Tricarboxylic-Ligand-Decorated Lanthanoid-Inserted Heteropolyoxometalates Built by Mixed-Heteroatom-Directing Polyoxotungstate Units: Syntheses, Structures, and Electrochemical Sensing for 17β-Estradiol.

Organic-inorganic hybrid metal-oxide clusters have been pursued for many years, benefiting from their abundant structures and prominent performances. Upon our exploration, a family of unusual mixed-heteroatom (SbIII, PIII)-directing lanthanoid (Ln)-inserted heteropolyoxotungstates (Ln-HPOTs), [(CH3)2NH2]2Na7H3[Ln4(HPIII)W8(H2O)12(H2ptca)2O28][SbIIIW9O33]2·27H2O [Ln = Ce3+ (1), La3+ (2), Pr3+ (3)], functionalized by 1,2,3-propanetricarboxylic acid (H3ptca) was achieved. The intriguing trimeric [Ln4(HPIII)W8(H2O)12(H2ptca)2O28][SbIIIW9O33]212- polyanion was established by two trivacant [B-α-SbIIIW9O33]9- segments mounted on both sides and one rare [HPIIIW4O18]8- segment at the bottom, which are bridged via an organic-inorganic hybrid [W4Ln4(H2O)12O10(H2ptca)2]14+ central moiety. Such Ln-HPOTs involving dual-heteroatom-directing mixed building blocks, and even simultaneously modified by tricarboxylic ligands, are rather unseen in polyoxometalate chemistry. Moreover, the detection of 17β-estradiol through a 1-based electrochemical biosensor has been explored, demonstrating a low detection limit (7.08 × 10-14 M) and considerable stability.