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Molecular salts with diquat-based electron acceptors for nonlinear optics
Benjamin J Coe1, James A Harris, Bruce S Brunschwig
1School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. b.coe@man.ac.uk
Journal of the American Chemical Society
|March 10, 2005
Summary
Researchers investigated new dipolar chromophores with diquat electron acceptors. These molecules exhibit significantly enhanced optical properties and a rare 2D nonlinear optical response in charged compounds.
Area of Science:
- Materials Science
- Physical Chemistry
- Nonlinear Optics
Background:
- Dipolar chromophores are essential for nonlinear optical (NLO) materials.
- Electron acceptor groups significantly influence chromophore properties.
- Diquat units are known for strong electron-accepting capabilities.
Purpose of the Study:
- To synthesize and characterize novel dipolar chromophoric cations incorporating diquat-based electron acceptors.
- To investigate the optical and electronic properties of these new compounds.
- To evaluate their potential for nonlinear optical applications, particularly focusing on hyperpolarizability and NLO response dimensionality.
Main Methods:
- Stark spectroscopy was employed to probe the electronic structure and NLO properties.
- Molecular Orbital (MO) calculations were performed to complement experimental data and understand electronic characteristics.
- Comparison with a related stilbazolium chromophore was conducted.
Main Results:
- The diquat unit imparts strong electron-accepting properties, leading to significantly larger static first hyperpolarizabilities (β0) compared to stilbazolium analogs.
- Experimental and computational data confirmed the enhanced optical and electronic properties.
- One compound demonstrated a strong two-dimensional (2D) quadratic nonlinear optical response.
Conclusions:
- Diquat-based chromophores offer superior static first hyperpolarizabilities.
- The study presents a rare example of a charged molecule exhibiting a strong 2D quadratic NLO response.
- These findings highlight the potential of diquat-containing charged molecules for advanced NLO applications.
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