B. Chandrakantha

Synthesis and biological evaluation of novel substituted 1,3,4-thiadiazole and 2,6-di aryl substituted imidazo [2,1-b] [1,3,4] thiadiazole derivatives.

A new series of N-[5-(4-(alkyl/aryl)-3-nitro-phenyl)-[1,3,4-thiadiazol-2-yl]-2,2-dimethyl-propionamide 4 (a-l) and 6-(4-Methoxy-phenyl)-2-(4-alkyl/aryl)-3-nitro-phenyl)-Imidazo [2,1-b] [1,3,4] thiadiazole 6 (a-l) were synthesized starting from 5-(4-Fluoro-3-nitro-phenyl)-[1,3,4] thiadiazole-2-ylamine. The synthesized compounds were characterized by IR, NMR, mass spectral and elemental analysis. All the compounds were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by well plate method (zone of inhibition). Compounds 4a, 4c and 6e, 6g displayed appreciable activity at the concentration 0.5-1.0 mg/mL.

4-(3-Chloro­phen­yl)-3-[(2,6-difluoro­benz­yl)sulfan­yl]-5-(3,4,5-trimeth­oxy­phen­yl)-4H-1,2,4-triazole

In the title compound, C24H20ClF2N3O3S, the essentially planar triazole ring (r.m.s. deviation = 0.001 Å) forms dihedral angles of 22.35 (10), 68.17 (10) and 42.01 (10)° with the mean planes of the trimethoxyphenyl, chlorophenyl and difluorophenyl rings, respectively. A weak intramolecular C—H⋯π interaction occurs. In the crystal, molecules are linked into sheets lying parallel to the bc plane by C—H⋯O and C—H⋯N hydrogen bonds. The crystal packing also features weak C—H⋯π interactions.

2,6-DICHLORO-3-NITRO-PYRIDINE

The asymmetric unit of the title compound, C5H2Cl2N2O2, consists of two crystallographically independent molecules. The pyridine ring in each molecule is essentially planar, with maximum deviations of 0.004 (4) and 0.007 (4) Å. Short Cl⋯O [3.09 (3) and 3.13 (4) Å] and Cl⋯Cl [3.38 (12) Å] contacts were observed. No significant intermolecular interactions were observed in the crystal packing.

Ethyl 1,5-diphenyl-1H-pyrazole-4-carboxyl­ate

The asymmetric unit of the title compound, C18H16N2O2, contains two independent molecules (A and B). In molecule A, the pyrazole ring is inclined at angles of 48.86 (6) and 60.80 (6)° with respect to the two phenyl rings; the corresponding angles for molecule B are 46.86 (6) and 58.63 (6)°. In the crystal, molecules of type A are linked into sheets parallel to (001) via weak C—H⋯O hydrogen bonds, whereas the molecules of type B are linked into chains along [010] via weak C—H⋯O hydrogen bonds.

4-(1,2,4-Triazol-1-yl)aniline

In the title compound, C8H8N4, the dihedral angle between the triazole ring [maximum deviation = 0.003 (1) Å] and the benzene ring is 34.57 (7)°. In the crystal, molecules are linked into sheets lying parallel to the ac plane via intermolecular N—H⋯N and C—H⋯N hydrogen bonds. Aromatic π–π [centroid–centroid distance = 3.6750 (8) Å] stacking and N—H⋯π interactions are also observed.

Ethyl 1-tert-butyl-5-phenyl-1H-pyrazole-4-carboxyl­ate

In the title compound, C16H20N2O2, the pyrazole ring is essentially planar [maximum deviation = 0.008 (2) Å] and is inclined at an angle of 82.82 (10)° with respect to the phenyl ring. The crystal packing is consolidated by pairs of intermolecular C—H⋯O hydrogen bonds, which link the molecules into centrosymmetric dimers stacked along the a axis.

Redetermination of the structure of 4-amino-benzonitrile, C7H6N2

Abstract C7H6N2, monoclinic, P21/c (no. 14), a = 7.2382(6) Å, b = 5.4770(4) Å, c = 16.040(2) Å, β = 101.680(4)°, V = 622.7 Å3, Z = 4, Rgt(F) = 0.0500, wRref(F2) = 0.1377, T = 200 K.

Quinolin-3-amine.

In the crystal structur of the achiral title compound, C9H8N2, N—H⋯N hydrogen bonds connect the molecules into zigzag chains in [100]. Weak intermolecular N–H⋯π interactions further consolidate the crystal packing.

5-[(4-Meth­oxy­benz­yl)sulfan­yl]-2-methyl-1,3,4-thia­diazole

The title molecule, C11H12N2OS2, is twisted with a dihedral angle of 83.63 (12)° between the 1,3,4-thiadiazole and benzene rings. The methoxy group deviates slightly from the attached benzene ring, with a C—C—O—C torsion angle of 4.2 (4)°. In the crystal, molecules are linked by weak C—H⋯N interactions and stacked along the c axis.

4-(o-Tol-yl)piperazin-1-ium chloride.

In the title molecular salt, C11H17N2 +·Cl−, the piperazin-1-ium ring adopts a chair conformation with the aromatic ring in a pseudo-equatorial orientation. The dihedral angle between the benzene ring and the mean plane of the piperazin-1-ium ring is 51.22 (6)°. In the crystal, N—H⋯Cl hydrogen bonds link the molecules into chains propagating in [100]. Weak C—H⋯π interactions also ocur.