Multifunctional Uranyl-Based Framework with Labile Coordination Sites: Proton Conduction, Switchable Luminescence, Dielectric Relaxation, and Visible-Light Photochromism

Porous coordination polymers and supramolecular assembly frameworks, serve as a platform for the generation of novel functional systems, showing tunable magnetic, electric, optical, and mechanical features. Here, we report a truly multifunctional material based on a three-dimensional coordination framework employing photoluminescent uranium centers. Owing to the material's porosity, apart from distinct proton conductivity and visible light emission, the obtained material reveals humidity-induces switching of the latter, as well as dielectric relaxation dynamics. Moreover, the reported system shows affinity toward the organic solvents, which efficiently quench its emission properties. Additionally, the adsorption of simple alcohols activates visible-light photochromic behavior, leading to an optical memory effect present after their desorption. The observed adsorption of solvents and the related modification of the optical properties are possible not only due to porosity in the supramolecular lattice but also owing to labile coordination sites of uranium centers involving aqua and hydroxido ligands, which can be selectively exchanged by specific solvent molecules.