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Photoisomerization dynamics of stiff-stilbene in solution
M Quick1, F Berndt, A L Dobryakov
1Department of Chemistry, Humboldt-Universität zu Berlin , Brook-Taylor-Strasse 2, D-12489 Berlin, Germany.
The Journal of Physical Chemistry. B
|January 28, 2014
Summary
Photoinduced isomerization in stiff-stilbene involves trans-to-cis and cis-to-trans pathways with varying barriers and timescales. Viscosity influences the reaction, suggesting a common isomerization mechanism involving central double bond torsion for related compounds.
Area of Science:
- Photochemistry
- Physical Chemistry
- Spectroscopy
Background:
- 1,1'-bis-indanyliden (stiff-stilbene) undergoes photoinduced isomerization.
- Understanding isomerization mechanisms is crucial for molecular dynamics and photochemistry.
Purpose of the Study:
- To investigate the photoinduced isomerization of stiff-stilbene in solution.
- To elucidate the reaction pathways, timescales, and energy barriers involved.
- To compare the isomerization mechanism with parent stilbene.
Main Methods:
- Broadband transient absorption spectroscopy
- Femtosecond Raman spectroscopy
- Quantum-chemical calculations (XMCQDPT2)
Main Results:
- Trans-to-cis isomerization exhibits viscosity-independent and viscosity-dependent components with distinct energy barriers.
- Cis-to-trans isomerization shows ultrafast oscillatory relaxation and slower decay, also dependent on solvent viscosity.
- Calculations identified stationary points and barriers, though the perpendicular conformation (P) was not directly observed.
Conclusions:
- The isomerization of stiff-stilbene proceeds through multiple timescales and involves torsion about the central double bond.
- Viscosity dependence suggests a common isomerization pathway shared with parent stilbene.
- The study provides detailed insights into the photodynamics and reaction mechanisms of stiff-stilbene.
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