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Royal Society of Chemistry, CrystEngComm, 6(13), p. 2096

DOI: 10.1039/c0ce00393j

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Syntheses, structural aspects, luminescence and magnetism of four coordination polymers based on a new flexible polycarboxylate

Journal article published in 2011 by Qilong Zhu ORCID, Tianlu Sheng, Ruibiao Fu, Shengmin Hu, Chaojun Shen, Xiao Ma, Xiao, Xintao Wu
This paper is available in a repository.
This paper is available in a repository.

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Abstract

Four novel coordination polymers, {Na2[Co3(H2TTHA)2(H2O)12](H2O)2}[middle dot]4(H2O) (1), {Na[Cu4(H2TTHA)(HTTHA)(H2O)8](H2O)3}[middle dot]5(H2O) (2), [Cd3(TTHA)(H2O)4] (3) and [Ca5(HTTHA)2(H2O)8] (4), (H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid) have been synthesized by self-assembly of the flexible hexapodal acid H6TTHA and corresponding metal salts. The four complexes exhibit novel frameworks with different topologies due to diverse coordination modes and different conformations of the flexible H6TTHA. Complex 1 shows a 3D network with (4,4,6)-connected topology constructed from parallel one-dimensional hybrid ribbons with nearly planar 24-membered rings, in which all Co(ii) atoms are located in one plane. Complex 2 features a 3D (3,4,4,4,7)-connected network bridged by sodium ions from 2D layer structures which are formed through the interconnection of the tetranucleate units and the flexible ligands. Complex 3 possesses hybrid layers constructed from zigzag Cd-O chains. These layers are further linked by the TTHA6- ligands with two configurations, leading to another 3D (3,3,8)-connected framework. The metal ions in complex 4 are connected into wall-like infinite metal chains which are bridged by the carboxylate groups of ligands into a 3D (3,3)-connected hybrid framework. The framework is further furnished with the ligands forming hydrophobic channels with approximate sizes 3.5 A [times] 9 A based on the distances of the opposite atoms. The enantiometric pairs of ligands are formed in spite of no asymmetric carbon atom in complexes 1-3. Variable temperature magnetic studies down to 2 K reveal antiferromagnetic interactions in complexes 1 and 2. Complexes 3 and 4 are both highly emissive at room temperature. And the luminescent intensities are largely enhanced once they are frozen to 10 K.