Sulfonium polyoxometalates: A new class of solid-state photochromic hybrid organic-inorganic materials

Abstract

For the very first time, sulfonium polyoxometalate (POM) assemblies are shown to develop efficient solid-state photochromism in ambient conditions. The optical properties of the already known Rb0.75(NH4) 5.25[(Mo3O8)2O(O 3PC(CH2S(CH3)2)OPO3) 2]·8H2O (1) and a new material (Me 3S)4[Mo8O26] (2) under UV excitation are investigated by diffuse reflectance spectroscopy, revealing that the color change effect is highly tunable playing with the nature of the POM. A mechanism involving the photoreduction of Mo6+ cations associated with electron transfers from the sulfonium cations toward the POMs is proposed. © 2013 American Chemical Society.