scholarly journals Synthesis, Structure and Bonding Nature of Heavy Dipnictene Radical Anions

2021 ◽  
Author(s):  
Hanns Micha Weinert ◽  
Christoph Wölper ◽  
Julia Haak ◽  
George Cutsail III ◽  
Stephan Schulz
Keyword(s):  
Cyclic Voltammetry ◽  
Radical Anions ◽  
Structure And Bonding ◽  
Reversible Reduction

Cyclic voltammetry studies of two L(X)Ga-substituted dipnictenes [L(R2N)GaE]2 (E = Sb, R = Me 1; E =Bi; R = Et 2; L = HC[C(Me)NDipp]2; Dipp= 2,6-i-Pr2C6H3) showed reversible reduction events....

scholarly journals Síntesis regioespecífica y estudio electroquímico de dos derivados carboxílicos C60 solubles en agua

2021 ◽  
Author(s):  
Juan D. Villada ◽  
Álvaro Duarte-Ruiz ◽  
Manuel N. Chaur
Keyword(s):  
Cyclic Voltammetry ◽  
Liquid Chromatography ◽  
Electronic Properties ◽  
Reaction Times ◽  
C60 Fullerene ◽  
Reduction Processes ◽  
Vis Spectroscopy ◽  
Highperformance Liquid Chromatography ◽  
Electron Transfers ◽  
Reversible Reduction

We report a new methodology for the synthesis of two highly symmetric equatorial malonate hexaadducts of C60 fullerene. The synthetic methodology is based on a series of protection and deprotection steps that allow the preparation of a fullerene [60] functionalized with six symmetrical positioned malonate addends without using complicated and expensive separation techniques (highperformance liquid chromatography, HPLC) or long reaction times. This methodology allowed us to prepare the carboxylic adducts 6 (equatorial octacarboxylic tetraadduct of C60) and 8 (equatorial dodecacarboxylic hexakisadduct of C60). As far as we  now, compound 6 has not yet been reported. We also studied the electronic properties of the main compounds by UV-Vis spectroscopy and cyclic voltammetry (CV). The reported fullerene adducts exhibited several reversible reduction processes whose electron transfers are controlled by diffusion. 

tripod-Eisen- und tripod-Cobalt-Komplexe mit Acetonitril als Stützliganden (tripod = RCH2C(CH2PPh2)3; R = H, Ph) / tripod-Iron and tripod-Cobalt-Complexes with Acetonitrile as Supporting Ligands (tripod = RCH2C(CH2PPh2)3; R = H, Ph)

1993 ◽  
Vol 48 (12) ◽  
pp. 1707-1714 ◽  
Author(s):  
A. Asam ◽  
B. Janssen ◽  
G. Huttner ◽  
L. Zsolnai ◽  
O. Walter
Keyword(s):  
Cyclic Voltammetry ◽  
Analytical Techniques ◽  
Cobalt Complexes ◽  
X Ray ◽  
Tripod Ligands ◽  
Reversible Reduction

The tripod ligands RCH2C(CH2PPh2)3 react with (CH3CN)6Fe(BF4)2 to yield the tripod-Fe(II) complexes RCH2C(CH2PPh2)3Fe(CH3CN)3(BF4)2 (R = H, la; R = Ph, lb). The octahedral low spin Fe(II) compounds are shown by cyclic voltammetry to undergo reversible one electron oxidation at +1.47 V (vs. SCE) to give the corresponding Fe(III) derivatives.In a similar way (CH3CN)6Co(BF4)2 reacts with the same tripod ligands to produce the tripod-Co(II) complexes RCH2C(CH2PPh2)3Co(CH3CN)2(BF4)2 (R = H, 2a; R = Ph, 2b). The compounds are paramagnetic (2a, g = 2.123; 2b, g = 2.129). The structure of complex 2b shows that the tripod ligand is facially coordinated with one longer (233.1 pm) and two shorter (about 222 pm) Co—P bonds. Reversible reduction is found for 2a at —0.30 V by cyclic voltammetry. The compounds have been characterized by spectroscopic and analytical techniques including X-ray analyses.

Correlation of the first reduction potential of selected radiosensitizers determined by cyclic voltammetry with theoretical calculations

2011 ◽  
Vol 76 (8) ◽  
pp. 937-946 ◽  
Author(s):  
Miroslav Gál ◽  
Viliam Kolivoška ◽  
Marta Ambrová ◽  
Ján Híveš ◽  
Romana Sokolová
Keyword(s):  
Experimental Study ◽  
Cyclic Voltammetry ◽  
Radical Anion ◽  
Reduction Potential ◽  
Theoretical Calculations ◽  
Dft Method ◽  
Basis Set ◽  
Radical Anions ◽  
Electron Affinities ◽  
Electron Reduction

Radiosensitizers are drugs that make cancer cells more sensitive to radiation therapy. The cytotoxic properties of such compounds are due to the fact that in the cell these compounds undergo one-electron reduction to generate radical anions. Therefore, their theoretical and/or experimental study is of high interest. To determine the correlation between reduction potential determined by cyclic voltammetry measurements and some physicochemical properties of selected radiosensitizers theoretical calculations of electron affinities based on the DFT method with B3LYP functional at the level of 6-311++G** basis set in vacuum were utilized. Very good correlation was found between electron affinities of radiosensitizers and their reduction potential and so called E71 potential that account for the energy necessary to transfer the first electron to an electroactive group at pH 7 in aqueous medium to form a radical anion.

scholarly journals Integrated Study of the Dinitrobenzene Electroreduction Mechanism by Electroanalytical and Computational Methods

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Andrey S. Mendkovich ◽  
Mikhail A. Syroeshkin ◽  
Ludmila V. Mikhalchenko ◽  
Mikhail N. Mikhailov ◽  
Alexander I. Rusakov ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Quantum Chemical ◽  
Bond Cleavage ◽  
Digital Simulation ◽  
Radical Anions ◽  
Theoretical Methods ◽  
Controlled Potential Electrolysis ◽  
Proton Donors ◽  
Controlled Potential ◽  
Integrated Study

Electroreduction of 1,2-, 1,3-, and 1,4-dinitrobenzenes in DMF has been investigated by a set of experimental (cyclic voltammetry, chronoamperometry, and controlled potential electrolysis) and theoretical methods (digital simulation and quantum chemical calculations). The transformation of only one nitro group is observed in the presence of proton donors. The process selectivity is provided by reactions of radical anions' intermediate products. The key reactions here are protonation of radical anions of nitrosonitrobenzenes and N-O bond cleavage in radical anions of N-(nitrophenyl)-hydroxylamines.

Radikalionen, 69 [1, 2] Die elektrochemische Reduktion aromatischer Nitro-Verbindungen in aprotischer Lösung / Radical Ions, 69 [1, 2] The Electrochemical Reduction of Aromatic Nitro Compounds in Aprotic Solution

1985 ◽  
Vol 40 (11) ◽  
pp. 1463-1475 ◽  
Author(s):  
Hans Bock ◽  
Ulrike Lechner-Knoblauch
Keyword(s):  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Redox Reactions ◽  
Electrochemical Behaviour ◽  
Nitro Compounds ◽  
Radical Ions ◽  
Aromatic Nitro Compounds ◽  
Reduction Potentials ◽  
Aromatic Nitro ◽  
Reversible Reduction

The reduction potentials of 40 aromatic nitro compounds Rπ(NO2)n with Rπ = benzene, naphthalene, anthracene, fluorene and carbazole and n = 1 to 4 nitro groups are determined by cyclic voltammetry in DMF under aprotic conditions. The perturbation by the strongly electron accepting substituents can be rationalized via correlation with HMO eigenvalues. Based on reversibility criteria, the electrochemical behaviour is discussed and the compounds are classified with respect to reversible or irreversible one-electron transfer as well as up to 4 (quasi)-reversible reduction steps. The CV data measured can be used to predict redox reactions of aromatic nitro compounds in inert solvents.

Hexaborate Cluster Radical Anions [B6Haln Hal'6-n].- and [B6Hal5R].-(Hai, Hal' = CI, Br, I; R = H, alkyl). Chemical or Electrochemical Generation, Vibrational, UV-Vis and EPR Spectroscopy

1999 ◽  
Vol 54 (9) ◽  
pp. 1103-1108 ◽  
Author(s):  
Matthias Wanner ◽  
Wolfgang Kaim ◽  
Volker Lorenzen ◽  
Wilhelm Preetz
Keyword(s):  
Cyclic Voltammetry ◽  
Epr Spectroscopy ◽  
The Other ◽  
Cluster Core ◽  
Radical Anions ◽  
Spin Distribution ◽  
Electrochemical Generation ◽  
Other Hand ◽  
Vis Spectroscopy ◽  
The Stability

Paramagnetic hexaborate clusters with mixed halide, halide/alkyl or halide/hydride substitution were prepared from oxidizable dianionic precursors and were characterized by cyclic voltammetry, EPR, vibrational and UV-VIS spectroscopy. The EPR studies reveal increasing g anisotropy and EPR linewidths on replacing Cl by Br and especially by I substituents; on the other hand, the replacement of one halide by one alkyl (CH3 or CH2CN) or hydride substituent in [B6Hal5R]∙- causes decreasing radical persistence and g anisotropy. These results indicate a fairly uniform participation of the cluster core and the substituent sphere in the spin distribution as a major factor for the stability of these non-π radicals.

Reactions of aromatic radical-anions and ethyllithium with silica gel and Brönsted acids

1990 ◽  
Vol 55 (3) ◽  
pp. 686-694 ◽  
Author(s):  
Jan Kratochvíla ◽  
Zdeněk Salajka ◽  
Antonín Kazda ◽  
Zbyněk Kadlc ◽  
Mihnea Gheorghiu
Keyword(s):  
Silica Gel ◽  
Aromatic Compounds ◽  
Organometallic Compounds ◽  
Radical Anions ◽  
Liquid Media ◽  
Structure And Bonding ◽  
Activated Silica Gel ◽  
Increasing Temperature ◽  
Hydroxy Groups ◽  
Acidic Hydrogen

Electric conductivities of radical-anions prepared from several aromatic compounds (biphenyl, naphthalene, benzophenone, anthracene, phenanthrene) and sodium in tetrahydrofuran have been measured and a suitability of radical-anions for titration of silica gel and acid impurities in liquid media have been investigated. The reactivity of the radical-anions and ethyllithium with acidic hydrogen of silica gel hydroxy groups is approximately equal in spite of substantial differences in structure and bonding character of the above compounds. Highest amounts of radical-anions and ethyllithium are decomposed by thermally non-activated silica gel (1.7 to 1.8 mmol g-1 for Davison, grade 952). With the increasing temperature of dehydration of silica gel (200-900 °C), the amount of decomposed organometallic compounds decreases approximately linearly.

The redox properties of ferrocenyl-substituted aryl azines

2002 ◽  
Vol 80 (3) ◽  
pp. 250-262 ◽  
Author(s):  
Vittorio A Sauro ◽  
Mark S Workentin
Keyword(s):  
Cyclic Voltammetry ◽  
Radical Anion ◽  
General Characteristic ◽  
Redox Properties ◽  
Quantum Yields ◽  
X Ray ◽  
Long Wavelength ◽  
Fluorescence Quantum Yields ◽  
Reduction Potentials ◽  
Reversible Reduction

A series of ferrocenyl substituted azines (1-Fc/Ar, where Ar = 4-NO2C6H4, 4-CNC6H4, 4-OCH3C6H4, C5H4N, ferrocene, anthracene, and pyrene) were investigated by electrochemical and photochemical techniques. All the 1-Fc/Ar exhibited oxidation waves within 60 mV of each other, consistent with the expected oxidation of the ferrocene moiety. The reduction properties of 1-Fc/Ar is governed by the nature of the Ar substituent. The standard reduction potentials suggest that ferrocene has comparable electron donating abilities as a 4-methoxyphenyl and 4-dimethyl aminophenyl group. The anthracenyl azines exhibit one-electron reversible reduction followed by dimerization of the radical anion resulting in dimerization rate constants (kd) between 5.1 × 104 and 1.5 × 105 M–1 s–1. 1-Fc/Anth and related azines undergo photochemical E/Z isomerization of the C=N bonds to produce E/Z and Z/Z isomers from the thermodynamically most stable E/E form. Fluorescence at 77 K, was observed for these compounds only after long- wavelength irradiation to produce a mixture of E/E, E/Z, and Z/Z isomers. Fluorescence quantum yields of 0.042, 0.090, and 0.176 were determined for 2-Anth/H, 2-Anth/Anth, and 1-Fc/Anth, respectively. The electrochemical, photochemical, and X-ray data suggest that the azine unit is a conjugation "limiter" and may be a general characteristic of azine molecules.Key words: azines, electrochemistry, cyclic voltammetry, reduction, electron transfer.

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