A novel photochromism material based on both pyrimidinium and polyoxometalate: (C4N2H4–C4N2H3) [Mn(H2O)6]0.5{SiW12O40}0.5ˑ5H2O

Cylindrical HPIII-SbIII-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 (t1/2) of 42.5 s, and it also exhibits noteworthy photochromism under visible light irradiation with a half-life (t1/2) of 157.2 s. The possible photochromic mechanism is proposed and verified by the experimental results.

Tetra-Ln3+-Implanted Tellurotungstates Covalently Modified by dl-Malic Acid: Proton Conduction and Photochromic Properties

Three unique dl-malic acid covalently modified tetra-Ln3+-implanted tellurotungstates [H2(CH3)2]9NaH9[Ln4(H2O)14W6O13(OH)5(Mal)2(B-α-TeW9O33)4]·48H2O [Ln = La3+ (1), Ce3+ (2), Pr3+ (3); H3Mal = dl-malic acid] were fabricated by reacting Na2TeO3, Na2WO4·2H2O, Mal, and LnCl3·6H2O with dimethylamine hydrochloride in an aqueous solution. The most prominent architectural feature of these compounds is the covalent connection mode of an organic ligand and a polyoxometallate backbone, which is relatively rare in the realm of polyoxotungstates. The tetrameric polyanion can be deemed as four [TeW9O33]8- fragments fused together via an intriguing hexanuclearity [W6O13(OH)5(Mal)2Ln4(H2O)14]13+ cluster. Impedance measurements manifest that all three complexes display splendid proton conduction properties, with an exceptional conductivity for 2 up to 2.48 × 10-2 S·cm-1 under 85 °C and 95% relative humidity. Moreover, compounds 1 and 3 exhibited fast reversible photochromic properties with allochroic half-life periods t1/2 of 1.046 and 0.544 min, respectively.

Post-functionalization through covalent modification of organic counter ions: a stepwise and controlled approach for novel hybrid polyoxometalate materials

Post-functionalization of Class I type polyoxometalate-organic hybrids through covalent modification of the organic counter ions in a step-wise and controlled manner is reported for the first time. The properties of the post-functionalized hybrids have been studied and compared with those of their parent hybrids revealing marked differences in properties.