Complexation of calix[4]resorcinearene with Cobalt(III) cationic complexesin water-organic media

The host-guest complexation constants for calix[4]resorcinearene and comple x cations [Co(His)(2)](+), [Co(En)(2)C2O4](+), and [Co(Dipy)(3)](3+) (His = L-histidine anion, En = ethylenediamine, and Dipy 2,2-dipyridyl) in weakly alkaline and alkaline water-organic media (dimethyl sulfoxide, isopropanol , and methanol) were determined by pH-metric titration. The stability of th e complexes depends not only on the charge of the complex cation and the de gree of deprotonation of the host anion but also on the nature of the ligan d environment of the metal ion.