title: Spin frustration in a family of pillared kagomé layers of high-spin cobalt(II) ions.
abstract: Based on the analogous kagomé [Co3 (imda)2 ] layers (imda=imidazole-4,5-dicarboxylate), a family of pillar-layered frameworks with the formula of [Co3 (imda)2 (L)3 ]⋅(L)n ⋅xH2 O (1: L=pyrazine, n=0, x=8; 2: L=4,4'-bipyridine, n=1, x=8; 3: L=1,4-di(pyridin-4-yl)benzene, n=1, x=13; 4: L=4,4'-di(pyridin-4-yl)-1,1'-biphenyl, n=1, x=14) have been successfully synthesized by a hydrothermal/solvothermal method. Single-crystal structural analysis shows a significant increase in the interlayer distances synchronized with the extension of the pillar ligands, namely, 7.092(3) (1), 10.921(6) (2), 14.780(5) (3), and 19.165(4) Å (4). Despite the wrinkled kagomé layers in complexes 2-4, comprehensive magnetic characterizations revealed weakening of interlayer magnetic interactions and an increase in the degree of frustration as the pillar ligand becomes longer from 1 to 4; this leads to characteristic magnetic ground states. For compound 4, which has the longest interlayer distance, the interlayer interaction is so weak that the magnetic properties observed within the range of temperature measured would correspond to the frustrated layer.
authors.affiliation: Key Laboratory of Bioinorganic and Synthetic, Chemistry of Ministry of Education, School of Chemistry & Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275 (P.R. China) http://ce.sysu.edu.cn/tml/
authors.forename: Long-Fei
authors.initials: LF
authors.lastname: Wang
authors.forename: Cui-Jin
authors.initials: CJ
authors.lastname: Li
authors.forename: Yan-Cong
authors.initials: YC
authors.lastname: Chen
authors.forename: Ze-Min
authors.initials: ZM
authors.lastname: Zhang
authors.forename: Jiang
authors.initials: J
authors.lastname: Liu
authors.forename: Wei-Quan
authors.initials: WQ
authors.lastname: Lin
authors.forename: Yan
authors.initials: Y
authors.lastname: Meng
authors.forename: Quan-Wen
authors.initials: QW
authors.lastname: Li
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: Tong
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007477:Ions / Q000737:chemistry; D008280:Magnetics; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D007477:Ions; D009942:Organometallic Compounds; D011725:Pyridines; D003035:Cobalt; C034306:4,4'-bipyridyl
keywords: cobalt; layered compounds; magnetic properties; metal-organic frameworks; spin frustration