Two Innovative Fumaric Acid Bridging Lanthanide-Encapsulated Hexameric Selenotungstates Containing Mixed Building Units and Electrochemical Performance for Detecting Mycotoxin.

Two particular fumaric acid bridging lanthanide-encapsulated selenotungstates [H2N(CH3)2]16Na8[Ln3(H2O)7]2 [W4O8(C4H2O4) (C4H3O4)]2[SeW6O25]2[B-α-SeW9O33]4·46H2O [Ln = Ce3+ (1), La3+ (2)] were acquired by the deliberately designed step-by-step synthetic strategy, which are composed of four trilacunary Keggin [B-α-SeW9O33]8- and two original [SeW6O25]10- building units together with one fumaric acid bridging heterometallic [Ln3(H2O)7]2[W4O8(C4H2O4) (C4H3O4)]228+ entity. Particularly, this heterometallic cluster contains four fumaric acid ligands, which play two different roles: one works as the pendant decorating the cluster and the other acts as the linker connecting the whole structure. In addition, the 1@DDA hybrid material was produced through the cation exchange of 1 and dimethyl distearylammonium chloride (DDA·Cl) and its beehive-shaped film of 1@DDA was prepared by the breath figure method, which can be further used to establish an electrochemical biosensor for detecting a kind of mycotoxin-ochratoxin A (OX-A). The 1@DDA beehive-shaped film-based electrochemical biosensor exhibits good reproducibility and specific sensing toward OX-A with a low detection limit of 29.26 pM. These results highlight the huge feasibility of long-chain flexible ligands in building lanthanide-encapsulated selenotungstates with structural complexity and further demonstrate great electrochemical application potentiality of polyoxometalate-involved materials in bioanalysis, tumor diagnosis, and iatrology.