Ultrafast trans → cis Photoisomerization Dynamics of Alkyl-Substituted Stilbenes in a Supramolecular Capsule

Christopher J. Otolski, A. Mohan Raj, Gaurav Sharma, Rajeev Prabhakar, Vaidhyanathan Ramamurthy, Christopher G. Elles

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Ultrafast spectroscopy reveals the effects of confinement on the excited-state photoisomerization dynamics for a series of alkyl-substituted trans-stilbenes encapsulated in the hydrophobic cavity of an aqueous supramolecular organic host-guest complex. Compared with the solvated compounds, encapsulated trans-stilbenes have broader excited-state absorption spectra, excited-state lifetimes that are 3-4 times longer, and photoisomerization quantum yields that are 1.7-6.5 times lower in the restricted environment. The organic capsule disrupts the equilibrium structure and restricts torsional rotation around the central C=C double bond in the excited state, which is an important motion for the relaxation of trans-stilbene from S1 to S0. The location and identity of alkyl substituents play a significant role in determining the excited-state dynamics and photoisomerization quantum yields by tuning the relative crowding inside the capsule. The results are discussed in terms of distortions of the ground- and excited-state potential energy surfaces, including the topology of the S1-S0 conical intersection.

Original languageEnglish (US)
Pages (from-to)5061-5071
Number of pages11
JournalJournal of Physical Chemistry A
Issue number24
StatePublished - Jun 20 2019

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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