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

Abstract

The formation constants in THF solutions of calcium complexes diazatetralactams bearing two side-chains were found in the range 4.6 < log β_ML < 8.2 and follow the substituent sequence Boc < Me ∼ CH₂CO₂Me < CH₂CONMe₂ < CH₂Py. 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.