Effect of the acyl group and the dodecylsulfonate chain on the inclusion of pyrene inside the cavity of beta-cyclodextrin.
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.
Rima
Jamil
J
Laboratory of Physical Chemistry, Environmental Engineering and Biology, Faculty of Science II, Lebanese University, Fanar, Lebanon. J.rima@ul.edu.lb
Kyriacos
Soula
S
Rida
Maurice Abou
MA
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*
D017738:Alkanesulfonic Acids; D011721:Pyrenes; D047392:beta-Cyclodextrins; C017273:dodecylsulfonic acid