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This paper presents the effects of incorporating thienyl and phenyl rings as the terminal ring in the cinnamoyl counterparts of chalcones with donor-acceptor-donor (D-A-D) push-pull setting, on their photophysical responses. Two fluoro-methoxy substituted chalcone derivatives with distinct cinnamoyl systems, 4-methylthiophene-2-carbaldehyde (2F4MA48) and 2,4-dimethylbenzaldehyde (2F4MA96), were synthesized. Characterization of these chalcone derivatives was performed using nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR) and single-crystal X-ray diffraction (SCXRD). Comparative studies on the linear and nonlinear optical responses were carried out through both experimental analyses and theoretical density functional theory (DFT) calculations. The electronic absorption spectra computed using DFT were compared with the UV-Vis spectra to elucidate the intramolecular charge transfer mechanism via the hole-electron distribution and interfragmentary charge transfer analyses. Molecular properties were examined through electrostatic potential (ESP) maps, π-electron localization function (ELF-π), and frontier molecular orbitals (FMOs). The incorporation of thienyl ring is found to give a stronger push-pull effect and greater electron delocalization. Experimental nonlinear optical responses were investigated using Z-scan technique with a continuous-wave incident laser at a wavelength of 532 nm. Both compounds showed two-photon-induced reverse saturation absorption (RSA) and self-defocusing responses. It was observed that the thienyl-based chalcone, exhibited greater optical nonlinearity in terms of nonlinear absorption (NLA), nonlinear refraction (NLR), and optical limiting. The experimental third-order nonlinear optical susceptibility (χ(3)) was determined to be 8.04 × 10−8 esu for 2F4MA48 and 1.08 × 10−8 esu for 2F4MA96. The onset limiting threshold (FS) was found to be 2.63 kJ cm−2 for 2F4MA48 and 5.23 kJ cm−2 for 2F4MA96. The steep optical limiting traces of 2F4MA48 show superior performance compared to 2F4MA96.

A new series of 3-O-substituted xanthone derivatives were synthesised and evaluated for their anti-cholinergic activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The results indicated that the xanthone derivatives possessed good AChE inhibitory activity with eleven of them (5, 8, 11, 17, 19, 21-23, 26-28) exhibited significant effects with the IC50 values ranged 0.88 to 1.28 µM. The AChE enzyme kinetic study of 3-(4-phenylbutoxy)-9H-xanthen-9-one (23) and ethyl 2-((9-oxo-9H-xanthen-3-yl)oxy)acetate (28) showed a mixed inhibition mechanism. Molecular docking study showed that 23 binds to the active site of AChE and interacts via extensive π–π stacking with the indole and phenol side chains of Trp86 and Tyr337, besides the hydrogen bonding with the hydration site and π–π interaction with the phenol side chain of Y72. This study revealed that 3-O-alkoxyl substituted xanthone derivatives are potential lead structures, especially 23 and 28 which can be further developed into potent AChE inhibitors.

In the title benzohydrazide derivative, C14H12N2O4, the azomethine C=N double bond has an E configuration. The hydrazide connecting bridge, (C=O)—(NH)—N=(CH), is nearly planar with C—C—N—N and C—N—N=C torsion angles of −177.33 (10) and −174.98 (12)°, respectively. The 4-hydroxyphenyl and 3,4-dihydroxyphenyl rings are slightly twisted, making a dihedral angle of 9.18 (6)°. In the crystal, molecules are connected by N—H...O and O—H...O hydrogen bonds into a three-dimensional network, while further consolidated via π–π interactions [centroid–centroid distances = 3.6480 (8) and 3.7607 (8) Å]. The conformation is compared to those of related benzylidene-4-hydroxybenzohydrazide derivatives.

The molecular structure of the title compound, C13H7Cl3OS, consists of a 2,5- dichlorothiophene ring and a 2-chlorophenyl ring linked via a prop-2-en-1-one spacer. The dihedral angle between the 2,5-dichlorothiophene and 2-chlorophenyl rings is 9.69 (12)°. The molecule has an E configuration about the C=C bond and the carbonyl group is syn with respect to the C=C bond. The molecular conformation is stabilized by two intramolecular C—H...Cl contacts and one intramolecular C—H...O contact, forming S(5)S(5)S(6) ring motifs. In the crystal, the molecules are linked along the a-axis direction through van der Waals forces and along the b axis by face-to-face π-stacking between the thiophene rings and between the benzene rings of neighbouring molecules, forming corrugated sheets lying parallel to the bc plane. The intermolecular interactions in the crystal packing were further analysed using Hirshfield surface analysis, which indicates that the most significant contacts are Cl...H/ H...Cl (28.6%), followed by C...H/H...C (11.9%), C...C (11.1%), H...H (11.0%), Cl...Cl (8.1%), O...H/H...O (8.0%) and S...H/H...S (6.6%).

In the title chalcone derivative, C15H9BrCl2O, the aryl rings are inclined to each by 14.49 (17)°, and the configuration about the C=C bond is E. There is a short intramolecular C—H...Cl contact present resulting in the formation of an S(6) ring motif. In the crystal, the shortest intermolecular contacts are Cl...O contacts [3.173 (3) Å] that link the molecules to form a 21 helix propagating along the b-axis direction. The helices stack up the short crystallographic a axis, and are linked by offset π–π interactions [intercentroid distance = 3.983 (1) Å], forming layers lying parallel to the ab plane. A quantification of the intermolecular contacts in the crystal were estimated using Hirshfeld surface analysis and two-dimensional fingerprint plots.

A new polymorphic form of the title compound, C8H8O3, is described in the centrosymmetric monoclinic space group P21/c with Z′ = 1 as compared to the first polymorph, which crystallizes with two conformers (Z′ = 2) in the asymmetric unit in the same space group. In the crystal of the second polymorph, inversion dimers linked by O—H...O hydrogen bonds occur and these are linked into zigzag chains, propagating along the b-axis direction by C—H...O links. The crystal structure also features a weak π–π interaction, with a centroid-to-centroid distance of 3.8018 (6) Å. The second polymorph of the title compound is less stable than the reported first polymorph, as indicated by its smaller calculated lattice energy.

In this study, a new monoclinic polymorph (space group C2/c) of 2,2′-methylenebis(isoindoline-1,3-dione), C17H10N2O4, is reported and compared to the previously reported triclinic polymorph (space group P\overline{1}). Similarly, both polymorphs consist of a unique molecule in the asymmetric unit (Z′ = 1). The molecular conformations of the two polymorphs are very similar, as shown by the r.m.s. deviation of 0.368 Å (excluding all H atoms). The intermolecular interactions of both polymorphs are described along with the Hirshfeld surface analysis, and the lattice energies are calculated.

The molecular structure of the title chalcone derivative, C15H10FNO3, is nearly planar and the molecule adopts a trans configuration with respect to the C=C double bond. The nitro group is nearly coplanar with the attached benzene ring, which is nearly parallel to the second benzene ring. In the crystal, molecules are connected by pairs of weak intermolecular C—H...O hydrogen bonds into inversion dimers. The dimers are further linked by another C—H...O hydrogen bond and a C—H...F hydrogen bond into sheets parallel to (104). π–π interactions occur between the sheets, with a centroid–centroid distance of 3.8860 (11) Å. Hirshfeld surface analysis was used to investigate and quantify the intermolecular interactions.

The molecular structure of the title compound, C13H6Cl4OS, consists of a 2,5-dichlorothiophene ring and a 2,4-dichlorophenyl ring linked via a prop-2-en-1-one spacer. The dihedral angle between the 2,5-dichlorothiophene ring and the 2,4-dichlorophenyl ring is 12.24 (15)°. The molecule has an E configuration about the C=C bond and the carbonyl group is syn with respect to the C=C bond. The molecular conformation is stabilized by intramolecular C—H...Cl contacts, producing S(6) and S(5) ring motifs. In the crystal, the molecules are linked along the a-axis direction through face-to-face π-stacking between the thiophene rings and the benzene rings of the molecules in zigzag sheets lying parallel to the bc plane along the c axis. The intermolecular interactions in the crystal packing were further analysed using Hirshfield surface analysis, which indicates that the most significant contacts are Cl...H/ H...Cl (20.8%), followed by Cl...Cl (18.7%), C...C (11.9%), Cl...S/S...Cl (10.9%), H...H (10.1%), C...H/H...C (9.3%) and O...H/H...O (7.6%).

In the molecule of the title compound, C17H14BrFO3, the aromatic rings are tilted with respect to the enone bridge by 13.63 (14) and 4.27 (15)°, and form a dihedral angle 17.91 (17)°. In the crystal, centrosymmetrically related molecules are linked by pairs of C—H...O hydrogen bonds into dimeric units, forming rings of R22(14) graph-set motif. The dimers are further connected by weak C—H...O hydrogen interactions, forming layers parallel to (10\overline{1}). Hirshfeld surface analysis shows that van der Waals interactions constitute the major contribution to the intermolecular interactions, with H...H contacts accounting for 29.7% of the surface.

In the title chalcone–thiophene derivative, C13H6Cl3FOS, the aromatic rings are inclined to one another by 12.9 (2)°, and the thiophene ring is affected by π-conjugation. In the crystal, molecules are linked by C—H...F hydrogen bonds, forming an R22(8) ring motif. A Hirshfeld surface analysis was conducted to verify the contribution of the different intermolecular interactions. The shape-index surface clearly shows that the two sides of the molecules are involved in the same contacts with neighbouring molecules and the curvedness plots show flat surface patches characteristic of planar stacking.

In the cation of the title salt, C17H23N2O+·Br−, the adamantyl moiety and the pyridiniminium ring are inclined to the ketone bridge by torsion angles of −78.1 (2) (C—C—C=O) and 58.3 (2)° (C—C—N—C), respectively, and the ketone bridge has a C—C—C—N torsion angle of 174.80 (15)°. In the crystal, the cations are connected into chains parallel to the c axis by C—H...O hydrogen bonds. The chains are further linked into layers parallel to the bc plane by N—H...Br and C—H...Br hydrogen bonds, C—H...π interactions and π–π stacking interactions [centroid-to-centroid distance = 3.5657 (11) Å]. A Hirshfeld surface analysis, which comprises the dnorm surface, electrostatic potential map and two-dimensional fingerprint plots, was carried out to verify the contribution of the various intermolecular interactions.

In title compound, C17H15ClO3, the dihedral angle between the benzene and chlorophenyl rings is 18.46 (7)°. In the crystal, molecules are linked by C—H...O hydrogen contacts, enclosing an R22(14) ring motif, and by a further C—H...O hydrogen contact, forming a two-dimensional supramolecular structure extending along the direction parallel to the ac plane. Hirshfeld surface analysis shows that van der Waals interactions constitute the major contribution to the intermolecular interactions, with H...H contacts accounting for 36.2% of the surface.

In the bischalcone molecule of the title compound, C24H18O4·2C3H7NO, the central benzene and terminal hydroxyphenyl rings form a dihedral angle of 14.28 (11)° and the central C=C double bond adopts a trans configuration. In the crystal, the bischalcone and solvate molecules are interconnected via O—H...O hydrogen bonds, which were investigated by Hirshfeld surface analysis. Solid-state fluorescence was measured at λex = 4400 Å. The emission wavelength appeared at 5510 Å, which corresponds to yellow light and the solid-state fluorescence quantum yield (Ff) is 0.18.

In the cation of the title salt, C20H19N2O+·Br−, the phenyl rings are inclined to one another by 38.38 (8)°, whereas the central phenyl ring and the pyridiniminium ring are almost perpendicular with a dihedral angle of 87.37 (9)°. The N+=C cationic double bond was verified by the shortened bond length of 1.337 (2) Å. In the crystal, the Br− anion is linked to the cation by an N—H...Br hydrogen bond. C—H...O hydrogen bonds link adjacent pyridiniminium cations into inversion dimers with an R22(18) graph-set motif. These dimers are stacked in a phenyl–phenyl T-shaped geometry through C—H...π interactions. A Hirshfeld surface analysis was conducted to verify the contributions of the different intermolecular interactions.

The asymmetric unit of the title compound, C24H14F4O2, comprises of one and a half molecules; the half-molecule is completed by crystallographic inversion symmetry. In the crystal, molecules are linked into a three-dimensional network by C—H...F and C—H...O hydrogen bonds. Some of the C—H...F links are unusually short (< 2.20 Å). Hirshfeld surface analyses (dnorm surfaces and two-dimensional fingerprint plots) for the title compound are presented and discussed.

The asymmetric unit of the title compound, C15H15N3O3·0.5H2O, comprises two 2-{[(4-iminiumyl-3-methyl-1,4-dihydropyridin-1-yl)methyl]carbamoyl}benzoate zwitterions (A and B) and a water molecule. The dihedral angles between the pyridine and phenyl rings in the zwitterions are 53.69 (10) and 73.56 (11)° in A and B, respectively. In the crystal, molecules are linked by N—H...O, O—H...O, C—H...O and C—H...π(ring) hydrogen bonds into a three-dimensional network. The crystal structure also features π–π interactions involving the centroids of the pyridine and phenyl rings [centroid–centroid distances = 3.5618 (12) Å in A and 3.8182 (14) Å in B].

The compounds 2-(1-benzofuran-2-yl)-2-oxoethyl 2-nitrobenzoate, C17H11NO6 (I), and 2-(1-benzofuran-2-yl)-2-oxoethyl 2-aminobenzoate, C17H13NO4 (II), were synthesized under mild conditions. Their molecular structures were characterized by both spectroscopic and single-crystal X-ray diffraction analysis. The molecular conformations of both title compounds are generally similar. However, different ortho-substituted moieties at the phenyl ring of the two compounds cause deviations in the torsion angles between the carbonyl group and the attached phenyl ring. In compound (I), the ortho-nitrophenyl ring is twisted away from the adjacent carbonyl group whereas in compound (II), the ortho-aminophenyl ring is almost co-planar with the carbonyl group. In the crystal of compound (I), two C—H...O hydrogen bonds link the molecules into chains propagating along the c-axis direction and the chains are interdigitated, forming sheets parallel to [20-1]. Conversely, pairs of N—H...O hydrogen bonds in compound (II) link inversion-related molecules into dimers, which are further extended by C—H...O hydrogen bonds into dimer chains. These chains are interconnected by π–π interactions involving the furan rings, forming sheets parallel to the ac plane.

In the title compounds, (2E,2′E)-3,3′-(1,4-phenylene)bis[1-(2-methoxyphenyl)prop-2-en-1-one], C26H22O4 (I), (2E,2′E)-3,3′-(1,4-phenylene)bis[1-(3-methoxyphenyl)prop-2-en-1-one], C26H22O4 (II) and (2E,2′E)-3,3′-(1,4-phenylene)bis[1-(3,4-dimethoxyphenyl)prop-2-en-1-one], C28H26O6 (III), the asymmetric unit consists of a half-molecule, completed by crystallographic inversion symmetry. The dihedral angles between the central and terminal benzene rings are 56.98 (8), 7.74 (7) and 7.73 (7)° for (I), (II) and (III), respectively. In the crystal of (I), molecules are linked by pairs of C—H...π interactions into chains running parallel to [101]. The packing for (II) and (III), features inversion dimers linked by pairs of C—H...O hydrogen bonds, forming R22(16) and R22(14) ring motifs, respectively, as parts of [201] and [101] chains, respectively.

A new organic potential nonlinear optical (NLO) material 1-(3,4-dimethoxyphenyl)-3-(3-fluorophenyl)prop-2-en-1-one (DMP3FP) is crystallized in acetone. The single crystal X-ray diffraction data shows that material crystallizes into centro-symmetric orthorhombic space group Pbca with a = 15.6552(6) Å, b = 8.5571(3) Å, c = 20.7697(7) Å. The functional groups in DMP3FP molecule are identified by Fourier Transfer Infrared (FTIR) spectra. The thermal stability and melting point are determined using thermo gravimetric analysis/differential thermal analysis (TGA/DTA). Using UV Visible spectral studies direct band gap energy of the crystal is determined to be 3.19 eV. The nonlinear absorption coefficient and optical power limiting of the crystal was studied using Z-scan technique. The crystal exhibits a self-focusing effect at a wavelength of 532 nm showing optical limiting and reverse saturable absorption by having excited state absorption coefficient greater than ground state absorption coefficient. Keywords: Nonlinear, Optical power limiting, Z-scan, Self-focusing

The title indolin-2-one compound, C28H23FN4O·C2H6O, crystallizes as a 1:1 ethanol solvate. The ethanol molecule is disordered over two positions with refined site occupancies of 0.560 (14) and 0.440 (14). The pyrazole ring makes dihedral angles of 84.16 (10) and 85.33 (9)° with the indolin-2-one and indole rings, respectively, whereas the dihedral angle between indolin-2-one and indole rings is 57.30 (7)°. In the crystal, the components are linked by N—H...O and O—H...O hydrogen bonds, forming an inversion molecule–solvate 2:2 dimer with R44(12) ring motifs. The crystal structure is consolidated by π–π interaction between pairs of inversion-related indolin-2-one rings [interplanar spacing = 3.599 (2) Å].

Adamantyl-based compounds are commercially important in the treatments for neurological conditions and type-2 diabetes, aside from their anti-viral abilities. Their values in drug design are chronicled as multi-dimensional. In the present study, a series of 2-(adamantan-1-yl)-2-oxoethyl benzoates, 2(a–q), and 2-(adamantan-1-yl)-2-oxoethyl 2-pyridinecarboxylate, 2r, were synthesized by reacting 1-adamantyl bromomethyl ketone with various carboxylic acids using potassium carbonate in dimethylformamide medium at room temperature. Three-dimensional structures studied using X-ray diffraction suggest that the adamantyl moiety can serve as an efficient building block to synthesize 2-oxopropyl benzoate derivatives with synclinal conformation with a looser-packed crystal packing system. Compounds 2a, 2b, 2f, 2g, 2i, 2j, 2m, 2n, 2o, 2q and 2r exhibit strong antioxidant activities in the hydrogen peroxide radical scavenging test. Furthermore, three compounds, 2p, 2q and 2r, show good anti-inflammatory activities in the evaluation of albumin denaturation.

A series of five new 2‐(1‐benzofuran‐2‐yl)‐2‐oxoethyl 4-(un/substituted)benzoates 4(a–e), with the general formula of C8H5O(C=O)CH2O(C=O)C6H4X, X = H, Cl, CH3, OCH3 or NO2, was synthesized in high purity and good yield under mild conditions. The synthesized products 4(a–e) were characterized by FTIR, 1H-, 13C- and 1H-13C HMQC NMR spectroscopic analysis and their 3D structures were confirmed by single-crystal X-ray diffraction studies. These compounds were screened for their antimicrobial and antioxidant activities. The tested compounds showed antimicrobial ability in the order of 4b < 4a < 4c < 4d < 4e and the highest potency with minimum inhibition concentration (MIC) value of 125 µg/mL was observed for 4e. The results of antioxidant activities revealed the highest activity for compound 4e (32.62% ± 1.34%) in diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 4d (31.01% ± 4.35%) in ferric reducing antioxidant power (FRAP) assay and 4a (27.11% ± 1.06%) in metal chelating (MC) activity.

This paper describes an efficient and regioselective method for the synthesis of novel fluorinated spiro-heterocycles in excellent yield by cascade [5+1] double Michael addition reactions. The compounds 7,11-bis(4-fluorophenyl)-2,4-dimethyl- 2,4-diazaspiro[5.5] undecane-1,3,5,9-tetraone (3a) and 2,4-dimethyl-7,11-bis (4-(trifluoromethyl)phenyl)-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (3b) were characterized by single-crystal X-ray diffraction, FT-IR and NMR techniques. The optimized geometrical parameters, infrared vibrational frequencies and NMR chemical shifts of the studied compounds have also been calculated using the density functional theory (DFT) method, using Becke-3-Lee-Yang-Parr functional and the 6-311G(d,p) basis set. There is good agreement between the experimentally determined structural parameters, vibrational frequencies and NMR chemical shifts of the studied compounds and those predicted theoretically. The calculated natural atomic charges using NBO method showed higher polarity of 3a compared to 3b.The calculated electronic spectra are also discussed based on the TD-DFT calculations.

Single-crystal X-ray structures of dimeric quinoxaline aldehyde (QA), quinoxaline dihydrazone (DHQ) and HQNM (Goswami S et al. 2013 Tetrahedron Lett. 54, 5075–5077. (doi:10.1016/j.tetlet.2013.07.051); Goswami S et al. 2014 RSC Adv. 4, 20 922–20 926. (doi:10.1039/C4RA00594E); Goswami S et al. 2014 New J. Chem. 38, 6230–6235. (doi:10.1039/C4NJ01498G)) are reported along with the theoretical study. Among them, QA is not acting as an active probe, but DHQ and HQNM are serving as selective and sensitive probe for the Fe3+ cation and the Ni2+ cation, respectively. DHQ can also detect the Fe3+ in commercial fruit juices (grape and pomegranate).

The semi- and thiosemicarbazones of benzophenone derivatives (L1–L6) had been synthesized and their respective Cu(II) complexes (1–6) were obtained as precipitates by interaction with CuCl2 in ethanolic solution. All these compounds were characterized by 1H and 13C NMR, IR, UV–Vis and elemental analysis (CHN). The structures of L1 and L4 were further elucidated by X-ray crystallography. Antifungal activities of the ligands and Cu(II) complexes were carried out to ascertain their effectiveness in the inhibition of Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), a highly virulent pathogen against Cavendish banana in tropical region. A few of the complexes showed noteworthy inhibition on the growth of Foc TR4 with complex 6 was the most potent antifungal agent.

In the title compound, C15H10BrFO, the olefinic double bond adopts an E conformation. The molecule is non-planar as seen by the dihedral angle of 48.92 (11)° between the bromophenyl and fluorophenyl rings. The carbonyl group is twisted from the plane of the bromophenyl ring and the olefinic double bond. The trans conformation of the C=C double bond in the central enone group is confirmed by the C—C=C—C torsion angle of −165.7 (2)°.

The title bis-chalcone compound, C24H16Cl2O2, crystallizes with one half-molecule in the asymmetric unit. The molecule has crystallographic inversion symmetry and lies about an inversion centre at the centroid of the central benzene ring. The olefinic double bonds adopt E configurations. The s-trans conformation of the central C—C bond of the enone group is confirmed by a C—C—C=C torsion angle of −162.88 (17)°.

The title compound, C15H10BrNO3, is close to planar, as seen by the dihedral angle of 3.32 (17)° between the bromophenyl and nitrophenyl rings. In the crystal, molecules are linked by weak C—H...O hydrogen bonds, forming chains propagating along the c-axis direction.

The title bis-chalcone compound, C24H16F2O2, crystallizes with one half-molecule in the asymmetric unit. The molecule lies about an inversion centre at the centroid of the central benzene ring. The olefinic double bonds adopt E conformations. In the crystal, C—H...O hydrogen bonds form sheets of molecules in the ac plane and C—H...F hydrogen bonds form zigzag chains along the a-axis direction. These combine to generate a three-dimensional network of molecules stacked along the c-axis direction.

The title compound, C16H14N2O3, has an E conformation about the azobenzene [—N=N– = 1.2481 (16) Å] linkage. The benzene rings are almost coplanar [dihedral angle = 1.36 (7)°]. The O atoms of the carboxylic acid group are disordered over two sets of sites and were refined with an occupancy ratio of 0.5:0.5. The two disordered components of the carboxylic acid group make dihedral angles of 1.5 (14) and 3.8 (12)° with the benzene ring to which they are attached. In the crystal, molecules are linked via pairs of O—H...O hydrogen bonds, forming inversion dimers. The dimers are connected via C—H...O hydrogen bonds, forming ribbons lying parallel to [120]. These ribbons are linked via C—H...π interactions, forming slabs parallel to (001).

The asymmetric unit of the titled compound, C22H20FN5S, comprises two independent molecules (A and B), both of which have a trans conformation with respect to the methene C=C [1.342 (2) and 1.335 (2) Å] and the acyclic N=C [1.283 (2) and 1.281 (2) Å] bonds. In molecule A, the triazole ring makes dihedral angles of 55.01 (12) and 18.17 (9)° with the benzene and indole rings, respectively. The corresponding dihedral angles for molecule B are 54.54 (11) and 14.60 (10)°, respectively. In the crystal, molecules are consolidated into –A–B–A–B– chains along [010] via N—H...N hydrogen bonds. The chains are further linked into layers parallel to the ac plane via π–π interactions involving inversion-related triazole rings [centroid–centroid distances = 3.3436 (11)–3.4792 (13) Å].

The title compound, C23H22FN5S, exists in a trans conformation with respect to the methene C=C and the acyclic N=C bonds. The 1,2,4-triazole-5(4H)-thione ring makes dihedral angles of 88.66 (9) and 84.51 (10)°, respectively, with the indole and benzene rings. In the crystal, molecules are linked by pairs of N—H...S hydrogen bonds, forming inversion dimers with an R22(8) ring motif. The dimers are linked via C—H...π interactions, forming chains along [1-10]. The chains are linked via π—π interactions involving inversion-related triazole rings [centroid–centroid distance = 3.4340 (13) Å], forming layers parallel to the ab plane.

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.

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 IC50 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.

Four pyrazole compounds, 3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde (1), 5-(4-bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde (2), 1-[5-(4-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone (3) and 1-[3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl]propan-1-one (4), have been prepared by condensing chalcones with hydrazine hydrate in the presence of aliphatic acids, namely formic acid, acetic acid and propionic acid. The structures were characterized by X-ray single crystal structure determination. The dihedral angles formed between the pyrazole and the fluoro-substituted rings are 4.64(7)° in 1, 5.3(4)° in 2 and 4.89(6)° in 3. In 4, the corresponding angles for molecules A and molecules B are 10.53(10)° and 9.78(10)°, respectively.

Biphenyl-based compounds are clinically important for the treatments of hypertension and inflammatory, while many more are under development for pharmaceutical uses. In the present study, a series of 2-([1,1'-biphenyl]-4-yl)-2-oxoethyl benzoates, 2(a-q), and 2-([1,1'-biphenyl]-4-yl)-2-oxoethyl pyridinecarboxylate, 2(r-s) were synthesized by reacting 1-([1,1'-biphenyl]-4-yl)-2-bromoethan-1-one with various carboxylic acids using potassium carbonate in dimethylformamide at ambient temperature. Single-crystal X-ray diffraction studies revealed a more closely packed crystal structure can be produced by introduction of biphenyl moiety. Five of the compounds among the reported series exhibited significant anti-tyrosinase activities, in which 2p, 2r and 2s displayed good inhibitions which are comparable to standard inhibitor kojic acid at concentrations of 100 and 250 μg/mL. The inhibitory effects of these active compounds were further confirmed by computational molecular docking studies and the results revealed the primary binding site is active-site entrance instead of inner copper binding site which acted as the secondary binding site.

Flavokawain B (1) is a natural chalcone extracted from the roots of Piper methysticum, and has been proven to be a potential cytotoxic compound. Using the partial structure of flavokawain B (FKB), about 23 analogs have been synthesized. Among them, compounds 8, 13 and 23 were found in new FKB derivatives. All compounds were evaluated for their cytotoxic properties against two breast cancer cell lines, MCF-7 and MDA-MB-231, thus establishing the structure–activity relationship. The FKB derivatives 16 (IC50 = 6.50 ± 0.40 and 4.12 ± 0.20 μg/mL), 15 (IC50 = 5.50 ± 0.35 and 6.50 ± 1.40 μg/mL) and 13 (IC50 = 7.12 ± 0.80 and 4.04 ± 0.30 μg/mL) exhibited potential cytotoxic effects on the MCF-7 and MDA-MB-231 cell lines. However, the methoxy group substituted in position three and four in compound 2 (IC50 = 8.90 ± 0.60 and 6.80 ± 0.35 μg/mL) and 22 (IC50 = 8.80 ± 0.35 and 14.16 ± 1.10 μg/mL) exhibited good cytotoxicity. The lead compound FKB (1) showed potential cytotoxicity (IC50 = 7.70 ± 0.30 and 5.90 ± 0.30 μg/mL) against two proposed breast cancer cell lines. It is evident that the FKB skeleton is unique for anticancer agents, additionally, the presence of halogens (Cl and F) in position 2 and 3 also improved the cytotoxicity in FKB series. These findings could help to improve the future drug discovery process to treat breast cancer. A molecular dynamics study of active compounds revealed stable interactions within the active site of Janus kinase. The structures of all compounds were determined by 1H-NMR, EI-MS, IR and UV and X-ray crystallographic spectroscopy techniques.

The title 1,3,4-oxadiazole-2-thione derivative, C18H20N4OS2, crystallized with two independent molecules (A and B) in the asymmetric unit. The 2-thienyl rings in both molecules are rotationally disordered over two orientations by approximately 180° about the single C—C bond that connects it to the oxadiazole thione ring; the ratios of site occupancies for the major and minor components were fixed in the structure refinement at 0.8:0.2 and 0.9:0.1 in molecules A and B, respectively. The 1,3,4-oxadiazole-2-thione ring forms dihedral angles of 7.71 (16), 10.0 (11) and 77.50 (12)° (molecule A), and 6.5 (3), 6.0 (9) and 55.30 (12)° (molecule B) with the major and minor parts of the disordered thiophene ring and the mean plane of the adjacent piperazine ring, respectively, resulting in approximately V-shaped conformations for the molecules. The piperazine ring in both molecules adopts a chair conformation. The terminal benzene ring is inclined towards the mean plane of the piperazine ring with N—C—C—C torsion angles of −58.2 (3) and −66.2 (3)° in molecules A and B, respectively. In the crystal, no intermolecular hydrogen bonds are observed. The crystal packing features short S...S contacts [3.4792 (9) Å] and π–π interactions [3.661 (3), 3.664 (11) and 3.5727 (10) Å], producing a three-dimensional network.

A series of N-ethyl phthalimide esters 4(a-n) were synthesized and characterized by spectroscopic studies. Further, the molecular structure of majority of compounds were analysed by single crystal X-ray diffraction studies. The X-ray analysis revealed the importance of substituents on the crystal stability and molecular packing. All the synthesized compounds were tested for in vitro antioxidant activity by DPPH radical scavenging, FRAP and CUPRAC methods. Few of them have shown good antioxidant activity.

The asymmetric unit of the title compound, C17H18O3, comprises three independent molecules with similar geometries. In each molecule, the carbonyl group is twisted away from the napthalene ring system, making dihedral angles of 1.0 (2), 1.05 (19)° and 1.5 (2)°. The butene group in all three molecules are disordered over two sets of sites, with a refined occupancy ratio of 0.664 (6):0.336 (6). In the crystal, molecules are oriented with respect to their carbonyl groups, forming head-to-head dimers via O—H...O hydrogen bonds. Adjacent dimers are further interconnected by C—H...O hydrogen bonds into chains along the a-axis direction. The crystal structure is further stabilized by weak C—H...π interactions.

In the title compound, C24H23NO2, a whole molecule is disordered over two sets of sites with occupancies in a ratio of 0.692 (6):0.308 (6). In the major disorder component, the naphthalene ring system forms a dihedral angle of 68.6 (5)° with the benzene ring. The corresponding angle in the minor component is 81.6 (10)°. In the crystal, molecules are linked into chains propagating along the b-axis direction via weak C—H...O hydrogen bonds. The crystal packing is further consolidated by weak C—H...π interactions.

The asymmetric unit of the title hydrated salt, C22H25N2+·C6H4ClO3S−·H2O, comprises two 2-[4-(diethylamino)styryl]-1-methylquinolin-1-ium cations, two 4-chlorobenzenesulfonate anions and two solvent water molecules. One ethyl group of both cations displays disorder over two positions in a 0.659 (2):0.341 (2) ratio in one molecule and in a 0.501 (2):0.499 (2) ratio in the other. The sulfonate group of one anion is also disordered over two positions in a 0.893 (7):0.107 (7) ratio. The dihedral angle between the mean plane of the quinolinium ring system and that of benzene ring is 10.57 (18)° in one cation and 14.4 (2)° in the other. In the crystal, cations, anions and water molecules are linked into chains along the [010] direction by O—H...Osulfonate hydrogen bonds, together with weak C—H...Osulfonate and C—H...Cl interactions. The cations are stacked by π–π interactions, with centroid–centroid distances in the range 3.675 (2)–4.162 (3) Å.

The title compound, C20H28O3, known as `trichodermaerin' [systematic name: (4E)-4,9,15,16,16-pentamethyl-6-oxatetracyclo[10.3.1.01,10.05,9]hexadec-4-ene-7,13-dione], is a diterpene lactone which was isolated from Trichoderma asperellum. The structure has a tetracycic 6–5–7–5 ring system, with the cyclohexanone ring adopting a twisted half-chair conformation and the cyclopentane ring adopting a half-chair conformation, whereas the cycloheptene and tetrahydrofurananone rings are in chair and envelope (with the methyl-substituted C atom as the flap) conformations, respectively. The three-dimensional architecture is stabilized by C—H...O interactions.

The title compound crystallizes as a hemihydrate, C18H20N2O5·0.5H2O. The molecule exists in an E conformation with respect to the C=N imine bond. The 4-methoxyphenyl unit is disordered over two sets of sites with a refined occupancy ratio of 0.54 (2):0.46 (2). The dihedral angles between the benzene rings are 29.20 (9) and 26.59 (9)°, respectively, for the major and minor components of the 4-methoxy-substituted ring. All methoxy substituents lie close to the plane of the attached benzene rings [the Cmethyl—O—C—C torsion angles range from −4.0 (12) to 3.9 (2)°]. In the crystal, the components are linked into chains propagating along [001] via N—H...O and O—H...O hydrogen bonds and weak C—H...O interactions.

There are two independent molecules in the asymmetric unit of the title compound, C16H17NO4, with similar conformations but some differences in their bond angles. Each molecule adopts a trans configuration with respect to the methylidene C=N bond and is twisted with a dihedral angle between the two substituted benzene rings of 80.52 (7)° in one molecule and 83.53 (7)° in the other. All methoxy groups are approximately coplanar with the attached benzene rings, with Cmethyl—O—C—C torsion angles ranging from −6.7 (2) to 5.07 (19)°. In the crystal, independent molecules are linked together by O—H...N and O—H...O hydrogen bonds and a π–π interaction [centroid–centroid distance of 3.6030 (9) Å], forming a dimer. The dimers are further linked by weak C—H...O interactions and another π–π interaction [centroid–centroid distance of 3.9452 (9) Å] into layers lying parallel to the ab plane.

In the structure of the title salt, C20H20NO+·C6H4FO3S−, the 4-(ethoxyphenyl)ethenyl unit is disordered over two positions with a refined site-occupancy ratio of 0.610 (6):0.390 (6). The cation is nearly planar, the dihedral angle between the quinolinium and benzene rings being 6.7 (4) and 1.7 (7)° for the major and minor components, respectively. The ethoxy group is essentially coplanar with the benzene ring [C—O—C—Cmethy = 177.1 (8) and 177.8 (12)° for the major and minor components, respectively]. In the crystal, cations and anions are linked into chains along the b-axis direction by C—H...Osulfonyl weak interactions. These chains are further connected into sheets parallel to (001) by C—H...Osulfonyl weak interactions. The chains are also stacked along the a axis through π–π interactions involving the quinolinium and benzene rings [centroid–centroid distances = 3.636 (5) Å for the major component and 3.800 (9) Å for the minor component]. C—H...π interactions are also present.

In the title mixed salt, 2C16H15N2+·C6H4ClO3S−·NO3−, one of the cations shows whole molecule disorder over two sets of sites in a 0.711 (7):0.289 (7) ratio. The 4-chorobenzenesulfonate anion is also disordered over two orientations in a 0.503 (6):0.497 (6) ratio. The cations are close to planar, the dihedral angles between the pyridinium and indole rings being 1.48 (3)° in the ordered cation, and 5.62 (3) and 2.45 (3)°, respectively, for the major and minor components of the disordered cation. In the crystal, the cations are stacked in an antiparallel manner approximately along the a-axis direction and linked with the anions via N—H...O hydrogen bonds and C—H...O interactions, generating a three-dimensional network. Weak C—H...π and π–π interactions [with centroid–centroid distances of 3.561 (2)–3.969 (7) Å] are also observed.

In the structure of the title nicotinonitrile derivative, C19H15N3O, the pyridine ring makes dihedral angles of 11.50 (7) and 43.36 (8)° with the 4-aminophenyl and phenyl rings, respectively, and the dihedral angle between the phenyl rings is 36.28°. In the crystal, molecules are linked by N—H...N hydrogen bonds into wave-like sheets parallel to (10-2). These sheets are stacked by π–π interactions between the 4-aminophenyl rings of adjacent sheets, with centroid–centroid distances of 3.7499 (9) Å. C—H...π interactions are also present.

In the title 3-cyanopyridine derivative, C21H19N3O4, the 3-cyano-substituted pyridine ring forms dihedral angles of 2.35 (5) and 41.60 (5)° with the unsubstituted pyridine and 2,4,5-trimethoxy-substituted benzene rings, respectively. The dihedral angle between the unsubstituted pyridine and benzene rings is 39.84 (5)°. The methoxy groups form Cmethyl—O—C—(C,N) torsion angles in the range 0.80 (15)–11.45 (15)°. In the crystal, molecules related by 21 screw axes are linked by weak C—H...N hydrogen bonds along [010]. In addition, weak C—H...π interactions and π–π stacking interactions between pyridine rings, with a centroid–centroid distance of 3.6448 (6) Å, are observed.