First series of mixed (PIII, SeIV)-heteroatomoriented rare-earth-embedded polyoxotungstates containing distinct building blocks

Abstract

By a self-assembly reaction strategy accompanying the step-by-step introduction of simple reactants, a series of unprecedented mixed-heteroatom-oriented rare-earth-embedded heteropolyoxotungstates [H₂N(CH₃)₂]₁₂Na₂[RE₂(H₂O)₇(W₄O₉)(HPSeW₁₅O₅₄) (SeW₉O₃₃)₂]·44H₂O (RE = Ce³⁺ (1), Pr³⁺ (2), Nd³⁺ (3), Sm³⁺ (4), Gd³⁺ (5), Tb³⁺ (6), Ho³⁺ (7), Er³⁺ (8)) were successfully achieved. It is worth highlighting that their polyoxoanions were synergistically established by two trivacant Keggin Se^IV-inserted [B-α-SeW₉O₃₃]⁸⁻ clusters and one trivacant Dawson P^III-and-Se^IV-inserted [HPSeW₁₅O₅₄]¹⁰⁻ segment. Significantly, [HPSeW₁₅O₅₄]¹⁰⁻ is a rarely reported polyoxometalate (POM) unit and can be viewed as a new member derived from one plenary Dawson P^III-and-Se^IV-inserted polyoxoanion by removing three {WO₆} octahedra in the polar position. Moreover, the composite of 1 and carboxyl-functionalized multi-walled carbon nanotubes (CMWCNTs) was modified onto a glass carbon electrode (GCE) to construct the 1@CMWCNT-GCE electrochemical sensor (ECS). In PBS buffer (pH 7.00), we investigated the electrochemical sensing properties of 1@CMWCNT-GCE ECS toward simultaneously detecting dopamine (DA) and uric acid (UA). The 1@CMWCNT-GCE ECS exhibited good sensing performances toward DA and UA with a low detection limit (1.61 μmol L⁻¹ for DA and 5.41 μmol L⁻¹ for UA) and high stability. This work not only shows that the synergistic interaction of diverse heteroatoms (Has) can facilitate creating captivating structures of POMs, but also promotes the applications of POM-based materials in recognizing bioactive molecules.