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Design of organic molecules with large two-photon absorption cross sections
M Albota1, D Beljonne, J L Brédas
1School of Applied Physics and Engineering, and Developmental Resource for Biophysical Imaging Opto-Electronics, Cornell University, Ithaca, NY 14853, USA.
Science (New York, N.Y.)
|September 11, 1998
Summary
Researchers designed molecules with high two-photon absorption (TPA) cross sections by utilizing symmetric charge transfer. These novel bis(styryl)benzene derivatives show significantly enhanced TPA, enabling brighter imaging and photosensitization.
Area of Science:
- Molecular design
- Photophysics
- Organic chemistry
Background:
- Two-photon absorption (TPA) is crucial for advanced optical applications.
- Designing molecules with large TPA cross sections (delta) remains a challenge.
- Understanding structure-property relationships is key to optimizing TPA materials.
Purpose of the Study:
- To develop a molecular design strategy for achieving large TPA cross sections.
- To synthesize and characterize novel bis(styryl)benzene derivatives with tailored electronic structures.
- To investigate the correlation between molecular symmetry, charge transfer, and TPA properties.
Main Methods:
- Synthesis of bis(styryl)benzene derivatives with donor-pi-donor, donor-acceptor-donor, and acceptor-donor-acceptor motifs.
- Experimental measurement of two-photon absorption cross sections (delta).
- Quantum chemical calculations to analyze electronic structure and charge redistribution upon excitation.
Main Results:
- Synthesized molecules exhibited exceptionally large delta values, up to 400 times that of trans-stilbene.
- Quantum chemical calculations confirmed substantial symmetric charge redistribution upon excitation.
- Experimental and calculated delta values showed good agreement, validating the design strategy.
Conclusions:
- Symmetric charge transfer in conjugated systems is an effective strategy for enhancing TPA cross sections.
- The developed molecules offer potential for unprecedented brightness in two-photon fluorescent imaging.
- These materials could also enhance photosensitivity in two-photon sensitization applications.