Exploiting the Pyrazole-Carboxylate Mixed Ligand System in the Crystal Engineering of Coordination Polymers

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• 作者：Chris S. Hawes ; Boujemaa Moubaraki ; Keith S. Murray ; Paul E. Kruger ; David R. Turner ; Stuart R. Batten
• 刊名：Crystal Growth & Design
• 出版年：2014
• 出版时间：November 5, 2014
• 年：2014
• 卷：14
• 期：11
• 页码：5749-5760
• 全文大小：667K
• ISSN：1528-7505

文摘

The utility of the pyrazole-carboxylate mixed ligand system has been probed with the synthesis of five new coordination polymers, derived from bis-pyrazole ligand 4,4鈥?methylenebis(3,5-dimethyl-1H-pyrazole) H₂L1, large semirigid dicarboxylate coligands, and the deliberately designed and synthesized ligand para-((3,5-dimethyl-1H-pyrazol-4-yl)methylene)benzoic acid H₂L4. Complex poly-[Co(H₂L1)(L2)(OH₂)]路1/2H₂O 1 features the coligand (S,S)-1,4,5,8-naphthalenetetracarboxylic diimide-N,N鈥?bis(2-propionate) L2, and comprises chiral two-dimensional sheets, associating via substantial 蟺鈥撓€ stacking interactions. Complexes 2 and 3 contain the coligand 1,4-bis((3-carboxyphenyl)methyl)piperazine L3. Complex poly-[Co(H₂L1)₂(L3)] 2 is a two-dimensional polymer containing octahedral Co(II) ions, whereas modifying the synthesis conditions gave complex poly-[Co₂(HL1)₂(L3)] 3, a three-dimensional 伪-Po structure containing pyrazolate-bridged dimers of tetrahedral Co(II) ions, displaying weak antiferromagnetic coupling. Magnetic data for complex 3 fitted well to a S = 3/2 Heisenberg (鈭?JS₁.S₂) dimer model with J = 鈭?.2 cm^鈥? and g = 2.25. We then prepared the new heteroditopic ligand para-((3,5-dimethyl-1H-pyrazol-4-yl)methylene)-benzoic acid H₂L4, and the complexes poly-[Co(HL4)₂]路H₂O 4 and poly-[Cu(HL4)₂]路2MeOH 5, which demonstrate for the first time the tendency of flexible pyrazole-carboxylate coordination polymers with perfectly commensurate linker dimensions to lead to low-dimensional assemblies. These results give fresh insight into the structural properties of flexible bispyrazole-carboxylic acid systems as a function of coligand dimensions, and provide new directions for designed polymeric cluster compounds.