Pyridine-substituted calix[4]pyrrole: a new cation receptor

Abstract

Novel pyridine-substituted calix[4]pyrrole (CP), has been synthesised and characterised by different analytical techniques (¹H NMR, microanalysis and mass spectroscopy). The cation-binding behaviour of this receptor was investigated by proton NMR spectroscopy, conductometric and UV titrations. ¹H NMR measurements reveal the sites of interaction of the ligand with metal cations in deuterated acetonitrile (CD₃CN). The results show that introduction of one pyridine group to the pendent arm of the modified CP enables the produced hybrid to bind with metal cations [Cd(II), Pb(II), Hg(II)] in acetonitrile. No interaction was observed between this ligand and other metal cations in acetonitrile. The composition of the anion complexes was established through conductance measurements. In all cases, 1:1 complexes are formed. The thermodynamics of metal cations complexation in acetonitrile is discussed.

Keywords:

• pyridine calix[4]pyrrole
• proton NMR
• conductometric titration
• thermodynamic parameters

Acknowledgements

The authors gratefully acknowledge the financial support of this work by Lebanese University under contract No. 23185.