Humidity Sensitive Structural Dynamics and Solvatomagnetic Effects in a 3D Co(II)-Based Coordination Polymer

• Published in: Inorganic chemistry 2018-04, Vol.57 (7), p.4070-4076
• Main Authors: Wang, Long-Fei, Qiu, Jiang-Zhen, Wu, Si-Guo, Chen, Yan-Cong, Li, Cui-Jin, Li, Quan-Wen, Liu, Jun-Liang, Tong, Ming-Liang
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.8b00235

A chiral Co­(II)-based coordination polymer, [Co3(pimda)2(H2O)5] (1, H3pimda = 2-propyl-1H-imidazole-4,5-dicarboxylic acid) with 3D hyperkagomé topology is reported. Upon heating/cooling, the water molecules which are coordinated to a pair of crystallographically symmetric Co­(II) ions are removed/recovered discretely in two steps, giving [Co3(pimda)2(H2O)4] (2) and [Co3(pimda)2(H2O)3] (3), which is evidenced by the reversible single-crystal-to-single-crystal (SCSC) structural transformations. As the coordination geometry of the two Co­(II) ions changes from octahedron to trigonal bipyramid, obvious color change from pink for 1 to dark violet for 2 and 3 is observed. Further magnetic measurements demonstrate the presence of a solvatomagnetic effect from paramagnets for 1 and 2 to weak ferromagnet for 3. Moreover, as revealed by the variable-temperature crystallographic measurements, the first and second dehydration temperatures could be controlled from 298 K (25 °C) and 383 K (110 °C) sealed in a capillary (high humidity) to 255 K (−18 °C) and 307 K (34 °C) in dry N2 (low humidity), indicating the strong humidity sensitivity of the structural dynamics.