Joanna Bojarska

Intramolecular hydrogen bond between 4-oxo and 3-carboxylic groups in quinolones and their analogs. Crystal structures of 7-methyl- and 6-fluoro-1,4-dihydro-4-oxocinnoline-3-carboxylic acids

Abstract Crystal structures of two cinnoline analogs of quinolones and statistics on quinolones molecular forms observed in the crystal state have been determined. It has been shown that common quinolones may be divided into two main types, depending on presence of proton acceptor, usually aliphatic amine group, capable of protonation under mild conditions. Quinolones lacking amine group or having one(s) bound to an aromatic system exist at physiological pH mainly in a free acid form, in which acidic hydrogen atom is locked into an intramolecular hydrogen bond. The phenomenon enhances permeability of quinolones through lipophilic cell membranes but decreases the concentration of carboxylate form capable of specific binding with bacterial DNA. Molecular (neutral) form was observed exclusively in the crystalline state for these quinolones. The dominant forms seem different for quinolones having amine substituents with unconjugated lone pair electrons at N atom. Even in the crystalline state, they may exist also in a zwitterionic form, which was found to dominate in secondary amines crystallised at neutral pH. Our limited data suggest that position and order of amine group may play important role in controlling quinolones absorption, transport and concentration and thus their biological profile.

2,9-Di-3-pentyl­anthra[1,9-def:6,5,10-d′e′f′]diisoquinoline-1,3,8,10-tetrone

The asymmetric unit of the title compound, C34H30N2O4, contains four independent half-molecules, the complete molecules being generated by inversion symmetry. The molecules each have planar (within 4σ) perylenetetracarboxylic diimide fragments with bent side chains. In one of the independent molecules, each 3-pentyl fragment is disordered over two conformations in a 7:3 ratio. In the crystal, π–π interactions link molecules into stacks propagated in [010]. The crystal packing also exhibits weak intermolecular C—H⋯O hydrogen bonds.

Three new olanzapine structures: the acetic acid monosolvate, and the propan-2-ol and propan-2-one hemisolvate monohydrates

The crystal structures of three new solvates of olanzapine [systematic name: 2-methyl-4-(4-methylpiperazin-1-yl)-10H-thieno[2,3-b][1,5]benzodiazepine], namely olanzapine acetic acid monosolvate, C17H20N4S·C2H4O2, (I), olanzapine propan-2-ol hemisolvate monohydrate, C17H20N4S·0.5C3H8O·H2O, (II), and olanzapine propan-2-one hemisolvate monohydrate, C17H20N4S·0.5C3H6O·H2O, (III), are presented and compared with other known olanzapine forms. There is a fairly close resemblance of the molecular conformation for all studied analogues. The crystal structures are built up through olanzapine dimers, which are characterized via C-H...π interactions between the aliphatic fragment (1-methylpiperazin-4-yl) and the aromatic fragment (benzene system). All solvent (guest) molecules participate in hydrogen-bonding networks. The crystal packing is sustained via intermolecular N(host)-H···O(guest), O(guest)-H···N(host), O(guest)-H···O(guest) and C(host)-H···O(guest) hydrogen bonds. It should be noted that the solvent propan-2-ol in (II) and propan-2-one in (III) show orientational disorder. The propan-2-ol molecule lies close to a twofold axis, while the propan-2-one molecule resides strictly on a twofold axis through the carbonyl C atom. In both cases, the water molecules present positional disorder of the H atoms.

CRYSTAL STRUCTURE OF A PERINDOPRIL CYCLIZATION PRODUCT, C19H30N2O4

The title compound is a product of perindopril intramolecular cyclization. It crystallizes in the tetragonal, non-centrosymmetric space group P4 1 2 1 2 (No. 92) with a = 9.3574(2), b = 9.3574(2), c = 45.6369(9) A, V = 3996.01(14) A3 and Z = 8. The crystal consists of one molecule in the asymmetric unit. The packing exhibits weak intermolecular C-H···O=C contacts forming two C(5) and C(10) chains, which together result in graph-set descriptor R3 3 (18) motif, running along the crystallographic a-axis.

An orthorhombic polymorph of a cyclization product of perindopril.

Low-temperature X-ray diffraction experiments were employed to investigate the crystal structures of an orthorhombic polymorph of the intramolecular cyclization product of perindopril, a popular angiotensive-converting enzyme (ACE) inhibitor, namely ethyl (2S)-2-[(3S,5aS,9aS,10aS)-3-methyl-1,4-dioxo-5a,6,7,8,9,9a,10,10a-octahydro-3H-pyrazino[1,2-a]indol-2-yl]pentanoate, C19H30N2O4, (Io), and its tetragonal equivalent, (It), which was previously reported at ambient temperature [Bojarska et al. (2013). J. Chil. Chem. Soc. 58, 1415-1417]. Polymorph (Io) crystallizes in the orthorhombic space group P2(1)2(1)2(1) with two molecules in the asymmetric unit, while tetragonal form (It) crystallizes in the space group P4(1)2(1)2 with one molecule in the asymmetric unit. The geometric parameters of (Io) are very similar to those of (It). The six-membered rings in both polymorphs adopt a slightly deformed chair conformation and the piperazinedione rings are in a boat conformation. However, the proline rings adopt an envelope conformation in (Io), while in (It) the ring exists in a slightly deformed half-chair conformation. The most significant difference between the two structures is the orientation of the ethyl pentanoate chain. Molecules associate in pairs in a head-to-tail manner forming infinite columns. In (Io), molecules are related by a twofold screw axis forming identical columns, while in (It), molecules in successive neighbouring columns are related by alternating twofold screw axes and fourfold screw axes. In both cases, the crystal packing is stabilized by weak intermolecular C-H···O interactions only.

Novel pseudopolymorph of the active metabolite of perindopril.

The dimethyl sulfoxide hemisolvate of perindoprilat [systematic name: (1S)-2-((S)-{1-[(2S,3aS,7aS)-2-carboxyoctahydro-1H-indol-1-yl]-1-oxopropan-2-yl}azaniumyl)pentanoate dimethyl sulfoxide hemisolvate], C(17)H(28)N(2)O(5)·0.5C(2)H(6)OS, an active metabolite of perindopril, has been synthesized, structurally characterized by single-crystal X-ray diffraction and compared with its ethanol disolvate analogue [Pascard et al. (1991). J. Med. Chem. 34, 663-669]. Both compounds crystallize in the orthorhombic P2(1)2(1)2(1) space group in the same zwitterionic form, with a protonated alanine N atom and an anionic carboxylate group at the n-alkyl chain. The three structural units present in the unit cell (two zwitterions and the solvent molecule) are held together by a rich system of O-H···O, N-H···O and C-H···O hydrogen-bond contacts.

Analysis of supramolecular interactions in alendroniate alkali metal salts: synthesis, structure, and properties of novel sodium alendronate polymorph

A new polymorph of anhydrous sodium alendronate, C4H12NO7P2Na, has been synthesized and characterized by single crystal X-ray diffraction as well as infrared spectroscopy and thermal analysis. The title compound crystallizes in the monoclinic P21/c space group. Asymmetric unit consists of one alendronic anion and one sodium cation. An interplay of classical strong O-H…O, N-H…O and non-classical weak C-H…O hydrogen bonds creates 3D framework in the crystal. Contrary to previously reported sodium alendronate salts, in which Na+ cation is surrounded by six-coordinated sphere, in compound (1), the Na+ cation is five-coordinated in a distorted trigonal-bipyramidal geometry. In order to provide a detailed investigation of the molecular arrangement in view of intermolecular interactions, the title compound was compared with alendronic acid and other known alkali metal alendronate salts, retrieved from the Cambridge Crystal Structure Database. The intercontacts were qualitatively and quantitatively compared using Hirshfeld surface analysis. It highlights that strong O…H/H…O and subtle H…H contacts play an influential role in the total surface area. The Me+…H/H…Me+ and Me+…O/O…Me+ contacts are meaningful as well. These evidently simple systems show a diverse complexity. Moreover, the powder X-ray diffraction, DSC, thermogravimetry/derivative thermogravimetry, and FT-IR results are also reported.