A New Cryptophane Receptor Featuring Three endo ‐Carboxylic Acid Groups: Synthesis, Host Behavior and Structural Study

Examples of a new type of cryptophane molecule incorporating aromatic groups in the bridges ( 1 – 4 ) and, for the first time, being also supplied with three endo ‐positional ionizable carboxylic acid functions ( 1 ) have been synthesized and characterized. The cryptophane triester 2 yielded a solvate (channel inclusion compound) with trichloromethane and water, the X‐ray crystal structure of which is reported. The complexation of 1 with low‐molecular‐weight alcohols in solution was studied, and the liquid–liquid extraction of different metal ions including alkali (Na + , Cs + ), alkaline earth (Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ ), and the lanthanide metal ions Eu 3+ and Yb 3+ in an extraction system containing metal nitrate buffer/H 2 O/ 1 /CHCl 3 was examined. Molecular modeling calculations of the cryptophanes 1 and 2 , and of the Eu 3+ complex of 1 were carried out contributing to the discussion.