Structural Diversity, Luminescence, and Magnetic Properties of Eight Co(II)/Zn(II) Coordination Polymers Constructed from Semirigid Ether-Linked Tetracarboxylates and Bend Dipyridyl-Triazole Ligands

Abstract

Eight coordination polymers based on H4L1/H4L2 (5,5′-(1,4/1,3-phenylenebis(methoxy))diisophthalic acid) and 3/4-abpt (4-amino-3,5-bis(3/4-pyridyl)-1,2,4-triazole) ligands were synthesized: [Co4(L1)2(4-abpt)(H2O)10.5]n (1), {[Zn2(L1)(4-abpt)(H2O)3]·5H2O}n (2), {[Co(H2L1)(3-abpt)(H2O)2]·0.5H4L1}n (3), {[Co2(L1)(4-abpt)2]·4H2O}n (4), {[Zn2(L2)(4-abpt)(H2O)]·2.5H2O}n (5), {[Zn2(L2)(4-abpt)(H2O)]·3H2O}n (6), {[Co1.5(HL2)(3-abpt)(H2O)]·H2O}n (7), and {[Zn1.5(HL2)(3-abpt)(H2O)]·H2O}n (8). Their structures were characterized by EA, IR, powder X-ray diffraction, thermogravimetric analysis (TGA), and single crystal X-ray diffraction. Complex 1 exhibits a three-dimensional (3D) metal–organic framework (MOF) composed of an interesting tetranuclear Co4(μ2-H2O)3(μ2-COO)4 cluster and 76-membered ring. Complex 2 shows a two-dimensional (2D) sheetlike network assembled by a one-dimensional (1D) [Zn2(L1)(H2O)3]n ribbon and 4-abpt linker. Complex 3 is a 1D nanotube coordination polymer constructed from parallel Co2(H2L1)2 rings pillared by two rows of 3-abpt spacers, which contains H4L1 guest molecule. Complex 4 displays a beautiful 3D porous MOF built by 2D sheetlike [Co2(L1)]n networks pillared by 4-abpt spacers. Complex 5 features a porous 3D MOF with regular nanosized rectangle tunnel. Complex 6 exhibits a 3D structure constructed from a double-layered [Zn2(L2)(H2O)]n network and 4-abpt linker. Complexes 7 and 8 are isostructural 3D polymers completed by 2D [Co1.5/Zn1.5(HL2)(H2O)]n networks pillared by 3-abpt spacers. H4L1 and H4L2 are fully or partly deprotonated in these complexes and exhibit six types of coordination modes. The 3/4-abpt ligands act as bidentate linkers. TGA shows that both tetracarboxylates ligands are thermally stable to 300 °C. Zn(II) complexes 2 and 8 are strong luminescent emitters. Variable-temperature magnetic studies indicate that complexes 1, 4, and 7 exhibit antiferromagnetic coupling between carboxyl-bridging CoII ions.