A series of calix (aza‐)crowns 6a‐f and 11a,b has been prepared by reaction of either calix dimethyl ester 4 or calix diacid dichloride 10 with an appropriate diamine. The complexation with both di‐ and trivalent cations has been qualitatively studied using fast‐atom bombardment mass spectrometry.
Ostaszewski, R., Stevens, T. W., Verboom, W., Reinhoudt, D. N., & Kaspersen, F. M. (1991). Calix(aza-)crowns as potential ionophores for divalent and trivalent cations. Recueil des travaux chimiques des Pays-Bas, 110(6), 294-298. https://doi.org/10.1002/recl.19911100608