Synthesis, crystal structures, and luminescent properties of Pb(II) and Sr(II) coordination polymers constructed by 5-methyl-1H-pyrazole-3-carboxylic acid

Abstract

Two new coordination polymers, {[Pb(HMPCA)₂]}_n (1) and {[Sr(HMPCA)₂(H₂O)₂]·H₂O}_n (2) (H₂MPCA = 5-methyl-1H-pyrazole-3-carboxylic acid), have been synthesized and characterized by elemental analysis, IR spectroscopy, X-ray diffraction, and thermogravimetric analysis. Compound 1 forms a one-dimensional (1-D) chain, and a two-dimensional (2-D) supramolecular framework is constructed by hydrogen bonding. The HMPCA^– in 1 adopts two coordination modes, a N,O-chelate and a μ₃-κN, O: κO, O′: κO′ mode. The structure of 2 is a 1-D Sr–O–Sr chain built up by two waters bridging a pair of distrontium [Sr(H₂O)(HMPCA)(μ₂-HMPCA)]₂ units, and the chains are further extended into a 2-D supramolecular layer via hydrogen bonds. In addition to a N,O-chelate, the HMPCA^– in 2 exhibit a third coordination mode, μ₂-κN, O: κO. The thermal decomposition and luminescent properties of 1 and 2 in the solid state have also been investigated.

Two new 1D coordination polymers, {[Pb(HMPCA)₂]}_n (1), bridged by HMPCA⁻, and {[Sr(HMPCA)₂(H₂O)₂]·H₂O}_n (2), connected by the HMPCA⁻ and bridging waters, have been obtained via the reactions of H₂MPCA with metal salts.

Keywords:

• Lead(II)
• Strontium(II)
• 5-Methyl-1H-pyrazole-3-carboxylic acid
• Crystal structure
• Luminescent property

Acknowledgements

The authors thank the Natural Science Foundation of China (No. 20971060, 21101018) and the International Science and Technology Cooperation Project of Changzhou city (CZ20110023), the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Science Foundation from Key Laboratory of Fine Petro-chemical Technology of Jiangsu for financial support.