A new Pb II (ethylenediaminetetraacetate) coordination polymer with a two-dimensional layer structure
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TRUCTURE OF ORGANIC COMPOUNDS
A New PbII(Ethylenediaminetetraacetate) Coordination Polymer with a Two-Dimensional Layer Structure1 D. Zhao*, R. H. Zhang, and F. F. Li Department of Physics and Chemistry, Henan Polytechnic University, Jiaozuo, 454000, China *e-mail: [email protected] Received June 14, 2015
Abstract—A new PbII−edta4– coordination polymer, Pb2(edta)(H2O)0.76 (edta4– = ethylenediaminetetraacetate) was synthesized under hydrothermal condition. Single crystal X-ray analysis reveals that it represents a novel two-dimensional (2D) Pb2+–edta4– layer structure with a (4,82)-topology. Each edta4– ligand employs its four carboxylate O and two N atoms to chelate one PbII atom (hexa-coordinated) and connects five PbII atoms (ennea-coordinated) via its four carboxylate groups to form 2D layer framework. Adjacent layers are packed into the overall structure through vander Waals interactions. DOI: 10.1134/S1063774516070142
INTRODUCTION Over the course of past twenty years, the interest in crystal engineering of metal–organic frameworks is rapidly increasing for their intrinsic architectural beauty and aesthetically pleasing structures, as well as their potential applications (catalysis, magnetism, electric conductivity and nonlinear optics) as functional materials. A variety of frameworks with novel topologies can be constructed by one or more organic ligands interlocked by metal ions [1–6]. To our knowledge, the selection of suitable organic ligands is crucial for constructing extended coordination frameworks. Among them, flexible ligands can bend or rotate to adopt the appropriate conformation and hold the energetic minimum when coordinating to the metal centers, which often cause structural diversities. As one of the most fascinating ligands, ethylenediaminetetraacetic acid (H4edta) is selected as a cluster ligand for several reasons. On one hand, edta ligandcan act as a tetradentate, pentadentate or hexadentate ligand to form a six-coordinate octahedron, seven-coordinate distorted monocapped trigonal prism or pentagonal bipyramid [7, 8]. On the other hand, the carboxylate groups may be completely or partially deprotonated, and can act as hydrogen bond acceptors as well as hydrogen bond donors to assemble supramolecular structures [9]. Thus, we speculate that interesting structures can be obtained based on the edta4– ligand and PbII centralion under hydrothermal conditions. In this paper, we designed a new compound, [Pb2(edta)(H2O)0.76]n, and determined its structure by singe-crystal X-ray diffraction analysis. 1 The article is published in the original.
EXPERIMENTAL Synthesis. All chemicals purchased from Sinopharm Chemical Reagent Co. Ltd. of analytical grade were obtained from commercial sources and used without further purification. A mixture of H4edta (0.05 g), Pb(NO3)2 (0.2 g), KOH (0.10 g), and H2O (10 mL) was stirred at room temperature. The mixture was then heated in a 20 mL Teflon-lined reaction vessel at 433 K for 3 days. After the mixture had been cooled to room temperature, a few colorless sheet-sh
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