Heteroaryl chalcones: design, synthesis, X-ray crystal structures and biological evaluation.

Chalcone derivatives have attracted increasing attention due to their numerous pharmacological activities. Changes in their structures have displayed high degree of diversity that has proven to result in a broad spectrum of biological activities. The present study highlights the synthesis of some halogen substituted chalcones 3(a-i) containing the 5-chlorothiophene moiety, their X-ray crystal structures and the evaluation of possible biological activities such as antibacterial, antifungal and reducing power abilities. The results indicate the tested compounds show a varied range of inhibition values against all the tested microbial strains. Compound 3c with a p-fluoro substituent on the phenyl ring exhibits elevated antimicrobial activity, whereas the compounds 3e and 3f displayed the least antimicrobial activities. The compounds 3d, 3e, 3f and 3i showed good ferric and cupric reducing abilities, and the compounds 3b and 3c showed the weakest reducing power in the series.

Structural correlation of some heterocyclic chalcone analogues and evaluation of their antioxidant potential.

A series of six novel heterocyclic chalcone analogues 4(a-f) has been synthesized by condensing 2-acetyl-5-chlorothiophene with benzaldehyde derivatives in methanol at room temperature using a catalytic amount of sodium hydroxide. The newly synthesized compounds are characterized by IR, mass spectra, elemental analysis and melting point. Subsequently; the structures of these compounds were determined using single crystal X-ray diffraction. All the synthesized compounds were screened for their antioxidant potential by employing various in vitro models such as DPPH free radical scavenging assay, ABTS radical scavenging assay, ferric reducing antioxidant power and cupric ion reducing antioxidant capacity. Results reflect the structural impact on the antioxidant ability of the compounds. The IC0 values illustrate the mild to good antioxidant activities of the reported compounds. Among them, 4f with a p-methoxy substituent was found to be more potent as antioxidant agent.

(Z)-N-[2-(N'-Hy-droxy-carbamimido-yl)phen-yl]acetamide.

The asymmetric unit of the title compound, C9H11N3O2, contains two mol-ecules (A and B), which exist in Z conformations with respect to their C=N double bond. The dihedral angles between the benzene ring and the pendant hy-droxy-carbamimidoyl and acetamide groups are 28.58 (7) and 1.30 (5)°, respectively, in mol-ecule A and 25.04 (7) and 27.85 (9)°, respectively, in mol-ecule B. An intra-molecular N-H⋯N hydrogen bond generates an S(6) ring in both mol-ecules. Mol-ecule A also features an intra-molecular C-H⋯O inter-action, which closes an S(6) ring. In the crystal, the mol-ecules are linked by N-H⋯O, N-H⋯N, O-H⋯O, O-H⋯N, C-H⋯O and C-H⋯N hydrogen bonds and C-H⋯π inter-actions, generating a three-dimensional network.

4-(4-Bromo-phen-yl)-1-(2,6-difluoro-benz-yl)-3-(3,4,5-trimeth-oxy-phen-yl)-1H-1,2,4-triazole-5(4H)-thione.

In the title compound, C(24)H(20)BrF(2)N(3)O(3)S, the triazole ring (r.m.s. deviation = 0.0107 Å) makes dihedral angles of 28.18 (14), 63.76 (14) and 77.01 (18)°, respectively, with the trimeth-oxy-, bromo-, and difluoro-substituted benzene rings. The C atoms of the meta meth-oxy groups are roughly coplanar with their ring [displacements = -0.289 (4) and 0.083 (7) Å], whereas the C atom of the para group is displaced [1.117 (3) Å]. In the crystal, inversion dimers linked by two pairs of C-H⋯O hydrogen bonds occur. The ring motif of the two hydrogen bonds to their symmetry-generated O-atom acceptors is R(2) (2)(8).

2-[(E)-4-Diethyl-amino-2-hy-droxy-benzyl-idene]hydrazinecarboxamide.

Two mol-ecules make up the asymmetric unit of the title compound, C(12)H(18)N(4)O(2), and both feature an intra-molecular O-H⋯N hydrogen bond, which generates an S(6) ring. The diethyl-amino group of one of the mol-ecules is disordered over two sets of sites in a 0.59 (2):0.41 (2) ratio. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into sheets lying parallel to the ac plane and C-H⋯π inter-actions are also observed.

Ethyl 1-(2,4-dichloro-benz-yl)-4-oxo-7-trifluoro-meth-yl-1,4-dihydro-quinoline-3-carboxyl-ate.

In the title compound, C(20)H(14)Cl(2)F(3)NO(3), the trifluromethyl group is disordered over two sets of sites in a 0.784 (10):0.216 (10) ratio. The quinoline ring system is essentially planar with a maximum deviation of 0.058 (2) Šfor the N atom and forms dihedral angles of 89.23 (11) and 8.13 (17)°, respectively with the mean planes of the benzene ring and the carboxyl-ate group. In the crystal, pairs of weak C-H⋯O and C-H⋯F hydrogen bonds link mol-ecules into centrosymmetric dimers. The crystal structure is further stabilized by weak π-π [centroid-centroid distance = 3.624 (2) Å] inter-actions.

3-(3-Cyano-benz-yl)-1-methyl-1H-imidazol-3-ium hexa-fluoro-phosphate.

In the title compound, C(12)H(12)N(3) (+)·PF(6) (-), the hexa-fluoro-phosphate anion is disordered over two orientations with refined site occupancies of 0.8071 (17) and 0.1929 (17). The dihedral angle between the imidazole and benzene rings in the cation is 71.26 (7)°. In the crystal, the cations and anions are linked by C-H⋯F and C-H⋯N hydrogen bonds into a three-dimensional network.

Ethyl 4-{[1-(2,4-dichloro-benz-yl)-1H-1,2,3-triazol-4-yl]meth-oxy}-8-(trifluoro-meth-yl)quinoline-3-carboxyl-ate.

In the title compound, C(23)H(17)Cl(2)F(3)N(4)O(3), the triazole ring makes dihedral angles of 50.27 (6) and 82.78 (7)° with the quinoline ring system and the dichloro-substituted benzene ring. The dihedral angle between the quinoline and dichloro-substituted benzene rings is 38.17 (4)°. In the crystal, mol-ecules are linked via C-H⋯N, C-H⋯F and C-H⋯O hydrogen bonds into a three-dimensional network. The crystal is further consolidated by C-H⋯π contacts to the triazole ring and inversion-related π-π inter-actions between the benzene and pyridine rings of quinoline systems [centroid-centroid distance = 3.7037 (7) Å].

[2,6-Bis(biphenyl-4-yl)-4-hy-droxy-4-(pyridin-2-yl)cyclo-hexane-1,3-di-yl]bis-[(pyridin-2-yl)methanone]-butan-2-one (1/1).

In the title solvate, C(47)H(37)N(3)O(3)·C(4)H(8)O, the cyclo-hexane ring adopts a chair conformation and the plane through its near coplanar atoms forms dihedral angles of 82.58 (7), 89.27 (7), 60.30 (8), 54.54 (7) and 72.03 (7)°, respectively, with the three pyridine rings and the two attached benzene rings. The rings of the biphenyl units are twisted from each other, making dihedral angles of 35.27 (7) and 45.41 (7)°. All the rings are in equatorial orientations in the cyclo-hexane ring, except for the C=O-bonded pyridine ring in position 1, which is axial. Intra-molecular O-H⋯N and C-H⋯O hydrogen bonds form one S(5) and three S(6) ring motifs. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds into a chain along the c axis. The crystal structure also features weak C-H⋯π inter-actions and aromatic π-π stacking [centroid-centroid distances = 3.5856 (10) and 3.7090 (9) Å].

(Z)-3-(4-Methyl-phen-yl)-2-[(2-phenyl-cyclo-hex-2-en-1-yl)imino]-1,3-thia-zol-idin-4-one.

The title compound, C(22)H(22)N(2)OS, exists in a cis conformation with respect to the N=C bond. The cyclo-hexene ring adopts a distorted sofa conformation. The thia-zolidine ring is essentially planar with a maximum deviation of 0.025 (2) Šand forms dihedral angles of 63.50 (7) and 57.52 (6)° with the benzene rings. In the crystal, mol-ecules are linked by C-H⋯O and C-H⋯N hydrogen bonds, generating R(2) (2)(8) ring motifs, and forming infinite chains along the c axis. The crystal is further consolidated by C-H⋯π inter-actions.

(Z)-3-(4-Bromo-phen-yl)-2-[(2-phenyl-cyclo-hex-2-en-1-yl)imino]-1,3-thia-zol-idin-4-one.

The title compound, C(21)H(19)BrN(2)OS, exists in a cis conformation with respect to the N=C bond [1.2602 (14) Å]. The cyclo-hexene ring adopts a distorted half-chair conformation and the C-N bond lies in an equatorial orientation. The thia-zolidine ring forms dihedral angles of 53.76 (7) and 57.22 (7)° with the benzene and bromo-substituted benzene rings, respectively. The dihedral angle between the benzene and bromo-substituted benzene rings is 76.06 (7)°. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds generate R(2) (2)(14) loops. The crystal is further consolidated by weak C-H⋯π inter-actions.

(Z)-3-(4-Chloro-phen-yl)-2-(2-phenyl-cyclo-hex-2-en-1-yl-imino)-thia-zolidin-4-one.

The title compound, C(21)H(19)ClN(2)OS, exists in a cis conformation with respect to the N=C bond [1.2608 (13) Å]. The cyclo-hexene ring adopts a distorted half-chair conformation. The thia-zolidine ring is close to being planar (r.m.s. deviation = 0.057 Å) and makes dihedral angles of 62.92 (6) and 56.32 (6)°, respectively, with the benzene ring and the chloro-substituted benzene ring. The dihedral angle between the benzene ring and the chloro-substituted benzene ring is 72.91 (6)°. In the crystal, mol-ecules are linked by C-H⋯O and C-H⋯N hydrogen bonds into undulating sheets lying parallel to the bc plane. The crystal is further consolidated by C-H⋯π inter-actions.

Dimethyl 4-[3-(4-meth-oxy-phen-yl)-1-phenyl-1H-pyrazol-4-yl]-2,6-dimethyl-1,4-dihydro-pyridine-3,5-dicarboxyl-ate dihydrate.

In the title compound, C(27)H(27)N(3)O(5)·2H(2)O, the dihydro-pyridine ring adopts a flattened boat conformation. The central pyrazole ring is essentially planar [maximum deviation of 0.003 (1) Å] and makes dihedral angles of 50.42 (6) and 26.44 (6)° with the benzene rings. In the crystal, mol-ecules are linked via N-H⋯O, O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds into two-dimensional networks parallel to the bc plane. The crystal structure is further consolidated by weak C-H⋯π inter-actions.

1-(6-Chloro-1,3-benzothia-zol-2-yl)hydrazine.

The asymmetric unit of the title compound, C(7)H(6)ClN(3)S, consists of two crystallographically independent mol-ecules (A and B). The dihedral angle between the benzothia-zole ring system and the hydrazine group is 8.71 (6)° in mol-ecule A and 7.16 (6)° in mol-ecule B. The N-N-C-N and N-N-C-S torsion angles involving the hydrazine group are 170.89 (9) and -9.96 (13)°, respectively, in mol-ecule A and 172.50 (9) and -7.43 (13)°, respectively, in mol-ecule B. In the crystal, neighbouring mol-ecules are connected via pairs of N-H⋯N hydrogen bonds, generating R(2) (2)(8) ring motifs, and are connected further by N-H⋯N hydrogen bonds into sheets lying parallel to the ab plane. The crystal studied was an inversion twin, the refined ratio of the twin components being 0.50 (3):0.50 (3).

Diethyl 2,6-dimethyl-4-(5-phenyl-1H-pyrazol-4-yl)-1,4-dihydro-pyridine-3,5-dicarboxyl-ate.

In the title compound, C(22)H(25)N(3)O(4), the dihydro-pyridine ring adopts a flattened boat conformation. The pyrazole ring makes a dihedral angle of 29.04 (5)° with the benzene ring. The mol-ecular structure is stabilized by an intra-molecular C-H⋯O hydrogen bond which generates an S(9) ring motif. In the crystal, mol-ecules are linked via N-H⋯O and C-H⋯N hydrogen bonds into a two-dimensional network parallel to the ab plane. The crystal structure is further consolidated by weak C-H⋯π inter-actions.

2,2-Diphenyl-N-(1,3-thia-zol-2-yl)acetamide.

In the title mol-ecule, C(17)H(14)N(2)OS, the mean plane of the acetamide group forms dihedral angles of 75.79 (5), 81.85 (6) and 12.32 (5)° with the two phenyl rings and the thia-zole ring, respectively. In the crystal, N-H⋯N hydrogen bonds link pairs of mol-ecules into inversion dimers with R(2) (2)(8) ring motifs. The crystal packing is further stabilized by C-H⋯π inter-actions and by π-π inter-actions with a centroid-centroid distance of 3.6977 (5) Å.

N-(3,4-Difluoro-phen-yl)-2,2-diphenyl-acetamide.

In the title compound, C(20)H(15)F(2)NO, the mean plane of the acetamide group makes dihedral angles of 88.26 (6), 78.30 (7) and 9.83 (6)° with the two terminal benzene rings and difluoro-substituted benzene ring, respectively. One F atom is disordered over two orientations rotated by 180°, with a site-occupancy ratio of 0.557 (2):0.443 (2). An intra-molecular C-H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, mol-ecules are linked via N-H⋯O hydrogen bonds into chains along the c axis. The crystal structure is further consolidated by C-H⋯π inter-actions.

4-Methyl-benzoic acid-N'-[(E)-4-methyl-benzyl-idene]pyridine-4-carbohydrazide-water (1/1/1).

In the title hydrated 1:1 adduct, C(8)H(8)O(2)·C(14)H(13)N(3)O·H(2)O, the Schiff base mol-ecule exists in an E conformation with respect to the N=C bond [1.2843 (13) Å] and the dihedral angle between the pyridine ring and the benzene ring is 1.04 (5)°. In the crystal, mol-ecules are linked by N-H⋯O, C-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds into sheets lying parallel to the ab plane. The crystal structure also features π-π inter-actions with centroid-centroid distances of 3.6224 (6) and 3.7121 (6) Å.

3-Chloro-4-methyl-quinolin-2(1H)-one.

The title compound, C(10)H(8)ClNO, is almost planar (r.m.s. deviation for the 13 non-H atoms = 0.023 Å). In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds generate R(2) (2)(8) rings. Weak aromatic π-π stacking inter-actions [centroid-centroid distance = 3.7622 (12) Å] also occur.

10a-Hy-droxy-9-(4-meth-oxy-phen-yl)-3,4,5,6,7,8a,9,10a-octa-hydro-1H-xanthene-1,8(2H)-dione.

In the title compound, C(20)H(22)O(5), the tetra-hydro-pyran, cyclo-hexene and cyclo-hexane rings of the xanthene ring system adopt half-chair, half-boat and chair conformations, respectively. The mean plane of the four roughly planar atoms of the tetra-hydro-pyran ring (r.m.s. deviation = 0.111 Å) forms a dihedral angle of 82.91 (4)° with the meth-oxy-benzene group. In the crystal, mol-ecules are linked via O-H⋯O and C-H⋯O hydrogen bonds into sheets lying parallel to the ac plane. The crystal is further consolidated by weak C-H⋯π inter-actions.