3-Ethyl-4-methyl-1H-pyrazol-2-ium-5-olate.

The title compound, C(6)H(10)N(2)O, is a zwitterionic pyrazole derivative. The crystal packing is predominantly governed by a three-center iminium-amine N(+)-H⋯O(-)⋯H-N inter-action, leading to an undulating sheet-like structure lying parallel to (100).

4-{[5-(4-Chloro-phen-yl)-1-(4-fluoro-phen-yl)-1H-pyrazol-3-yl]carbon-yl}-N-ethyl-piperazine-1-carboxamide.

The asymmetric unit of the title compound, C(23)H(23)ClFN(5)O(2), contains two crystallographically independent mol-ecules. In one mol-ecule, the pyrazole ring makes dihedral angles of 43.93 (7) and 35.82 (7)°, respectively, with the fluoro- and chloro-substituted benzene rings, while the corresponding angles in the other mol-ecule are 52.26 (8) and 36.85 (7)°. The piperazine rings adopt chair conformations. In the crystal, adjacent mol-ecules are connected via inter-molecular N-H⋯O, C-H⋯F, C-H⋯N and C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to the bc plane. The crystal structure is further stabilized by a weak π-π inter-action with a centroid-centroid distance of 3.6610 (8) Šand by C-H⋯π inter-actions.

1,3-Dimethyl-4-phenyl-sulfanyl-1H-pyrazol-5-ol.

In the title compound, C(11)H(12)N(2)OS, the pyrazole ring makes a dihedral angle of 85.40 (8)° with the phenyl ring. In the crystal, inter-molecular N-H⋯O and C-H⋯O hydrogen bonds link mol-ecules into a two-dimensional network parallel to the bc plane.

5-Ethyl-4-phenyl-1H-pyrazol-3(2H)-one.

The asymmetric unit of the title compound, C(11)H(12)N(2)O, consists of two crystallographically independent mol-ecules (A and B) with similar geometries. Both mol-ecules exist in a keto form, the C=O bond length being 1.286 (2) Šin A and 1.283 (2) Šin B. The dihedral angles between the pyrazole ring and the attached phenyl ring are 43.28 (12) and 46.88 (11)°, respectively, for A and B. The ethyl unit in mol-ecule B is disordered over two positions with a site-occupancy ratio of 0.508 (5):0.492 (5). In the crystal, each of the independent mol-ecules forms a centrosymmetric dimer with an R(2) (2)(8) ring motif through a pair of N-H⋯O hydrogen bonds. These dimers are further connected into a three-dimensional network by inter-molecular N-H⋯O and C-H⋯O hydrogen bonds. Inter-molecular C-H⋯π inter-actions are also present.

3-Isobutyl-4-phenyl-sulfan-yl-1H-pyrazol-5-ol.

The asymmetric unit of the title compound, C(13)H(16)N(2)OS, contains two independent mol-ecules (A and B). The pyrazole ring [maximum deviations = 0.0049 (17) Šin mol-ecule A and 0.0112 (19) Šin mol-ecule B] makes a dihedral angle of 70.23 (11) and 73.18 (12)° with the phenyl ring in mol-ecules A and B, respectively. The isobutyl group in mol-ecule B is disordered over two sets of sites with a ratio of refined occupancies of 0.858 (5):0.142 (5). In the crystal, mol-ecules A and B are linked via a pair of inter-molecular N-H⋯O hydrogen bonds, generating an R(2) (2)(8) ring motif. These ring motifs are further linked into two-dimensional arrays parallel to the bc plane by inter-molecular N-H⋯O and weak C-H⋯S hydrogen bonds. The crystal is further stablized by weak π-π inter-actions [centroid-centroid distances = 3.5698 (13) and 3.5287 (12) Å].

5-Ethyl-2-(4-fluoro-phen-yl)-4-phen-oxy-1H-pyrazol-3(2H)-one.

In the title compound, C(17)H(15)FN(2)O(2), the essentially planar pyrazole ring [maximum deviation = 0.026 (1) Å] makes dihedral angles of 72.06 (7) and 33.05 (7)°, with the phenyl and fluoro-benzene rings, respectively. The dihedral angle between the two six-membered rings is 87.88 (7)°. In the crystal, inter-molecular N-H⋯O and C-H⋯F hydrogen bonds link the mol-ecules into layers lying parallel to the bc plane.

Synthesis and antimicrobial activities of novel 1,5-diaryl pyrazoles.

Novel 1,5-diaryl pyrazole derivatives viz. 5-(4-chlorophenyl)-1-(4-fluorophenyl)-1H-pyrazole-3-carboxamides (2a-e, 3, 3a-f), 2-(5-(4-chlorophenyl)-1-(4-fluorophenyl)-1H-pyrazole-3-yl)thiazoles (6a-c,7, 8, 9a-c, 10, 11) were synthesized by varying the active part (amide group) of pyrazole, characterized using IR, (1)H NMR, mass spectral data and screened for their antibacterial activity against Escherichia coli (ATTC-25922), Staphylococcus aureus (ATTC-25923), Pseudomonas aeruginosa (ATTC-27853), Klebsiella pneumonia. Similarly all these compounds were screened for their antifungal activity against Aspergillus flavus (NCIM No. 524), Aspergillus fumigates (NCIM No. 902), Penicillium marneffei and Trichophyton mentagrophytes. Interestingly all the synthesized compounds exhibited good antibacterial (except 2a-c, 8, 9a) and antifungal activity (except 2a-c, 6a, 8, 9a).

N,N'-Bis(4-fluoro-phen-yl)urea.

The asymmetric unit of the title compound, C(13)H(10)F(2)N(2)O, contains one and a half N,N'-bis-(4-fluoro-phen-yl)urea mol-ecules. One of the mol-ecules has crystallographic twofold rotation symmetry. The benzene rings are twisted from each other by dihedral angles of 29.69 (6)° for the mol-ecule in a general position and 89.83 (6)° for the symmetry-generated mol-ecule. In the crystal structure, a pair of inter-molecular N-H⋯O hydrogen bonds link symmetry-related mol-ecules into chains along the b axis, forming R(2) (1)(6) ring motifs.

5-Ethyl-4-methyl-1H-pyrazol-3(2H)-one.

In the title compound, C(6)H(10)N(2)O, the 2,3-dihydro-1H-pyrazole ring is approximately planar, with a maximum deviation of 0.013 (1) Å. Pairs of inter-molecular N-H⋯O hydrogen bonds link neighboring mol-ecules into dimers, generating R(2) (2)(8) ring motifs. These dimers are further linked into two-dimensional arrays parallel to the bc plane by inter-molecular N-H⋯O hydrogen bonds. The crystal structure is further stabilized by C-H⋯π inter-actions.

5-Pentyl-4-phenyl-sulfonyl-1H-pyrazol-3-ol.

In the title compound, C(14)H(18)N(2)O(3)S, the 1H-pyrazole ring is approximately planar, with a maximum deviation of 0.005 (1) Å. The dihedral angle formed between the 1H-pyrazole and phenyl rings is 79.09 (5)°. Pairs of inter-molecular N-H⋯O and O⋯H⋯N hydrogen bonds form dimers between neighboring mol-ecules, generating R(2) (2)(10) ring motifs. These dimers are further linked by intermolecular N-H⋯O and O-H⋯N hydrogen bonds into two-dimensional arrays parallel to the ac plane. The crystal structure is also stabilized by C-H⋯π inter-actions.