Cylindrical HP^III-Sb^III-Templated Five-Layer Polyoxotungstate with Conspicuous Photochromism Triggered by UV or Visible Light

The heteroanion (HA) component plays an important role in the templating of heteropolyoxometalate (HPA) structures, but polyoxometalates (POMs) formed from two different templates are rarely reported. Herein, we present a five-layer POM [H₂N(CH₃)₂]₁₄{[(HPO₃)₄W₆O₁₀][HPSbW₁₅O₅₄]₂}·16H₂O (1) prepared by two kinds of different HA templates. The multilayer heteropolyanion {[(HPO₃)₄W₆O₁₀][HPSbW₁₅O₅₄]₂}^14- in 1 consists of two trivacant diheteroatom-templated ([HPO₃]^2- and [SbO₃]^3-) [HPSbW₁₅O₅₄]^11- subunits linked by one unusual [(HPO₃)₄W₆O₁₀]⁸⁺ subcluster via twelve corner-sharing oxygen atoms. Compound 1 was systematically characterized by IR, UV, PXRD, TGA, XPS, and Raman spectra. Compound 1 exhibits good photochromism under UV irradiation with a half-life (t_1/2) of 42.5 s, and it also exhibits noteworthy photochromism under visible light irradiation with a half-life (t_1/2) of 157.2 s. The possible photochromic mechanism is proposed and verified by the experimental results.