A new [Co(HO)(OH)] unit-incorporating polyoxotungstate for sensitive detection of dichlorvos

A new [Co 21 (H 2 O) 4 (OH) 12 ] 30+ unit-incorporating polyoxotungstate, Na 18 [Co(H 2 O) 6 ] 2 {[Na(H 2 O) 4 ] 2 [Na(H 2 O) 2 ] 2 [Co(H 2 O) 3 ] 2 [Co 21 (H 2 O) 4 (OH) 12 ](SiW 10 O 37 ) 6 }·24H 2 O (denoted as Co 25 Si 6 W 60 ), 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 [Co 21 (H 2 O) 4 (OH) 12 (SiW 10 O 37 ) 6 ] 30− core in Co 25 Si 6 W 60 is composed of a square-like [Co 21 (H 2 O) 4 (OH) 12 ] 30+ nanosheet encapsulated by six dilacunary Keggin [α-SiW 10 O 37 ] 10− moieties in a staggered fashion, resulting in a remarkable sandwich-type assembly. Furthermore, the unique Co 25 Si 6 W 60 -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. A new [Co 21 (H 2 O) 4 (OH) 12 ] 30+ unit-incorporating polyoxotungstate (denoted as Co 25 Si 6 W 60 ) has been hydrothermally synthesized and fully characterized. The unique Co 25 Si 6 W 60 -based biosensing system offers an environmentally-friendly route for detecting dichlorvos.