Self-assembly of Mn(II), Co(II) and Cu(II)-base coordination polymers from 5,5'-bipyrimidine ligands : structures and magnetism.
| Autor: | CHENG, HAN-TING, 鄭漢亭 |
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| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 This essay mainly discusses about the four self-assembly of Mn(II), Co(II) and Cu(II) coordination polymers using a multi-dentate N-donor ligand, 5,5'-bipyrimidine (bpm), with vanadate, sulfate and acetate anions. In the first part, two coordination polymers, {[Mn2(bpm)(VO3)4(H2O)4]•2H2O}n (1), and {[Co2(bpm)(VO3)4(H2O)4]•H2O}n (2), are synthesized through self-assembly of bpm with ammonium vanadate and manganese(II) and cobalt(II) ions, respectively. Compounds 1 and 2 are isostructures, in which [VO5]n metallic chain formed by the edge-shared vanadate anions, and the planar μ4-bpm ligands connect the metal ions to a three-dimensional structure. In the second part, two Cu(II) coordination polymers, {[Cu4(OAc)6(OMe)2(bpm)]•H2O•2MeOH}n (3), and [Cu(SO4)(bpm)]n (4), are synthesized by self-assembly of 5,5'-bpm and Cu(II) ions with acetate and sulfate anions, respectively. The structure of compound 3 contains a Cu4 and a Cu2 subunits, which are crosslinked by twisted μ4-5,5'-bpm to form a three-dimensional structure. The structure of compound 4 is a three-dimensional network, which is constructed by the layers made from corner-shared Cu(II) and SO42- ions and the twist-μ2-bpm pillars. The magnetic measurements indicate that the antiferromagnetic coupling was dominated between Mn(II) ions through vanadate bridges in compound 1, while compound 2 shows the antiferromagnetic coupling and strong spin orbital coupling. For compound 3, the strong antiferromagnetic coupling was dominated from Cu2 and Cu4 subunits. In compound 4, both ferromagnetic and antiferromagnetic interactions were presented giving non-canceled magnetic moment at low-temperature. Furthermore, compound 4 exbits spin-canting below 3 K. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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