Carbamoylmethylphosphinoxide Derivatives Based on the Triphenylmethane Skeleton. Synthesis and Extraction Properties

Two different strategies were used to synthesize tri(2-alkoxy-5-nitrophenyl)methanes 6a,b. The
X-ray structures of 6a and its precursor 5 show the molecules in a conformation with a
syn-orientation of the nitro and alkoxy groups. Hydrogenation and acylation by the appropriate
active ester gave the corresponding tri-CMPO derivatives 4a,b. Their ability to complex lanthanide
ions was studied by NMR spectroscopy and by nuclear magnetic relaxation dispersion and further
characterized by quantum mechanical calculations. Extraction experiments from acidic solution to
dichloromethane reveal a reasonable selectivity of Am(III) over Eu(III), but in contrast to similar
tetra-CMPOs derivatives of calix[4]arenes the distribution coefficients strongly decrease with
increasing concentration of HNO3.