cg0600344_si_003.cif (16.46 kB)

One-Dimensional Chains, Two-Dimensional Corrugated Sheets Having a Cross-Linked Helix in Metal−Organic Frameworks:  Exploring Hydrogen-Bond Capable Backbones and Ligating Topologies in Mixed Ligand Systems

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posted on 02.08.2006, 00:00 by D. Krishna Kumar, Amitava Das, Parthasarathi Dastidar
Six intriguing metal−organic coordination polymers, {Co(μL1)(μL2)(H2O)}n (1a), {Zn(μL1)(μL2)(H2O)}n (1b), {[Zn(H2O)4(μL1‘)Zn(L2)2]·H2O}n (2), {[Co(H2O)4(μL1‘ ‘)Co(L2)2(H2O)2]·H2O}n (3), {Zn(μL1‘ ‘)(μL2)}n (4), {[Cd(H2O)(μL1‘ ‘)(μL2)·2H2O]}n (5), and {[Co(H2O)4(μL1‘ ‘)Co(L3)2](H2O)2]·1.3H2O]}n (6) (L1 = N-(4-pyridyl)isonicotinamide, L1‘ = N-(3-pyridyl)isonicotinamide, L1‘ ‘ = N-(4-pyridyl)nicotinamide, L2 = maleate, L3 = succinate), have been synthesized and characterized by single-crystal X-ray diffraction. 1a, 1b, 4, and 5 display a grid architecture, whereas 2, 3, and 6 display a one-dimensional polymeric chain. 5 is an example of a chiral metal−organic framework (due to the presence of a right-handed helix) assembled from achiral components. The supramolecularly recognizable backbone, namely, secondary amide of N-donor ligands does not show typical self-recognition. This study represents one of the limited explorative studies on counterion free mixed ligand systems containing an N-donor exo-bidentate ligand with a supramolecularly recognizable backbone and O-donor carboxylate ligand.