Rigid-Flexible-Ligand-Ornamented Lanthanide-Incorporated Selenotungstates and Photoluminescence Properties

Currently, organic–inorganic hybrid lanthanide-incorporated polyoxometalates (POMs) have emerged as a prominent research area. Herein, we employed a simple raw material assembly method to synthesize two neoteric mixed-organic -ligand-ornamented lanthanide (Ln) incorporated selenotungstates [H2N(CH3)2]16Na2 [Ln4(H2O)6(HPZDA)2(HFMA)2W8O21][B-α-SeW9O33]4·29H2O (Ln = Sm3+ (1), La3+ (2); H2PZDA = 2,3-pyrazine dicarboxylic acid, H2FMA = fumaric acid). 1 and 2 are isomorphic with the polyanions constructed from four trivacant Keggin [B-α-SeW9O33]8– ({SeW9}) segments and a rigid-flexible-ligand-ornamented dodeca-nuclear W–Ln heterometallic [Ln4(H2O)6(HPZDA)2(HFMA)2W8O21]14+ cluster. Moreover, the solid-state fluorescence spectrum of 1 at room temperature mainly exhibits the characteristic emission peak of Sm3+ cations. Additionally, energy transfer from {SeW9} to Sm3+ ions in 1 has been demonstrated by time-resolved spectroscopy. This work presents a feasible dual-ligand synergistic strategy for constructing novel POM derivatives and POM-based fluorescent materials.