Spectroscopic studies on the radical-cation dimer of a model compound of poly(p-phenylenevinylene). Similarities between the dimer and the state of positive polarons in the sulfuric-acid-treated polymer

Akira Sakamoto, Yukio Furukawa, Mitsuo Tasumi

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Abstract

Reversible dimerization of the radical cations of a model compound [CH3(C6H4CH=CH)2C6H 4CH3] of poly-(p-phenylenevinylene) (PPV) in dichloromethane solution has been studied by electronic absorption, electron spin resonance, and resonance Raman spectroscopy. The electronic absorption spectrum of the radical-cation monomer drastically changes upon dimerization; the absorption maxima of the monomer are located at 636 and 1200 nm (15 700 and 8330 cm-1) and those of the dimer at 527 and 981 nm (19 000 and 10 200 cm-1). The monomer - dimer equilibrium constants (K's) at various temperatures have been determined from the observed temperature dependence of the electronic absorption spectra. From the van't Hoff plot of ln K against 1/T, the heat of dimerization ΔH has been evaluated to be -12.6 kcal mol-1. Electron spin resonance measurements have shown that the unpaired spins of the radical-cation monomers make a pair in the dimer. Such a radical-cation dimer is a good model of interchain interaction between polarons that are created on neighboring chain of PPV. The resonance Raman spectra of sulfuric-acid-treated PPV have been analyzed on the basis of the spectra of the radical-cation monomer and dimer. Sulfuric-acid-treated PPV is considered to contain positive polarons that interact with other polarons, in addition to positive polarons without such interaction.

Original languageEnglish
Pages (from-to)1726-1732
Number of pages7
JournalJournal of Physical Chemistry B
Volume101
Issue number10
Publication statusPublished - 1997 Mar 6
Externally publishedYes

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Polarons
polarons
sulfuric acid
Sulfuric acid
Dimers
Cations
Polymers
monomers
Monomers
Positive ions
dimers
Dimerization
cations
dimerization
polymers
electronic spectra
Paramagnetic resonance
Absorption spectra
electron paramagnetic resonance
absorption spectra

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

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title = "Spectroscopic studies on the radical-cation dimer of a model compound of poly(p-phenylenevinylene). Similarities between the dimer and the state of positive polarons in the sulfuric-acid-treated polymer",
abstract = "Reversible dimerization of the radical cations of a model compound [CH3(C6H4CH=CH)2C6H 4CH3] of poly-(p-phenylenevinylene) (PPV) in dichloromethane solution has been studied by electronic absorption, electron spin resonance, and resonance Raman spectroscopy. The electronic absorption spectrum of the radical-cation monomer drastically changes upon dimerization; the absorption maxima of the monomer are located at 636 and 1200 nm (15 700 and 8330 cm-1) and those of the dimer at 527 and 981 nm (19 000 and 10 200 cm-1). The monomer - dimer equilibrium constants (K's) at various temperatures have been determined from the observed temperature dependence of the electronic absorption spectra. From the van't Hoff plot of ln K against 1/T, the heat of dimerization ΔH has been evaluated to be -12.6 kcal mol-1. Electron spin resonance measurements have shown that the unpaired spins of the radical-cation monomers make a pair in the dimer. Such a radical-cation dimer is a good model of interchain interaction between polarons that are created on neighboring chain of PPV. The resonance Raman spectra of sulfuric-acid-treated PPV have been analyzed on the basis of the spectra of the radical-cation monomer and dimer. Sulfuric-acid-treated PPV is considered to contain positive polarons that interact with other polarons, in addition to positive polarons without such interaction.",
author = "Akira Sakamoto and Yukio Furukawa and Mitsuo Tasumi",
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T1 - Spectroscopic studies on the radical-cation dimer of a model compound of poly(p-phenylenevinylene). Similarities between the dimer and the state of positive polarons in the sulfuric-acid-treated polymer

AU - Sakamoto, Akira

AU - Furukawa, Yukio

AU - Tasumi, Mitsuo

PY - 1997/3/6

Y1 - 1997/3/6

N2 - Reversible dimerization of the radical cations of a model compound [CH3(C6H4CH=CH)2C6H 4CH3] of poly-(p-phenylenevinylene) (PPV) in dichloromethane solution has been studied by electronic absorption, electron spin resonance, and resonance Raman spectroscopy. The electronic absorption spectrum of the radical-cation monomer drastically changes upon dimerization; the absorption maxima of the monomer are located at 636 and 1200 nm (15 700 and 8330 cm-1) and those of the dimer at 527 and 981 nm (19 000 and 10 200 cm-1). The monomer - dimer equilibrium constants (K's) at various temperatures have been determined from the observed temperature dependence of the electronic absorption spectra. From the van't Hoff plot of ln K against 1/T, the heat of dimerization ΔH has been evaluated to be -12.6 kcal mol-1. Electron spin resonance measurements have shown that the unpaired spins of the radical-cation monomers make a pair in the dimer. Such a radical-cation dimer is a good model of interchain interaction between polarons that are created on neighboring chain of PPV. The resonance Raman spectra of sulfuric-acid-treated PPV have been analyzed on the basis of the spectra of the radical-cation monomer and dimer. Sulfuric-acid-treated PPV is considered to contain positive polarons that interact with other polarons, in addition to positive polarons without such interaction.

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