Multinuclear Lanthanide-Implanted Tetrameric Dawson-Type Phosphotungstates with Switchable Luminescence Behaviors Induced by Fast Photochromism.

A series of benzoate-decorated lanthanide (Ln)-containing tetrameric Dawson-type phosphotungstates [N(CH)]H[{(PWO)Ln(HO)Ln(CHCOO)(HO)]}{[(PWO)Ln(HO)}]Cl·98HO [Ln = Sm (), Eu (), and Gd ()] were made using a facile one-step assembly strategy and characterized by several techniques. Notably, the Ln-containing tetrameric Dawson-type polyoxoanions [{(PWO)Ln(HO)Ln(CHCOO)(HO)]}{[(PWO)Ln(HO)}] are all established by four monolacunary Dawson-type [PWO] segments, encapsulating a Ln ion with two benzoates coordinating to the Ln ions. - exhibit reversible photochromism, which can change from intrinsic white to blue for 6 min upon UV irradiation, and their colors gradually recover for 30 h in the dark. The solid-state photoluminescence spectra of and display characteristic emissions of Ln components based on 4f-4f transitions. Time-resolved emission spectra of and were also measured to authenticate the energy transfer from the phosphotungstate and organic chromophores to Eu. In particular, shows an effectively switchable luminescence behavior induced by its fast photochromism.