[Potential cardiotonics. 16. Molecular and crystal structures of three polymorphic forms and a hydrochloride monohydrate of 3-cyano-2-morpholino-5-(pyridin-4-yl)pyridine (AWD 122-14)]. / Potentielle Kardiotonika. 16. Mitteilung3: Molekül-und Kristallstrukturen dreier polymorpher Formen und eines Hydrochlorid-Monohydrates von 3-Cyan-2-morpholino-5-(pyrid-4-yl) pyridin (AWD 122-14).

The results of an X-ray structure analysis of the alpha-modification were the starting point for the prediction and establishment of further polymorphic and pseudopolymorphic, respectively, forms of AWD 122-14. A complete structure determination of the gamma- and delta-modifikation as well as of a hydrochloride monohydrate could be carried out. Molecular parameters, conformational flexibility, and intermolecular interactions are discussed in this paper.

X-ray studies on piroxicam modifications.

The anti-inflammatory drug piroxicam, 4-hydroxy-2-methyl-N-(2-pyridyl)2H-1,2- benzothiazine-3-carboxamide-1,1-dioxide, crystallizes in three different forms, two anhydrates and one monohydrate. Crystal structure analyses of the monohydrate and one of the anhydrate were carried out by Bordner et al. and Kojic-Prodic et al., respectively. In this paper the results of the analysis of the third piroxicam modification and of an independently performed structure determination of the monohydrate are reported. Molecular structures and hydrogen bonding of all modifications are discussed.

[X-ray structural analysis of 3 crystalline modifications of 3-cyan-5-methyl-5-(pyridinyl)-1,2-dihydro-pyrid-2-one (milrinone)]. / Röntgenstrukturanalytische Untersuchungen an drei kristallinen Modifikationen des 3-Cyan-6-methyl-5-(pyrid-4-yl)-1,2-dihydropyrid-2-on (Milrinon).

The crystal and molecular structures of the alpha-, beta-, and gamma-modification of the cardiotonic compound milrinone have been determined by X-ray structure analyses. In all modifications the molecules exist in the lactam form. Because of steric hindrances the pyridine rings deviate considerably from coplanarity. The dihedral angle amounts to 45 degrees in milrinone-alpha, 43.7 degrees in milrinone-beta, and 57.5 degrees in milrinone-gamma. In the three crystal structures molecules are connected via hydrogen bonds forming dimers. These are centrosymmetric in milrinone-alpha and -beta. In milrinone-gamma the molecules within a dimer are symmetry related by a twofold axis. The dimers are linked by charge transfer interactions. This leads to infinite chains in the alpha- and beta-modification and to infinite layers in milrinone-gamma.