• Spectroscopy and Spectral Analysis
  • Vol. 39, Issue 6, 1915 (2019)
SUN Tian-lei1、*, YAN Jing-hui1, GENG Ai-fang1, ZHANG Hong2, and ZOU Ming-qiang3、4
Author Affiliations
  • 1[in Chinese]
  • 2[in Chinese]
  • 3[in Chinese]
  • 4[in Chinese]
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    DOI: 10.3964/j.issn.1000-0593(2019)06-1915-07 Cite this Article
    SUN Tian-lei, YAN Jing-hui, GENG Ai-fang, ZHANG Hong, ZOU Ming-qiang. Design and Synthesis of Rare Earth Organic-Inorganic Hybrid Material Based on Polyoxometalate and 1,4,5,8-Naphthalenediimide Derivatives[J]. Spectroscopy and Spectral Analysis, 2019, 39(6): 1915 Copy Citation Text show less

    Abstract

    Based on the concept of organic-inorganic hybrid materials, take advantage of the fact that rare earth terbium nitrate [Tb(NO3)3], organic ligands BINDI (BINDI=N,N′-bis (5-isophthalic acid)-1,4,5,8-naphthalenediimide and the Keggin-type polyoxometallate H4SiW12O40·26H2O will react under solvothermal conditions to successfully synthesize a polyacid rare earth coordination polymer Tb4[SiW12O40]·[BINDI)]2·[DMA]16. The structure, composition, thermal stability, luminescence properties and photochromic properties of the rare earth polymer are characterized by X-ray single crystal diffractometer, X-ray powder diffractometer, infrared spectrometer, thermal gravimetric analyzer, ultraviolet-visible absorption spectrometer, elemental analyzer, fluorescence spectrometer and electron paramagnetic resonance spectrometer. X-ray single crystal diffraction analysis revealed that the rare-earth coordination polymer is crystallized in the tetragonal crystal system, and the space group is P42/n, exhibiting the 3D chiral double helix network structural characteristics. Among them, the polyacid anion SiW12O40 (abbreviated as {SiW12}) is embedded in the pores formed by rare earth organic groups; Through infrared and ultraviolet absorption spectroscopy analysis we found that rare earth Tb3+ and ligand (BINDI) have been coordinated to form a bond; Fluorescence spectroscopy indicated that at the excitation wavelength of 380 nm, the ligand shows the strongest fluorescence emission peak at 441 nm, while the strongest emission peak of the compound is at 471 nm. Since the trivalent europium ion is not easily oxidized and is difficult to be reduced, the fluorescence emission of the compound cannot be attributed to the electron radiation transition between the metal and the ligand, and the emission peak of the compound is similar with the emission peak of the ligand. Therefore, the fluorescence is mainly the luminescence of the ligand BINDI. In addition, the special transitional emission band of Tb(Ⅲ) ions does not appear, because the color of the sample has break due to illumination during the fluorescence test, that is, the phenomenon of photochromism has arisen, resulting in photoinduced electron transfer to cause fluorescence quenching. The reason for the fluorescence quenching of metal complexes is usually photoelectron transfer, and the direction of electron transfer is the transfer of electrons in the ligand to the metal orbit (LMCT). The red shift or blue shift of the maximum emission peak after complex formation is caused by the change of electron distribution in the molecule resulting from electron transfer, which gives rise to the decrease or increase of the HOMO-LUMO energy gap. The fluorescence spectrum of the compound is red-shifted compared to the fluorescence spectrum of the ligand. Furthermore, electron paramagnetic resonance spectrometer manifests that owing to the electron transfer of the BINDI ligands in the compound to form free radicals under ultraviolet and visible light irradiation, and the polyoxometallate under light excitation, the occurrence of W5+→W6+ further promotes the photochromism of the compound. Therefore, the compound has extremely acute photochromic properties.
    SUN Tian-lei, YAN Jing-hui, GENG Ai-fang, ZHANG Hong, ZOU Ming-qiang. Design and Synthesis of Rare Earth Organic-Inorganic Hybrid Material Based on Polyoxometalate and 1,4,5,8-Naphthalenediimide Derivatives[J]. Spectroscopy and Spectral Analysis, 2019, 39(6): 1915
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