Syntheses, structures and properties of nickel(II) and manganese(II) coordination polymers based on V-shaped bis-imidazole and aromatic carboxylate ligands

Solvent-Assisted Control of Metal-Organic Nanotube Size and Morphology

While intensive studies have focused on the synthesis and characterization of new metal-organic nanotube (MONT) structures, the lack of size and morphology control remains an obstacle in broadening applications for this class of materials. Herein, we demonstrate control of MONT crystallite size and morphology by tuning polarity and the protic/aprotic nature of solvents, including dimethylformamide, N-methyl-2-pyrrolidone, ethanol, and 2-methyltetrahydrofuran, for the isostructural syntheses of two MONTs. Through a combination of transmission electron microscopy, powder X-ray diffraction, and selected area electron diffraction, we find that MONT crystallite sizes can be tuned while maintaining control over the relative dispersity without significantly altering the underlying crystal structure.

The first coordination compound of 6-fluoro-nicotinate: the crystal structure of a one-dimensional nickel(II) coordination polymer containing the mixed ligands 6-fluoro-nicotinate and 4,4'-bi-pyridine

A one-dimensional nickel(II) coordination polymer with the mixed ligands 6-fluoro­nicotinate (6-Fnic) and 4,4′-bi­pyridine (4,4′-bpy), namely, [Ni(H₂O)₂(6-Fnic)₂(4,4′-bpy)·3H₂O]_n, (1), was prepared. The nickel(II) ion in 1 is octa­hedrally coordinated by the O atoms of two water mol­ecules, two O atoms from O-monodentate 6-fluoro­nicotinate ligands and two N atoms from bridging 4,4′-bi­pyridine ligands.

A one-dimensional nickel(II) coordination polymer with the mixed ligands 6-fluoro­nicotinate (6-Fnic) and 4,4′-bi­pyridine (4,4′-bpy), namely, catena-poly[[di­aqua­bis­(6-fluoro­pyridine-3-carboxyl­ato-κO)nickel(II)]-μ-4,4′-bi­pyri­dine-κ²N:N′] trihydrate], {[Ni(6-Fnic)₂(4,4′-bpy)(H₂O)₂]·3H₂O}_n, (1), was prepared by the reaction of nickel(II) sulfate hepta­hydrate, 6-fluoro­nicotinic acid (C₆H₄FNO₂) and 4,4′-bi­pyridine (C₁₀H₈N₂) in a mixture of water and ethanol. The nickel(II) ion in 1 is octa­hedrally coordinated by the O atoms of two water mol­ecules, two O atoms from O-monodentate 6-fluoro­nicotinate ligands and two N atoms from bridging 4,4′-bi­pyridine ligands, forming a trans isomer. The bridging 4,4′-bi­pyridine ligands connect symmetry-related nickel(II) ions into infinite one-dimensional polymeric chains running in the [10] direction. In the extended structure of 1, the polymeric chains and lattice water mol­ecules are connected into a three-dimensional hydrogen-bonded network via strong O—H⋯O and O—H⋯N hydrogen bonds, leading to the formation of distinct hydrogen-bond ring motifs: octa­meric R₈⁸(24) and hexa­meric R₈⁶(16) loops.