Calix[4]arens derivatives are of great interest as ionophores for chemical sensors: ion-selective electrodes (ISE) or optodes. Rather rigid and lipophilic macrocyclic structure of p-tert-butyl-calix[4]arens, in which four hydroxy groups can be modified by introducing variety substituents leads to new derivatives. Among them compounds with phosphonic acid or esters groups are so far relatively less studied [1].
We present here structures and complexing properties of p-tert-butyl-calix[4]arens new derivatives bearing different phosphonate functional groups [2, 3]. The potentiometric selectivity coefficients were determined and the complex formation constants were calculated. Complexing properties towards alkali and alkali earth cations, transitional metal ions and ammonium and guadinium ions of ionophores 1-5 are strongly dependent on the rearrangement of the substituents in p-tert-butyl-calix[4]aren skeleton. Different factors such as the nature of the binding sites, their position on calixarene backbone and the role of different plasticizers in the membrane are discussed.

References
1. S. Kunsagi-Mate, G. Nagy, P. Jurecka and L. Kollar, Tetrahedron 58, 5119- 5124, 2002
2. M. Hoffmann, A. Konitz, A.Sikorski, U. Lesinska, M. Bochenska,
J. Incl. Phenomena and Macrocyclic Chemistry, (2003)in press.
3. M. Bochenska, M. Hoffmann, U. Lesinska, J. Incl. Phenomena and Macrocyclic Chemistry, submited (2003).