A new [Co21(H2O)4(OH)12]30+ unit incorporated polyoxotungstate for sensitive detection of dichlorvos

A new [Co21(H2O)4(OH)12]30+ unit incorporated polyoxotungstate, Na18[Co(H2O)6]2{[Na(H2O)4]2[Na(H2O)2]2[Co(H2O)3]2[Co21 (H2O)4(OH)12](SiW10O37)6}·24H2O (denoted as Co25Si6W60), has been hydrothermally synthesized and fully characterized by elemental analyses, thermogravimetric analysis, bond valence sum (BVS) calculations, IR spectrum, UV-Vis spectrum, diffuse reflectance spectrum, powder X-ray diffraction and single-crystal structural analysis. The most remarkable feature is that the gigantic [Co21(H2O)4(OH)12(SiW10O37)6]30– core in Co25Si6W60 is built up of a square-like [Co21(H2O)4(OH)12]30+ nanosheet encapsulated by six dilacunary Keggin [α-SiW10O37]10– moieties in the staggered fashion, resulting in a remarkable sandwich-type assembly. Furthermore, the unique Co25Si6W60-based biosensing system, as a simple, rapid, and highly sensitive electrochemical platform, offers an environmentally-friendly route for detecting dichlorvos in the field of both food safety and environmental pollution.