Heterometallic Sr-II-M-II (M = Co, Ni, Zn and Cu) Coordination Polymers: Synthesis, Temperature-Dependent Structural Transformation, and Luminescent and Magnetic Properties

摘要

The use of pyridine-2,4-dicarboxylic acid (H2pydc) in the construction of Sr-II and Sr-II-M-II (M = Co, Ni, Zn and Cu) coordination polymers is reported. Eight complexes, that is, [Sr(pydc)H2O](n) (1), [MSr(pydc)(2)(H2O)(2)](n) (M = Co (2), Ni (3), Zn (4)), [ZnSr(pydc)(2)(H2O)(7)](n)center dot 4nH(2)O (5), [SrCu(pydc)(2)](n) (6), [SrCu-(pydc) (2)(H2O)(3)](n)center dot 2nH(2)O (7), and [Cu3Sr2(pydc)(4)(Hpydc)(2)(H2O)(2)](n) (8), have been synthesized via dexterously choosing the appropriate strontium sources and transition metal salts, and rationally controlling the temperature of the reaction systems. Complexes 1, 2 (3, 4), 6, and 8 display four types of 3-D framework structures. Complexes 5 and 7 exhibit a 2-D network and a 1-D chain structure, respectively. The 2-D complex 7 can be reversibly transformed into 3-D compound 6 through temperature-induced solvent-mediated structural transformation. The luminescent property studies indicated that complex 1 shows a strong purple luminescent emission and 4 exhibits a strong violet luminescence emission. The magnetic properties of 2, 3, and 8 were also studied. Antiferromagnetic M-II center dot center dot center dot M-II interactions were determined for these complexes.