New Advances in the One-Dimensional Coordination Polymer Copper(II) Alkanoates Series: Monotropic Polymorphism and Mesomorphism

Abstract

The polymorphism in the copper(II) alkanoates, recently discovered for one member, has been thoroughly studied for the whole series, from 3 to 16 C atoms. Three polymorphic phases have been found, all of them sharing the same molecular unit, the paddle-wheel, which grows forming a 1D coordination polymer or catena. The three polymorphs are defined by a different packing of these catenae and a specific arrangement of the alkyl chains. Ten new crystal structures of those compounds have been solved by high resolution powder diffraction and presented in this paper. The polymorphism in this series has been found to be monotropic and is responsible for the complex thermal behavior observed. The most characteristic feature, the endothermic−exothermic effect, has been explained for the first time in these compounds by a combination of data from differential scanning calorimetry (in normal and modulated modes), powder X-ray diffraction and Fourier transform infrared spectroscopy. These techniques, together with small-angle X-ray scattering and optical microscopy, were used to analyze the hexagonal columnar discotic liquid crystal phase of copper(II) alkanoates. Thus, new information has been found in the packing and stacking of the discs formed by the paddle-wheel units, also maintained in the mesophase.

Unraveling the Decomposition Process of Lead(II) Acetate: Anhydrous Polymorphs, Hydrates, and Byproducts and Room Temperature Phosphorescence

“…Anhydrous lead­(II) acetate belongs to the family of metal alkanoates, which have shown their ability to present polymorphism − and/or polymesomorphism . ,− In particular, the lead­(II) alkanoate series has been studied in depth for some decades. − These compounds present two mesophases, rotator (members with n ≥ 4, with n being the number of C atoms) , and a liquid-crystal phase (6 ≤ n ≤ 12). The shortest members of the series ( n ≤ 7) ,, show also a great tendency to form different kinds of glass states: regular, rotator, and liquid-crystal glasses .…”

Production and Characterization of a New Copper(II) Propanoate-Isonicotinamide Adduct Obtained via Slow Evaporation and using Supercritical CO2 as an Antisolvent

“…Figure a,b shows the structures of Cu­(C 3 ) 2 and the Cu 2 (C 3 ) 4 (INA) 4 adduct obtained at 100 K. The color change from the original cyan of the Cu­(C 3 ) 2 to a lighter blue can be attributed to the change in the coordination of the copper from five (square pyramidal) in the alkanoate to six (distorted octahedral) in the adduct. The paddle-wheel structure of Cu­(C 3 ) 2 is constructed by four bridging carboxylate ligands (μ 3 ) that form catenae in a one-dimensional (1D) coordination polymer arrangement (Figure a), typical of all the Cu­(II) alkanoates. − The paddle wheels, and therefore the catenae, disappear in the new complex, where two-metal units are coordinated by two bridging (μ 2 ) and two chelating carboxylates (μ 2 ) from the propionate anions, and four N atoms from INA molecules. Each Cu ion in the binuclear unit is coordinated by four O atoms (two of them from two different bridging carboxylates, and the other two from the chelating carboxylate), in the plane approximately, while the N atoms are in the apical vertices of the distorted octahedron (see Figure b).…”

“…The synthesis and behavior of copper­(II) alkanoates has been widely studied during the last decades. − The paddle-wheel configuration in which the carboxylate ligands bond both copper­(II) atoms with a bridging ligand confers on these compounds interesting features. They present monotropic polymorphism and mesomorphism, as a hexagonal columnar discotic liquid crystal .…”

“…They present monotropic polymorphism and mesomorphism, as a hexagonal columnar discotic liquid crystal . Recent research has explored the thermal behavior and structure of the copper­(II) alkanoate series in both crystal and liquid crystal phases, where the dimeric complex molecular units are present . Important applications of the copper­(II) alkanoates result from their magnetic properties , and their potential use in the production of nanoreactors. − Special interest arises from their biological activity, as they have proven pharmaceutical activity in diverse fields such as antiinflammatory, antirheumatic, and antitumoral − as well as fungicidal activity, − for which they have been extensively studied as wood preservatives.…”

Effect of mesogenic organic salts on vulcanization and physical properties of rubber compounds

“…The processes involved from the totally ordered crystal phase at low temperature to the isotropic liquid phase constitute the ‘stepwise melting mechanism’. Thus, different solid (plastic crystal, rotator or condis) or fluid (liquid crystal) mesophases may appear in these salts, as well as enantiotropic or monotropic polymorphs in the crystal phase . It is worth noting that all of the solid mesophases have a plastic nature, making them interesting from the rheological point of view.…”