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

Hawes, Chris S.; Moubaraki, Boujemaa; Murray, Keith S.; Kruger, Paul E.; Turner, David R.; Batten, Stuart R.

Abstract

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′-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)]·1/2H2O 1 features the coligand (S,S)-1,4,5,8-naphthalenetetracarboxylic diimide-N,N′-bis(2-propionate) L2, and comprises chiral two-dimensional sheets, associating via substantial π–π 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 α-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 (−2JS1.S2) dimer model with J = −3.2 cm–1 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]·H2O 4 and poly-[Cu(HL4)2]·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.

Citation

Hawes, C. S., Moubaraki, B., Murray, K. S., Kruger, P. E., Turner, D. R., & Batten, S. R. (2014). Exploiting the Pyrazole-Carboxylate Mixed Ligand System in the Crystal Engineering of Coordination Polymers. Crystal Growth and Design, 14(11), 5749-5760. https://doi.org/10.1021/cg501004u

• Journal Article Type: Article
• Online Publication Date: Oct 9, 2014
• Publication Date: Nov 5, 2014
• Deposit Date: Jun 15, 2023
• Journal: Crystal Growth & Design
• Print ISSN: 1528-7483
• Electronic ISSN: 1528-7505
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 14
• Issue: 11
• Pages: 5749-5760
• DOI: https://doi.org/10.1021/cg501004u
• Keywords: Condensed Matter Physics; General Materials Science; General Chemistry