Selective PseudoRotaxane Type Complex Formation o

Authors: Tatsuya Morozumi Nao Sato Hiroshi Nakamura

Publish Date: 2006/06/21

Volume: 56, Issue: 1-2, Pages: 141-148

PDF Link

Abstract

Inclusion complexation behavior of 236−triOmethylβcyclodextrin TMβCD with zincII 51015tri4tbutylphenyl204nalkyloxyphenylporphyrin covalently linked with violgen by a polymethylene chain Znt buPC n V2+ n=4 6 8 10 and 12 was investigated by means of 1H NMR UV/Vis absorption spectroscopies in acetonitrilewater 11 v/v The 1H NMR spectra indicated that ZntbuPC n V2+ presumably existed as a mixture of a dimer and a monomer in high concentration 1×10−3 mol dm−3 and the dimer was degraded by the complex formation with TMβCD The 1H NMR spectra of these compounds as a function of TMβCD showed the selective formation of 11 =ZntbuPC n V2+ TMβCD pseudorotaxane type complexes The chemical modification by tbutyl groups on porphyrin showed a good protective effect on inclusion of benzene groups into the TMβCD cavity These rotaxane formation constants K were determined by titration studies using UV/Vis absorption spectroscopy These complex formation constants were somewhat affected by the spacer methylene chain between the porphyrin and viologen The value of K for ZntbuPC4V2+·TMβCD is 10×103 M−1 which is the smallest whereas those for ZntbuPC n V2+·TMβCD n=8 10 12 were similar 10×104 M−1

Keywords: