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Voltammetric study of the transfer of keggin-type heteropolyanions across the nitrobenzene/water interface

1991; Elsevier BV; Volume: 302; Issue: 1-2 Linguagem: Inglês

10.1016/0022-0728(91)85037-p

2590-2954

Toshiyuki Osakai, Sadayuki Himeno, Atsuyoshi Saito,

Conducting polymers and applications

Abstract A voltammetric study has been made for the transfer of four 18-heteropolymolybdate anions including Dawson anions, i.e. [P2Mo18O62]6−, [As2Mo18O62]6−, [S2Mo18O62]4− and [P2 Mo18O61]4−, and of a related anion [S2VMo17O62]5− at the nitrobenzene(NB)—water(W) interface. With regard to the hexavalent and pentavalent anions, well-developed voltammetric waves due to their phase transfer could be obtained under certain conditions. The tetravalent anions, however, gave no wave in the polarizable potential range but showed an increase in the final current rise owing to their transfer from NB to W. From the voltammetric data, the standard ion transfer potential (ΔNBwφjθ) and standard Gibbs transfer energy (ΔGtr,jθ,NB→W) have been determined (or estimated) for the heteropolyanions. It has been found that ΔNBWφjθ and ΔGtr,jθ,NB→W depend primarily on the ionic charge. This is in line with our previous result obtained for Keggin anions in 1991. A possible mechanism has also been proposed for the transfer of the hexavalent Dawson anions.