An organic chromophore -modified samarium-containing polyoxometalate: excitation-dependent color tunable behavior from the organic chromophores to the lanthanide ion

Abstract

Here, an organic–inorganic hybrid lanthanide-based polyoxometalate (Ln-POM) [N(CH₃)₄]₃K₂Sm(C₇H₅O₂)(H₂O)₂(α-PW₁₁O₃₉)·11H₂O (1) was successfully synthesized and characterized well by several physicochemical techniques. In the polyanion of 1, the benzoic acid ligand directly binds a Sm³⁺ ion for the formation of an organic–inorganic hybrid polyanion. This organic–inorganic hybrid structure can effectively sensitize the emissions of the Sm³⁺ ion, which was confirmed by the photoluminescence and time-resolved emission spectroscopy of 1. The photoluminescence study demonstrates that the Sm³⁺ ion possesses a relatively high-symmetry coordination geometry, which is consistent with the structural analysis of Sm³⁺ in 1. Furthermore, the polyanion of 1 can form a 3D 4,8-topology framework through the linkage of K1 and K2 ions. In addition, the photoluminescence properties of 1 have been explored, revealing that 1 shows reversible color-tunable photoluminescence based on the excitation from 260 nm to 350 nm, and emitting colors from blue to pink.