Pseudo-isomeric zinc/copper coordination polymers based on 3-(2-pyridyl)pyrazole-5-carboxylic acid

• 3-(2-Pyridyl)pyrazole-5-carboxylate and Zn or Cu ions form 2D MOFs.
• The two MOFs have pseudo-isomeric crystal structures.
• The Zn MOF shows increased fluorescence compared to free ligand.
• Cu MOF has antiferromagnetic intra-dimer and ferromagnetic inter-dimer exchanges.

Reaction of 3-(2-pyridyl)pyrazole-5-carboxylic acid (H2L) with Zn(II) or Cu(II) perchlorate yielded [ZnL]n (1) and [CuL]n (2) with similar composition. The ligand L2 − adopts the same μ3κ5 coordination mode. The Zn(II) and Cu(II) atom takes square pyramid coordination polyhedron with some discrepancy. Bigger difference in the dimeric secondary building blocks leads to distinct two-dimensional metal–organic frameworks. The Zn(II) complex fluoresces stronger than the free ligand. The Cu(II) polymer displays strong antiferromagnetic intra-dimer exchange and ferromagnetic inter-dimer exchange.

2D MOFs formed by 3-(2-pyridyl)pyrazole-5-carboxylate and Zn(II) or Cu(II) have similar compositions and coordination modes, but significant discrepancy in the dimeric secondary building blocks causes different coordination networks.Figure optionsDownload as PowerPoint slide