Synthesis and Study of New β-Cyclodextrin 'Dimers' Having a Metal Coordination Center and Carboxamide or Urea Linkers

The synthesis of new 'bridged' β-cyclodextrin (β-CD) 'dimers' 7-12 was successfully achieved by two one-pot reactions from β-CD (3) and 6^A-azido-6^A-deoxy-β-CD (4). The 'phosphine imine' reaction was shown to be a superior approach compared to the Mitsunobu reaction as coupling strategy for the preparation of these 'dimers'. NMR Data, along with molecular-modelling calculations, suggest a 'helical-like' arrangement for the phenanthro-line-diyl-linked 'dimer' derivative 9. Complexation properties of 9 were established by UV-VIS-spectrophotometric titration toward four metals. Among them Cu^II or Eu^III ions were complexed selectively by 9, but no complexation occurred wish La^III and Zn^II. In addition a specific and interesing esterase activity toward the phosphodiester bond of bis(4-nitrophenyl) phosphate anion was found in the case of the Cu^IIcomplex of 9.