Synthesis and ionophore properties of a series of new tetrapyrazolic macrocycles

The synthesis of several macrocycles containing two bipyrazolic subunits, with different cavity sizes and with donor-group-bearing side arms attached, is reported. Their alkali cation binding ability has been studied from two aspects : extraction and transport through an artificial liquid membrane. Macrocycles described here show a high selectivity towards Li⁺ and Na⁺ cations; furthermore one of them is remarkably well adapted to extract selectively and to transport efficiently the lithium cation in competitive conditions.