New Approaches to Cyclodextrin-Based Organic Nanotubes
Final Report Abstract
Within the project we developed a new and improved methodology for the synthesis of cyclodextrin nano tubes (CyNTs). α-Cyclodextrin-PEG polyrotaxanes had been synthesized with thio-methyl-fluorenyl stopper groups, cleavable under well-defined and mild reaction conditions using a safety catch approach. Furthermore we found rotaxa-polymerization which allows to synthesize polyrotaxanes from derivatives of β-cyclodextrin in one step in one pot in very good fields. These new polyrotaxanes are already soluble in organic solvents without any post-modification. Rotaxa-polymerization will be the basis for large scale synthesis of polyrotaxanes in the near future. In addition, crosslinking of cyclodextrin polyrotaxanes with toluene-2,4-diisocyanate was found to be superior to the classical crosslinking with epichlorhydrin because it can be performed under homogenous conditions in DMF/LiCl solution and it directly furnishes a CyNTs being well soluble in organic solvents. All polyrotaxanes and CyNTs had been extensively characterized by COSY and DOSY NMR in close cooperation with our partner the group of Haskell Beckham at Georgia Tech, Atlanta, USA. Another highly favored two step approach to cyclodextrin nanotubes by crosslinking through metathesis reaction of allylated polyrotaxanes completely failed. Most common Grubbs’ catalysts had been tested but without success. Nevertheless, the other results provided a reliable basis for further successful syntheses of tubular polymers in near future.
Publications
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„Templatgesteuerte Synthese von tubularen α-Cyclodextrinsystemen“ Universität des Saarlandes, Saarbrücken 2014
Sebastian Witti
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One Pot Synthesis of a Polyisoprene Polyrotaxane and Conversion to a Slide-Ring Gel. Macromolecular Rapid Communications, (2015)
Kali, G., Eisenbarth, H., Wenz, G.
