title: Effect of the acyl group and the dodecylsulfonate chain on the inclusion of pyrene inside the cavity of beta-cyclodextrin.
abstract: The solubilization of pyrene in aqueous solution of beta-cyclodextrin (beta-CD) or its derivatives such as beta-CD-hexanoyl, beta-CD-benzoyl and beta-CD-dodecylsulfonate was investigated by spectrophotometry. Linear and non-linear regression methods were used to estimate the association constants (K(1)). A 1:1 stoichiometric ratio and different effects of the hexanoyl, benzoyl and dodecylsulfonate groups on the association constant were observed for the binary inclusion complex between pyrene and beta-CD. The formation constant was shown to decrease when beta-CD was modified by a dodecylsulfonate chain. The value of K(1) was 190+/-10 L mol(-1) for the [pyrene/beta-CD] complex and 145 L mol(-1) for the [pyrene/beta-CD-dodecylsulfonate] complex. Partitioning of the pyrene molecules between the dodecylsulfonate chains and cyclodextrin cavities can explain the decrease in the association constant value. In the cases of beta-CD-hexanoyl and beta-CD-benzoyl derivatives, no association constants were detected. Results suggest that the high hydrophobicity of the hexanoyl and benzoyl groups prevents the inclusion of pyrene molecules inside the cyclodextrin cavity.
authors: Laboratory of Physical Chemistry, Environmental Engineering and Biology, Faculty of Science II, Lebanese University, Fanar, Lebanon. J.rima@ul.edu.lb
authors: Jamil
authors: J
authors: Rima
authors: Soula
authors: S
authors: Kyriacos
authors: Maurice Abou
authors: MA
authors: Rida
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D008954:Models, Biological; D011721:Pyrenes / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D047392:beta-Cyclodextrins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D017738:Alkanesulfonic Acids; D011721:Pyrenes; D047392:beta-Cyclodextrins; C017273:dodecylsulfonic acid