Investigation on electronic structures and second-order nonlinear optical properties of stilbazolium and its related cations with extended π-conjugation by semiempirical calculation

Xuan Ming Duan, Naoyuki Nishimura, Hideo Konami, Shuji Okada, Hidetoshi Oikawa, Hiro Matsuda, Hachiro Nakanishi

Research output: Contribution to journalConference articlepeer-review

4 Citations (Scopus)

Abstract

The electronic structures of substituted stilbazolium and its related cationic species with extended π-conjugated systems were investigated by semiempirical calculation using MNDO Hamiltonian with PM3 parametrization and their second-order hyperpolarizabilities (β) at zero frequency were calculated using the TDHF method. The β-conjugated systems studied were naphthylenevinylene group (Nv) instead of phenylenevinylene group (Pv) of stilbazolium and/or 4-substituted quinolinium group (Qu+) or 6-substituted isoquinolinium group (Iq+) instead of pyridinium group (Py+) of stilbazolium, and the properties of six cationic skeletons composed of these systems were compared with an electrically neutral molecule of 4-dimethylamino-4′-nitrostilbene (DANS). In HOMO and LUMO, more inclined electron distribution was found especially for cationic species with extended π-conjugation compared with DANS. Though the dipole moments in ground and excited states (μg and μe, respectively) are in the same direction for DANS, those of many of cationic species are in the opposite direction resulting in larger Δμ (= μeg) than DANS. The calculated β values of cations are several times larger than those of DANS with the same band gap. Among the cations with the same substituent, β value effectively increases by extending conjugated system from Pv to Nv and/or Py+ to Iq+. Especially, Nv-Iq+ skeleton seemed to be better from the point of view to break the trade-off relationship between absorption and β value.

Original languageEnglish
Pages (from-to)105-126
Number of pages22
JournalMolecular Crystals and Liquid Crystals Science and Technology Section B: Nonlinear Optics
Volume20
Issue number1
Publication statusPublished - 1999 Jan 1
EventProceedings of the 1997 International Symposium on Organic Polymeric Materials for Optical Communication and Information Storage - Taejon, S Kor
Duration: 1997 Oct 301997 Nov 1

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Condensed Matter Physics

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