Bismuth(III) Complex of the [S4]•– Radical Anion: Dimer Formation via Pancake Bonds

2017 ◽  
Vol 139 (46) ◽  
pp. 16490-16493 ◽  
Author(s):  
Ryan J. Schwamm ◽  
Matthias Lein ◽  
Martyn P. Coles ◽  
Christopher M. Fitchett
Keyword(s):  
Radical Anion ◽  
Dimer Formation

Synthesis and Electrochemical Reduction of Methyl 3-Halo-1-benzothiophene-2-carboxylates

2004 ◽  
Vol 69 (1) ◽  
pp. 242-260 ◽  
Author(s):  
Michal Rejňák ◽  
Jiří Klíma ◽  
Jiří Svoboda ◽  
Jiří Ludvík
Keyword(s):  
Cyclic Voltammetry ◽  
Radical Anion ◽  
Preparative Method ◽  
Platinum Electrodes ◽  
Disk Electrode ◽  
Dimer Formation ◽  
Halide Anion ◽  
Primary Radical ◽  
Heterocyclic Radical ◽  
Ece Mechanism

A preparative method of synthesis of the new methyl 3-iodo-1-benzothiophene-2-carboxylate was elaborated. Electrochemical behavior of methyl 3-chloro-, bromo- and iodo-1-benzothiophene-2-carboxylates 1-3, and of their reduction and dimer products 4, 5 in anhydrous dimethylformamide has been investigated at mercury and platinum electrodes using polarography, cyclic voltammetry and voltammetry on a rotating platinum disk electrode. The reduction in divided cells follows the ECE mechanism (electron - chemical step - electron), where the primary radical anion is split into a halide anion and neutral heterocyclic radical, which is immediately reduced by the second electron and protonated. The only reduction product is the methyl 1-benzothiophene-2-carboxylate (5); whereas the EDim mechanism (electron - dimer formation) leading to the dimeric species 4 was not observed under the above conditions. Reduction of 1-3 on platinum causes formation of a blocking film on the electrode. Sonication during electrolysis successfully reactivates the electrode.

DLTS study of the oxygen dimer formation kinetics in silicon

2009 ◽  
Vol 404 (23-24) ◽  
pp. 4576-4578
Author(s):  
Nikolai Yarykin ◽  
Jörg Weber
Keyword(s):  
Dimer Formation ◽  
Formation Kinetics

Association of radical anion with alkali cations. IV. ESR study of the 4-nitrobenzophenone radical anion

1980 ◽  
Vol 45 (2) ◽  
pp. 369-375 ◽  
Author(s):  
Stanislav Miertuš ◽  
Ondrej Kyseľ
Keyword(s):  
Hyperfine Splitting ◽  
Radical Anion ◽  
Esr Spectroscopy ◽  
Supporting Electrolyte ◽  
Esr Spectra ◽  
Proton Donor ◽  
Alkali Cations

The 4-nitrobenzophenone radical anion prepared by electrolysis was studied by ESR spectroscopy. On the basis of the interpretation of ESR spectra, the conformation of this system was estimated. The effect of the concentration of supporting electrolyte and of the presence of a proton-donor agent (C2H5OH) was examined. It is assumed that changes in hyperfine splitting constants are caused by association.

Stability of radical anions derived from substituted 5-nitrofurans investigated by ESR spectroscopy

1985 ◽  
Vol 50 (7) ◽  
pp. 1594-1601 ◽  
Author(s):  
Jiří Klíma ◽  
Larisa Baumane ◽  
Janis Stradinš ◽  
Jiří Volke ◽  
Romualds Gavars
Keyword(s):  
Radical Anion ◽  
High Stability ◽  
Esr Spectroscopy ◽  
Reaction Path ◽  
Order Reaction ◽  
Second Order ◽  
Radical Anions ◽  
Second Order Reaction ◽  
Unpaired Electron Density ◽  
The Stability

It has been found that the decay in dimethylformamide and dimethylformamide-water mixtures of radical anions in five of the investigated 5-nitrofurans is governed by a second-order reaction. Only the decay of the radical anion generated from 5-nitro-2-furfural III may be described by an equation including parallel first- and second-order reactions; this behaviour is evidently caused by the relatively high stability of the corresponding dianion, this being an intermediate in the reaction path. The presence of a larger conjugated system in the substituent in position 2 results in a decrease of the unpaired electron density in the nitro group and, consequently, an increase in the stability of the corresponding radical anions.

scholarly journals Solvent Exposure and Ionic Condensation Drive Fuzzy Dimerization of Disordered Heterochromatin Protein Sequence

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 915
Author(s):  
Jazelli Mueterthies ◽  
Davit A. Potoyan
Keyword(s):  
Phase Separation ◽  
Low Complexity ◽  
Nuclear Bodies ◽  
Disordered Proteins ◽  
Solvent Exposure ◽  
Ion Release ◽  
Dimer Formation ◽  
Eukaryotic Organisms

Proteins with low complexity, disordered sequences are receiving increasing attention due to their central roles in the biogenesis and regulation of membraneless organelles. In eukaryotic organisms, a substantial fraction of disordered proteins reside in the nucleus, thereby facilitating the formation of nuclear bodies, nucleolus, and chromatin compartmentalization. The heterochromatin family of proteins (HP1) is an important player in driving the formation of gene silenced mesoscopic heterochromatin B compartments and pericentric regions. Recent experiments have shown that the HP1a sequence of Drosophila melanogaster can undergo liquid-liquid phase separation under both in vitro and in vivo conditions, induced by changes of the monovalent salt concentration. While the phase separation of HP1a is thought to be the mechanism underlying chromatin compartmentalization, the molecular level mechanistic picture of salt-driven phase separation of HP1a has remained poorly understood. The disordered hinge region of HP1a is seen as the driver of salt-induced condensation because of its charge enriched sequence and post-translational modifications. Here, we set out to decipher the mechanisms of salt-induced condensation of HP1a through a systematic study of salt-dependent conformations of single chains and fuzzy dimers of disordered HP1a hinge sequences. Using multiple independent all-atom simulations with and without enhanced sampling, we carry out detailed characterization of conformational ensembles of disordered HP1a chains under different ionic conditions using various polymeric and structural measures. We show that the mobile ion release, enhancement of local transient secondary structural elements, and side-chain exposure to solvent are robust trends that accompany fuzzy dimer formation. Furthermore, we find that salt-induced changes in the ensemble of conformations of HP1a disordered hinge sequence fine-tune the inter-chain vs. self-chain interactions in ways that favor fuzzy dimer formation under low salt conditions in the agreement with condensation trends seen in experiments.

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