Syntheses, Structural Evolutions, and Properties of Cd(II) Coordination Polymers Induced by Bis(pyridyl) Ligand with Chelated or Protonated Spacer and Diverse Counteranions
2017-04-13T00:00:00Z (GMT) by
Hydrothermal reaction of Cd(II) metal salts, diverse organic acids, as well as flexible bis(pyridyl) ligand leads to the formation of 10 complexes, namely, [Cd2LCl4]n (1), [Cd(H2L)(SO4)2(H2O)2]n·6nH2O (2), [CdL(malonate)]n·5nH2O (3), [Cd2L(malonate)Cl2(H2O)]n·nH2O (4), [Cd2(H2L)(succinate)3]n·4nH2O (5), [Cd2L(fumarate)2(H2O)2]n·2nH2O (6), [Cd2L(m-BDC2–)2]n·2nH2O (7), [Cd2(L)(p-BDC2–)2(H2O)3]n·3nH2O (8), [Cd3(L)2(p-BDC2–)3(H2O)4]n·nH2O (9), and [Cd3(H2L)(p-BDC2–)2(SO4)2(H2O)3]n·2nH2O (10) (L = N,N′-bis(pyridin-3-ylmethyl)ethane-1,2-diamine, m-BDC2– = m-benzene dicarboxylate dianion, p-BDC2– = p-benzene dicarboxylate dianion), which have been characterized by elemental analysis, infrared, thermogravimetric analysis, PL, powder and single-crystal X-ray diffraction. Structural analyses indicate that the diverse coordination modes of the bis(pyridyl) ligand with a chelated or protonated spacer, the feature of different inorganic and organic anions, can effectively influence the topological structures of these complexes. Complex 1 presents a three-dimensional (3D) hybrid network which is accomplished by the interconnection of adjacent Cd(II) cations through L molecules and μ2-Cl– anions. Complex 2 exhibits an interesting pseudo 2-fold interpenetrated network formed by the interconnection of a [Cd-H2L2+]n pcu net and [SO42+-H2O]n pcu net. In complexes 3 and 4, adjacent Cd(II) cations are all bridged by dicarboxylate and L to generate a sql layer. In contrast, complex 5 presents 3-fold parallel interpenetrated sql layer owing to the protonated spacer of H2L2+ cation which extends the size of the quadrate window. The organic dicarboxylates in complexes 6 and 7 present more abundant coordination modes which join adjacent Cd(II) cations together with L molecules, thus giving rise to a different 3D framework with sra and snk topology. The p-BDC2– dianions in complexes 8, 9, and 10 present different coordination modes and join adjacent Cd(II) cations together with L molecules and H2L2+ cations to form a diverse ladder chain, tfc and new (44.611)(66) topology. Luminescent investigation reveals that the emission maximum of these 10 complexes varies from 376 to 450 nm.
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