Double Trigonal Pyramidal {SeO3} Groups Bridged 2-Picolinic Acid Modified Cerium-Inlaid Polyoxometalate Including Mixed Selenotungstate Subunits for Electrochemically Sensing Ochratoxin A

An organic–inorganic hybrid trigonal pyramidal {SeO3} group, bridged cerium-inlaid polyoxometalate (POM) Na16[Se2Ce4(H2O)8W4(HPIC)4O10][B-β-SeW8O30]2[Se2W12O46]2·60H2O (1) (HPIC = 2-picolinic acid), containing two disparate selenotungstate (ST) building blocks was synthesized by a one-step assembly strategy, which is established by two asymmetric sandwich-type {[Ce2(H2O)4W2(HPIC)2O4][B-β-SeW8O30][Se2W12O46]}10– moieties joined by double trigonal pyramidal {SeO3} groups. Its outstanding structural trait is that it contains two types of ST building blocks, Keggin-type [B-β-SeW8O30]8– and Dawson-like [Se2W12O46]12–, which are extremely rare in ST chemistry. Remarkably, [Se2W12O46]12– is first obtained in lanthanide-inlaid STs. Furthermore, 1@PPy conductive film (PPy = polypyrrole) was prepared by electrochemical polymerization and served as the electrode material, and then nano-gold particles (NGPs) were deposited on the surface of 1@PPy conductive film by an electrochemical deposition method in order to immobilize the aptamer of ochratoxin A. With the help of exonuclease I (EN I), the oxidation peak of the metalized Ag works as the detection signal to achieve the detection of ochratoxin A (OTXA). This study offers an available approach for creating organic–inorganic hybrid heteroatom-bridged lanthanide-inlaid POMs and reveals the likelihood of extending heteroatom-bridged lanthanide-inlaid POMs into electrochemical biosensing applications.