Four pH-Dependent 1D Co-II/Ni-II Coordination Polymers Based on a Terphenyl-2,2 ',4,4 '-Tetracarboxylic Acid: Syntheses, Structures, and Magnetic Properties

摘要

Four Co-II/Ni-II coordination polymers, namely, [M(H3L)(2)(H2O)(2)](n) (1, 2) and [M(H2L)(H2O)(3)](n) (3, 4), (M = Co for 1 and 3, M = Ni for 2 and 4, H4L = terphenyl-2,2,4,4-tetracarboxylic acid) were synthesized through hydrothermal reactions at different pH values and structurally characterized. Single crystal X-ray crystallographic analysis reveals that compounds 1 and 2 are isostructural and exhibit a 1D [M-2(H3L)(2)](n) loop-like infinite chain, whereas compounds 3 and 4 are also isostructural and show a 1D pendant H2L attached [M(H2O)](n) chain motif. Additionally, variable-temperature magnetic susceptibility measurement shows weak antiferromagnetic coupling among the adjacent central Co-II atoms in 1 and 3.