title: Time-resolved fluorescence study of exciplex formation in diastereomeric naproxen-pyrrolidine dyads.
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.
authors.affiliation: Institute of Chemical Kinetics and Combustion SB RAS , Institutskaya st., 3, 630090 Novosibirsk, Russia.
authors.forename: Ekaterina A
authors.initials: EA
authors.lastname: Khramtsova
authors.forename: Viktor F
authors.initials: VF
authors.lastname: Plyusnin
authors.forename: Ilya M
authors.initials: IM
authors.lastname: Magin
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Kruppa
authors.forename: Nikolay E
authors.initials: NE
authors.lastname: Polyakov
authors.forename: Tatyana V
authors.initials: TV
authors.lastname: Leshina
authors.forename: Edurne
authors.initials: E
authors.lastname: Nuin
authors.forename: M Luisa
authors.initials: ML
authors.lastname: Marin
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Miranda
mesh_terms: D009288:Naproxen / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism
chemical_list: D011759:Pyrrolidines; D009288:Naproxen; C032519:pyrrolidine