title: Enantioselective detection of chiral phosphorescent analytes in cyclodextrin complexes.
abstract: Inclusion complexes between camphorquinone (CQ) and cyclodextrins (CDs) in deoxygenated aqueous solutions are shown to exhibit relatively strong room temperature phosphorescence (RTP). Among the various CDs tested, alpha-CD showed the strongest RTP signals. Interestingly, these signals differed significantly for the two enantiomers of CQ; the phosphorescence lifetime of (+)-CQ was about four times longer than that of (-)-CQ, being 352+/-16 and 89+/-6mus, respectively. This enantiomeric selectivity is attributed to a difference in dissociation rates (competing with the radiative emission process) for the diastereoisomeric inclusion complexes dealt with, which have a 2:1 stoichiometry (alpha-CD:CQ:alpha-CD). Time-resolved RTP detection using different delay times enables the determination of the two enantiomers in a mixture without involving a separation technique. The minimum detectable fraction of (+)-CQ in a 2mM sample was 13%.
authors.affiliation: Department of Analytical Chemistry and Applied Spectroscopy, Laser Centre, Vrije Universiteit, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands.
authors.forename: Carmen
authors.initials: C
authors.lastname: García-Ruiz
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Scholtes
authors.forename: Freek
authors.initials: F
authors.lastname: Ariese
authors.forename: Cees
authors.initials: C
authors.lastname: Gooijer