E.P.R. studies and INDO calculations on the molecular structure of radicals derived from some N-alkylpyridinium salts

Guerin—Ouler, Daniele; Nicollin, C.; Sieiro, C.; Lamy, C.

doi:10.1080/00268977700101601

Cited by 19 publications

(2 citation statements)

References 20 publications

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“…Most of the characterization of viologen radical cations has been spectroscopic: only the methyl viologen radical cation has been crystallographically characterized . Several of the alkyl viologen radical cations have been studied by ESR, ,− UV−vis, , and IR ,, spectroscopy. Many of those investigations addressed the reversible π-dimerization of the radical cations in solution.…”

Section: Introductionmentioning

confidence: 99%

Isolation and Characterization of Phenyl Viologen as a Radical Cation and Neutral Molecule

Porter¹,

Vaid²

2005

J. Org. Chem.

120

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The chemical synthesis, isolation, and characterization of phenyl viologen (PV) as a dication, radical cation, and neutral species are described. Single-crystal X-ray diffraction of PV(2+)2Cl(-.)2H2O and PV(.+)PF(6)(-).pyridine reveals the expected differences in bond lengths and also a structural change from two coplanar central rings in PV(.+) to a twist of 36 degrees between the two central rings in PV(2+). The phenyl viologen radical cation exhibits behavior characteristic of many radical cations, including weak pi-dimerization in the solid state and reversible pi-dimerization in solution. Electrical conductivity measurements of neutral phenyl viologen, the first such measurements of a neutral viologen, reveal that it is a significantly better conductor than the radical cation. Differences in geometric relaxation during charge transfer offer a possible explanation for the higher conductivity of the neutral viologen.

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Section: Introductionmentioning

confidence: 99%

Isolation and Characterization of Phenyl Viologen as a Radical Cation and Neutral Molecule

Porter¹,

Vaid²

2005

J. Org. Chem.

120

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“…Due to its favorable redox properties and potential application in the solar-energy storage and electrochromic display devices, the solution chemistry of MV2+ has been extensively studied. [1][2][3][4][5][6] The photolysis of MV2+ on semiconductor and polymer surfaces has been also reported. [7][8][9] In the present studies the silica gel surface, which is mainly composed of siloxane (=Si-O-Si=) and silanol (=SiOH) groups, is used as a host system.…”

Section: Introductionmentioning

confidence: 99%

Formation of Methylviologen Radical Monopositive Cations and Ensuing Reactions with Polychloroalkanes on Silica Gel Surfaces

Mao¹,

Breen²,

Thomas³

1995

J. Phys. Chem.

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A Spectroscopic Study of the Reduction of Geometrically Restrained Viologens

Benniston¹,

Harriman²,

Li³

et al. 2007

Chemistry A European J

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A small series of N,N'-dimethyl-4,4'-bipyridinium dication derivatives (commonly known as viologens) has been synthesized and fully characterized; a short dialkoxy tether attached at the 3,3'-positions is used to alter the central dihedral angle. These angles were determined by both single-crystal X-ray diffraction and by computational studies made for the dication, radical cation, and neutral species in a solvent reservoir. The dihedral angle derived for the dication controls the first reduction potential, whereas the geometry of the resultant pi-radical cation determines the magnitude of the second reduction potential. The optical absorption spectra recorded for the various species, and especially those of the radical cations, and the EPR spectral parameters of the pi-radical cations also depend on the molecular geometry. In particular, the central dihedral angle influences the spin density distribution around the aromatic nucleus and, by way of comparison to the parent viologen, it has been possible to resolve the angle dependence from the inherent inductive effect of the strap. These results are considered in terms of the degree of electronic communication between the two aromatic rings, as controlled by the length of the tether.

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E.P.R. studies and INDO calculations on the molecular structure of radicals derived from some N-alkylpyridinium salts

Abstract: The electrochemical reduction of N-alkylpyridinium salts leading to dipyridinium compounds is analysed by means of E.P.R. spectroscopy. The molecular structure of N-N'-dialkyl dipyridinium cation radicals involved is deduced from the E.P.R. results and from INDO calculations.

Cited by 19 publications

References 20 publications

Isolation and Characterization of Phenyl Viologen as a Radical Cation and Neutral Molecule

Isolation and Characterization of Phenyl Viologen as a Radical Cation and Neutral Molecule

Formation of Methylviologen Radical Monopositive Cations and Ensuing Reactions with Polychloroalkanes on Silica Gel Surfaces

A Spectroscopic Study of the Reduction of Geometrically Restrained Viologens

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