A Novel Helical Double-Layered Cobalt(II)−Organic Framework with Tetranuclear [Co₄(μ₃-OH)₂] Clusters Linked by an Unsymmetrical Pyridylbenzoate Ligand

Abstract

A novel cobalt(II)−organic framework, [Co 2 (OH)(3,4-PBC) 3 ] n (I), has been acquired by the reaction of CoO with an unsymmetrical pyridylbenzoate ligand, 3-pyrid-4-ylbenzoic acid (3,4-PBC). Singlecrystal X-ray diffraction studies reveal that it is comprised of [Co II 4 (µ 3 -OH) 2 ] clusters linked by the unsymmetrical ligand 3,4-PBC, forming a novel helical double-layered metal−organic architecture. A significant overall antiferromagnetic behavior has been observed for this compound.The construction of novel metal coordination polymers, based on the interactions between metal ions and organic ligands, has attracted widespread interests because of their potential applications and intriguing variety of architectures and topologies. 1-6 In particular, the helical coordination polymers are of particular interest, owing to the fundamental role of helicity in biology and their potential utilization in chiral separation, asymmetric catalysis, and nonlinear optic applications, and many helical metal-organic assemblies and chiral coordination polymers have been constructed on the basis of helical topology. [7][8][9] Lin et al. have explored the synthesis of novel optical and magnetic materials via the use of unsymmetrical pyridylcarboxylate and analogous bridging ligands. 10 The presence of different functional groups in these kinds of ligands may render interesting properties of the resulting coordination polymers, and the lack of a center of symmetry on these kinds of ligands makes it possible to produce helical polymers. Double-layered structure can be regarded as a unique molecular "floor" directly linked by pillars through covalent bonds, hydrogen bonds, or other weak interactions. The interesting ionic components are concentrated in the central portions of each layer, and the organic portions form hydrophilic layers that sandwich the ionic portions. The double-layered metal-organic frameworks have been reported to show the spongelike dynamic behavior of reducing the interlayer spacing dramatically in response to guest removal, and the charged bilayer compound Na-Adc has been designed as an interesting new biomaterial. 11 However, the occurrence of pillared-layer complexes with helical character is particularly rare, although the helical layer motif (a layer b) Tellini, V. H. S.; Jover, A.; Galantini, L.; Pavel, N. V.;Meijide, F.; Tato, J. V.

Three coordination compounds of cobalt with organic carboxylic acids and 1,10-phenanthroline as ligands: syntheses, structures and photocatalytic properties

“…3.304 (4) 3.307 (3) Transition [27][28][29]. The results show that all three compounds exhibit good thermal stabilities.…”

Three-dimensional iron-series coordination networks based on antiferromagnetic and ferromagnetic dinuclear motifs with mixed carboxylate and aqua bridges

“…Along this line, we have obtained three iron-series coordination polymers based on [M 2 (l-COO) 2 (l-H 2 O)] dinuclear motifs and 4-(3-pyridyl)benzoic acid (4,. Compared with the 4,4-and 3,3-analogs [28][29][30][31][32][33][34][35][36], the 4,3-Hpybz ligand remains largely unexplored. Only very recently, a few complexes of this ligand with Mn(II), Zn(II), Cd(II) and Pb(II) were structurally characterized [37].…”

A Novel Twofold Interpenetrating 2D (3,5)-Connected Cd(II) Coordination Framework with (52.6)(55.64.7) Topology

“…Thus, far, the design and synthesis of new ligands with various coordinating modes and multiextending connectors have greatly contributed to this field [24][25][26][27][28][29][30][31]. Pyridyl carboxylate and multipyridyl organic ligands have been widely used to assemble functional coordination polymers with novel topologies [32][33][34][35][36][37][38][39][40][41]. A few large multipyridyl or multipyridyl carboxylate organic compounds were utilized as multifunctional spacers to construct some novel coordination polymers with fascinating structures and/or special properties [42][43][44][45][46][47].…”