Synthesis and molecular recognition of novel oligo(ethylenediamino) bridged bis(β-cyclodextrin)s and their copper(II) complexes: Enhanced molecular binding ability and selectivity by multiple recognition

Document Type

Article

Publication Date

3-16-2001

Abstract

Four bridged bis(β-cyclodextrin)s tethered by different lengths of oligo(ethylenediamine)s have been synthesized and their inclusion complexation behavior with selected substrates elucidated by circular dichroism spectroscopy and fluorescence decay. In order to study their binding ability quantitatively, inclusion complexation stability constants with four dye guests, that is, brilliant green (BG), methyl orange (MO), ammonium 8-anilino-1-naphthalenesulfonic acid (ANS), and sodium 6-(p-toluidino)-2-naphthalene-sulfonate (TNS), have been determined in aqueous solution at 25°C with spectrophotometric, spectropolarimetric, or spectrofluorometric titrations. The results obtained indicate that the two tethered cyclodextrin units might cooperatively bind to a guest, and the molecular binding ability toward model substrates, especially linear guests such as TNS and MO, could be extended. The tether length plays a crucial role in the molecular recognition, the binding constants for ANS and TNS decrease linearly with an increase in the tether length of dimeric cyclodextrin. The Gibbs free energy changes (-ΔGo) for the unit increment per ethylene are 0.99 kJ mol-1 for ANS and 0.44 kJ mol-1 for TNS, respectively. On the other hand, the presence of a copper(II) ion in metallobis(β-cyclodextrin)s oligo(ethylenediamino) tethers enhances not only the original binding ability, but also the molecular selectivity through triple or multiple recognition, as compared with the parent bis(β-cyclodextrin)s. © Wiley-VCH Verlag GmbH, 2001.

Publication Source (Journal or Book title)

Chemistry - A European Journal

First Page

1281

Last Page

1288

This document is currently not available here.

Share

COinS