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Issue 13, 2018
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Binuclear Mn2+ complexes of a biphenyltetracarboxylic acid with variable N-donor ligands: syntheses, structures, and magnetic properties

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Abstract

Four new manganese(II) metal–organic frameworks based on H4bpta (H4bpta = 3,3′,5,5′-biphenyltetracarboxylic acid) and N-donor ligands, namely [Mn2(4,4′-bipy)(bpta)]n (1), [Mn2(1,4-bib)2(bpta)]n·2n(H2O·DMF) (2), [Mn2(1,3-bimb)2(bpta)]n·2nH2O (3), and [Mn2(1,4-bimb)2(bpta)]n·2nH2O (4) (4,4′-bipy = 4,4′-bipyridine, 1,4-bib = 1,4-bis(imidazol-1-yl)benzene, 1,3-bimb = 1,3-bis((1H-imidazol-1-yl)methyl)benzene, and 1,4-bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene), have been obtained under solvothermal conditions. In these complexes, the fully deprotonated bpta4− ligands link binuclear SBUs to construct 2D layers with (4,4)-connected topologies. Complex 1 is a 3D network with 1D zigzag chains built up from 4-connected bpta4− ligands that contain carboxylate groups bridging Mn2+ ions in a rather rare synsyn geometry. Complex 2 exhibits a 3D porous network with synanti bridging dimeric subunits. Complex 3 is a (3,4)-connected 2D novel network with double helix chains formed by cis-1,3-bimb linkers. The structure of complex 4 is similar to that of 2, but it consists of tiny pores due to trans-1,4-bimb linkers. Magnetic studies reveal that 1 is perfectly fitted by the modified Fisher model to yield an effective intrachain antiferromagnetic coupling (J = −2.21(1) cm−1). Complexes 2–4 show antiferromagnetic interactions (J = −1.57(2) cm−1 for 2, and J = −0.68(2) cm−1 for 3) in dimeric units of Mn2(μ-COO)22+ related to double synanti and synsyn carboxylate bridges. An important repetitive feature of all these complexes with synanti or synsyn carboxylate bridges is that the antiferromagnetic coupling is very small. In addition, the gas sorption exploration of 2 exhibits relatively high sorption of CO2 but very low sorption of N2, making it a promising material for CO2/N2 separation.

Graphical abstract: Binuclear Mn2+ complexes of a biphenyltetracarboxylic acid with variable N-donor ligands: syntheses, structures, and magnetic properties

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Publication details

The article was received on 14 Jan 2018, accepted on 10 Feb 2018 and first published on 12 Feb 2018


Article type: Paper
DOI: 10.1039/C8CE00058A
Citation: CrystEngComm, 2018,20, 1818-1831
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    Binuclear Mn2+ complexes of a biphenyltetracarboxylic acid with variable N-donor ligands: syntheses, structures, and magnetic properties

    F. Su, C. Zhou, C. Han, L. Wu, X. Wu, L. Sun, J. Su, S. Feng, L. Lu and M. Zhu, CrystEngComm, 2018, 20, 1818
    DOI: 10.1039/C8CE00058A

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