Calix[4]pyrroles with bulky substituents and their anion binding studies

Abstract

Calix[4]pyrrole derivatives with bulky substituents at their meso-positions were synthesized via mixed condensation of pyrrole with cyclohexanone and acetophenone derivatives. Anion binding studies, carried out by isothermal titration calorimetry in 1,2-dichloroethane with Cl − and CH3 CO − 2 anions in the form of their tetrabutylammonium salts, revealed that these new calix[4]pyrrole derivatives can bind the aforementioned anions as effectively as the unsubstitutedparent system, octamethylcalix[4]pyrrole (1). Structural characterizations of new calix[4]pyrroles were carried out by using 1 H and 13 C NMR spectroscopy corroborated with mass spectrometry.