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Solvent-dependent dual fluorescence of the push-pull system 2-diethylamino-7-nitrofluorene
M A B Larsen1, A B Stephansen, E Alarousu
1Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark. theis@chem.ku.dk.
Physical Chemistry Chemical Physics : PCCP
|February 10, 2018
Summary
Solvent polarity influences the excited state pathways of 2-diethylamino-7-nitrofluorene. Computational and spectroscopic studies reveal dual fluorescence and non-radiative decay routes, with solvents dictating molecular behavior.
Area of Science:
- Photochemistry
- Computational Chemistry
- Molecular Spectroscopy
Background:
- Molecular push-pull systems exhibit complex excited-state dynamics.
- Understanding solvent effects is crucial for controlling photochemical reactions.
Purpose of the Study:
- To elucidate the solvent-dependent excited-state behavior of 2-diethylamino-7-nitrofluorene.
- To identify key excited-state minima and deactivation pathways.
- To correlate spectroscopic observations with theoretical predictions.
Main Methods:
- Femtosecond transient absorption spectroscopy.
- Density functional theory (DFT) calculations.
- Computational identification of excited-state minima and transition states.
Main Results:
- Dual fluorescence observed, attributed to planar and twisted excited-state minima.
- Non-radiative decay pathways identified, involving twisting around aryl-nitrogen bonds.
- Ultrafast intersystem crossing observed in cyclohexane, facilitated by El-Sayed mechanism.
Conclusions:
- Solvent polarity significantly alters the potential energy landscape of the excited state.
- Solvent choice dictates fluorescence lifetime, non-radiative decay, and intersystem crossing pathways.
- The study provides insights into controlling molecular photophysics through solvent engineering.
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