Quantifying weak interactions in ferroelectric and paraelectric phases of phenazine and chloroanilic acid co-crystal using experimental and theoretical electron densities.

The co-crystal of phenazine and chloroanilic acid is known to display paraelectric properties at room temperature. It shows a paraelectric to ferroelectric phase transition at 253 K and has an incommensurately modulated ferroelectric phase below 137 K. High-resolution synchrotron X-ray data were collected at 160 K to model the experimental electron-density distributions, and derived topological properties from the electron density were used to quantify the weak interactions responsible for the origin of the ferroelectric phase. The structure and non-covalent interactions are analysed using Hirshfeld surfaces and energy frameworks. The topological properties, energies, atomic charges and molecular electrostatic potential surfaces are determined from the experimental data, further supported by theoretical calculations. The results from the ferroelectric phase are compared with the paraelectric phase. Although the structural descriptions indicate neutral phenazine and chloroanilic acid molecules in the ferroelectric phase, the topological properties of the electron density indicate a considerable amount of proton transfer in the O-H...O hydrogen bond. Indeed, the displaced H atom in the O-H...O hydrogen bond suggests a mixed covalent/polar nature of chemical bonding. Subtle changes in the chemical bonding and proton-transfer pathways could be detected from the high-resolution electron-density studies.

Crystal structure, DFT and Hirshfeld surface analysis of (E)-N'-[(1-chloro-3,4-di-hydro-naph-thal-en-2-yl)methyl-idene]benzohydrazide monohydrate.

In the title compound, C18H15ClN2O·H2O, a benzohydrazide derivative, the dihedral angle between the mean plane of the di-hydro-naphthalene ring system and the phenyl ring is 17.1 (2)°. In the crystal, O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds link the benzohydrazide and water mol-ecules, forming a layer parallel to the bc plane. Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (45.7%) and H⋯C/C⋯H (20.2%) contacts.

A click chemistry approach for the synthesis of cyclic ureido tethered coumarinyl and 1-aza coumarinyl 1,2,3-triazoles as inhibitors of Mycobacterium tuberculosis H37Rv and their in silico studies.

Nucleoside bases like uracil, pharmacophoric triazoles and benzimidazolones have been used during the present study to design molecular matrices for antitubercular activity, employing Click Chemistry. Click triazoles 4/7/10 have been obtained by the reaction of 4-(Azidomethyl)-2H-chromen-2-ones/quinolin-2(1H)-ones 3 and propargyl ethers 2/6/9 derived from theophylline/6-methyl uracil/2-benzimidazolone respectively. In addition to spectral data structures have been confirmed by single crystal X-ray diffraction studies in case of uracil bis alkyne (6) and theophylline mono triazole (4c). Theophylline linked mono triazoles, 4(a-d) and 6-methyl uracil linked bis triazoles, 7(a-e) have been found to inhibit Mycobacterium tuberculosis H37Rv with MIC values in the range 55.62-115.62 µM. Benzimidazolone bis triazoles, 10(a-n) showed better activity with MIC in the range 2.33-18.34 µM. Molecular modeling studies using Surflex-Dock algorithm supported our results.

Crystal structure of 4-(4b,8a-di-hydro-9H-pyrido[3,4-b]indol-1-yl)-7-methyl-2H-chromen-2-one.

The title compound, C21H14N2O2, was prepared by Pictet-Spengler cyclization of tryptamine and 4-formyl coumarin. In the mol-ecule, the dihedral angle between the mean planes of the coumarin and ß-carboline ring systems is 63.8 (2)°. In the crystal, mol-ecules are linked via N-H⋯N hydrogen bonds, forming chains along the b-axis direction. Within the chains, there are a number of offset π-π inter-actions present [shortest inter-centroid distance = 3.457 (2) Å].

The crystal structure of 6-(4-chloro-phen-yl)-2-(4-methyl-benz-yl)imidazo[2,1-b][1,3,4]thia-diazole-5-carbaldehyde.

In the title imidazo[2,1-b][1,3,4]thia-diazole derivative, C19H14ClN3OS, the 4-methyl-benzyl and chloro-phenyl rings are inclined to the planar imidazo[2,1-b][1,3,4]thia-diazole moiety (r.m.s. deviation = 0.012 Å) by 64.5 (1) and 3.7 (1)°, respectively. The mol-ecular structure is primarily stabilized by a strong intra-molecular C-H⋯O hydrogen bond, leading to the formation of a pseudo-seven-membered S(7) ring motif, and a short intra-molecular C-H⋯N contact forming an S(5) ring motif. In the crystal, mol-ecules are linked by pairs of C-H⋯S hydrogen bonds, forming inversion dimers. The dimers are linked by C-H⋯O and C-H⋯π inter-actions, forming chains propagating along [110].

Crystal structure of 6,6'-dimethyl-2H,2'H-3,4'-bichromene-2,2'-dione.

In the title compound, C20H14O4, the dihedral angle between the two coumarin ring systems is 52.37 (19)°, showing a gauche arrangement across the C-C bond which links the two units. The carbonyl groups of the two coumarin units adopt an s-trans arrangement. In the crystal, pairs of C-H⋯O hydrogen bonds and π-π inter-actions [centroid-centroid distance = 3.631 (2) Å] connect the mol-ecules into inversion dimers.

Crystal structure of 3-({[(morpholin-4-yl)carbono-thio-yl]sulfan-yl}acet-yl)phenyl benzoate.

In the title compound, C20H19NO4S2, the morpholine ring adopts the expected chair conformation. The central phenyl ring makes dihedral angles of 67.97 (4) and 7.74 (3)°, respectively, with the benzoate phenyl ring and the morpholine mean plane. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming zigzag chains along the b-axis direction. C-H⋯π inter-actions link centrosymmetrically related mol-ecules, reinforcing the three-dimensional structure.

Crystal structure of 3-[(E)-2-(4-phenyl-1,3-thia-zol-2-yl)hydrazin-1-yl-idene]indolin-2-one.

In the title mol-ecule, C17H12N4OS, the thia-zole ring forms a dihedral angle of 10.8 (2)° with the phenyl ring and an angle of 3.1 (3)° with the indole ring system [which has a maximum deviation of 0.035 (2) Å]. The dihedral angle between the planes of the phenyl ring and the indole ring system is 11.5 (1)°. An intra-molecular N-H⋯O hydrogen bond is observed. In the crystal, pairs of N-H⋯O hydrogen bonds form inversion dimers with an R (2) 2(8) graph-set motif.

4-{[Bis(2-hy-droxy-eth-yl)amino]-meth-yl}-6-meth-oxy-2H-chromen-2-one.

In the title compound, C(15)H(19)NO(5), an intra-molecular O-H⋯O hydrogen bond links the hy-droxy-ethyl side chains, forming a seven-membered ring. In the crystal, mol-ecules are linked into chains via O-H⋯O hydrogen bonds along the b axis. Further, mol-ecules are linked by weak inter-molecular C-H⋯O and π-π stacking inter-actions [centroid-centroid distance = 3.707 (4) Å].