Bis{phenyl[di(methoxyethyloxy)phosphoryl]methyl}amine as a new ligand for metal ions and cationic organic molecules

The bis(phenylphosphorylmethyl)amine containing binding units based on “crown-ether like” ester moiety was tested as a supramolecular host molecule. The complexation properties towards metal ions (Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Ba2+) and hydrochlorides of amino acids (Lys, Arg), diethylenetriamine (2EN3A) and pentaethylenehexaamine (5EN6A) were studied. In order to assess the binding affinities of the receptor to selected guest molecules in various solvents, the ESI-MS and NMR techniques were applied. The results were also supported by theoretical studies. The ESI–MS studies revealed the selective binding of Cs+ and 5EN6 by the phosphonate molecule, whereas NMR investigation in solution indicated tighter association of the host–guest system obtained for Mg2+ and Arg. The discrepancies between the results originating from both used methods are most likely caused by influence of the solvent on intermolecular interactions.