Organic–inorganic hybrids assembled from plenary Keggin-type germanotungstate units and 3d–4f heterometal clusters

Abstract

Two kinds of organic–inorganic 3d–4f heterometal hybrids based on plenary α-Keggin-type germanotungstates [Cu₂(H₂O)₃(PA)₃] [Ln_0.5Na_0.5Cu₂(H₂O)₁₂(PA)₃][α-GeW₁₂O₄₀]·5H₂O [Ln = La³⁺ (1), Ce³⁺ (2)] and [Cu₂(H₂O)₂(PA)₃][Cu(PA)₂][Ln(H₂O)₇][α-GeW₁₂O₄₀]·7H₂O [Ln = Tb³⁺ (3), Dy³⁺ (4), HPA = 2-picolinic acid] were prepared via the strategy of combining an in situ assembly reaction and stepwise synthesis in the aqueous solution. The most remarkable structural characteristic of 1–2 is that neighboring structural units are connected into a 1-D chain alignment by the bridging di-copper [Cu₂(H₂O)₃(PA)₃]⁺ subunits, whereas the most outstanding structural feature of 3–4 is that neighboring structural units are interconnected to generate a zigzag 1-D chain alignment by the bimetallic bridging [Cu₂(H₂O)₃(PA)₃]⁺ subunits, and then adjacent zigzag 1-D chains are integrated into a fascinating 2-D sheet structure by heterobimetallic bridging {Tb(H₂O)₇[Cu(PA)₂]_0.5}³⁺ subunits and [Cu(PA)₂] groups. As far as we know, 1–4 represent the first examples of plenary Keggin heterometal germanotungstates including organic 3d–4f heterometal subunits so far. The electrochemical sensing properties towards the detection of Acetaminophen of 1/3@CMWCNT–Nafion/GCE electrochemical sensors were investigated, showing that 1/3@CMWCNT–Nafion/GCE electrochemical sensors exhibit good stability and good sensing performance towards AC detection.