Three Coordination Polymers of Cu(II)/Mn(II) Based on 3-(2,5-Dicarboxylphenyl)picolinic Acid: Structure and Magnetism

Three coordination polymers [Cu(Hdppa)(H2O)](n) (1), {[Cu-2(dppa)(mu(2)-OH)(H2O)]center dot H2O}, (2) and {[Mn-3(dppa)(2) (H2O)(4)]center dot 2H(2)O}(n) (3) (H(3)dppa=3-(2,5-dicarboxylphenyl) picolinic acid) have been synthesized by hydrothermal method and characterized by elemental analysis, IR spectra, PXRD and TGA. The single-crystal X-ray diffraction analysis showed that compound 1 crystalized in monoclinic system, P2(1)/c space group, a=1.371(2) nm, b =0.805(11) nm, c=1.266(19) nm, beta=112.74(3)degrees, Z=4. Compound 2 crystalized in triclinic system, P (1) over bar space group, a=0:839(4) nm, b=1.039(5) nm, c=1.110 (5) nm, alpha=98.31 degrees, beta=110.63(3)degrees, gamma=111.90(3), Z=2. Compound 2 crystalized in triclinic system, P (1) over bar space group, a=0.881(6) nm, b=0.939(6) nm, c=1.038(7) nm, alpha=100.29 degrees, beta=97.99(10)degrees, gamma=111.13(7)degrees, Z=1. For 1, Cu(II) were bridged by Hdppa(2-) ligands to form a 1D chain structure. For 2 and 3, Cu(II) and Mn(II) were respectively linked by dppa(3-) ligands to form 2D layers and further extend to a 3D supramolecular structure through the hydrogen bonding interaction. Magentic susceptibility measurement indicated there were strong ferromagnetic interactions in 1 and 2, and their magnetic exchange constant was 4.44 and 8.94 cm(-1) respectively. There was antiferromagnetic interaction between the neighboring Mn(II) ions in 3. CCDC: 1442371, 1; 1442366, 2; 1442367, 3.