Synthesis and surface grafting of a β-cyclodextrin dimer facilitating cooperative inclusion of 2,6-ANS.

Lars W Städe,Thorbjørn T Nielsen,Kim L Larsen,Kyoko Shimizu,Reinhard Wimmer,Laurent Duroux

doi:10.3762/bjoc.11.58

Abstract

A novel β-cyclodextrin (β-CD) dimer was synthesized and surface-grafted by click chemistry onto azide-functionalized quartz surfaces in order to introduce the cooperative features of the β-CD dimer to solid surfaces. Using NMR and fluorescence spectroscopy, it is shown that the free β-CD dimer forms a 1:1 complex with the fluorescent guest molecule, 2-anilinonaphthalene-6-sulfonic acid (otherwise known not to form 1:2 complexes with parent β-CD), with an apparent association constant of 7300 M−1. Further, it is shown using total internal reflection fluorescence spectroscopy that the inclusion of the fluorescent guest into both cavities of the β-CD dimer is maintained when grafted onto a solid surface.

Highlights

Since the initial reports [1,2,3,4] of the cooperative effects exerted by β-cyclodextrin (β-CD) dimers, they have been suggested for a wide range of applications, for example, for catalysis [5,6] and photochemistry [7,8], as synthetic enzymes [5] and in general to obtain improved binding affinity for the inclusion of lipophilic molecules [5,9]
The fractions corresponding to the main peak were collected and analyzed by NMR, which confirmed the presence of the expected chemical shifts
While the emission spectral envelope obtained on the bare slide, as expected, resembles that of free 2,6-ANS in solution (Figure 4), the fluorescence intensity (FI) appears relatively higher and is accompanied by a blue shift to 452 nm for the control slide grafted with PA

Summary

Introduction

Since the initial reports [1,2,3,4] of the cooperative effects exerted by β-cyclodextrin (β-CD) dimers, they have been suggested for a wide range of applications, for example, for catalysis [5,6] and photochemistry [7,8], as synthetic enzymes [5] and in general to obtain improved binding affinity (as compared to parent β-CD) for the inclusion of lipophilic molecules [5,9]. We probe the complex formation of the surface-grafted β-CD dimer with 2,6-ANS by employing a sensitive surface technique, total internal reflection fluorescence (TIRF) spectroscopy.

Results

Conclusion