Synthesis, crystal structure and water-induced reversible crystal-to-amorphous transformation property of [Co2(2,4-pydc)2(bpa)(H2O)6](H2O)2

Synthesis and crystal structure of poly[[bis(aqua-κO)tetrakis(μ-4,4′-bipyridine-κ2 N:N′)hexakis(3-chlorobenzoato)-κ5 O;κ2 O:O′-tricobalt(II)] methanol disolvate]

A novel ladder-chain cobalt(II) coordination polymer, {[Co3(C7H4ClO2)6(C10H8N2)4(H2O)2]·2CH3OH} n , was synthesized and characterized. The structure contains two CoII centres with different octahedral environments, [Co(1)N3O3] and [Co(2)N2O4]. The O-donating 3-chlorobenzoate anions (3-Clbenz) act as the terminal ligands, while the N-donating 4,4′-bipy molecules play the role of linkers. The Co(1) ions are linked by 4,4′-bipy molecules into linear chains. Two such chains are joined by [Co(2)(3-Clbenz)2(H2O)2] units via two 4,4′-bipy bridging ligands, thus forming the ladder-chain structure. The crystal packing of the title compound is stabilized by supramolecular interactions, such as hydrogen bonding, π–π and halogen...π contacts, giving a three-dimensional framework. The spectroscopic and thermal properties of the title compound have also been investigated.

Crystal structure of a novel one-dimensional zigzag chain-like cobalt(II) coordination polymer constructed from 4,4'-bi-pyridine and 2-hy-droxy-benzoate ligands

The synthesis, crystal structure and physical properties of a novel one-dimensional zigzag chain-like Co^II coordination polymer, [Co₂(2-OHbenz)₄(4,4′-bpy)_2.5(H₂O)]_n, constructed from 4,4′-bi­pyridine (4,4′-bpy) and 2-hy­droxy­benzoate (2-OHbenz) are reported.

A novel one-dimensional zigzag chain-like Co^II coordination polymer constructed from 4,4′-bi­pyridine (4,4′-bpy) and 2-hy­droxy­benzoate (2-OHbenz) ligands, namely, catena-poly[[(4,4′-bi­pyridine-κN)­(μ-2-hy­droxy­benzoato-κ²O:O′)(2-hy­droxy­benzoato-κ²O,O′)cobalt(II)]-μ-4,4′-bi­pyridine-κ²N:N′-[aquahemi(μ-4,4′-bi­pyridine-κ²N:N′)(2-hy­droxy­benzoato-κO(2-hy­droxy­benzoato-κ²O:O′)cobalt(II)], [Co₂(C₇H₅O₃)₄(C₁₀H₈N₂)_2.5(H₂O)]_n, has been synthesized by reacting cobalt(II) nitrate trihydrate, 4,4′-bpy and 2-hy­droxy­benzoic acid in a mixture of water and methanol at room temperature. There are two independent Co^II centers, Co1 and Co2, in the asymmetric unit, revealing a distorted octa­hedral geometry with chromophore types of [CoN₂O₄] and [CoN₂O₃O′], respectively. The Co1 ions are doubly bridged by 2-OHbenz ligands with syn–anti coordination mode, generating a dinuclear unit. The bridging 4,4′-bpy ligands connect these dinuclear units and the mononuclear Co2 chromophores, providing a one-dimensional alternating zigzag chain-like structure. In the crystal, inter­molecular hydrogen bonds, C—H⋯π and π–π stacking inter­actions are observed and these help to consolidate the packing. In addition, the physical properties of the title compound are reported.

Solvent-mediated supramolecular templated assembly of a metal organophosphonate via a crystal–amorphous–crystal transformation

Three monophosphonoester-based supramolecular assemblies were synthesized and fully characterized. These complexes showed a reversible crystal–amorphous–crystal transformation with changes in their emission properties.

Solvent-Induced Change of Electronic Spectra and Magnetic Susceptibility of Co(II) Coordination Polymer with 2,4,6-Tris(4-pyridyl)-1,3,5-triazine

One-dimensional coordination polymer [Co(Piv)2(4-ptz)(C2H5OH)2]n (compound 1, Piv(-) = pivalate, 4-ptz = 2,4,6-tris(4-pyridyl)-1,3,5-triazine) was synthesized by interaction of Co(II) pivalate with 4-ptz. Desolvation of 1 led to formation of [Co(Piv)2(4-ptz)]n (compound 2), which adsorbed N2 and H2 at 78 K as a typical microporous sorbent. In contrast, absorption of methanol and ethanol by 2 at 295 K led to structural transformation probably connected with coordination of these alcohols to Co(II). Formation of 2 from 1 was accompanied by change of color of sample from orange to brown and more than 2-fold decrease of molar magnetic susceptibility (χM) in the temperature range from 2 to 300 K. Resolvation of 2 by ethanol or water resulted in restoration of spectral characteristics and χM values almost to the level of that of 1. χMT versus T curves for 1 and samples, obtained by resolvation of 2 by H2O or C2H5OH, were fitted using a model for Co(II) complex with zero-field splitting of this ion.