Solvothermal synthesis, structure and magnetism of two novel 3D metal-organic frameworks based on infinite helical Mn-O-C rod-shaped building units

Two novel coordination polymers Mn-3(BTC)(2)(DMF)(4) 1 and Mn-3(BTC)(2)(DMF)(3)(Pyd) 2 have been synthesized under solvothermal conditions and structurally characterized. Crystal data for 1: monoclinic P2(1)/c, a = 17.876(4) angstrom, b = 11.797(2) angstrom, c = 18.848(4) angstrom, beta = 116.35(3)degrees, Z = 4. Crystal data for 2: monoclinic P2(1)/c, a = 17.711(4) angstrom, b = 11.849(2) angstrom, c = 18.903(4) angstrom, 114.86(3)degrees, Z = 4. In the structures, the carboxyl groups of BTC ligands bridge the metal centers to form infinite helical Mn-O-C rod-shaped building units running along the 2(1) screw axes. Meanwhile the adjacent helical rods twist each other via benzene rings of BTC ligands to lead to a three-dimensional network with one-dimensional about 6 x 8 angstrom(2) quadrangular channels along the [100] direction. TGA, IR and magnetic properties have been investigated. (c) 2006 Elsevier B.V. All rights reserved.