INFLUENCE OF FLUORINATED ALCOHOLS ON CYCLODEXTRIN - PYRENE COMPLEXATION

An investigation of the effect of fluorinated alcohols on complexation between pyrene and beta- and gamma-cyclodextrin (CD) in aqueous solut ion is reported. Using fluorescence spectrophotometric analysis, pyren e I/III vibronic band ratios were monitored upon the addition of CD, b oth in the absence and presence of fluorinated alcohols, as well as in the presence of their nonfluorinated alcohol analogs. The fluorinated alcohols studied were 2,2,2-trifluoroethanol and 2,2,3,3,3-pentafluor o-1-propanol. In aqueous solution, the alcohols were found to have no effect on the pyreneI/III ratio in the absence of CD, but a strong eff ect when CD was present. For beta-CD, the stoichiometry of the CD/pyre ne complex was found to be predominantly 2 : 1, whereas for gamma-CD i t was 1 : 1. Apparent complexation equilibrium constants for the CD/py rene complexes in the absence and presence of the alcohols were calcul ated by use of nonlinear regression analysis. Interactions between the alcohols and CDs were also investigated using H-1 and F-19 techniques .