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Jet-Cooled Spectroscopy of Amino-Substituted Cinnamates
Hugo Maurer1, Wybren Jan Buma1,2
1Van 't Hoff Institute for Molecular Sciences, Faculty of Science, University of Amsterdam, Science Park 904, 1098 XHAmsterdam, The Netherlands.
The Journal of Physical Chemistry. A
|August 13, 2026
Summary
Amino-substituted cinnamate UV filters show altered electronic structures and dynamics compared to hydroxy- or methoxy-substituted versions. This molecular design approach enhances UV-absorbing materials by suppressing unwanted pathways and improving stability.
Area of Science:
- Photochemistry
- Photophysics
- Spectroscopy
- Computational Chemistry
Background:
- UV filters are crucial for stability and safety, dependent on photochemical and photophysical relaxation pathways.
- Cinnamate derivatives are widely used UV filters, but their excited-state dynamics require further investigation.
Purpose of the Study:
- To investigate the gas-phase photochemical and photophysical relaxation pathways of amino-substituted cinnamate derivatives.
- To understand how amino group substitution influences the excited-state structure and dynamics of cinnamate UV filters.
Main Methods:
- Resonance Enhanced Multiphoton Ionization (REMPI)
- UV-UV depletion spectroscopy
- Pump-probe ion yield measurements
- Photoelectron velocity-map imaging (VMI)
- Electronic structure calculations
Main Results:
- Amino substitution caused significant red shifts in the S1 absorption band and altered the ordering of low-lying excited states.
- Excited-state lifetimes were in the nanosecond range, dominated by S1 state relaxation to the ground state.
- Population transfer to long-lived 1nπ* states, which promote intersystem crossing in other derivatives, was strongly suppressed.
Conclusions:
- Amino substitution profoundly influences the properties of cinnamate-based UV filters.
- This substitution offers a novel molecular design strategy for developing improved UV-absorbing materials with enhanced stability.
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