Playing with Polyoxometalates to Build Molecular Materials Exhibiting Negative Solid-State Photochromism

Four novel ionic assemblies combining polyoxometalates (POMs) and the cationic photochromic spiropyran SPPy<sup>+</sup> (1',3',3'-trimethyl-6-nitro-8-pyridiniomethylspiro[2<i>H</i>-[1]benzopyran-2,2'-indoline]), namely, <b>(SPPy)<sub>2</sub>[W<sub>6</sub>O<sub>19</sub>]·2CH<sub>3</sub>CN</b>, <b>(SPPy)<sub>2.6</sub>(H)<sub>0.4</sub>[PW<sub>12</sub>O<sub>40</sub>]·CH<sub>3</sub>CN</b>, <b>(SPPy)<sub>2.1</sub>(H)<sub>1.9</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]·CH<sub>3</sub>CN</b>, and <b>(SPPy)<sub>3.7</sub>(H)<sub>0.3</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]</b>, were synthesized and extensively characterized using complementary techniques, including structural characterization of <b>(SPPy)<sub>2</sub>[W<sub>6</sub>O<sub>19</sub>]·2CH<sub>3</sub>CN</b> by X-ray diffraction. In particular, solid-state <sup>13</sup>C NMR spectroscopy was used for the first time on POM/Spiro compounds to assess the proportion of the merocyanine form in these supramolecular materials. Strikingly, in contrast to the deeply colored <b>(SPPy)<sub>2.6</sub>(H)<sub>0.4</sub>[PW<sub>12</sub>O<sub>40</sub>]·CH<sub>3</sub>CN</b> and <b>(SPPy)<sub>2.1</sub>(H)<sub>1.9</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]·CH<sub>3</sub>CN</b> assemblies, which are nonphotochromic in the solid state at room temperature, <b>(SPPy)<sub>2</sub>[W<sub>6</sub>O<sub>19</sub>]·2CH<sub>3</sub>CN</b> and <b>(SPPy)<sub>3.7</sub>(H)<sub>0.3</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]</b> exhibit strong photocontrast under soft-light irradiation. These observations highlight the crucial role of both the nature of the POM and the synthesis conditions on the optical properties of the final materials. The solid-state photochromic properties of these species have been fully investigated, and the coloration and fading kinetic parameters have been determined. Importantly, once discolored, <b>(SPPy)<sub>2</sub>[W<sub>6</sub>O<sub>19</sub>]·2CH<sub>3</sub>CN</b> and <b>(SPPy)<sub>3.7</sub>(H)<sub>0.3</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]</b> turn back to a colored state in the dark, making them the first POM/Spiro hybrid materials to exhibit solid-state negative photochromism.

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Journal
Inorganic Chemistry
Published
2025-09-22
DOI
https://doi.org/10.1021/acs.inorgchem.5c02938
Citations
1
Primary Topic
Photochromic and Fluorescence Chemistry
Type
article
Field-Weighted Citation Impact
0.52
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article

Playing with Polyoxometalates to Build Molecular Materials Exhibiting Negative Solid-State Photochromism

Jérôme Marrot, Mohamed Haouas, Pierre Mialane, Olivier Oms et al.
1 citations
Inorganic Chemistry
Photochromic and Fluorescence Chemistry
0.52
article

Playing with Polyoxometalates to Build Molecular Materials Exhibiting Negative Solid-State Photochromism

Jérôme Marrot, Mohamed Haouas, Pierre Mialane, Olivier Oms, Cédric Viravaux, Rémi Dessapt, Anne Dolbecq
article en
1 citations

Abstract

Four novel ionic assemblies combining polyoxometalates (POMs) and the cationic photochromic spiropyran SPPy<sup>+</sup> (1',3',3'-trimethyl-6-nitro-8-pyridiniomethylspiro[2<i>H</i>-[1]benzopyran-2,2'-indoline]), namely, <b>(SPPy)<sub>2</sub>[W<sub>6</sub>O<sub>19</sub>]·2CH<sub>3</sub>CN</b>, <b>(SPPy)<sub>2.6</sub>(H)<sub>0.4</sub>[PW<sub>12</sub>O<sub>40</sub>]·CH<sub>3</sub>CN</b>, <b>(SPPy)<sub>2.1</sub>(H)<sub>1.9</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]·CH<sub>3</sub>CN</b>, and <b>(SPPy)<sub>3.7</sub>(H)<sub>0.3</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]</b>, were synthesized and extensively characterized using complementary techniques, including structural characterization of <b>(SPPy)<sub>2</sub>[W<sub>6</sub>O<sub>19</sub>]·2CH<sub>3</sub>CN</b> by X-ray diffraction. In particular, solid-state <sup>13</sup>C NMR spectroscopy was used for the first time on POM/Spiro compounds to assess the proportion of the merocyanine form in these supramolecular materials. Strikingly, in contrast to the deeply colored <b>(SPPy)<sub>2.6</sub>(H)<sub>0.4</sub>[PW<sub>12</sub>O<sub>40</sub>]·CH<sub>3</sub>CN</b> and <b>(SPPy)<sub>2.1</sub>(H)<sub>1.9</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]·CH<sub>3</sub>CN</b> assemblies, which are nonphotochromic in the solid state at room temperature, <b>(SPPy)<sub>2</sub>[W<sub>6</sub>O<sub>19</sub>]·2CH<sub>3</sub>CN</b> and <b>(SPPy)<sub>3.7</sub>(H)<sub>0.3</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]</b> exhibit strong photocontrast under soft-light irradiation. These observations highlight the crucial role of both the nature of the POM and the synthesis conditions on the optical properties of the final materials. The solid-state photochromic properties of these species have been fully investigated, and the coloration and fading kinetic parameters have been determined. Importantly, once discolored, <b>(SPPy)<sub>2</sub>[W<sub>6</sub>O<sub>19</sub>]·2CH<sub>3</sub>CN</b> and <b>(SPPy)<sub>3.7</sub>(H)<sub>0.3</sub>[β-Mo<sub>8</sub>O<sub>26</sub>]</b> turn back to a colored state in the dark, making them the first POM/Spiro hybrid materials to exhibit solid-state negative photochromism.

Inorganic ChemistryVol. 64(39)
Centre National de la Recherche Scientifique (FR), Université de Versailles Saint-Quentin-en-Yvelines (FR), Université Paris-Saclay (FR), Institut des Matériaux Jean Rouxel (FR), Institut Lavoisier de Versailles (FR), Nantes Université (FR)
Openalex Percentile: Top 33%
Photochromic and Fluorescence Chemistry
0.52
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