Cross-sensitive potentiometric sensors based on anti-crown ether (C₆HgF₄)₃

In this work we explore the possibility of using anti-crown ether (C₆HgF₄)₃ as a membrane-active component for potentiometric cross-sensitive sensors. Anti-crown ligands were already employed as ionophores in plasticized polymeric membranes, however the results of these studies are contradictory. In [1] mercury-carborundum-3 was employed to construct a chloride-selective sensor, while in [2] another anti-crown ligand was reported to be selective towards tetramethyl amine cations. At the same time some recent studies have explored the interaction between three-mercury anticrown ethers and anions and reported on formation of sandwich-type complexes [3].
In order to clarify the electrochemical sensitivity patterns of anti-crown based sensors we have studied plasticized polymeric membranes containing cation and anion-exchanging additives and various solvents-plasticizers. We explored the electrochemical sensitivity of these membranes in a wide variety of aqueous solutions of inorganic salts. Alkaline, alkaline-earth and d-elements salts with different anions were studied. It was found that the sensors based on anti-crown (C₆HgF₄)₃ exhibit cationic sensitivity and no considerable anionic responses were observed. The highest sensitivity values were obtained for Cs⁺ (51 mV/dec) among single-charged cations, and for Pb²⁺ (19 mV/dec) among double-charged cations. No sharp selectivity towards particular cations was found. These features can be successfully employed in construction of cross-sensitive polymeric sensors for developing novel multisensor arrays.

References

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