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The racemic title compound, [Fe(C5H5)(C16H27O2)], comprises an α,ω-diol-substituted undecyl chain with a ferrocenyl substituent at at one terminus. The alkane chain is inclined to the substituted ring of the ferrocene grouping by 84.22 (13)°. The ferrocene rings are almost eclipsed and parallel. The crystal structure features O—H...O and C—H...O hydrogen bonds and C—H...π contacts that stack the molecules along the c-axis direction. A Hirshfeld surface analysis reveals that H...H interactions (83.2%) dominate the surface contacts.

Various N- and S-containing 5-membered heterocycles such as imidazole-2-thiones, thiazolidinones and thiazolidin-2-imines are among the most eminent biologically active organic heterocycles and are present in many marketed drugs. In view of their synthetic and biological significance, an efficient synthesis of two novel thiazolidine-2-imines (4a-b) utilizing a three-component one-pot approach starting from an aldimine, an alkyne and isothiocyanates has been developed. The reaction proceeded via a 5-exo digonal (5-exo dig) cyclization of a propargyl thiourea, formed in situ in the presence of Zn(II)-catalyst. The structures of the resulting products are elucidated by spectroscopic methods and X-ray crystallography. A DFT study explored the structural, thermodynamic and molecular electrostatic potential parameters for the compounds. The newly synthesized compounds (4a & 4b) were evaluated for the inhibition of tyrosinase both in vitro and in silico. The in vitro results revealed that the synthesized thiazolidine-2-imines (4a-b) showed good inhibition activity towards mushroom tyrosinase (IC50 = 1.151 ± 1.25 and 2.079 ± 0.87 μM respectively) in comparison to the kojic acid standard (IC50 = 16.031 ± 1.27 μM) a commonly used anti-pigment agent in plant and animal tissues. The experimental inhibition was further assessed by molecular docking studies between synthesized ligands and the human tyrosinase protein complex to investigate the intermolecular interactions responsible for tyrosinase inhibition activity.

The title centrosymmetric NiII complex, [Ni(NCS)2(C15H22N2O2)2], crystallizes with one half molecule in the asymmetric unit of the monoclinic unit cell. The complex adopts an octahedral coordination geometry with two mutually trans benzyl-2-(heptan-4-ylidene)hydrazine-1-carboxylate ligands in the equatorial plane with the axial positions occupied by N-bound thiocyanato ligands. The overall conformation of the molecule is also affected by two, inversion-related, intramolecular C—H...O hydrogen bonds. The crystal structure features N—H...S, C—H...S and C—H...N hydrogen bonds together with C—H...π contacts that stack the complexes along the b-axis direction. The packing was further explored by Hirshfeld surface analysis. The thermal properties of the complex were also investigated by simultaneous TGA–DTA analyses.

The title salt, C10H21N2O+·C7H12NO4S−, comprises a 3-methacrylamido-N,N,N-trimethylpropan-1-aminium cation and a 2-acrylamido-2-methylpropane-1-sulfonate anion. The salt crystallizes with two unique cation–anion pairs in the asymmetric unit of the orthorhombic unit cell. The crystal studied was an inversion twin with a 0.52 (4):0.48 (4) domain ratio. In the crystal, the cations and anions stack along the b-axis direction and are linked by an extensive series of N—H...O and C—H...O hydrogen bonds, forming a three-dimensional network. Hirshfeld surface analysis was carried out on both the asymmetric unit and the two individual salts. The contribution of interatomic contacts to the surfaces of the individual cations and anions are also compared.

In the title compound, the asymmetric unit comprises an N,N,N-trimethyl-1-(4-vinylphenyl)methanaminium cation and a 4-vinylbenzenesulfonate anion, C12H18N+·C8H7O3S−. The salt has a polymerizable vinyl group attached to both the cation and the anion. The methanaminium and vinyl substituents on the benzene ring of the cation subtend angles of 86.6 (3) and 10.5 (9)° to the ring plane, while the anion is planar excluding the sulfonate O atoms. The vinyl substituent on the benzene ring of the cation is disordered over two sites with a refined occupancy ratio of 0.542 (11):0.458 (11). In the crystal, C—H...O hydrogen bonds dominate the packing and combine with a C—H...π(ring) contact to stack the cations and anions along the a-axis direction. Hirshfeld surface analysis of the salt and of the individual cation and anion components is also reported.

In the structure of the title compound C33H29BrClNO4, (I), the hexahydro-2H-acridine ring system has a hydroxyethyl substituent on the N atom and a 3-bromo-6-chloro-2-hydroxyphenyl substituent on the central C atom at the 9-position. An unusual feature of the molecule is that the substituents at the 3- and 5-positions of the outer cyclohexenone rings are phenyl rings rather than the more common dimethyl substituents. C atoms on both of the cyclohexenone rings are disordered over two sites. In the crystal structure, O—H...O, C—H...O and C—H...π(ring) hydrogen bonds combine with an Br—O and unusual C—Br...π(ring) halogen bonds to generate a three dimensional network with molecules stacked along the a-axis direction.

The title compound, C24H21N3O3, crystallizes with two unique but closely r.m.s. overlay fit = 0.215 Å) comparable molecules (1 and 2) in the asymmetric unit of the triclinic unit cell. In molecule 1, the dihedral angles between the central imidazlole ring and the benzene-ring substituents are 42.51 (9), 45.41 (9) and 56.92 (8)°, respectively. Comparable data for molecule 2 are 39.36 (10), 34.45 (11) and 60.34 (8)°, respectively. The rings at the 2-positions carry p-nitro substituents that subtend dihedral angles of 12.9 (4)° in molecule 1 and 11.7 (4)° in molecule 2 to their respective benzene ring planes. The imidazole rings also have propan-2-ol substituents on the 1-N atoms, which adopt extended conformations for the N—C—C—C chains. In the crystal, classical O—H...N hydrogen bonds combine with C—H...O, C—H...N and C—H...π(ring) hydrogen bonds and stack the molecules along the a-axis direction.

The title compound, C16H13N3OS, comprises an oxadiazolethione ring bound to the N atom of an almost planar carbazole ring system (r.m.s. deviation = 0.0088 Å) through an ethylene chain. The oxadiazole ring is inclined to the the carbazole ring system by 40.71 (6)°. In the crystal, N—H...O, N—H...S, C—H...N and C—H...S hydrogen bonds combine with C—H...π(ring) and π–π contacts to stack the molecules along the b-axis direction.

The closely related title compounds, 3-(2,5-dimethoxy-3,4,6-trimethylphenyl)propyl methacrylate, C18H26O4 (I), and 3-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)propyl methacrylate, C16H20O4 (II), are monomers suitable for the preparation of redox polymers. They consist of a propylmethacrylate group and three methyl substituents on dimethoxybenzene and quinone cores, respectively. Both crystal structures feature weak C—H...O hydrogen bonds and C—H...π(ring) contacts between methyl groups and the six-membered rings.

The title compound, C24H21ClN2O, crystallizes with two unique molecules in the asymmetric unit. In each molecule, the central imidazole ring is substituted at the 2-, 4- and 5-positions by benzene rings. The 2-substituted ring carries a Cl atom at the 4-position. One of the imidazole N atoms in each molecule has a propan-2-ol substituent. In the crystal, a series of O—H...N, C—H...O and C—H...Cl hydrogen bonds, augmented by several C—H...π(ring) interactions, generate a three-dimensional network of molecules stacked along the a-axis direction.

The title compound, [Co(NCS)2(C15H22N2O2)2] or C32H44CoN6O4S2, was prepared from cobalt(II) nitrate, benzyl carbazate and ammonium thiocyanate in the presence of 4-heptanone. The compound crystallizes with two centrosymmetric complexes in which the cobalt(II) atoms have a trans-CoO2N4 octahedral coordination geometry. In the crystal, N—H...S, C—H...S and C—H....π contacts stack the complex molecules along the b-axis direction.

The title compound C12H8Br2N2O, lies on an inversion centre in the space group P21/n. Doubts are cast on the report of a polymorph of this structure in the non-centrosymmetric space group P21 [Zhu, R.-T., Liu, J.-C., Jin, S., Liu, B. & Guo J.-P. (2006). Hecheng Huaxue (Chin. J. Synth. Chem.) 14, 591] as ADDSYM alerts point strongly to a centrosymmetric structure. In the crystal, C—H...O and C—H...Br hydrogen bonds together with offset π–π interactions stack the molecules along the a-axis direction.

In the title solvate, C15H12N2OS·C2H6OS, the thioxoimidazolidin-4-one molecule and solvent molecule are linked by an N—H...O hydrogen bond. The planar imidazolidine ring (r.m.s. deviation = 0.022 Å) is inclined to the phenyl substituents in the 5-position by 69.57 (7) and 72.62 (6)°. In the crystal, N—H...O, C—H...O and C—H...S hydrogen bonds, together with C—H...π interactions, generate [100] chains, which stack along the a-axis direction.

The isomeric derivatives 1,2-bis(iodomethyl)benzene, (I), and 1,3-bis(iodomethyl)benzene (II), both C8H8I2, were prepared by metathesis from their dibromo analogues. The ortho-derivative, (I), lies about a crystallographic twofold axis that bisects the C—C bond between the two iodomethyl substituents. The packing in (I) relies solely on C—H...I hydrogen bonds supported by weak parallel slipped π–π stacking interactions [inter-centroid distance = 4.0569 (11) Å, inter-planar distance = 3.3789 (8) Å and slippage = 2.245 Å]. While C—H...I hydrogen bonds are also found in the packing of (II), type II, I...I halogen bonds [I...I = 3.8662 (2) Å] and C—H...π contacts feature prominently in stabilizing the three-dimensional structure.

The title compound, C16H10, crystallizes with four unique molecules, designated 1–4, in the asymmetric unit of the monoclinic unit cell. None of the molecules is planar, with the benzene rings of molecules 1–4 inclined to one another at angles of 42.41 (4), 24.07 (6), 42.59 (4) and 46.88 (4)°, respectively. In the crystal, weak C—H...π(ring) interactions, augmented by even weaker C[triple-bond]C—H...π(alkyne) contacts, generate a three-dimensional network structure with interlinked columns of molecules formed along the c-axis direction.

In the title compound, C15H22O4, the fully substituted benzene ring carries a methyl propanoate, two methoxy and three methyl substituents. Both methoxy substituents are almost orthogonal to the benzene ring plane. The methyl propanoate group is almost planar, r.m.s. deviation 0.0138 Å, and is inclined to the benzene ring plane by 80.26 (14)°. In the crystal, C—H...O hydrogen bonds form head-to-tail chains of molecules along the b-axis direction that are supported by very weak C—H...π(ring) contacts.

2-(4-Chlorophenyl)-2-oxoethyl 3-bromobenzoate, C15H10BrClO3, was synthesized in a single-step reaction by condensation of 3-bromobenzoic acid with 2-bromo-1-(4-chlorophenyl)ethanone in dimethylformamide in the presence of triethylamine as a catalyst. The structure consists of an aryl ketone moiety linked to an aryl ester unit by a methylene group. Both units are reasonably planar (r.m.s. deviations of 0.119 and 0.010 Å for the aryl ketone and aryl ester units, respectively) and are almost orthogonal, with an angle of 88.60 (3)° between them. In the crystal, molecules form five separate sets of inversion dimers. Three of these are generated by two C—H...O interactions and a C—H...Br contact, and form chains along c and along the ab cell diagonal. In addition, two inversion-related π–π stacking interactions between like aryl rings again form chains of molecules but in this instance along the bc diagonal. These contacts generate infinite layers of molecules parallel to (011) and stack the molecules along the a-axis direction.

The title compound, C12H20NO2, was synthesized from 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (hydroxy-TEMPO) and propargyl bromide. The six-membered ring adopts a flattened chair conformation and carries a propynyloxy substituent in an equatorial orientation at the 4-position. The N—O bond length of the piperidin-1-oxyl unit is 1.289 (3) Å. In the crystal, C—H...O hydrogen bonds combine with unusual C—H...π interactions involving the alkyne unit as acceptor to generate a three-dimensional network.

The title compound C25H29BrClNO4, comprises a 3,3,6,6-tetramethyltetrahydroacridine-1,8-dione ring system that carries a hydroxyethyl substituent on the acridine N atom and a 3-bromo-5-chloro-2-hydroxyphenyl ring on the central methine C atom of the dihydropyridine ring. The benzene ring is inclined to the acridine ring system at an angle of 89.84 (6)° and this conformation is stabilized by an intramolecular O—H...O hydrogen bond between the hydroxy substituent on the benzene ring and one of the carbonyl groups of the acridinedione unit. In the crystal, O—H...O, C—H...O and C—H...Br hydrogen bonds combine to stack molecules in interconnected columns propagating along the a-axis direction.

The title compounds, [Co2(C8H11BrO3)(CO)6], (1), and [Co2(C12H16Br2O4)(CO)6], (2), result from the replacement of two carbonyl ligands from dicobalt octacarbonyl by the alkynes 4-hydroxybut-2-ynyl 2-bromo-2-methylpropanoate and but-2-yne-1,4-diyl bis(2-bromo-2-methylpropanoate), respectively. Both molecules have classic tetrahedral C2Co2 cluster cores with the CoII atoms in a highly distorted octahedral coordination geometry. The alkyne ligands both adopt a cis-bent conformation on coordination. In the crystal structure of (1), classical O—H...O and non-classical C—H...O contacts form inversion dimers. These combine with weak O...O and Br...O contacts to stack the molecules into interconnected columns along the b-axis direction. C—H...O and C—H...Br contacts stabilize the packing for (2), and a weak Br...O contact is also observed. Interconnected columns of molecules again form along the b-axis direction.

The title compound, C21H16N2O, has an almost planar (r.m.s. deviation = 0.0074 Å) 1,2-dibenzylidenehydrazine backbone with an approximately orthogonal almost planar (r.m.s. deviation = 0.0368 Å) phenylethanone substituent on one of the imine C atoms. The dihedral angle between the two mean planes is 76.99 (4)°. In the crystal, molecules are linked via C—H...O hydrogen bonds and C—H...π contacts, forming a three-dimensional structure with molecules stacked along the a-axis direction.

The title molecule, [Fe2(C5H5)2(C12H8O3)], briefly reported previously [Zhang (2015). Private Communication (CCDC reference 1056736). CCDC, Cambridge, England], comprises two ferrocenyl units connected by an acid anhydride bridge. Both ferrocene units have near coplanar [dihedral angles between the ring planes = 2.84 (4) and 1.74 (13)°] and eclipsed [pseudo torsion angles = 6.3 (2) and 5.1 (2)°] cyclopentadienyl (Cp) rings. A twist through the anhydride linkage results in a dihedral angle of 73.81 (8)° between the two substituted Cp rings planes. An intramolecular C—H...O hydrogen bond is also found. In the crystal, C—H...O hydrogen bonds link the molecules into a three-dimensional network.

In the molecule of the title compound, C12H16O3, the methyl and aldehyde substituents are disordered over four inversion-related C atoms on the benzene ring with an occupancy ratio of 0.75:0.25. The crystal structure features weak C—H...O hydrogen bonds and C—H...π contacts between a methoxy/methyl group and the benzene ring.

In the title compound, [Fe(C5H5)(C7H8ClO)], the ferrocene cyclopentadiene rings are slightly staggered and inclined to one another at an angle of 0.79 (13)°. In the crystal, C—H...Cl and C—H...O hydrogen bonds each form inversion dimers and these combine with an edge-to-face C—H...π hydrogen bond to stack the molecules along the b-axis direction.

The title compound, C18H26N2O2, crystallizes with two half-molecules in the asymmetric unit, both lying about inversion centres situated at the centers of the cyclohexane rings. In the crystal, the two molecules are linked by a pair of N—H...O hydrogen bonds, forming an inversion dimer with an R22(18) ring motif; the dimers are linked by a second pair of N—H...O hydrogen bonds, enclosing an R22(18) ring motif, forming chains along [1-10] which are linked by bifurcated C—H...(O,O) hydrogen bonds, forming slabs parallel to the ab plane.

In the title compound, C21H22BrNO4, the tetrahydroacridine-1,8-dione unit has a bromohydroxyphenyl-substituent on the central carbon atom of the dihydropyridine ring and a 2-hydroxyethyl substituent on the nitrogen atom. An intramolecular O—H...O hydrogen bond forms between the hydroxyl substituent on the benzene ring and a carbonyl oxygen from the acridinedione, forming an S(8) ring. The hydroxyl group of the 2-hydroxyethyl residue is disordered over two sites with an occupancy ratio of 0.572 (6):0.428 (6). In the crystal structure O—H...O and C—H...O hydrogen bonds together with Br...O halogen bonds stack the molecules along the b-axis direction.

Methyl 4-hydroxy-3-nitrobenzoate, (I), C8H7NO5, crystallizes with two unique molecules, A and B, in the asymmetric unit of the triclinic unit cell. The space group was assigned as P-1, with lattice parameters a = 0.72831(15), b = 1.0522(2), c = 1.1410(2) nm, α = 83.38(3), β = 80.83(3), γ = 82.02(3)°, Z = 4, V = 0.8510(3) nm3, Mr = 197.15, Dc = 1.539 g/m3, µ= 0.131 mm−1, F(000) = 408, R = 0.1002 and wR = 0.2519. In the crystal structure, 12 hydrogen bonding and two p-stacking interactions link the molecules into infinite stacked sheets parallel to (101).

The title compound (3) was prepared from 4-chloroaniline in good yield on successive oxidation and methylation and its crystal and molecular structure is reported. The compound crystallizes in the monoclinic space group P 21/n with unit cell dimensions a = 13.5698(8), b = 3.7195 (3), c = 13.5967 (8) Å, ß = 91.703(3) °, V = 685.96 (10) Å3. The molecule is essentially planar with a dihedral angle of 6.2(3) ° between the nitro group and the phenyl ring. The crystal structure is stabilised by π...π contacts between adjacent benzene rings together with C–H...O hydrogen bonds and close Cl...O contacts.

The title compound, C27H28N2O, is a lophine (2,4,5-triphenyl-1H-imidazole) derivative with an n-pentyl chain on the amine N atom and a 4-methoxy substituent on the benzene ring. The two phenyl and methoxybenzene rings are inclined to the imidazole ring at angles of 25.32 (7), 76.79 (5) and 35.42 (7)°, respectively, while the methoxy substituent lies close to the plane of its benzene ring, with a maximum deviation of 0.126 (3) Å for the methoxy C atom. In the crystal, inversion dimers linked by pairs of C—H...O hydrogen bonds generate R22(22) loops. These dimers are stacked along the a-axis direction.

In the title compound, C11H12N2O2S, the thiazole and phenyl rings are inclined at 56.99 (6)° to one another. The thiazole ring is planar with an r.m.s. deviation for the five ring atoms of 0.0274 Å. The presence of the phenylimine substituent is confirmed with the C=N distance to the thiazole ring of 1.2638 (19) Å. The molecule adopts a Z conformation with respect to this bond. The –OH group of the hydroxyethyl substituent is disordered over two positions with relative occupancies 0.517 (4) and 0.483 (4). In the crystal, O—H...O hydrogen bonds, augmented by C—H...N contacts, form dimers with R22(11) rings and generate chains along the b axis. Parallel chains are linked in an obverse fashion by weak C—H...S hydrogen bonds. C—H...O hydrogen bonds together with C—H...π contacts further consolidate the structure, stacking molecules along the b axis.

The title compound, C11H12O3, is essentially planar, with an r.m.s. deviation of 0.179 Å from the mean plane through the 14 non-H atoms in the molecule. The benzene ring and the pyranone mean plane are inclined at 13.12 (6)° to one another and the pyranone ring adopts a flattened chair conformation. In the crystal, O—H...O hydrogen bonds and C—H...O contacts form R12(6) rings and link molecules into chains along b. Additional C—H...O contacts generate inversion dimers, with R22(8) ring motifs, and form sheets parallel to (-102) which are linked by C—H...π interactions.

The title molecule, C14H14O4, lies on a twofold rotation axis that bisects the central benzene ring, with only one half-molecule in the asymmetric unit. The pyranone systems adopt distorted twist- boat conformations, with the two methylene C atoms displaced by 0.537 (1) and 0.163 (2) Å from the best-fit plane through the remaining five C and O atoms (r.m.s. deviation = 0.073 Å). In the crystal, bifurcated C—H...(O,O) hydrogen bonds link pairs of adjacent molecules in an obverse fashion, stacking molecules along c. These contacts are further stabilized by very weak π–π interactions between adjacent benzene rings with centroid–centroid distances of 4.1951 (4) Å. Additional C—H...O contacts link these stacks, giving a three-dimensional network.

The title compound, C7H6OS, crystallizes with two similar molecules, 1 and 2, in the asymmetric unit. Both molecules are essentially planar with r.m.s. deviations of 0.0193 and 0.0107 Å for the planes through the nine non-H atoms of molecules 1 and 2, respectively. The thiophene and 4,5-dihydrocyclopentadienone rings are inclined at 2.40 (13)° in 1 and 0.64 (13)° in 2. In the crystal structure π–π [3.6542 (17) Å] and C—H...π contacts stack the molecules into columns in an inverse fashion along the b axis. An extensive series of C—H...O hydrogen bonds links the columns, generating an extended network structure.

The title compound, C15H24N2O2, crystallizes with two unique molecules, (I) and (II), in the asymmetric unit, differing in the orientation of the acryloyl units with respect to the piperidine rings. The acrylamide units are essentially planar in both molecules (r.m.s. deviations = 0.042 and 0.024 Å, respectively), as are the C3N chains of the acryloyl units. The carbonyl O atoms of the acryloyl systems lie significantly out of these planes, viz. by −0.171 (9) Å for molecule (I) and by 0.33 (1) Å for molecule (II). The acrylamide and acryloyl planes are inclined at 68.7 (4)° and 59.8 (3)° in the two molecules. The piperidine rings each adopt twist boat conformations. In the crystal, strong N—H...O hydrogen bonds link the molecules into zigzag C(4) chains along b. Additional C—H...O contacts result in the formation of stacks along a.

In the title molecule, C16H14O4S, the dihydrocyclopentathiophenone ring system is almost planar, with an r.m.s. deviation of 0.060 Å from the best fit plane through all nine non-H atoms. The cyclopentanone ring adopts a severely flattened envelope conformation with the C atom carrying the OH and ethylcarboxylate substituents at the flap. This atom lies only 0.185 (3) Å from the plane through the other four C atoms. The phenyl substituent is inclined at 43.37 (5)° to the dihydrocyclopentathiophenone mean plane. In the crystal, molecules are linked by pairs of O—H...O hydrogen bonds, forming inversion dimers with R22(10) ring motifs. Weak C—H...O hydrogen bonds also link molecules into chains along c, while an approximately orthogonal set of C—H...O contacts form chains along b, resulting in layers lying parallel to (100). Inversion dimers also form through weaker R22(12) C—H...S contacts, which combine with C—H...O contacts to form stacks along b.

The title compound, C17H15N3OS, crystallizes with two unique molecules, denoted 1 and 2, in the asymmetric unit. The two molecules are closely similar and overlay with an r.m.s. deviation of 0.053 Å. Both molecules adopt E configurations with respect to the C=N bonds. The dihedral angles between the benzothiophene groups and N-bound phenyl rings are 36.36 (9)° for molecule 1 and 29.71 (9)° for molecule 2. The C=N—NH—C(O)NH ethylidene–hydrazinecarboxamide units are also reasonably planar, with r.m.s. deviations of 0.061 and 0.056 Å, respectively, for the two molecules. The methyl substituents lie 0.338 (3) and 0.396 (3) Å, respectively, from these planes. The C=N—NH—C(O)NH planes are inclined to the phenyl rings at 13.65 (11) and 15.56 (11)°, respectively, in molecules 1 and 2. This conformation is enhanced by weak intramolecular C—H...O hydrogen bonds between ortho-H atoms of the two phenyl rings and the carbonyl O atoms, which generate S(6) rings in each molecule. In the crystal, pairs of molecules are linked by pairs of intermolecular N—H...O hydrogen bonds into dimers. Alternating dimers are further interconnected by weak C—H...O contacts into zigzag rows along b. The rows are stacked along a by C—H...π contacts involving the benzene ring from molecule 2 and the thiophene ring from molecule 1 of adjacent benzothiophene units.

In the title molecule, C11H11ClO3, the fused pyran ring adopts a half-chair conformation. In the crystal, intermolecular O—H...O hydrogen bonds link molecules into chains along [100]. These chains are interconnected by weak intermolecular C—H...O contacts which generate R22(8) ring motifs, forming sheets parallel to (001). Tetragonal symmetry generates an equivalent motif along b. Furthermore, the sheets are linked along the c axis by offset π–π stacking interactions involving the benzene rings of adjacent molecules [with centroid–centroid distances of 3.839 (2) Å], together with an additional weak C—H...O hydrogen bond, resulting in an overall three-dimensional network.

The title compound, C12H14O3, consists of a chromanone unit with an –OH substituent at the 4-position and methyl substituents on the remaining C atoms of the aromatic ring. The fused pyranone ring adopts a distorted envelope conformation with the methylene group adjacent to the carbonyl carbon as the flap atom. The crystal structure is stabilized by classical O—H...O hydrogen bonds and weak C—H...O and C—H...π interactions, generating a three-dimensional network.

In the title compound, [Co(C13H9)(C28H20)], the Co atom is sandwiched between cyclopentadienyl and cyclobutadienyl rings that are inclined at a dihedral angle of 2.6 (3)°. The four phenyl rings are tilted with respect to the cyclobutadienyl plane so that the C4Ph4 unit constitutes a four-bladed propeller. The phenyl ring of the phenyl-alkyne substituent is inclined to the cyclopentadienyl ring at an angle of 34.92 (18)°. The crystal structure is stabilized solely by C—H...π interactions which generate a three-dimensional network.

In the title compound, C14H12ClNO2, the chloro- and methoxy-substituted benzene rings are close to orthogonal [dihedral angle = 79.20 (3)°]. These rings also make angles of 45.9 (3) and 33.5 (3)° with the amide –CONH– unit. The methoxy substituent lies close to the methoxybenzene ring plane, with a maximum deviation of 0.142 (3) Å for the methyl C atom. The N—H bond is anti to the 2-chloro substituent of the aniline ring. In the crystal structure, intermolecular N—H...O hydrogen bonds form C(4) chains augmented by a weak C—H...O interaction involving an ortho H atom of the methoxy benzene ring that generates an R21(6) motif. The chains stack the molecules into columns down the b axis. Adjacent columns are linked by additional C—H...O and C—H...π contacts, generating a three-dimensional network.

The title compound, C13H10ClNO, (I), is a polymorph of the structure, (II), first reported by Gowda et al. [Acta Cryst. (2008), E64, o462]. In the original report, the compound crystallized in the orthorhombic space group Pbca (Z = 8), whereas the structure reported here is monoclinic P21/c (Z = 4). The principal difference between the two forms lies in the relative orientations of the phenyl and benzene rings [dihedral angle = 8.90 (13)° for (I) and 61.0 (1)° for (II)]. The inclination of the amide –CONH– units to the benzoyl ring is more similar [15.8 (7)° for (I) and 18.2 (2)° for (II)]. In both forms, the N—H bonds are anti to the 3-chloro substituents of the aniline rings. In the crystal, intermolecular N—H...O hydrogen bonds form C(4) chains along c. These chains are bolstered by weak C—H...O interactions that generate R21(6) and R21(7) ring motifs.

In the title compound, C21H20N2O3, the naphthalimide unit is almost planar (r.m.s. deviation for the 15 non-H atoms = 0.059 Å). The carboximide N atom and the five C atoms of the 2-methylprop-2-enoyl substituent also lie in a plane (r.m.s. deviation = 0.009 Å), which subtends an angle of 84.34 (7)° to the naphthalamide plane. This orients the =CH2 group of the vinyl fragment towards the naphthalimide rings, giving the molecule an extended configuration. The piperidine ring adopts a chair conformation and there is evidence for some delocalization between the naphthalene and piperidine units, the C—Npip bond length being 1.404 (4) Å. In the crystal structure, π–π contacts with centroid–centroid distances of 3.5351 (18) and 3.7794 (18) Å supported by C—H...O hydrogen bonds link adjacent molecules in a head-to-tail fashion, forming dimers. These are further stabilized by other C—H...O contacts of varying strength, which stack the molecules down the b axis.

The title compound, C15H15NO, (I), is a polymorph of the structure (II) reported by Gowda et al. [Acta Cryst. (2008), E64, o1494]. Compound (II) crystalllizes in the space group C2/c (Z = 8), whereas the title compound occurs in space group P21/c (Z = 4). The two molecular structures differ slightly in the relative orientations of their central amide group with respect to the benzoyl ring [dihedral angles of 55.99 (7) for (I) and 59.96 (11)° for (II)] and in the inclination of the benzoyl and aniline rings [88.67 (8) for (I) and 81.44 (5)° for (II)]. In the crystal structure of (I), molecules are linked by N—H...O hydrogen bonds, forming C(4) chains, which are augmented by weak C—H...O interactions. The structure is further stabilized by C—H...π contacts involving both of the aromatic rings.

In the title compound, C9H8Br2O2, the molecule is essentially planar with an r.m.s. deviation of 0.0652 Å from the mean plane through all non-H atoms and a dihedral angle of 7.1 (2)° between the benzene ring plane and the carboxylate substituent. In the crystal structure, weak C—H...Br hydrogen bonds and weak intermolecular O...Br contacts [3.095 (2) Å], link adjacent molecules into layers parallel to (102). Additional weak intermolecular C—H...O hydrogen bond interactions stack the layers above and below the molecular plane and down the a axis.

The title compound, C15H12FNO, was prepared by the reaction of cinnamoyl chloride with 4-fluoroaniline and crystallizes with two molecules A and B in the asymmetric unit. The two unique molecules are closely similar and overlay with an r.m.s. deviation of 0.0819 Å. The fluorobenzene and phenyl rings are inclined to one another at 73.89 (7) and 79.46 (7)°, respectively, in molecules A and B. The amide C—N—C(O)—C portions of the molecules are planar (r.m.s. deviations = 0.035 and 0.028 Å) and are inclined at 45.51 (9) and 47.71 (9), respectively, to the fluorobenzene rings in molecules A and B. The 2-fluoroacetamide units and the benzene rings each adopt E configurations with respect to the C=C bonds. In the crystal structure, intermolecular N—H...O hydrogen bonds augmented by weak C—H...π interactions link molecules into rows in a head-to-tail fashion along a. Additional weak C—H...O contacts further stabilize the packing, forming a three-dimensional network stacked down a.

In the title compound, C15H15NO, the C—N—C(O)—C amide unit is planar (r.m.s. deviation = 0.003 Å) and subtends dihedral angles of 44.71 (5) and 43.33 (5)° with the two o-tolyl rings. These aromatic rings are inclined at 4.94 (7)° to one another. The ortho-methyl groups of the two tolyl rings are anti to one another. In the crystal structure, N—H...O hydrogen bonds augmented by C—H...π interactions link the molecules in a head-to-head fashion into chains along a. Independent chains pack in a herringbone pattern along c.

The title compound, C14H12ClNO2, was prepared by refluxing 4-chlorobenzoyl chloride with o-anisidine in CHCl3. The methoxyphenyl–amide segment of the molecule is almost planar, with a dihedral angle of 5.10 (7)° between the benzene ring and the C—N—C(O)—C fragment. A weak intramolecular N—H...O contact forms an S(5) ring and contributes to the planarity of this portion of the molecule. The two benzene rings are inclined at an angle of 26.74 (7)°. In the crystal structure, intermolecular Cl...O interactions of 3.1874 (9) Å generate centrosymmetric dimers. These are further linked by C—H...O and C—H...π interactions, forming inversion related sheets parallel to [001].

The title compound, C15H23NO2S, contains cyclohexyl and ethyl substituents on the sulfonamide N atom and the cyclohexyl ring adopts a classic chair conformation. The dihedral angle between the benzene ring plane and the mean plane through the six atoms of the cyclohexyl ring is 59.92 (6)°. In the crystal structure, C—H...O hydrogen bonds link molecules into sheets extending in the bc plane.