Yan Bing, Liang Rongchang, Zheng Kangting, Li Rui, Ma Pengtao, Wang Jingping, Niu Jingyang
Henan Key Laboratory of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, China.
Inorg Chem. 2021 Jun 7;60(11):8164-8172. doi: 10.1021/acs.inorgchem.1c00798. Epub 2021 May 20.
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.
通过简便的一步组装策略制备了一系列苯甲酸修饰的含镧系元素（Ln）的四聚体道森型磷钨酸盐[N(CH)]H[{(PWO)Ln(HO)Ln(CHCOO)(HO)]}{[(PWO)Ln(HO)}]Cl·98HO [Ln = Sm ()、Eu ()和Gd ()]，并采用多种技术对其进行了表征。值得注意的是，含Ln的四聚体道森型多金属氧酸盐[{(PWO)Ln(HO)Ln(CHCOO)(HO)]}{[(PWO)Ln(HO)}]均由四个单缺位道森型[PWO]片段构成，其中一个Ln离子被两个与Ln离子配位的苯甲酸酯所包裹。 - 表现出可逆光致变色现象，在紫外光照射下6分钟内可从原本的白色变为蓝色，且在黑暗中30小时内颜色逐渐恢复。 和 的固态光致发光光谱基于4f - 4f跃迁显示出Ln组分的特征发射。还测量了 和 的时间分辨发射光谱，以验证从磷钨酸盐和有机发色团到Eu的能量转移。特别是， 因其快速的光致变色表现出有效的可切换发光行为。
