Organic–inorganic hybrid phosphite-participating S-shaped penta-CeIII-incorporated tellurotungstate as an electrochemical enzymatic hydrogen peroxide sensor for β-d-glucose detection

Abstract

Polyoxometalate chemistry has made rapid advances in innovative structural chemistry. The lower valence state and lone electron pair effect of the subgroup-valence heteroatom Te(IV) can be introduced into tungsten–oxygen systems to construct complicated tellurotungstate (TT) aggregates. Thus, for the first time, we synthesized a phosphite-participating S-shaped penta-Ce^III-incorporated tetrameric TT aggregate, Na₄K₃H₆[Ce₅W₄(Hpica)₆H₂P₂O₁₂(H₂O)₄]{[B-β-TeW₇O₂₈]₂[B-β-TeW₈O₃₀]₂}·94H₂O (1) (Hpica = 2-picolinic acid). The molecular structure of 1 consists of one tetrameric [Ce₅W₄(Hpica)₆H₂P₂O₁₂(H₂O)₄]{[B-β-TeW₇O₂₈]₂[B-β-TeW₈O₃₀]₂}¹³⁻ (1a) hybrid polyanion constructed from two symmetrical sandwich-like {[Ce₂W₂(Hpica)₃ HP^IIIO₆(H₂O)₂][B-β-TeW₇O₂₈][B-β-TeW₈O₃₀]}⁸⁻ ({Ce₂W₂P^IIITe₂}) moieties linked by a Ce³⁺ cation. Interestingly, the sandwich-like {Ce₂W₂P^IIITe₂} moiety can be viewed as a heterometal cluster [Ce₂W₂(Hpica)₃HP^IIIO₆(H₂O)₂]¹⁰⁺{Ce₂W₂P^III} group integrating a tetravacant [B-β-TeW₈O₃₀]⁸⁻ fragment and a pentavacant [B-β-TeW₇O₂₈]¹⁰⁻ fragment. Furthermore, 1 was converted into nano-1 with the help of ultrasonication in organic solution. Nano-1 was then complexed with NH₂-graphene (NH₂-G), and a bi-component nano-1/NH₂-G nanocomposite was prepared. Without further assembly and modification, the as-prepared nano-1/NH₂-G nanocomposite was first used as a sensor to detect hydrogen peroxide. This nano-1/NH₂-G-based H₂O₂ sensor shows excellent reproducibility, stability, and anti-interference ability. In quick succession, with the assistance of glucose oxide, an electrochemical enzymatic method based on the nano-1/NH₂-G-based H₂O₂ sensor was developed and further applied for the specific detection of β-D-glucose. This enzymatic sensor also displays good detection performance. The present work provides new insight into electrochemical sensors based on the nano-1/NH₂-G nanocomposite and their potential application in enzymatic glucose sensing.