We report the crystal structures and magnetic properties of nine mononuclear complexes and one 1D coordination polymer containing Cu^II/Cu^I ions.

Martensitic phase transitions and self‐healing in molecular compounds are extremely rare, and while they carry potential for rapid energy transduction, they are currently found only by serendipity. Here, we report the observation of both phenomena in a coordination compound of glycinamide (Glyam), [Ni(H₂O)₂(Glyam)₂]I₂ (1). Upon cooling to 205–213 K, the high‐temperature polymorph of this material (1_RT) transforms into twinned crystals of the low‐temperature polymorph (1_LT(twinned)), while upon heating, it is converted back to 1_RT in the temperature range 217–223 K. When this transformation occurs in single crystals, evolution of cracks is observed upon cooling that disappear upon heating. The forward transition 1_RT→1_LT(twinned) is completed in a few seconds, while the reverse one, 1_LT(twinned)→1_RT, proceeds up to several hours, contrary to the fast transition in polycrystalline samples. We determined the concomitant presence of 1_RT and 1_LT(twinned) in the same single crystal. The crystal structure analysis revealed complex inter‐ and intramolecular displacements of atoms during the transition. To the best of our knowledge, this is only the second report where a thermally induced reversible martensitic phase transition and self‐healing are observed in crystals of a coordination compound, and indicates the potential generality of these extraordinary phenomena.

Three new coordination compounds of copper(II) with glycine (HGly) and 2,2'-bipyridine (bipy) were synthesized by solution-based and mechanochemical methods: [Cu(Gly)(H2O)(bipy)][Cu(Gly)(SO4)(bipy)]·6H2O (1a·6H2O), [Cu(Gly)(H2O)(bipy)]2SO4 (1b), [Cu(...

Reactions of copper(II) sulfate with 2,2′-bipyridine (bipy) and amino acids with nonpolar side chains (l-alanine (HAla), l-valine (HVal), or l-phenylalanine (HPhe)) were investigated under different solution-based and mechanochemical methods. Five new ternary coordination compounds were obtained by a solution-based synthesis and three of them additionally by the liquid-assisted mechanochemical method: {[Cu(μ-l-Ala)(H₂O)(bipy)]₂SO₄·2H₂O}_n (1a·2H₂O), {[Cu(μ-l-Ala)(H₂O)(bipy)][Cu(l-Ala)(H₂O)(bipy)]SO₄·2.5H₂O}_n (1b·2.5H₂O), {[Cu(μ-l-Val)(H₂O)(bipy)][Cu(l-Val)(H₂O)(bipy)]₃(SO₄)₂·4H₂O}_n (2·4H₂O), [Cu(l-Phe)(H₂O)(bipy)][Cu(l-Phe)(SO₄)(bipy)]∙8H₂O (3·8H₂O), and [Cu(l-Phe)(H₂O)(bipy)][Cu(l-Phe)(SO₄)(bipy)]∙9H₂O (3·9H₂O). The compounds were characterized by single-crystal and powder X-ray diffraction, infrared spectroscopy, and a thermal analysis. Structural studies revealed two structural types, monomeric in 3·8H₂O and 3·9H₂O, polymeric architectures in 1a·2H₂O, and mixed structures (monomeric and polymeric) in 1b·2.5H₂O and 2·4H₂O. The copper(II) ion is either pentacoordinated or hexacoordinated, with an observed Jahn–Teller effect. The crystal structures are based on an intensive network of hydrogen bonds and π interactions. 1a·2H₂O and 2·4H₂O showed substantial in vitro antiproliferative activity toward human hepatocellular carcinoma (HepG2) and moderate activity toward human acute monocytic leukemia cell lines (THP-1).

The title compound, C₈H₇NO₅, is planar with an r.m.s. deviation for all non-hydrogen atoms of 0.018 Å. An intramolecular O—H...O hydrogen bond involving the adjacent hydroxy and nitro groups forms an S(6) ring motif. In the crystal, molecules are linked by O—H...O hydrogen bonds, forming chains propagating along the b-axis direction. The chains are linked by C—H...O hydrogen bonds, forming layers parallel to the bc plane. The layers are linked by a further C—H...O hydrogen bond, forming slabs, which are linked by C=O...π interactions, forming a three-dimensional supramolecular structure. Hirshfeld surface analysis was used to investigate intermolecular interactions in the solid state. The molecule was also characterized spectroscopically and its thermal stability investigated by differential scanning calorimetry and by thermogravimetric analysis.

In this study, we report the syntheses, crystal structures and magnetic properties of ternary copper(II) coordination compounds with l-homoserine (l-Hhser) and 1,10-phenanthroline (phen). Six new coordination compounds were obtained: [Cu(l-hser)(H₂O)(phen)]₂SO₄·5H₂O (1·5H₂O), [Cu(μ-l-hser)(H₂O)(phen)][Cu(l-hser)(H₂O)(phen)]₃(SO₄)₂∙12H₂O (2·12H₂O), {[Cu(μ-l-hser)(H₂O)(phen)][Cu(μ-l-hser)(phen)]SO₄·6H₂O}_n (3·6H₂O), {[Cu(μ-l-hser)(H₂O)(phen)]₂SO₄·3H₂O}_n (4·3H₂O), [Cu(l-hser)(H₂O)(phen)][Cu(l-hser)(CH₃OH)(phen)]SO₄·4H₂O (5·4H₂O) and {[Cu(l-hser)(CH₃OH)(phen)][Cu(μ-l-hser)(phen)]SO₄·5CH₃OH}_n (6·5CH₃OH). It was shown that slight differences in water content in the synthetic mixtures highly influence the final product, so in some cases, two or three different products were obtained. The compounds were characterized by single-crystal X-ray diffraction and ESR spectroscopy. Crystal packings are based on intensive networks of hydrogen bonds and π interactions. Most water solvent molecules in these microporous compounds are found in discrete pockets (1∙5H₂O, 2∙12H₂O, 3∙6H₂O, 4∙3H₂O). In 5∙4H₂O, water molecules are packed in pockets and 1D channels and in 6∙5CH₃OH methanol solvent molecules form 1D channels. ESR spectroscopy measured from room down to liquid nitrogen temperature was used for local magnetic characterization of copper centers. The spin Hamiltonian parameters obtained from the spectral simulation revealed copper coordination geometry that is in agreement with the structural results. Furthermore, ESR spectra revealed no significant exchange coupling between copper ions. 3·6H₂O showed pronounced antiproliferative activity toward human colon cancer cell lines (HCT116), human breast cancer cell line (MCF-7) and human lung cancer cell lines (H460).