title: A series of 3D metal organic frameworks based on [24-MC-6] metallacrown clusters: structure, magnetic and luminescence properties.
abstract: Four isostructural metal organic frameworks (MOFs), namely [Co6(HipO)6]·6H2O (1), [Mn6(HipO)6]·6H2O (2), [Cd6(HipO)6]·6H2O (3) and [Zn6(HipO)6]·7H2O (4) (H3ipO = 2-hydroxyisophthalic acid), were synthesized and structurally characterized. They have a 3D (4,6)-connected framework based on [24-MC-6] metallacrown clusters ([24-MC-6]-based MOFs). The arrangements of the 24-MC-6 metallacrown SBUs show a regular change indicated by the orientation of their symmetry axes, resulting in a special dense packing mode different from other [24-MC-6]-based MOFs. The analysis of SQUID measurements reveal that compound 1 displays the dominant antiferromagnetic exchanges in 300-10 K between the adjacent Co(II) ions and a ferromagnetic-like behavior at lower temperatures, whereas compound 2 shows an antiferromagnetic interaction between the adjacent Mn(II) ions. Compound 1 exhibits a magnetocaloric effect (MCE) with the resulting entropy change (-ΔS(m)) of 15.20 J kg(-1) K(-1) for ΔH = 50 kG at 6 K, which is the highest value among the cobalt-based MOFs with MCE reported so far. The luminescence properties of compounds 3 and 4 were studied, both of them exhibit photoluminescence in the solid state at room temperature which can be ascribed to intraligand π→π* transitions.
authors.affiliation: Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing, 210093, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.forename: Hua-Hong
authors.initials: HH
authors.lastname: Zou
authors.forename: Zi-Lu
authors.initials: ZL
authors.lastname: Chen
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Wei-Yin
authors.initials: WY
authors.lastname: Sun
authors.forename: Fu-Pei
authors.initials: FP
authors.lastname: Liang
mesh_terms: D018360:Crystallography, X-Ray; D049449:Luminescence; D060328:Magnetic Phenomena; D009942:Organometallic Compounds / Q000032:analysis / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds