Postfunctionalization of Keggin silicotungstates by general coupling procedures

Tetrabutyl ammonium (TBA) salts of organotin derivatives of polyoxometalates (TBA)5[SiW11O39{Sn(CH2)2COOH}] (1), (TBA)4[SiW11O39{Sn(CH2)2CO}] (2), (TBA)5[SiW11O39{Sn(CH2)2CONH(CH2)3N3}] (3), TBA5[SiW11O39{Sn(CH2)2CONH(CH2)3(N3C2H)C10H9Fe}] (4) and an ammonium salt (NH4)5[SiW11O39{Sn(CH2)2CONH(CH2)3N3}](3′) have been synthesized for the first time by adapting the organic functionalization strategies developed earlier for phosphotungstates. The products were characterized using FTIR, NMR, ESI MS, and electrochemical techniques. The Keggin silicotungstate is more nucleophilic than the Keggin phosphotungstate and displays reactivity previously known only for Dawson phosphotungstates. The methodology of CuAAC “click” reaction for silico- and phosphotungstates allows the coupling by a common protocol of diverse POMs with different redox properties, which is potentially useful for bioelectroanalytical applications with redox labels.

Graphical abstractTwo organic postfunctionalization strategies were employed to synthesize new Keggin silicotungstates for electrochemical applications. The products were characterized using FTIR, NMR, ESI MS, and electrochemical techniques.Figure optionsDownload full-size imageDownload as PowerPoint slide