Side-chain effects on ultraviolet absorption of organopolysilane radical anions

Ban, Hiroshi; Sukegawa, Ken; Tagawa, Seiichi

doi:10.1021/ma00179a010

Cited by 25 publications

(16 citation statements)

References 4 publications

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“…The ionic species have an unpaired electron delocalized over the silicon skeleton. Charged molecules of polysilanes were produced by a pulse radiolysis technique and displayed chromophores in the near-UV and IR region with very high extinction coefficients. , The transient spectra suggest that an excess electron or a hole is delocalized over a conjugated segment in a molecule. This indicates that the conjugated molecular orbital (σ-conjugation) is responsible for the absorption spectra of the ionic species.…”

Section: Introductionmentioning

confidence: 99%

Electronic Structure of Radical Anions and Cations of Polysilanes with Structural Defects

et al. 1999

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The electronic structure of a charged polysilane molecule is studied. The transient absorption spectroscopy was carried out for radical cations and anions of aryl-substituted polysilane molecules with Si-based defects by means of the nanosecond pulse radiolysis technique. Radical cations and anions of polysilanes displayed near-UV and IR absorption maxima at ca. 3.2−3.4 and 0.5−1 eV, respectively. They are ascribed to interband and subband transitions of polaron states and/or charge resonance states (CR) between σ-conjugated segments. The transition energy of the bands was strongly affected by the defects, showing a remarkable blue shift in IR absorption. The energy of the IR absorption band was interpreted as the degree of electron−phonon coupling. The energy rapidly increased from ca. 0.5 eV with an increase in the defect density and saturated at ca. 0.85 eV for radical cations and 0.95 eV for radical anions. It indicated that excess electrons and holes relatively localized at the defect structures, whereas the charges were delocalized in a conjugated segment in linear polysilanes.

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Section: Introductionmentioning

confidence: 99%

Electronic Structure of Radical Anions and Cations of Polysilanes with Structural Defects

et al. 1999

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“…3 One of these properties is that relatively stable polymer anions are generated by exposing polysilanes and polygermanes to ionizing radiation. [4][5][6] It was reported that both aliphatic and aromatic polysilane anions did not decay within 150 ns. 4 The half-life of polysilastyrene anions was reported to be 30 µ$ at room temperature.5 Poly(dibutylgermane) radical anions were also reported to be observed by pulse radiolysis studies.6 However, such stable polymer anions have not been observed for analogous aliphatic hydrocarbon polymers.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6] It was reported that both aliphatic and aromatic polysilane anions did not decay within 150 ns. 4 The half-life of polysilastyrene anions was reported to be 30 µ$ at room temperature.5 Poly(dibutylgermane) radical anions were also reported to be observed by pulse radiolysis studies.6 However, such stable polymer anions have not been observed for analogous aliphatic hydrocarbon polymers. In this respect, polysilanes and polygermanes make a sharp contrast to conventional C backbone polymers.…”

Section: Introductionmentioning

confidence: 99%

Ab initio MO studies on disilane, germylsilane, and digermane radical anions as prototypes of polymer anions with silicon and germanium backbones

Tada¹,

Yoshimura²

1993

J. Phys. Chem.

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Disilane, silylgermane, and digermane radical anions have been studied by ab initio molecular orbital theory, using the unified level of basis set as prototypes of polymer anions with Si and Ge backbones. These prototype anions have the same kind of minimum geometry (C2/, or C2*-like symmetry) with an unpaired electron occupying the Si-Si, Si-Ge, or Ge-Ge a* antibonding orbital with a large Si or Ge s diffuse orbital contribution. Little Si 3d or Ge 4d orbital participation is found for these anions. All these anions can exist as kinetically bound anions with positive first vertical ionization potential values. The stability of an unpaired electron is in the order SÍ2H6" < SiH3GeH3-< Gc2H6". The origin of this stability difference is also discussed. These results suggest that polymer anions with Si and Ge backbones have the same kind of molecular and electronic structures with no dir-dir conjugation and that their stability is in the order polysilane anion < Si-Ge copolymer anion < polygermane anion.

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“…The electronic absorption spectroscopy is convenient technique to determine the electronic excited states of polysilanes. Transient absorption spectra of polysilanes in organic solvents after electron beam irradiation show that the radical ions (cation and anion) of polysilanes have a strong absorption band at UV region [11,12]. This band is assigned to an electronic transition of unpaired electron on Si-Si skeleton.…”

Section: Introductionmentioning

confidence: 99%

“…The permethyl-oligosilane Si n (CH 3 ) 2n+2 (n = [8][9][10][11][12][13][14][15][16][17][18][19][20] was chosen as a model of polysilane. We showed that excess electron and hole are fully delocalized along the skeleton of linear polysilane.…”

Section: Introductionmentioning

confidence: 99%

The electronic structures of all trans form of permethyl-oligosilane radical cation with longer chain: A density functional theory study

Kawabata

Ohmori

Matsushige

et al. 2006

Journal of Organometallic Chemistry

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Side-chain effects on ultraviolet absorption of organopolysilane radical anions

Cited by 25 publications

References 4 publications

Electronic Structure of Radical Anions and Cations of Polysilanes with Structural Defects

Electronic Structure of Radical Anions and Cations of Polysilanes with Structural Defects

Ab initio MO studies on disilane, germylsilane, and digermane radical anions as prototypes of polymer anions with silicon and germanium backbones

The electronic structures of all trans form of permethyl-oligosilane radical cation with longer chain: A density functional theory study

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