Self assembled rotaxane and pseudo-rotaxanes based on beta-cyclodextrin inclusion compounds with trans-1,4-bis[(4-pyridyl)ethenyl]benzene-pentacyanoferrate(II) complexes

Sergio H Toma,Henrique E Toma

doi:10.1590/s0103-50532007000200006

Sergio H Toma, Henrique E Toma

Open Access

https://doi.org/10.1590/s0103-50532007000200006

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Abstract

Inclusion compounds of trans-1,4-bis[(4-pyridyl)ethenyl]benzene (BPEB) and their corresponding pentacyanoferrate(II) complexes with beta-cyclodextrin have been studied in aqueous solution by ¹H NMR and UV-Visible spectroscopy. All the inclusion compounds exhibit 1:1 stoichiometry is aqueous solution. In the presence of beta-cyclodextrin, the binuclear {[Fe(CN)5]2(BPEB)]6- complex is gradually converted into rotaxane species bearing [Fe(CN)5]3-end groups, by a self assembly inclusion mechanism, as confirmed by ¹H NMR spectroscopy.

Highlights

Self-assembled organization has been a subject of great relevance in supramolecular chemistry and nanotechnology,[1] and may be achieved by means of the association of molecular entities promoted by electrostatic forces, hydrogen bonding or van der Waals forces
Inclusion compounds of trans-1,4-bis[(4-pyridyl)ethenyl]benzene (BPEB) and their corresponding pentacyanoferrate(II) complexes with β-cyclodextrin have been studied in aqueous solution by 1H NMR and UV-Visible spectroscopy
By plotting ∆A/b[S] against -∆A/b, the slope is given by K and ∆ε can be obtained by extrapolation to infinite a Alternatively, for the NMR evaluation of the binding constant (Ka), the area of peaks of the Hα protons of the free complex [(FeCN5)2BPEB]6– and the rotaxane [(FeCN5)2(BPEB.β-CD)]6– species can be directly employed in the calculations

Summary

Introduction

Self-assembled organization has been a subject of great relevance in supramolecular chemistry and nanotechnology,[1] and may be achieved by means of the association of molecular entities promoted by electrostatic forces, hydrogen bonding or van der Waals forces. Inclusion compounds of trans-1,4-bis[(4-pyridyl)ethenyl]benzene (BPEB) and their corresponding pentacyanoferrate(II) complexes with β-cyclodextrin have been studied in aqueous solution by 1H NMR and UV-Visible spectroscopy.

Results

Conclusion