title: Different magnetic responses observed in Co, Co and Co-based MOFs.
abstract: Four magnetic MOFs with anisotropic Co(II) ions, {[Co5(H2O)2(μ3-OH)2(atz)2(stp)2]·1.5H2O}n (1), {[Co5(H2O)2(μ3-OH)2(trz)2(stp)2]·1.3H2O}n (2), {[Co5(H2O)6(μ3-OH)2(trz)2(stp)2]·2.5CH3OH}n (3) and {[Co3(H2O)4(Hdatrz)2(stp)2]·3H2O}n (4) (stp(3-) = 2-sulfoterephthalate, trz(-) = 1,2,4-triazolate, atz(-) = 3-amino-1,2,4-triazolate and Hdatrz = 3,5-diamino-1,2,4-triazole) were solvothermally isolated by varying the substituent groups appended on the N-heterocyclic triazole and structurally and magnetically characterized. Structural analyses indicate that the former two complexes are crystallographically isostructural, exhibiting pillared-layer frameworks with mixed triazolyl and carboxylate extended Co + Co layers supported by rigid stp(3-) connectors. Complex 3 is built from butterfly-shaped Co cluster-based layers, which are interconnected with single cobalt(ii) octahedra by ditopic stp(3-) bridges. By contrast, complex 4 consists of linear {Co3(μ-N1,N4-Hdatrz)2} subunits, which are extended by 3-connected stp(3-) linkers into a stable 3D framework. Magnetically, 1 exhibits ferromagnetic ordering below 2.7 K due to the well-organized alignment of the non-compensated resultant moment from octahedra and tetrahedral cobalt(ii) carriers, while 3 is in a non-zero paramagnetic state above 2.0 K resulting from the coexistence of intermetallic ferromagnetic and antiferromagnetic interactions. The magnetic competition between weak inter-subunit antiferromagnetic interactions and the external magnetic field makes 4 behave as a field-induced metamagnet with a critical field of 27.5 kOe. These interesting magnetostructural results suggest that the anisotropy of the moment carrier and the interlayer/intersubunit separations significantly dominate the magnetic responses in extended MOFs, providing an informative platform for the further development of interesting magnetic materials, both of academic and industrial interest.
authors.affiliation: College of Chemistry, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Tianjin Normal University, Tianjin 300387, P. R. China. encui_yang@163.com xiaojun_zhao15@163.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: College of Chemistry, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Tianjin Normal University, Tianjin 300387, P. R. China. encui_yang@163.com xiaojun_zhao15@163.com.
authors.forename: Zhong-Yi
authors.initials: ZY
authors.lastname: Liu
authors.affiliation: College of Chemistry, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Tianjin Normal University, Tianjin 300387, P. R. China. encui_yang@163.com xiaojun_zhao15@163.com.
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.affiliation: College of Chemistry, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Tianjin Normal University, Tianjin 300387, P. R. China. encui_yang@163.com xiaojun_zhao15@163.com.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.affiliation: College of Chemistry, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Tianjin Normal University, Tianjin 300387, P. R. China. encui_yang@163.com xiaojun_zhao15@163.com.
authors.forename: En-Cui
authors.initials: EC
authors.lastname: Yang
authors.affiliation: College of Chemistry, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Tianjin Normal University, Tianjin 300387, P. R. China. encui_yang@163.com xiaojun_zhao15@163.com and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300071, P. R. China.
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Zhao