title: Application of cyclodextrin-mediated capillary electrophoresis to simultaneously determine the apparent binding constants and thermodynamic parameters of naphthalenesulfonate derivatives.
abstract: Application of capillary electrophoresis (CE) to simultaneously determine the apparent binding constants and thermodynamic parameters for six positional and structural naphthalenesulfonate derivatives with beta-cyclodextrin (beta-CD) is presented. The change in electrophoresis mobilities was used to assess the binding constants by non-linear regression and three different linear plots methods (named double reciprocal, x-reciprocal and y-reciprocal). The substituent group(s) attached to the naphthalene ring considerably affected the inclusion behaviors of these naphthalenesulfonate derivatives. The binding constant varies over almost one order of magnitude and a highly selective sequence is obtained between these guest model compounds. Naphthalenesulfonates with the substituent(s) at the 2-position(s) displayed stronger interaction with beta-CD, and gave well compatible results by these four plot methods. While at least one substituent was substituted into the 1-position of naphthalene showed the weak interaction or no interaction with beta-CD. Comparison to three linear regression methods, the non-linear regression method proves to be the most suitable for these determinations. Additionally, apparent binding constants for each structural isomer with beta-CD at several temperature, and thermodynamic parameters for binding were also calculated and discussed.
authors.affiliation: Department of Chemistry, National Central University, Chung-Li 32054, Taiwan.
authors.forename: Jung-Yi
authors.initials: JY
authors.lastname: Hsiao
authors.forename: Szu-Hsun
authors.initials: SH
authors.lastname: Wu
authors.forename: Wang-Hsien
authors.initials: WH
authors.lastname: Ding