Assembly of chainlike polyoxometalate-based lanthanide complexes in one-pot reaction system

Abstract

A series of new chainlike polyoxometalate(POM)-based lanthanide (Ln) complexes, Na₁₀[Ln₆(H₂O)_x{As₄W₄₄(OH)₂(proline)₂O₁₅₁}]·nH₂O (Ln = Tb(III), x = 22 and n = 22 for 1; Ln = Dy(III), x = 22 and n = 25 for 2; Ln = Nd(III), x = 26 and n = 31 for 3) were isolated from a one-pot reaction system. In such a reaction system, the initial three discrete solutions, namely K₁₄[As₂W₁₉O₆₇(H₂O)] precursor in solution A, Ln³⁺ ion and proline in solution B, and NaCl in solution C, were simultaneously mixed together in one-pot reaction field with pH = 1.5 and heated at 80 °C for 1.5 h, leading to the isolation of crystalline compounds 1–3. The crystal structure of 1–3 contains a crown-type POM-based cluster embedded with four hydrated Ln(III) ions. Moreover, these clusters were further linked by extra two hydrate Ln(III) ions into one-dimensional chains. Photoluminescent properties of compounds 1–3 were also investigated, exhibiting the characteristic emission peaks of relevant Ln(III) ions.