Stability Constants of Some Macrocyclic Complexes of Ag(I) and Cu(II) in Mixed Solvents by Potentiometry

Abstract

Stability constants of complexes of Ag(I) and Cu(II) perchlorates and nitrates with some macrocyclic compounds in 90 and 75% (v/v) DMSO 1 water and 75% (v/v) DMF 1 water media have been determined by potentiometry. Silver and copper wires, and Coated Wire Ion Selective Electrodes (CWISE) were used as indicator electrodes. It was observed that complexation is stronger when the salt is present as a perchlorate than when it is as a nitrate. For both cations the stability constant values in 75% (v/v) DMF 1 water were somewhat higher than in 75% (v/v) DMSO. The macrocyclic effect due to cyclization of linear amine tosylates has been observed. Competitive potentiometry has been utilized to compare some of the results.

Molecular Structures and Stability Constants of Gossypol and Its Aza-Derivative Complexes with Silver(I) Cations Studied by Potentiometric, ESI MS, NMR, and AM1d Semiempirical Methods

“…It is interesting to note that the stability constant of the AgL + complex with the G8 Schiff base is comparable with other ones described in the literature and determined for selective ligands toward Ag + cations. [39][40][41][42][43][44][45] The lowest stability constant of all the complexes with Ag + cations that were studied was found for the G complexes. For this reason in the ESI spectrum of a mixture of G with Ag + cations no m/z signals of the respective complexes are observed, indicating that the unmodified gossypol molecule, as it occurs in cotton plants, is the weakest ligands under investigation (Table 3S, Supporting Information).…”