화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.117, No.50, 16206-16211, 2013
Time-Resolved Fluorescence Study of Exciplex Formation in Diastereomeric Naproxen-Pyrrolidine Dyads
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 (NPX)-N-1*-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 (k(1)-k(5)) for the elementary stages in each solvent system.