theoretical Evidence for Nitrogen–Fluorine Halogen Bonding in Silver-Initiated Radical Fluorinations

2019 ◽  
Author(s):  
Ryan Baxter ◽  
Alyssa Hua ◽  
Sarah Baker ◽  
Samantha Bidwell ◽  
Hrant Hratchian
Keyword(s):  
Reduction Potential ◽  
Halogen Bonding ◽  
Electronic Structure Calculations ◽  
Electrochemical Analysis ◽  
Single Electron ◽  
Halogen Bonds ◽  
Ambient Conditions ◽  
Electron Reduction ◽  
Theoretical Evidence ◽  
Structure Calculations

<div>We report experimental and computational evidence for nitrogen–fluorine halogen bonding in Ag(I)-initiated radical C–H fluorinations. Simple pyridines form [N–F–N]+ halogen bonds with Selectfluor to facilitate single-electron reduction by catalytic Ag(I). Pyridine electronics affect the extent of halogen bonding, leading to notable differences in selectivity between mono- and bis-fluorinated products. Electronic structure calculations show that halogen bonding to various pyridines alters the single-electron reduction potential of Selectfluor, which is consistent with experimental electrochemical analysis. Multinuclear correlation NMR also provides spectroscopic evidence for pyridine halogen bonding to Selectfluor under ambient conditions.</div>

scholarly journals Experimental and Theoretical Evidence for Nitrogen–Fluorine Halogen Bonding in Silver-Initiated Radical Fluorinations

2019 ◽  
Author(s):  
Ryan Baxter ◽  
Alyssa Hua ◽  
Sarah Baker ◽  
Samantha Bidwell ◽  
Hrant Hratchian
Keyword(s):  
Reduction Potential ◽  
Halogen Bonding ◽  
Electronic Structure Calculations ◽  
Electrochemical Analysis ◽  
Single Electron ◽  
Halogen Bonds ◽  
Ambient Conditions ◽  
Electron Reduction ◽  
Theoretical Evidence ◽  
Structure Calculations

<div>We report experimental and computational evidence for nitrogen–fluorine halogen bonding in Ag(I)-initiated radical C–H fluorinations. Simple pyridines form [N–F–N]+ halogen bonds with Selectfluor to facilitate single-electron reduction by catalytic Ag(I). Pyridine electronics affect the extent of halogen bonding, leading to notable differences in selectivity between mono- and bis-fluorinated products. Electronic structure calculations show that halogen bonding to various pyridines alters the single-electron reduction potential of Selectfluor, which is consistent with experimental electrochemical analysis. Multinuclear correlation NMR also provides spectroscopic evidence for pyridine halogen bonding to Selectfluor under ambient conditions.</div>

scholarly journals Role of single-electron reduction potential in inhibition of reverse transcriptase by streptonigrin and sakyomicin A.

1987 ◽  
Vol 40 (5) ◽  
pp. 702-705 ◽  
Author(s):  
YOSHIO INOUYE ◽  
KEIKO OOGOSE ◽  
YUKINORI TAKE ◽  
TAE KUBO ◽  
SHOSHIRO NAKAMURA
Keyword(s):  
Reverse Transcriptase ◽  
Reduction Potential ◽  
Single Electron ◽  
Electron Reduction

ON THE PREDICTION OF FERROMAGNETISM AND METAMAGNETISM IN 4d TRANSITION-METAL OVERLAYERS

1992 ◽  
Vol 06 (11) ◽  
pp. 605-615 ◽  
Author(s):  
OLLE ERIKSSON ◽  
R. C. ALBERS ◽  
A. M. BORING ◽  
G. W. FERNANDO ◽  
B. R. COOPER
Keyword(s):  
Electronic Structure ◽  
Transition Metal ◽  
Electronic Structure Calculations ◽  
Local Spin Density Approximation ◽  
Spin States ◽  
Density Approximation ◽  
Spin Polarized ◽  
Theoretical Evidence ◽  
Metal Overlayers ◽  
Structure Calculations

We present theoretical evidence for ferromagnetism in Ru and Rh overlayers on Ag(001). These predictions are based on ab-initio, spin-polarized, electronic-structure calculations within the framework of the local spin-density approximation. For Tc, Ru, Rh and Pd overlayers chemisorbed on Ag(001), only Ru and Rh exhibited ferromagnetism. Several metamagnetic spin states were found for the Ru overlayers.

scholarly journals Redox properties and prooxidant cytotoxicity of a neuroleptic agent 6,7-dinitrodihydroquinoxaline-2,3-dione (DNQX).

2013 ◽  
Vol 60 (2) ◽  
Author(s):  
Jonas Šarlauskas ◽  
Aušra Nemeikaitė-Čėnienė ◽  
Lina Misevičienė ◽  
Kastis Krikštopaitis ◽  
Žilvinas Anusevičius ◽  
...  
Keyword(s):  
Electrochemical Reduction ◽  
Bovine Leukemia Virus ◽  
Reduction Potential ◽  
Leukemia Virus ◽  
Redox Properties ◽  
Single Electron ◽  
Reduction Peak ◽  
Neuroleptic Agent ◽  
Electron Reduction ◽  
Dt Diaphorase

In order to characterize the possible mechanism(s) of cytotoxicity of a neuroleptic agent 6,7-dinitrodihydroquinoxaline-2,3-dione (DNQX) we examined the redox properties of DNQX, and its mononitro- (NQX) and denitro- (QX) derivatives. The irreversible electrochemical reduction of the nitro groups of DNQX was characterized by the reduction peak potentials (Ep,7) of -0.43 V and -0.72 V vs. Ag/AgCl at pH 7.0, whereas NQX was reduced at Ep,7 = -0.67 V. The reactivities of DNQX and NQX towards the single-electron transferring enzymes NADPH:cytochrome P-450 reductase and NADPH:adrenodoxin reductase/adrenodoxin complex were similar to those of model nitrobenzenes with the single-electron reduction potential (E¹₇) values of -0.29 V - -0.42 V. DNQX and NQX also acted as substrates for two-electron transferring mammalian NAD(P)H:quinone oxidoreductase (DT-diaphorase). The cytotoxicity of DNQX in bovine leukemia virus-transformed lamb kidney fibroblasts (line FLK) was prevented by antioxidants and an inhibitor of NQO1, dicoumarol, and was enhanced by the prooxidant alkylating agent 1,3-bis(2-chloromethyl)-1-nitrosourea. A comparison with model nitrobenzene compounds shows that the cytotoxicity of DNQX and NQX reasonably agrees with the ease of their electrochemical reduction, and/or their reactivities towards the used enzymatic single-electron reducing systems. Thus, our data imply that the cytotoxicity of DNQX in FLK cells is exerted mainly through oxidative stress.

Methemoglobin Formation in Human Erythrocytes by Nitroaromatic Explosives

2001 ◽  
Vol 56 (11-12) ◽  
pp. 1157-1163 ◽  
Author(s):  
Audronė Marozienė ◽  
Regina Kliukienė ◽  
Jonas Šarlauskas ◽  
Narimantas Čėnas
Keyword(s):  
Rate Constants ◽  
Reduction Potential ◽  
Reduced Glutathione ◽  
Human Erythrocytes ◽  
Single Electron ◽  
Oxidizing Agent ◽  
High Explosives ◽  
Structure Activity ◽  
Methemoglobin Formation ◽  
Electron Reduction

Abstract We have examined the structure-activity relationships in methemoglobin (MetHb) forma­tion by high explosives 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenyl-N-nitramine (tetryl) and 2,4,6-trinitrophenyl-N-nitraminoethylnitrate (pentryl), and a number of model nitroben-zenes. In lysed human erythrocytes the rate constants of oxyhemoglobin (OxyHb) oxidation increased with an increase in single-electron reduction potential (E17) or with a decrease of the enthalpies of single-electron reduction of nitroaromatics. Tetryl and pentryl oxidized Ox­yHb almost 3 times faster than TNT. Although the initial rates of MetHb formation in intact erythrocytes by tetryl, pentryl, and TNT matched their order of reactivity in the oxidation of OxyHb in lysed erythrocytes, TNT was a more efficient MetHb forming agent than tetryl and pentryl during a 24-h incubation. The decreased efficiency of tetryl and pentryl was attributed to their reaction with intraerythrocyte reduced glutathione (GSH) producing 2,4,6-trinitrophenyl-Sglutathione, which acted as a less efficient OxyHb oxidizing agent.

Message Passing Neural Networks for Partial Charge Assignment to Metal-Organic Frameworks

2020 ◽  
Author(s):  
Ali Raza ◽  
Arni Sturluson ◽  
Cory Simon ◽  
Xiaoli Fern
Keyword(s):  
Electronic Structure ◽  
Message Passing ◽  
Gas Adsorption ◽  
Metal Organic Frameworks ◽  
Computational Cost ◽  
Electronic Structure Calculations ◽  
High Fidelity ◽  
Partial Charges ◽  
Metal Organic ◽  
Structure Calculations

Virtual screenings can accelerate and reduce the cost of discovering metal-organic frameworks (MOFs) for their applications in gas storage, separation, and sensing. In molecular simulations of gas adsorption/diffusion in MOFs, the adsorbate-MOF electrostatic interaction is typically modeled by placing partial point charges on the atoms of the MOF. For the virtual screening of large libraries of MOFs, it is critical to develop computationally inexpensive methods to assign atomic partial charges to MOFs that accurately reproduce the electrostatic potential in their pores. Herein, we design and train a message passing neural network (MPNN) to predict the atomic partial charges on MOFs under a charge neutral constraint. A set of ca. 2,250 MOFs labeled with high-fidelity partial charges, derived from periodic electronic structure calculations, serves as training examples. In an end-to-end manner, from charge-labeled crystal graphs representing MOFs, our MPNN machine-learns features of the local bonding environments of the atoms and learns to predict partial atomic charges from these features. Our trained MPNN assigns high-fidelity partial point charges to MOFs with orders of magnitude lower computational cost than electronic structure calculations. To enhance the accuracy of virtual screenings of large libraries of MOFs for their adsorption-based applications, we make our trained MPNN model and MPNN-charge-assigned computation-ready, experimental MOF structures publicly available.<br>

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