Organic Salts Suppress Aggregation and Enhance the Hyperpolarizability of a π-Twisted Chromophore

Alexander J.T. Lou, Stefania Righetto, Elena Cariati, Tobin J. Marks*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Twisted intramolecular charge-transfer (TICT) chromophores exhibit extraordinary hyperpolarizabilities, β, and are therefore promising for electro-optic technologies. Nevertheless, centrosymmetric aggregate formation severely diminishes β in concentrated solutions or in polymer matrices. Herein, the remarkable effects of organic salts on the linear and nonlinear optical response of a high β benzimidazolium-based TICT chromophore, B2TMC-2, are reported. Addition of Bu4P+Br to B2TMC-2 solution in CHCl3 induces a halochromic blueshift, primarily reflecting interactions between Bu4P+Br and the B2TMC-2 cationic portion. DC electric-field induced second-harmonic generation (EFISH) measurements on B2TMC-2+Bu4P+Br solution reveal a large μβ=−22,160×10−48 esu, unprecedented for any chromophore with such a broad optical transparency window. Moreover, Bu4P+Br is shown to suppress B2TMC-2 aggregation, thereby preserving high μβ in concentrated solutions. This phenomenon should be applicable to many other NLO chromophores.

Original languageEnglish (US)
Pages (from-to)15801-15805
Number of pages5
JournalChemistry - A European Journal
Issue number59
StatePublished - Oct 22 2018


  • aggregation
  • electrostatic interactions
  • halochromism
  • hyperpolarizability
  • nonlinear optics

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry


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