title: Heterometallic Sr(II) -M(II) (M=Co, Ni, Zn and Cu) coordination polymers: synthesis, temperature-dependent structural transformation, and luminescent and magnetic properties.
abstract: The use of pyridine-2,4-dicarboxylic acid (H2 pydc) 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)H2 O]n (1), [MSr(pydc)2 (H2 O)2 ]n (M=Co (2), Ni (3), Zn (4)), [ZnSr(pydc)2 (H2 O)7 ]n ⋅4 nH2 O (5), [SrCu(pydc)2 ]n (6), [SrCu(pydc)2 (H2 O)3 ]n ⋅2 nH2 O (7), and [Cu3 Sr2 (pydc)4 (Hpydc)2 (H2 O)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) ⋅⋅⋅M(II) interactions were determined for these complexes.
authors.affiliation: Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Key Laboratory of Salt Lake Resources and Chemistry, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 (China).
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Chen
authors.forename: Qian
authors.initials: Q
authors.lastname: Gao
authors.forename: Wenqian
authors.initials: W
authors.lastname: Chen
authors.forename: Dandan
authors.initials: D
authors.lastname: Gao
authors.forename: Yahong
authors.initials: Y
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Wu
authors.initials: W
authors.lastname: Li
keywords: alkaline earth metals; heterometallic complexes; luminescence; magnetic properties; structural transformation