New scaffolds for supramolecular chemistry: upper-rim fully tethered 5-methyleneureido-5'-methyl-2,2'-bipyridyl cyclodextrins

Seven upper-rim fully tethered cyclodextrins (URFT-CDs) have been synthesised in a good average coupling yield using the one-step "phosphine imide" approach and their metal complexation behaviour with lanthanides and transition metals was explored. We observed that the A-TE-E light conversion process (antennae effect) occurs in the URFT-CD lanthanide complexes. A molecular redox switch based on the corresponding iron complexes is also reported. A reversible intramolecular translocation of the FeII and FeIII ions, between two distinct binding cavities has been monitored spectroscopically and achieved by chemical triggering. Finally, a negative allosteric control of ion recognition through the formation of a CD pseudocryptand is discussed.