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Heavy Atom at Bay of Perylene Significantly Improves Intersystem Crossing
Pandiselvi Durairaj1, Durga Mukkonathil1, Sunandan Sarkar1
1Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015, India.
The Journal of Physical Chemistry. A
|November 19, 2024
Summary
Bromine substitution at the bay position of perylenes distorts their structure, enhancing spin-orbit coupling (SOC) and promoting rapid intersystem crossing (ISC), which quenches fluorescence. Other substitutions do not significantly impact SOC or ISC.
Area of Science:
- Photophysics and Photochemistry
- Computational Chemistry
- Organic Electronics
Background:
- Perylenes are important organic chromophores with tunable photophysical properties.
- Understanding structure-property relationships is crucial for designing advanced materials.
- Spin-orbit coupling (SOC) and intersystem crossing (ISC) significantly influence luminescence.
Purpose of the Study:
- To investigate the effect of halogen substitution on perylene photophysical properties.
- To elucidate the role of structural distortion and heavy atom effect in modulating SOC and ISC.
- To understand how substitution position influences luminescence activity in perylenes.
Main Methods:
- Time-dependent density functional theory (TDDFT) with Tamm-Dancoff Approximation (TDA) was employed.
- Calculations focused on substituted perylene derivatives with varying halogen positions (bay, ortho, peri).
- Analysis included structural planarity, spin-orbit coupling, and intersystem crossing rates.
Main Results:
- Bromine substitution at the bay position significantly distorts the perylene π-system, enhancing SOC.
- Bay-substituted bromoperylenes exhibit rapid ISC, leading to fluorescence quenching.
- Substitutions at ortho/peri positions or with lighter groups maintain planarity and do not significantly enhance ISC.
Conclusions:
- The heavy atom effect of bromine is most effective at the bay position, inducing significant π-system distortion.
- Distorted π-systems are key for enhancing SOC and facilitating efficient ISC in perylene derivatives.
- Strategic substitution at the bay position is crucial for controlling luminescence via ISC in perylenes.
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