Abstract

The synthesis of podands (acyclic crown ethers) including a 1,3-bis(1H-pyrazol-1-yl)propane unit in their molecule is described. The key step of this synthesis was a regoioselective lipase-catalyzed transesterification of the dipyrazolic tetraethylester 1 with monomethylether polyethyleneglycols. The ionophoric properties of the podands 4a-d as carriers of cations were evaluated. Molecular modelling studies and quantum-chemical calculations were used in order to elucidate the superestructures of the complexes with ammonium cations.