The electrochemical behaviour of [Co(sep)]3+ bound with p-sulfonatothiacalix[4]arene and tetracarboxy-p-sulfonatocalix[4]arene in correlation with inclusive and non-inclusive binding modes

Abstract

The comparative study of the ion-pairing of Co(III) sepulchrate ([Co(sep)]3+) with p-sulfonatothiacalix[4]arene and p-sulfonatocalix[4]arene tetracarbonic acid by 1H NMR and pH-metric data in solution and X-ray data in solid state elucidates pH dependent effect of carboxylate groups on the stoichiometry and the mode of the ion pairing. The electrochemical data of [Co(sep)]3+ bound with both calix[4]arenes have been analyzed in the correlation with stoichiometry and the mode of their binding. The pH-dependent effect of tetracarboxy-p-sulfonatocalix[4]arene on the electrochemical behavior of [Co(sep)]3+ has been found to correlate with the participation of carboxylate groups in the host–guest binding.