SYNTHESIS AND CATION-BINDING PROPERTIES OF DIHYDROXYCROWNOPHANES AND THEIR DERIVATIVES

Dihydroxycrownophanes (2a-c) were conveniently synthesized by intramol ecular [2+2] photocycloaddition, and their derivatives with two cation -ligating side chains (3a-6a) were also readily prepared by the reacti on of 2a-c and the corresponding halides in the presence of NaH. All o f the crown compounds obtained were used as ionophores in single extra ction experiments of heavy metal cations including transition metal ca tions in a H2O-CH2Cl2 system. Although 3a did not extract any alkaline earth metal cation at pH 7.0, it showed high affinity toward Pb2+ eve n under acidic conditions (pH 4.7). Crownophanes (4a-c) having two 2-p yridylmethyl ligands efficiently extracted Ag+ with excellent selectiv ity.