Organic Salts Suppress Aggregation and Enhance the Hyperpolarizability of a π‐Twisted Chromophore
Abstract
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 01, 2018
- Source ID
- 10.1002/chem.201804365
Entities
People
- Alexander J.‐t. Lou
- Elena Cariati
- Stefania Righetto
- Tobin J. Marks
Organizations
- Air Force Office of Scientific Research
- Northwestern University
- University of Milan