Dual-heteroatom-templated lanthanoid-inserted heteropolyoxotungstates simultaneously comprising Dawson and Keggin subunits and their composite film applied for electrochemical immunosensing of auximone

Abstract

Two P^III–Sb^III-heteroatom-templated lanthanoid(Ln)-inserted polyoxotungstates [H₂N(CH₃)₂]₁₀NaH₉[Ln₄(H₂O)₁₄W₇O₁₅ (H₂MA)₄][Sb^IIIW₉O₃₃]₂[HP^IIISb^IIIW₁₅O₅₄]₂·44H₂O [Ln = Nd³⁺ (1), Pr³⁺ (2)] embellished with DL-malic acid (H₃MA) ligand were achieved for the first time. The [Ln₄(H₂O)₁₄W₇O₁₅(H₂MA)₄][Sb^IIIW₉O₃₃]₂[HP^IIISb^IIIW₁₅O₅₄]₂²⁰⁻ polyanion is assembled from two trivacant Keggin [B-α-Sb^IIIW₉O₃₃]⁹⁻ and two trivacant Dawson P^III–Sb^III-inserted [HP^IIISb^IIIW₁₅O₅₄]¹¹⁻ moieties linked via a central [Ln₄(H₂O)₁₄W₇O₁₅(H₂MA)₄]²⁰⁺ hybrid cluster. Moreover, adjacent polyanions are connected by Ln–O–W linkers, thus affording an intriguing 1-D structure. The 1@PPY (PPY = polypyrrole) conductive film was fabricated by the electrodeposition of 1 and pyrrole. By virtue of 1@PPY film modified glassy carbon electrode as the electrochemical immunosensor, electrochemical detection of auximone (herein indole-3-acetic acid) was realized. This research pioneers the preparation of P^III–Sb^III-heteroatom-templated Ln-inserted polyoxotungstates and develops the application of POM-based materials for detecting auximone in botany.