Effect of the acyl group and the dodecylsulfonate chain on the inclusion of pyrene inside the cavity of β-cyclodextrin |
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Authors: | Jamil Rima Soula Kyriacos Maurice Abou Rida |
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Affiliation: | aLaboratory of Physical Chemistry, Environmental Engineering and Biology, Faculty of Science II, Lebanese University, Fanar, Lebanon;bDepartment of Pharmaceutical Sciences, School of Pharmacy, Lebanese American University, Byblos, Lebanon;cLaboratory of Organometallic and Environmental Chemistry, Faculty of Science II, Lebanese University, Fanar, Lebanon |
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Abstract: | The solubilization of pyrene in aqueous solution of β-cyclodextrin (β-CD) or its derivatives such as β-CD-hexanoyl, β-CD-benzoyl and β-CD-dodecylsulfonate was investigated by spectrophotometry. Linear and non-linear regression methods were used to estimate the association constants (K1). 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 β-CD. The formation constant was shown to decrease when β-CD was modified by a dodecylsulfonate chain. The value of K1 was 190 ± 10 L mol−1 for the [pyrene/β-CD] complex and 145 L mol−1 for the [pyrene/β-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 β-CD-hexanoyl and β-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. |
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Keywords: | Modified β -cyclodextrin Hexanoyl Benzoyl Dodecylsulfonate Complexation UV absorption |
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