Clara Pereira - Lanthano phosphomolybdate-decorated silica nanoparticles: novel hybrid materials with photochromic properties

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      Publication Details (including relevant citation   information):

      "Lanthano phosphomolybdate-decorated silica nanoparticles:   novel hybrid materials with photochromic properties", Tânia   V. Pinto, Diana M. Fernandes, Clara Pereira,* Alexandra   Guedes, Ginesa Blanco, Jose M. Pintado, Manuel F. R. Pereira,   Cristina Freire, Dalton Transactions  2015, 44, 45824593.

      *corresponding authors


      Novel photochromic hybrid nanomaterials were prepared through the   immobilization of the lacunary Keggin-type phosphomolybdate   (TBA4H3[PMo11O39xH2O,   denoted as PMo11) and sandwich-type   lanthano phosphomolybdates   (K11[LnIII(PMo11O39)2xH2O,   denoted as   Ln(PMo11)2,   where LnIII = Sm, Eu, Gd, Tb and Dy)   onto positively-charged functionalized silica nanoparticles. The   functionalized silica nanoparticles were prepared by a one-step   co-condensation route between tetraethyl orthosilicate and   dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride,   presenting an average particle size of 95 ± 26 nm, a spherical   morphology and a pore diameter of 13.7 nm. All characterization   techniques proved the successful immobilization of the   phosphomolybdates. The photochromic properties of the resulting   hybrid nanomaterials in the solid state were evaluated by UV-Vis   spectroscopy and colorimetry. All materials revealed promising   photochromic properties under UV irradiation (λ = 254   nm). The lacunary phosphomolybdate anchored onto the silica   nanoparticles,   C18-SiO2@PMo11,   showed the best photoswitching properties, with the color   changing from green to dark-blue (ΔE* = 26.8). Among the   Ln(PMo11)2-based   hybrid nanomaterials, those containing higher Mo loadings –   EuIII- and   TbIII-based samples – presented more   significant color changes from green to dark-blue (ΔE* =   18.8–18.9). These results revealed that the optical properties of   the as-prepared hybrid nanomaterials did not depend directly on   the type of LnIII cation, but only on   the amount of Mo, which was the target element responsible for   the photochromic behavior.

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