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), (H(2)DABCO)(2)(HDMA)(0.5)Na(0.75)(H(3)O)(0.75)[Mo(8)O(27)]·3H(2)O (1), with a second hybrid organic-inorganic molybdate material, (H(2)DABCO)(HDABCO)[Fe(OH)(6)Mo(6)O(18)]·4H(2)O (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.