A Porous Coordination Polymer Assembled from 8-Connected {CoII 3(OH)} Clusters and Isonicotinate: Multiple Active Metal Sites, Apical Ligand Substitution, H2 Adsorption, and Magnetism

• Published in: Inorganic chemistry 2011-03, Vol.50 (6), p.2321-2328
• Main Authors: Chen, Qing, Lin, Jian-Bin, Xue, Wei, Zeng, Ming-Hua, Chen, Xiao-Ming
• Format: Article
• Language: English
• Subjects: Adsorption; Catalytic Domain; Cobalt - chemistry; Crystallography, X-Ray; Hydrogen - chemistry; Ligands; Magnetics; Models, Molecular; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; Polymers - chemical synthesis; Polymers - chemistry; Porosity
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic102015g

A microporous coordination polymer, namely, [Co3(ina)4(OH)(C2H5OH)3](NO3)·C2H5OH·(H2O)3 (1, or MCF-38, ina = isonicotinate), with 8-connected {Co3(OH)} clusters as the structural secondary building units, has been solvothermally synthesized. The hydroxo-centered Co(II) cluster involves multiple active metal sites. The interesting apical ligand substitutions have been directly observed, and the corresponding products of [Co3(ina)4(OH)(G) x (H2O) n ](NO3)·G·(H2O) m (1 ⊃ PrOH, G = PrOH, x = 2, n = 1, m = 3; 1 ⊃ BuOH, G = BuOH, x = 2, n = 1, m = 1, and 1 ⊃ MeOH, G = MeOH, x = 3, n = 0, m = 7) have also been obtained by solvothermal syntheses or crystal-to-crystal transformations. High-pressure H2 adsorption measurement at 77 K reveals that activated 1 can absorb 2.2 wt % H2 at 5 bar. The relative H2 absorption at low pressure (86% of the storage capacity at 1 bar) is higher than the corresponding values reported for some typical porous coordination polymers. The magnetic studies of 1 show a dominant antiferromagnetic coupling between Co(II) ions of intra- and inter-cluster.