From Solid-State Cluster Compounds to Functional PMMA-Based Composites with UV and NIR Blocking Properties, and Tuned Hues

New nanocomposite materials with UV-NIR blocking properties and hues ranging from green to brown were prepared by integrating inorganic tantalum octahedral cluster building blocks prepared via solid-state chemistry in a PMMA matrix. After the synthesis by the solid-state chemical reaction of the K(4)[{Ta(6)Br(i)(12)}Br(a)(6)] ternary halide, built-up from [{Ta(6)Br(i)(12)}Br(a)(6)](4−) anionic building blocks, and potassium cations, the potassium cations were replaced by functional organic cations (Kat(+)) bearing a methacrylate function. The resulting intermediate, (Kat)(2)[{Ta(6)Br(i)(12)}Br(a)(6)], was then incorporated homogeneously by copolymerization with MMA into transparent PMMA matrices to form a brown transparent hybrid composite Ta@PMMA(brown). The color of the composites was tuned by controlling the charge and consequently the oxidation state of the cluster building block. Ta@PMMA(green) was obtained through the two-electron reduction of the [{Ta(6)Br(i)(12)}Br(a)(6)](2−) building blocks from Ta@PMMA(brown) in solution. Indeed, the control of the oxidation state of the Ta(6) cluster inorganic building blocks occurred inside the copolymer, which not only allowed the tuning of the optical properties of the composite in the visible region but also allowed the tuning of its UV and NIR blocking properties.