RESUMO
The title compound, [CoCl(C(12)H(8)N(2))(2)(H(2)O)]Cl.[CoCl(2)(C(12)H(8)N(2))(2)].6H(2)O, is the first example of a new 1:1 cocrystal of the octahedral [CoCl(2)(phen)(2)] and [CoCl(phen)(2)(H(2)O)](+).Cl(-) complexes (phen is 1,10-phenanthroline). The latter form heterochiral dimers held by strong pi-pi stacking interactions via their phenathroline ligands, which confirms that pi stacking is an important and reliable synthon in supramolecular design. In addition, the crystal structure is networked by H(2)O...H(2)O, H(2)O...Cl(-) and H(2)O...Cl hydrogen bonds, which interconnect the different units of the cobalt complexes.
RESUMO
The title compound, C16H6N6 x C2H6O, is an ethanol solvate of an aromatic phenanthroline-based flat ligand. The latter exhibits a remarkable pi-pi stacking in the crystal structure, with interplanar distances of 3.27 and 3.40 A, which directs the columnar organization of the ligands. The ethanol solvent molecule is located in channels between these columns, being hydrogen bonded to one of the N-atom sites of the phenanthroline fragment.
RESUMO
The two polymorphs (Forms I and II) of [R,S]-ethambutol dihydrochloride transform enantiotropically and reversibly in a single-crystal-to-single-crystal phase transformation mode. These structurally very similar forms have been characterized and their thermodynamic relationship has been investigated by variable-temperature solid-state carbon-13 nuclear magnetic resonance, variable-temperature powder X-ray diffraction, differential scanning calorimetry, and optical microscopy. The nuclear magnetic resonance results are compared with those for the two polymorphs of the [S,S] diastereomer with known structures.
