Hyperpolarizability density analysis of the enhancement of second hyperpolarizability of π-conjugated oligomers by intermolecular interaction

Masayoshi Nakano, Ryohei Kishi, Tomoshige Nitta, Benoît Champagne, Edith Botek, Kizashi Yamaguchi

Research output: Contribution to journalArticle

Abstract

In a previous paper we found that the cofacial intermolecular π-π orbital interaction in stacking dimers significantly changes the longitudinal second hyperpolarizability (γ) of the isolated monomer. On the basis of this result, we investigate the longitudinal γ values of π-conjugated main chains (CnHn+2, 6 ≤ n≤ 16) interacting in both-end regions with two small-size cationic perturbing π-conjugated molecules, that is, allyl cations (C3H3 +). These interacting model systems exhibit remarkable enhancement of γ values as compared with those of isolated main chains in the whole chain-length region. The γ density analysis reveals that this enhancement is described by the virtual charge transfer between both-end perturbing molecules via the main chain. The analysis of orbital correlation diagram between the perturbing molecules and main chain molecule also clarifies that such feature of γ density distribution originates in the "weak intermolecular antibondinglike coupling" between the (lowest unoccupied molecular orbital [LUMO], LUMO+1) of cationic perturbing molecules and (highest unoccupied molecular orbital [HOMO], HOMO-1) of main chain molecule. The current result suggests the possibility of novel nano-size control of nonlinear optical (NLO) properties by adjusting the intermolecular orbital interactions between the main molecule and perturbing molecules. A possible control scheme of longitudinal γ for novel intermolecular interacting NLO systems using modified DNA wires is also proposed.

Original languageEnglish
Pages (from-to)702-710
Number of pages9
JournalInternational Journal of Quantum Chemistry
Volume102
Issue number5 SPEC. ISS.
DOIs
Publication statusPublished - 20 Apr 2005

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oligomers
Oligomers
Molecules
augmentation
Molecular orbitals
molecules
molecular orbitals
interactions
orbitals
Chain length
Optical systems
Dimers
density distribution
Cations
Charge transfer
deoxyribonucleic acid
Optical properties
monomers
Monomers
adjusting

Keywords

  • π-conjugated system
  • DNA
  • Hyperpolarizability
  • Intermolecular interaction
  • Nonlinear optics

Cite this

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title = "Hyperpolarizability density analysis of the enhancement of second hyperpolarizability of π-conjugated oligomers by intermolecular interaction",
abstract = "In a previous paper we found that the cofacial intermolecular π-π orbital interaction in stacking dimers significantly changes the longitudinal second hyperpolarizability (γ) of the isolated monomer. On the basis of this result, we investigate the longitudinal γ values of π-conjugated main chains (CnHn+2, 6 ≤ n≤ 16) interacting in both-end regions with two small-size cationic perturbing π-conjugated molecules, that is, allyl cations (C3H3 +). These interacting model systems exhibit remarkable enhancement of γ values as compared with those of isolated main chains in the whole chain-length region. The γ density analysis reveals that this enhancement is described by the virtual charge transfer between both-end perturbing molecules via the main chain. The analysis of orbital correlation diagram between the perturbing molecules and main chain molecule also clarifies that such feature of γ density distribution originates in the {"}weak intermolecular antibondinglike coupling{"} between the (lowest unoccupied molecular orbital [LUMO], LUMO+1) of cationic perturbing molecules and (highest unoccupied molecular orbital [HOMO], HOMO-1) of main chain molecule. The current result suggests the possibility of novel nano-size control of nonlinear optical (NLO) properties by adjusting the intermolecular orbital interactions between the main molecule and perturbing molecules. A possible control scheme of longitudinal γ for novel intermolecular interacting NLO systems using modified DNA wires is also proposed.",
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Hyperpolarizability density analysis of the enhancement of second hyperpolarizability of π-conjugated oligomers by intermolecular interaction. / Nakano, Masayoshi; Kishi, Ryohei; Nitta, Tomoshige; Champagne, Benoît; Botek, Edith; Yamaguchi, Kizashi.

In: International Journal of Quantum Chemistry, Vol. 102, No. 5 SPEC. ISS., 20.04.2005, p. 702-710.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Hyperpolarizability density analysis of the enhancement of second hyperpolarizability of π-conjugated oligomers by intermolecular interaction

AU - Nakano, Masayoshi

AU - Kishi, Ryohei

AU - Nitta, Tomoshige

AU - Champagne, Benoît

AU - Botek, Edith

AU - Yamaguchi, Kizashi

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