title: Windmill Co4 {Co4 (μ4 -O)} with 16 Divergent Branches Forming a Family of Metal-Organic Frameworks: Organic Metrics Control Topology, Gas Sorption, and Magnetism.
abstract: A series of highly connected metal-organic frameworks (MOFs), [Co8 (O)(OH)4 (H2 O)4 (ina)8 ](NO3 )2 ⋅2 C2 H5 OH⋅4 H2 O (1), [Co8 (O)(OH)4 (H2 O)4 (pba)8 ](NO3 )2 ⋅8 C2 H5 OH⋅28 H2 O (2), and [Co8 (O)(OH)4 (H2 O)4 (pbba)8 ](NO3 )2 ⋅guest (3), in which ina=isonicotinate, pba=4-pyridylbenzoate, and pbba=4-(pyridine-4-yl)phenylbenzoate, is reported. These MOFs contain a new secondary building unit (SBU), with a square Co4 (μ4 -O) central unit having the rare μ4 -O(2-) motif, which is decorated by the other four peripheral cobalt atoms through μ3 -OH in a windmill-like shape. This SBU holds 16 divergent connecting organic ligands, pyridyl-carboxylates, to form three different frameworks. The high porosity of desolvated 2 is shown by the efficient gas absorption of N2 , CO2 , CH4 , and H2 . In addition, 1 and 2 exhibit unusual canted antiferromagnetic behavior with spin-glass-like relaxation, with blocking temperatures that are fairly high, 20 K (1) and 10 K (2), for cobalt materials. The relationship between the metal clusters and linkers has been studied, in which the size and rotational degrees of freedom of the ligands are found to control the topology, gas sorption, and magnetic properties.
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Xue
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
authors.forename: Jian-Bin
authors.initials: JB
authors.lastname: Lin
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
authors.forename: Yong-Sheng
authors.initials: YS
authors.lastname: Wei
authors.affiliation: Department Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin, 541004, P. R. China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yin
authors.affiliation: Department Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin, 541004, P. R. China. zmh@mailbox.gxnu.edu.cn.
authors.forename: Ming-Hua
authors.initials: MH
authors.lastname: Zeng
authors.affiliation: Institut de Chimie de Strasbourg, CNRS-UMR7177, Université de Strasbourg, 4 rue Blaise Pascal, 67070, Strasbourg, France.
authors.forename: Mohamedally
authors.initials: M
authors.lastname: Kurmoo
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China. cxm@mail.sysu.edu.cn.|Department of Chemistry, Shantou University, Guangdong, 515063, P. R. China. cxm@mail.sysu.edu.cn.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Chen
keywords: cobalt clusters; gas sorption; magnetic properties; metal-organic frameworks; pyridine-carboxylate ligands