Organic-Inorganic Two-Dimensional Hybrid Networks Constructed from Pyridine-4-Carboxylate-Decorated...

Six organic-inorganic hybrid pyridine-4-carboxylate-decorated organotin (OT)-lanthanide (Ln) heterometallic antimotungstates [Ln(H₂O)₆(pca)]H[Sn(CH₃)₂(H₂O)]₃[B-β-SbW₉O₃₃]·12H₂O [Ln = La³⁺ (1), Ce³⁺ (2), Pr³⁺ (3), Nd³⁺ (4), Sm³⁺ (5), Eu³⁺ (6); Hpca = isonicotinic acid] have been prepared with the help of the structure-directing effect of the trivacant [B-α-SbW₉O₃₃]^9- segment toward [(CH₃)₂Sn]²⁺ and Ln³⁺ ions in an acidic water medium. The prominent architecture characteristic is that their structural units consist of a trivacant [B-β-SbW₉O₃₃]^9- segment stabilized by three [Sn(CH₃)₂(H₂O)]²⁺ groups and a [Ln(H₂O)₆(pca)]²⁺ cation, which are interconnected to propagate an intriguing two-dimensional (2D) network. For all we know, 1-6 stand for the first 2D OT-Ln heterometallic polyoxometalates. Furthermore, luminescence performances of solid-state 3-6 were deeply surveyed at ambient temperature. Energy migration from [B-β-SbW₉O₃₃]^9- and pca^- to Sm³⁺ centers in 5 was also studied. Comparative studies demonstrate that the contribution of [B-β-SbW₉O₃₃]^9- sensitizing the emission of Sm³⁺ is prominently larger than that of pca^- sensitizing the emission of Sm³⁺ in the emission process of 5. Most interestingly, 6 as a fluorescence probe exhibits high selectability and sensitivity for recognizing Zn²⁺ and Cu²⁺ in water.