Diradical character tuning for the third-order nonlinear optical properties of quinoidal oligothiophenes by introducing thiophene-S,S-dioxide rings

Ryohei Kishi, Shoki Ochi, Shioh Izumi, Akihiro Makino, Takanori Nagami, Jun Ya Fujiyoshi, Naoyuki Matsushita, Michika Saito, Masayoshi Nakano

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

To create a design guideline for efficient third-order nonlinear optical (NLO) molecules, the chain-length (n) dependences of the diradical character y and the longitudinal second hyperpolarizability γ of quinoidal oligothiophenes (QTs), from monomers to octamers, involving thiophene-S,S-dioxide rings are investigated by using the density functional theory method. It turns out that the diradical character of the modified QTs is reduced as compared to those of the pristine QTs. By introducing an appropriate number of oxidized rings into the QT framework, intermediate y values can be achieved even in the systems with large values of n, in which the pristine QTs are predicted to have pure diradical character. Such intermediate diradical oligomers are shown to exhibit enhanced γ values as compared to the pristine QTs with the same value for n. From the calculation results, the introduction of the optimal number of thiophene-S,S-dioxide rings is predicted to be an efficient chemical modification for optimizing the third-order NLO properties of open-shell QTs through tuning the diradical characters. Fine tuning: The effects of the introduction of different numbers of thiophene-S,S-dioxide rings in quinoidal oligothiophenes on the diradical character y and the longitudinal second hyperpolarizability γ are investigated by using density functional calculations. A strategy for the design of systems with highly efficient third-order nonlinear optical (NLO) properties is presented.

Original languageEnglish
Pages (from-to)1493-1500
Number of pages8
JournalChemistry - A European Journal
Volume22
Issue number4
DOIs
Publication statusPublished - 2016 Jan 22
Externally publishedYes

Keywords

  • density functional calculations
  • diradicals
  • oligthiophenes
  • open-shell singlet states
  • optical properties

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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