Guadalupe Hernández

Trimesic acid dimethyl sulfoxide solvate: space group revision

The structure of the title solvate, C9H6O6·C2H6OS, was determined 30 years ago [Herbstein, Kapon & Wasserman (1978 ▶). Acta Cryst. B34, 1613–1617], with data collected at room temperature, and refined in the space group P21. The present redetermination, based on high-resolution diffraction data, shows that the actual space group is more likely to be P21/m. The crystal structure contains layers of trimesic acid molecules lying on mirror planes. A mirror plane also passes through the S and O atoms of the solvent molecule. The molecules in each layer are interconnected through strong O—H⋯O hydrogen bonds, forming a two-dimensional supramolecular network within each layer. The donor groups are the hydroxyls of the trimesic acid molecules, while the acceptors are the carbonyl or the sulfoxide O atoms.

New chiral α-ketoimine-Pd(II) complexes and their anticancer activity

Optically pure α-ketoimines were obtained under solvent-free conditions starting from 2,2′-pyridil and (S)-(−)-1-phenylethylamine and (S)-(−)-1-(4-methylphenyl)ethylamine, respectively. These new chiral ketoimines were then complexed with palladium yielding new optically pure mono-Pd complexes 3A–B. The compounds have been characterized by IR, 1H NMR, and 13C NMR spectroscopies along with MS-FAB+ spectrometry. The crystal and molecular structure of 3A has been fully confirmed by single-crystal X-ray studies. In vitro studies of 3A–B display growth inhibition against leukemia (K-562 CML), colon cancer (HCT-15), breast cancer (MCF-7), central nervous system (U-251 Glio), and prostate cancer (PC-3) cancer cell lines.

Bis[4-(diphenyl­methyl­eneamino)phen­yl]methanone

The title molecule, C39H28N2O, is a well known dendron used in the synthesis of phenylazomethine dendrimers. The central benzophenone core is twisted, as expected, due to hindrance between H atoms: the dihedral angle between core benzene rings is 54.49 (5)°, identical to that of the stable polymorph of benzophenone (56°). For the same reason, phenyl groups substituting imine C atoms make a large dihedral angle, although similar for each imine: 71.83 (6) and 67.64 (5)°. The six aromatic rings in the molecule thus seem to be quite randomly oriented, and such an arrangement is not favorable for efficient stacking interactions in the crystal. The same behaviour is observed in the vast majority of diphenylimino-containing organics. The low triclinic crystal symmetry may be a consequence of these features.

1,3-Bis{(+)-(S)-[1-(1-naphth-yl)eth-yl]imino-meth-yl}benzene dichloro-methane solvate.

In the title compound, C32H28N2·CH2Cl2, the complete Schiff base and solvent molecules are both generated by crystallographic twofold axes, with the two C atoms of the former and the C atom of the latter lying on the rotation axis. The central benzene ring is substituted with two chiral groups including imine functionalities, with the common E configuration. The dihedral angle between the central benzene ring and the terminal naphthalene ring is 45.42 (9)° and that between the two naphthalene rings is 89.16 (8)°. The conformation of the Schiff base allows solvent molecules to fill the voids in the crystal, affording a stable 1:1 solvate, but the solvent interacts poorly with the Schiff base, as reflected by its rather high displacement parameters.

1,3-Bis[(-)-(S)-(1-phenyl-eth-yl)imino-meth-yl]benzene.

The title compound, C24H24N2, is an enantiomerically pure bis-aldimine, which displays twofold crystallographic symmetry, with two C atoms of the central benzene ring lying on the symmetry axis. The imine group is slightly twisted from the benzene core, with a dihedral angle of 12.72 (16)° between the benzene ring and the C=N—C* plane. The terminal phenyl rings make an angle of 66.44 (4)° and are oriented in opposite directions with respect to the benzene ring. In the crystal, molecules interact weakly through a C—H⋯π interaction involving the phenyl rings, and form chains along the 21 screw-axis in the [100] direction.

(–)-(S)-N,N′-Bis[1-(1-naphth­yl)eth­yl]­oxalamide

The title molecule, C26H24N2O2, displays C 2 symmetry, with the molecule located on a twofold axis perpendicular to the plane of the oxalamide unit –NH—CO—CO—NH–. The oxalamide core deviates from planarity, as reflected by the O=C—C=O and N—C—C—N torsion angles of 164.3 (5) and 163.2 (5)°, respectively. The naphthyl groups are oriented toward the same face of the oxalamide mean plane and make a dihedral angle of 43.76 (8)°. This conformation is suitable for the formation of intermolecular N—H⋯O hydrogen bonds, giving noncentrosymmetric dimers incorporating R 2 2(10) ring motifs. These nonbonding interactions propagate along the 61 screw axis normal to the molecular twofold axis, resulting in a single-stranded right-handed helix parallel to [001]. In the crystal, Δ helices are arranged side-by-side and interact through π–π contacts between naphthyl groups. The shortest centroid–centroid separation between interacting benzene rings is 3.623 (4) Å.

1,4-Bis{(+)-(S)-[1-(1-naphth­yl)eth­yl]imino­meth­yl}benzene

The title compound, C32H28N2, is a chiral bis-imine in which both imine groups display the common E configuration. The naphthyl groups present different orientations with respect to the central core, as reflected in the dihedral angles of 21.4 (2) and 78.83 (14)° between the benzene and naphthyl mean planes, thus the highest possible C 2 local molecular symmetry is not attained. This C 1 molecular conformation allows multiple C—H⋯π intermolecular contacts involving all aromatic rings, while no π–π interactions are available for the stabilization of the crystal structure. The resulting packing structure is based on molecules stacked along [100].

(S)-(+)-1-(1-Naphth­yl)-1-(2-thienylmethyl­ene)ethyl­amine

The title chiral imine, C17H15NS, has been obtained via a direct synthesis route. The imine group displays the common E configuration, and is almost coplanar with the thiophene heterocycle; the dihedral angle between the C=N—C group and the thiophene ring is 5.1 (8)°. In contrast, the naphthyl group makes an angle of 83.79 (13)° with the thiophene ring. The observed solid-state molecular conformation is suitable for the use of this molecule as an N,S-bidentate Schiff base ligand. The molecular packing features double C—H⋯π interactions between naphthyl groups of neighboring molecules, which form chains in the [100] direction. The crystal structure is further stabilized by a short C—H⋯π contact involving the methyl group and one ring of a naphthyl group. The resulting two-dimensional network is completed by a weak intermolecular C—H(imine)⋯π(thiophene) interaction.

Crystal structures of three mercury(II) complexes [HgCl2L] where L is a bidentate chiral imine ligand

Three complexes synthesized by coordination of chiral imines to HgCl2 have been characterized, in which the tetrahedral HgII centre has a geometry strongly distorted towards the disphenoidal geometry.

Straightforward solvent-free synthesis of new chiral benzene-1,3,5-tricarboxamides

A new series of chiral benzene-1,3,5-tricarboxamides (BTAs) 3a–e was prepared using the ecofriendly solvent-free approach, starting with benzene-1,3,5-tricarbonyl chloride 1 and appropriate optically pure primary amines 2a–e. All the reactions occur in a short time with excellent yields (>90%). The structures of the compounds have been characterized by Fourier transform infrared spectroscopy (FT–IR), Proton nuclear magnetic resonance (1H NMR), Carbon 13 nuclear magnetic resonance (13C NMR), electron ionization mass spectrometry (EI–MS), and elemental analysis.