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 IC 50 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.

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.

Phenacyl benzoates possess commercial importance due to their various applications in the fields of synthetic and photochemistry, such as photosensitive blocking groups owing to their ease of cleavage under mild conditions. In the present study, a series of ten new 2-(4-bromophenyl)-2-oxoethyl benzoates 2(a-j), with the general formula Br(C 6 H 4 )COCH 2 OCO(C 6 H 5Àn X n ), X ¼ Cl, NO 2 or NH 2 , and n ¼ 1 or 2, have been synthesized by reacting 4-bromophenacyl bromide with various substituted benzoic acids using potassium carbonate in DMF medium at room temperature. These reactions proceeded with ease under mild conditions producing high purity products in good yield. Each product was characterized by mass spectra, elemental analysis and melting points, its 3D structure was confirmed by single-crystal X-ray diffraction studies. The X-ray 3D structures showed the flexibility of the C(¼O)-O-C-C(¼O) connecting bridge in which 7 out of 10 compounds tend to form a torsion angle in the range of 70 to 91°, whereas the rest are slightly twisted with a torsion angles of À160, 163, 176 and 178°. Their molecular conformations are in good agreement with another 22 related structures. These synthesized compounds were screened for their abilities for DPPH radical scavenging and ferric reducing anti-oxidant power. The results indicate that these compounds displayed mild anti-oxidant ability when compared to the standard anti-oxidant BHT.

In the title solvate, C47H37N3O3·C4H8O, the cyclo­hexane 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 cyclo­hexane ring, except for the C=O-bonded pyridine ring in position 1, which is axial. Intra­molecular O—H⋯N and C—H⋯O hydrogen bonds form one S(5) and three S(6) ring motifs. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds into a chain along the c axis. The crystal structure also features weak C—H⋯π inter­actions and aromatic π–π stacking [centroid–centroid distances = 3.5856 (10) and 3.7090 (9) Å].

In the title compound, C17H15FN2O, the pyrazoline ring adopts a flattened envelope conformation. The dihedral angle between the fluoro-substituted benzene ring and the phenyl ring is 69.20 (5)°. In the crystal, a pair of C—H⋯O hydrogen bonds link neighbouring mol­ecules, forming an inversion dimer. The crystal structure is further consolidated by C—H⋯π inter­actions and by a π–π inter­action with a centroid–centroid distance of 3.7379 (6) Å.

The title compound, C22H22N2OS, exists in a cis conformation with respect to the N=C bond. The cyclo­hexene ring adopts a distorted sofa conformation. The thia­zolidine ring is essentially planar with a maximum deviation of 0.025 (2) Å and forms dihedral angles of 63.50 (7) and 57.52 (6)° with the benzene rings. In the crystal, mol­ecules 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 inter­actions.

In the title compound, C20H22O5, the tetra­hydro­pyran, cyclo­hexene and cyclo­hexane 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 tetra­hydro­pyran ring (r.m.s. deviation = 0.111 Å) forms a dihedral angle of 82.91 (4)° with the meth­oxy­benzene group. In the crystal, mol­ecules 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 inter­actions.

Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.001 Å; R factor = 0.019; wR factor = 0.052; data-to-parameter ratio = 23.8.The asymmetric unit of the title compound, C 7 H 6 ClN 3 S, consists of two crystallographically independent molecules (A and B). The dihedral angle between the benzothiazole ring system and the hydrazine group is 8.71 (6) in molecule A and 7.16 (6) in molecule B. The N-N-C-N and N-N-C-S torsion angles involving the hydrazine group are 170.89 (9) and À9.96 (13) , respectively, in molecule A and 172.50 (9) and À7.43 (13) , respectively, in molecule B. In the crystal, neighbouring molecules are connected via pairs of N-HÁ Á ÁN hydrogen bonds, generating R 2 2 (8) ring motifs, and are connected further by N-HÁ Á ÁN 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). Related literature