T. Narasimhamurthy

Hantzsch 1,4-dihydropyridine esters and analogs: candidates for generating reproducible one-dimensional packing motifs.

Examination of the symmetric Hantzsch 1,4-dihydropyridine ester derivatives of the prototypical nifedipine molecule indicates the tendency of this class of molecule to form a common packing motif. Crystal structure analysis of 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylic diesters and analogs reveals that they form extended chains, characterized as the C(6) packing motif, via intermolecular (amine) N-H...O=C (C3,C5 carbonyl) hydrogen bonds. In addition, all the prepared derivatives also satisfy the basic structural requirements for their high binding efficiency to the receptor. The reproducible C(6) packing motif observed among these compounds has a use in the design of solid-state materials.

3,3,6,6-Tetra-methyl-9-phenyl-3,4,5,6-tetra-hydro-9H-xanthene-1,8(2H,7H)-dione.

In the title compound, C23H26O3, the three six-membered rings of the xanthene system are non-planar, having total puckering amplitudes, Q T, of 0.443 (2), 0.202 (2) and 0.449 (2) Å. The central ring adopts a boat conformation and the outer rings adopt sofa conformations. The crystal structure is stabilized by van der Waals interactions.

Herring-bone π–π interactions in trans-2,6-diphenyl-2,3,5,6-tetrahydrothiapyran-4-one

The structure of the title compound, C(17)H(16)OS, is primarily stabilized by T-shaped and parallel-displaced aromatic clusters. The distances between the centroids of the aromatic pairs are in the range 4.34-5.30 A. In the crystal packing, the molecules dimerize by means of pi-pi interactions of both face-to-face and edge-to-face types, and the aromatic rings associate in a cyclic edge-to-face tetrameric arrangement of the herring-bone type. These herring-bone interactions appear to insulate hydrogen-bond interactions in the crystal structure.

(2E)-3-(4-Bromo-phen-yl)-1-(2-methyl-4-phenyl-3-quinol-yl)prop-2-en-1-one.

The conformation about the ethene bond [1.316 (3) Å] in the title compound, C25H18BrNO, is E. The quinoline ring forms dihedral angles of 67.21 (10) and 71.68 (10)° with the benzene and bromo-substituted benzene rings, respectively. Highlighting the non-planar arrangement of aromatic rings, the dihedral angle formed between the benzene rings is 58.57 (12)°.

C—halogen⋯π dimer and C—H⋯π interactions in 1-(2-bromo-4,5-di­meth­oxy­benzyl)-2-butyl-4-chloro-1H-imidazole-5-carbaldehyde and 2-butyl-4-chloro-1-(6-methyl-1,3-benzodioxol-5-ylmethyl)-1H-imidazole-5-carbaldehyde

The structures of the title compounds, C17H20BrClN2O3, (I), and C17H19ClN2O3, (II), are stabilized by intramolecular C-H...O and C-H...pi interactions. The stability of the molecular packing in (I) and (II) arises from a diverse set of weak intermolecular C-H...O, C-H...pi and C-halogen...pi interactions. In the crystal structure of (I), molecules aggregate in dimeric subunits via C-Br...pi interactions. The dimers are interlinked by C-H...O hydrogen bonds. The halogens cluster together and form a channel along the b axis. In (II), the packing is mainly governed by intermolecular C-H...O and C-H...pi interactions.

1,1'-(p-Phenyl-enedimethyl-ene)dipiperidin-4-one.

In the molecule of the title compound, C18H24N2O2, the piperidine rings are in chair conformations. The crystal structure is stabilized by intermolecular C—H⋯O hydrogen bonding. There are neither C—H⋯π nor π–π interactions in the structure.

(2E)-3-(4-Eth-oxy-phen-yl)-1-(2-methyl-4-phenyl-quinolin-3-yl)prop-2-en-1-one monohydrate.

The title hydrate, C27H23NO2·H2O, features an almost planar quinoline residue (r.m.s. deviation = 0.015 Å) with the benzene [dihedral angle = 63.80 (7) °] and chalcone [C—C—C—O torsion angle = −103.38 (18)°] substituents twisted significantly out of its plane. The configuration about the C=C bond [1.340 (2) Å] is E. In the crystal, molecules related by the 21 symmetry operation are linked along the b axis via water molecules that form O—H⋯Oc and O—H⋯Nq hydrogen bonds (c = carbonyl and q = quinoline). A C—H⋯O interaction also occurs.

Hydrogen-bonded sheets in 2-(2-aminophenyl)-1H-benzimidazol-3-ium dihydrogen phosphate.

The title salt, C(13)H(12)N(3)(+).H(2)PO(4)(-), contains a nonplanar 2-(2-aminophenyl)-1H-benzimidazol-3-ium cation and two different dihydrogen phosphate anions, both situated on twofold rotation axes in the space group C2. The anions are linked by O-H...O hydrogen bonds into chains of R(2)(2)(8) rings. The anion chains are linked by the cations, via hydrogen-bonding complementarities and electrostatic interactions, giving rise to a sheet structure with alternating rows of organic cations and inorganic anions. Comparison of this structure with that of the pure amine reveals that the two compounds generate characteristically different sheet structures. The anion-anion chain serves as a template for the assembly of the cations, suggesting a possible application in the design of solid-state materials.

Proton-bifurcated C-H (O,O) hydrogen bonds in 2,3-dichloro-6-nitrobenzylaminium chloride

In the crystal structure of the title salt, C7H7Cl2N2O2+.Cl-, the chloride anions participate in extensive hydrogen bonding with the aminium cations and indirectly link the molecules through multiple N+-H...Cl- salt bridges. There are two independent molecules in the asymmetric unit, related by a pseudo-inversion center. The direct intermolecular coupling is established by C-H...O, C-H...Cl and C-Cl...Cl(-) interactions. A rare three-center (donor bifurcated) C-H...(O,O) hydrogen bond is observed between the methylene and nitro groups, with a side-on intramolecular component of closed-ring type and a head-on intermolecular component.

2,2 `-Diaminodibenzyl: a rare case of crystallographically non-compliant molecular symmetry

The title compound,