Bibracchial diazatetralactams. Side-chain effects on cation binding and ionophoric properties

The formation constants in THF solutions of calcium complexes diazatetralactams bearing two side-chains were found in the range 4.6 < log beta(ML) < 8.2 and follow the substituent sequence Boc < Me similar to CH(2)CO(2)Me < CH(2)CONMe(2) < CH(2)Py. This side-chain effect was again observed in liquid-liquid extraction studies either with calcium or zinc picrates. Efficient zinc extraction constitutes the main difference with the dioxatetralactam series. The metallic ion transport across a chloroformic membrane studied with the pyridine derivative agrees well with extraction data, Specific ionophoric properties were evidenced with ion-selective electrodes.