Abstract
We have reported that tripodands bearing a bipyridine moiety at each terminal react with a transition metal to give the corresponding pseudocryptands as a host. We report here synthesis of a novel tripodand bearing six and nine amide groups to achieve a new binding mode. 1H NMR, ESI-MS, and UV-vis spectra suggest that the tripodand was converted to the corresponding C3 symmetric pseudocryptand by the complexation with Fe(II). Association constants with cations in the presence and absence of Cl– were determined by 1H NMR titrations, which showed that the cation binding affinity was enhanced by the addition of Cl–. This result indicates that the metallohost recognizes Cl– and the cations cooperatively. The association constants of [L2•Fe]2+ are much larger than those of [L1•Fe]2+.
