Luminescent and Proton Conducting Lanthanide Coordination Networks Based On a Zwitterionic Tripodal Triphosphonate

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• 作者：Montse Bazaga-García ; Giasemi K. Angeli ; Konstantinos E. Papathanasiou ; Inés R. Salcedo ; Pascual Olivera-Pastor ; Enrique R. Losilla ; Duane Choquesillo-Lazarte ; Gary B. Hix ; Aurelio Cabeza ; Konstantinos D. Demadis
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：August 1, 2016
• 年：2016
• 卷：55
• 期：15
• 页码：7414-7424
• 全文大小：631K
• 年卷期：0
• ISSN：1520-510X

文摘

The synthesis, structural characterization, luminescence properties, and proton conduction performance of a new family of isostructural cationic 2D layered compounds are reported. These have the general formula [Ln(H₄NMP)(H₂O)₂]Cl·2H₂O [Ln = La³⁺, Pr³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, H₆NMP = nitrilotris(methylphosphonic acid)], and contain Cl^– as the counterion. In the case of Ce³⁺, a 1D derivative, [Ce₂(H₃NMP)₂(H₂O)₄]·4.5H₂O, isostructural with the known lanthanum compound has been isolated by simply crystallization at room temperature. The octa-coordinated environment of Ln³⁺ in 2D compounds is composed by six oxygen atoms from three different ligands and two oxygens from each bound water. Two of the three phosphonate groups act as both chelating and bridging linkers, while the third phosphonate group acts solely as a bridging moiety. The materials are stable at low relative humidity at less at 170 °C. However, at high relative humidity transform to other chloride-free phases, including the 1D structure. The proton conductivity of the 1D materials varies in a wide range, the highest values corresponding to the La derivative (σ ≈ 2 × 10^–3 S·cm^–1 at RH 95% and 80 °C). A lower proton conductivity, 3 × 10^–4 S·cm^–1, was measured for [Gd(H₄NMP)(H₂O)₂]Cl·2H₂O at 80 °C, which remains stable under the work conditions used. Absorption and luminescence spectra were recorded for selected [Ln(H₄NMP)(H₂O)₂]Cl·2H₂O compounds. In all of them, the observed transitions are attributed solely to f–f transitions of the lanthanide ions present, as the H₄NMP^2– organic group has no measurable absorption or luminescence properties.