Theoretical and Experimental Studies of the Photoluminescent Properties of the Coordination Polymer [Eu(DPA)(HDPA)(H2O)2]·4H2O

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• 作者：Marcelo O. Rodrigues ; Nivan B. da Costa J&uacute ; nior ; Carlos A. de Simone ; Adriano A. S. Ara&uacute ; jo ; A. M. Brito-Silva ; Filipe A. Almeida Paz ; Maria E. de Mesquita ; Severino A. J&uacute ; nior ; Ricar
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：April 10, 2008
• 年：2008
• 卷：112
• 期：14
• 页码：4204 - 4212
• 全文大小：256K
• 年卷期：v.112,no.14(April 10, 2008)
• ISSN：1520-5207

文摘

We report on the hydrothermal synthesis of the [Eu(DPA)(HDPA)(HB>2O)₂]·4H₂O lanthanide-organic framework(where H₂DPA stands for pyridine-2,6-dicarboxylic acid), its full structural characterization including single-crystal X-ray diffraction and vibrational spectroscopy studies, plus detailed investigations on the experimentaland predicted (using the Sparkle/PM3 model) photophysical luminescent properties. We demonstrate that theSparkle/PM3 model arises as a valid and efficient alternative to the simulation and prediction of thephotoluminescent properties of lanthanide-organic frameworks when compared with methods traditionallyused. Crystallographic investigations showed that the material is composed of neutral one-dimensionalcoordination polymers ¹[Eu(DPA)(HDPA)(H₂O)₂] which are interconnected via a series of hydrogen bondinginteractions involving the water molecules (both coordinated and located in the interstitial spaces of thestructure). In particular, connections between bilayer arrangements of ¹[Eu(DPA)(HDPA)(H₂O)₂] are assuredby a centrosymmetric hexameric water cluster. The presence of this large number of O-H oscillators intensifiesthe vibronic coupling with water molecules and, as a consequence, increases the number of nonradiativedecay pathways controlling the relaxation process, ultimately considerably reducing the quantum efficiency( = 12.7%). The intensity parameters (₂, ₄, and ₆) were first calculated by using both the X-ray andthe Sparkle/PM3 structures and were then used to calculate the rates of energy transfer (W_ET) and back-transfer (W_BT). Intensity parameters were used to predict the radiative decay rate. The calculated quantumyield obtained from the X-ray and Sparkle/PM3 structures (both of about 12.5%) are in good agreement withthe experimental value (12.0 ± 5%). These results clearly attest for the efficacy of the theoretical modelsemployed in all calculations and create open new interesting possibilities for the design in silico of novel andhighly efficient lanthanide-organic frameworks.