Photoluminescent Lanthanide-Organic 2D Networks: A Combined Synchrotron Powder X-ray Diffraction and Solid-State NMR Study
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- 作者：Luí ; s Cunha-Silva ; Luí ; s Mafra ; Duarte Ananias ; Luí ; s D. Carlos ; Joã ; o Rocha ; Filipe A. Almeida Paz
- 刊名：Chemistry of Materials
- 出版年：2007
- 出版时间：July 10, 2007
- 年：2007
- 卷：19
- 期：14
- 页码：3527 - 3538
- 全文大小：695K
- 年卷期：v.19,no.14(July 10, 2007)
- ISSN：1520-5002
文摘
A series of two-dimensional lanthanide-organic materials (LnOFs), [Ln(H3NMP)]·1.5H2O [Ln3+ =La3+ (1), Pr3+ (2), Nd3+ (3), Sm3+ (4), or Eu3+ (5); H3NMP3- is a residue of nitrilotris(methylenephosphonicacid)], has been isolated as microcrystalline powders from hydrothermal synthesis and characterized byhigh-resolution laboratory and synchrotron powder X-ray diffraction (PXRD), solid-state NMR, FTIRand FT Raman spectroscopies, CHN elemental analysis, thermogravimetry, scanning electron microscopy,and energy dispersive analysis of X-ray spectroscopy. The crystal structure of [Pr(H3NMP)]·1.5H2O (2)has been solved from a combined study of ab initio methods using high-resolution PXRD data and high-resolution solid-state NMR techniques performed on [La(H3NMP)]·1.5H2O (1) (13C, 15N, 31P CPMASand 2D 1H-1H/31P HOMCOR/HETCOR). The structure contains a single lanthanide center which doesnot have water molecules in its first coordination sphere. This Ln3+ center acts as the node of a neutralundulated two-dimensional network, 
2[Pr(H3NMP)], having a (4,4) topology, which close packs alongthe [100] direction of the unit cell (adjacent layers are related by inversion). Water molecules ofcrystallization occupy the interlayer spaces, and a one-dimensional water cluster (spiral chain topology)is confined to the channels formed by the packing of adjacent layers. Removal of these water molecules(investigated by variable-temperature PXRD) leads to a new crystalline phase with a smaller interlayerspace. The material partially reabsorbs water from the surrounding environment, originating the parentphase. This dehydration/rehydration process has also been monitored by photoluminescence (PL)spectroscopy, revealing that the presence of water in the interlayer spaces does not affect much the PLproperties of [Eu(H3NMP)]·1.5H2O (5).
2[Pr(H3NMP)], having a (4,4) topology, which close packs alongthe [100] direction of the unit cell (adjacent layers are related by inversion). Water molecules ofcrystallization occupy the interlayer spaces, and a one-dimensional water cluster (spiral chain topology)is confined to the channels formed by the packing of adjacent layers. Removal of these water molecules(investigated by variable-temperature PXRD) leads to a new crystalline phase with a smaller interlayerspace. The material partially reabsorbs water from the surrounding environment, originating the parentphase. This dehydration/rehydration process has also been monitored by photoluminescence (PL)spectroscopy, revealing that the presence of water in the interlayer spaces does not affect much the PLproperties of [Eu(H3NMP)]·1.5H2O (5).