Smart Heterostructures for Tailoring the Optical Properties of Photochromic Hybrid Organic–Inorganic Polyoxometalates

A new concept of photoresponsive composites has been elaborated by intimately connecting a Photochromic Phase (PP), (H2DABCO)2(HDMA)0.5Na0.75(H3O)0.75[Mo8O27]·3H2O (1), with a second hybrid organic–inorganic molybdate material, (H2DABCO)(HDABCO)[Fe(OH)6Mo6O18]·4H2O (2) acting as an Oxidation Catalytic Phase (OCP) toward the former once photoexcited. The association of both the PP and the OCP in the composite drastically improves the bleaching process of the PP alone because of efficient electronic transfers through the OCP-PP interface without affecting significantly its photoinduced color change characteristic. Two OCP-PP composites with different PP weight percents have been obtained by associating 1 with 2. The optical properties of these composites before and after UV irradiation have been investigated by Diffuse Reflectance Spectroscopy, and the strong impact of the OCP on the fading kinetics of the PP has been clearly highlighted.

本研究构建了一种新型光响应复合材料的设计理念：将光致变色相（Photochromic Phase，PP）(H₂DABCO)₂(HDMA)₀.₅Na₀.₇₅(H₃O)₀.₇₅[Mo₈O₂₇]·3H₂O（化合物1），与第二种有机-无机杂化钼酸盐材料(H₂DABCO)(HDABCO)[Fe(OH)₆Mo₆O₁₈]·4H₂O（化合物2）紧密复合；其中化合物2在受光激发后可作为前者的氧化催化相（Oxidation Catalytic Phase，OCP）。相较于单一光致变色相，该复合材料中两相的协同作用可通过OCP-PP界面间的高效电子转移，大幅改善单一光致变色相的褪色过程，且不会显著影响其原有的光致变色特性。通过调控两种组分的质量占比，我们成功制备了两种不同PP质量分数的OCP-PP复合材料。采用漫反射光谱法对这两种复合材料在紫外辐照前后的光学性能进行了系统表征，结果清晰证实了氧化催化相对光致变色相褪色动力学的显著调控效应。