ROTAXANES WITH CHIRAL STOPPERS AND COMPLEXATION OF CATIONS BY PODAND AXLES WITH SUGAR TERMINAL GROUPS

The new pi-donor/pi-acceptor type rotaxanes 15, 16 bearing chiral suga r units as blocking groups have been synthesized in 2% and 6% yield, s tarting from acetobromo glucose 10 and the podands 8 or 9, followed by the reaction of the resulting axles 11 and 12 with the dicationic bis (bipyridinio) wheel precursor 13 and the bis(bromomethyl) compound 14. The capability of the podands 11 and 12 and of the rotaxanes 15 and 1 6 to form pedate-like complexes with metal salts was investigated by N MR; the effect of metal thiocyanate salt addition was monitored. Disti nct changes of proton shifts that indicate complex formation were only observed between the free axles 11, 12 and the metal salts, whereas n o major effects were found in case of the rotaxanes 15, 16. Glucose en tities were chosen as stopper units in order to support metal complexa tion as terminal groups and to introduce a source of chirality into th e molecules.