Solvents and auxiliary ligands co-regulate three antiferromagnetic Co(ii) MOFs based on a semi-rigid carboxylate ligand

Abstract

By reacting an asymmetry semi-rigid Y-shaped/L-shaped linker H₃cpta (H₃cpta = 3-(4′-carboxyphenoxy)phthalic acid) and Co(CH₃COO)₂·6H₂O under different N-donor ligands in different solvents, three new Co-based coordination polymers, [Co₃(cpta)₂(bpe)₃(H₂O)₄] (1) [Co(μ₂-H₂O)(μ₃-OH)(Hcpta)(bpe)(H₂O)·3(DMF)3(H₂O)] (2) and [Co₃(cpta)₂(bpa)₄] (3) have been obtained. They exhibit trinodal topological nets/layer, based on Co²⁺ ions and Y-shaped/L-shaped carboxylate linkers. 1 and 3 present 3D frameworks with the point symbol {4·10²}₂{10⁵·12}{4·8⁵}₂ for 1 and {4·8²}₂{8⁵·9}{4·6⁷·9²}₂ for 3. While, 2 exhibits a 2D layer with the point symbol {4·6·8}{4·6²·8³}{6²·8}. The magnetic studies indicate that all of the three complexes show antiferromagnetic exchanges transmitted through μ₃-carboxylate/μ₄-carboxylate bridges, μ₂-H₂O molecules and μ₃-OH ions between Co²⁺ ions, respectively. And the result of this research shows that the solvent and the secondary ligands could co-regulate coordination polymer with interesting properties, providing a constructive guidance when synthesizing versatile topologies with the same organic spacer but a different architecture.