Self-Assembly of a Series of Cobalt(II) Coordination Polymers Constructed from H₂tbip and Dipyridyl-Based Ligands

Abstract

A series of interesting Co(II)-H(2)tbip coordination polymers incorporating different auxiliary ligands, {[Co(tbip)(bipy)(H(2)O)(3)] x 0.5(bipy) x H(2)O}(n) (1), [Co(tbip)(bipy)](n) (2), {[Co(3)(tbip)(3)(dpe)(3)] x 0.5(dpe) x 3 H(2)O}(n) (3), [Co(2)(tbip)(2)(dpe)(H(2)O)](n) (4), [Co(2)(tbip)(2)(bpa)(H(2)O)](n) (5), and {[Co(2)(tbip)(2)(bpa)(2)] x 2.5 H(2)O}(n) (6) (H(2)tbip = 5-tert-butyl isophthalic acid; bipy = 4,4'-bipyridine; dpe = 1,2-di (4-pyridyl)ethylene; bpa = 1,2-bi(4-pyridyl)ethane) were synthesized. X-ray structural analyses of 1-6 reveal a diverse range of structures, ranging from 1D (1) to 2D (2, 6) to 3D (3, 4, 5). Complex 1 shows 1D zigzag bipy-bridged polymeric chains with the terminal tbip ligands as pendants, which are extended to a 3D hydrogen-bonded supramolecular framework involving 1D open channels which encapsulate guest bipy molecules. Polymers 2 and 6 feature similar 2D infinite layer frameworks consisting of cobalt dimers. The structure of 3 is constructed from [Co(2)(tbip)(2)](n) layers, which consists of alternating left- and right-handed helical chains, and further pillared by dpe ligands into a 3D six-connected self-penetrating 4(8).6(6).8 network. The prominent cavities in 3 are parallel to the (101) plane and encapsulate free dpe as guest molecules. Polymers 4 and 5 are isostructural, showing 2-fold interpenetrating 3D alpha-Po networks constructed from binuclear cobalt nodes. The thermal stabilities and X-ray powder diffraction studies indicate that the framework of 3 can keep stable after the loss of guest molecules. Studies of the magnetic susceptibilities of 2-6 reveal weak antiferromagnetic exchange interactions between adjacent Co(II) centers.

Crystal structure of poly[1,4-bis(2-methylbenzimidazol)butane-κ2 N:N′)bis(4,4′-oxybis(benzoato-κ4 O,O′:O′′,O′′′)dicadmium] monohydrate, C48H38Cd2N4O10

“…In particular, the great mass of organic ligands containing coordination sites of N and/or O donors are wildly utilized as designing points in the construction of MOFs [5][6][7]. Among them, the exible N-bridging ligands bearing alkyl spacers have been wildly used to allow the ligands to bend and rotate when it coordinates to metal centers.…”

Crystal structure of poly-[tetraaquabis(μ8-benzene-1,2,4,5-tetracarboxylato-1κ3 O 4:O 6:O 8:2κ4 O 2:O 2:O 5:O 5:3κ4 O 1:O<

“…[1][2][3][4][5][6]. The most e ective and facile approach for constructing new CPs is the judicious choice of various organic linkers such as benzenecarboxylates and N-donor ligands.…”

Crystal structure of catena-poly[diaquabis(μ2-3-carboxybenzene-1,2-dicarboxylato-1:2κ2 O:O′)-(μ2-1,4-bis(2-ethylbenzimidazol-1-ylmethyl)-benzene-1:1′κ2 N:N′)dizinc(II)], [Zn2(C26H26N4)(C9H4O6)2(H2O)2]

“…Hitherto, much e ort has been done on the rational design and controlled synthesis of desired and attractive coordination polymers [5,6]. And it indicates that the selection of multifunctional organic ligands containing appropriate coordination sites and proper spacers would be critical step to get complexes with versatile structures and desired properties [7][8][9]. On the other hand, aromatic multicarboxylate ligands, especially, benzenedicarboxylate and benzenetricarboxylate are excellent building blocks [10][11][12], not only because of their various coordination modes to metal ions, resulting from completely or partially deprotonated sites allowing for the large diversity of topologies, but also because of the strong coordinating ability of carboxylates, which can lead to good thermal stabilities of the materials and increase the possibility of their functionalization.…”