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

Abstract

A new [Co₂₁(H₂O)₄(OH)₁₂]³⁰⁺ unit-incorporating 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 via 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 composed of a square-like [Co₂₁(H₂O)₄(OH)₁₂]³⁰⁺ nanosheet encapsulated by six dilacunary Keggin [α-SiW₁₀O₃₇]¹⁰⁻ moieties in a 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.