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Related Experiment Video

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Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

Published on: May 29, 2018

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.

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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.