Time-resolved fluorescence study of exciplex formation in diastereomeric naproxen-pyrrolidine dyads

J Phys Chem B. 2013 Dec 19;117(50):16206-11. doi: 10.1021/jp4083147. Epub 2013 Dec 2.

Abstract

The influence of chirality on the elementary processes triggered by excitation of the (S,S)- and (R,S)- diastereoisomers of naproxen-pyrrolidine (NPX-Pyr) dyads has been studied by time-resolved fluorescence in acetonitrile-benzene mixtures. In these systems, the quenching of the (1)NPX*-Pyr singlet excited state occurs through electron transfer and exciplex formation. Fluorescence lifetimes and quantum yields revealed a significant difference (around 20%) between the (S,S)- and (R,S)- diastereomers. In addition, the quantum yields of exciplexes differed by a factor of 2 regardless of solvent polarity. This allows us to suggest a similar influence of the chiral centers on the local charge transfer resulting in exciplex and full charge separation that leads to ion-biradicals. A simplified scheme is proposed to estimate a set of rate constant values (k1-k5) for the elementary stages in each solvent system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Naproxen / chemistry*
  • Pyrrolidines / chemistry*
  • Spectrometry, Fluorescence
  • Stereoisomerism

Substances

  • Pyrrolidines
  • Naproxen
  • pyrrolidine