We systematically investigated the response characteristics upon anions of three types of organotin (Ⅳ) complexes. The results show that there are close relationship between the potentiometric response characteristics and structure of organotin(Ⅳ) complexes. These complexes exhibit selective potentiometric response to salicylate. The electrodes based on tetracoordinated organotin complexes show near-Nernst response to salicylate while the electrodes based on pentacoordinated and hexacoordinated organotin complexes show super- Nerst resonse to salicylate. Above all, the response characxteristics are influenced heavily by properties of the central metal. As properties of organic groups that connect directly to tin atom change, the potentiometric response characteristics and selectivity vary regularly. The relationship between structure of carriers and electrode performances are described by Hammett constant. The response mechanism was also investigated by use of impedance and IR spectroscopic techniques. The super-Nernst phenomena and response characteristics of electrodes based on hexacoordinated organotin complexes were also interpreted in this paper.

Key words: ORGANO TIN COMPOUNDS, STRUCTURE ACTIVITY RELATIONSHIP, ION SELECTIVE ELECTRODE, SALICYLIC ACID