Syntheses, structures, and magnetic properties of six coordination polymers based on 4,5-di(4′-carboxylphenyl)phthalic acid and different bis(imidazole) bridging linkers

Abstract

Six 4,5-di(4′-carboxylphenyl)phthalic acid (H₄DCP) based coordination polymers (CPs), namely {[Ni(1,4-bib)(HDCP)₂(H₂O)₂]_0.5[Ni(1,4-bib)(H₂O)₄]·2H₂O}_n (1), [Ni(H₂DCP)(1,4-bidb)₂(H₂O)]_n (2), [Co₂(DCP)(1,3-bib)]_n (3), {[Co₂(DCP)(1,4-bidb)₂]·2H₂O}_n (4), [Co(H₂DCP)(4,4′-bibp)]_n (5), and [Co₂(DCP)(4,4′-bibp)₂]_n (6), were synthesized under hydrothermal conditions in the presence of bis(imidazole) bridging linkers (1,3-bib = 1,3-bis(imidazol-1-yl)benzene, 1,4-bib = 1,4-bis(imidazol-1-yl)benzene, 1,4-bidb = 1,4-bis(imidazol-1-yl)-2,5-dimethyl benzene, 4,4′-bibp = 4,4′-bis(imidazol-1-yl)biphenyl). Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analysis. Single crystal X-ray diffraction analysis reveals that complex 1 is a cocrystal consisting of two independent chains. Complex 2 exhibits a traditional 2-fold 6⁶-dia parallel entangled network. Complex 3 displays a novel 3D binodal (5,7)-connected net based on binuclear {Co₂} units with the Schläfli symbol (3·4⁴·5⁴·6)(3²·4⁸·5⁸·6³). Complex 4 shows a 2-fold binodal (4,4)-connected bbf net with the point symbol (6⁴·8⁶)(6⁶)₂. Complex 5 affords a 2D (4⁴·6²)-sql net constructed from {Co₂} dinuclear units. Complex 6 displays a novel (3,8)-connected architecture with the Schläfli point symbol (4²·5)₂(4⁴·5¹⁰·6⁸·7⁴·8²) based on {Co₄(COO)₆} SBUs. Magnetic studies indicate complexes 3 and 6 exhibit weak ferromagnetic and antiferromagnetic properties, respectively.