3-Methyl-benzo[1,2-c:5,4-c']dichromen-6(8H)-one.

The title compound, C21H14O3, crystallizes with eight independent mol-ecules (A-H) in the asymmetric unit which are arranged in four groups of two mol-ecules each (AB, CD, EF and GH). In each mol-ecule, the pyran-2-one ring is planar (r.m.s. deviations vary from 0.001 to 0.017 Å), while the pyran ring has a screw-boat conformation. In the crystal, mol-ecules stack in two columns, along the [10-1] direction, composed of mol-ecules C, B, E and G, and D, A, F and H. Mol-ecules A and F are linked via C-H⋯O hydrogen bonds. In addition, there are a number of C-H⋯π contacts present involving all of the mol-ecules. These inter-actions result in the formation of a three-dimensional network.

4-Fluoro-N-(4-hy-droxy-benzyl-idene)aniline.

In the title compound, C13H10FNO, the benzene ring planes are inclined at an angle of 50.52 (8)°. A characteristic of aromatic Schiff bases with N-aryl substituents is that the terminal phenyl rings are twisted relative to the plane of the HC=N link between them. In this case, the HC=N unit makes dihedral angles of 10.6 (2) and 40.5 (2)° with the hy-droxy-benzene and fluro-benzene rings, respectively. In the crystal, O-H⋯N and C-H⋯F hydrogen bonds lead to the formation of chains along the c- and b-axis directions, respectively. C-H⋯π contacts link mol-ecules along a and these contacts combine to generate a three-dimensional network with mol-ecules stacked along the b-axis direction.

Crystal structure of (Z)-3-{3-(4-chloro-phen-yl)-2-[(4-chloro-phen-yl)imino]-2,3-di-hydro-thia-zol-4-yl}-2H-chromen-2-one.

In the title compound, C24H14Cl2N2O2S, the 2H-chromene ring system is approximately planar, with a maximum deviation of 0.025 (2) Å. The thia-zole ring is almost planar, with an r.m.s. deviation of 0.0022 Å, and makes a dihedral angle of 58.52 (7)° with the chromene ring system. The chromene ring system is inclined at angles of 58.3 (1) and 55.39 (9)° with respect to the two chloro-phenyl rings. The two chloro-phenyl rings show significant deviation from coplanarity, with a dihedral angle between them of 47.69 (8)°. The crystal structure features C-H⋯Cl inter-actions extending in (100) and propagating along the a-axis direction and weak π-π inter-actions [centroid-centroid separation = 3.867 (2) Å].

(E)-N'-(3,4-Di-meth-oxy-benzyl-idene)nicotinohydrazide monohydrate.

In the title hydrated compound, C15H15N3O3·H2O, the nicotinohydrazide mol-ecule adopts a trans conformation with respect to the C=N double bond. The dihedral angle between the benzene and pyridine rings is 5.10 (14)°. In the crystal, the solvent water mol-ecule acts as an acceptor, forming an N-H⋯O hydrogen bond supported by two C-H⋯O contacts. It also acts as a donor, forming bifurcated O-H⋯(O,O) and O-H⋯N hydrogen bonds that combine with the former contacts to form zigzag chains of mol-ecules along the c-axis direction. An additional O-H⋯O donor contact completes a set of six hydrogen bonds to and from the water mol-ecule and connects it to a third nicotinohydrazide mol-ecule. This latter contact combines with weaker C-H⋯O hydrogen bonds supported by a C-H⋯π contact to stack mol-ecules along b in a three-dimensional network.

(E)-1-([1,1'-Biphen-yl]-4-yl)-3-(2-methyl-phen-yl)prop-2-en-1-one.

In the title mol-ecule, C22H18O, the o-tolyl ring is connected through a conjugated double bond. The mol-ecule adopts an E conformation and the C-C=C-C torsion angle is 178.77 (13)°. The overall conformation may be described by the values of dihedral angles between the different planes. The terminal rings are twisted by an angle of 54.75 (8)°, while the biphenyl part is not planar, the dihedral angle between the planes of the rings being 40.65 (8)°. The dihedral angle between the benzene rings is 14.10 (7)°. There are three weak C-H⋯π inter-actions found in the crystal structure. No classic hydrogen bonds are observed.

Di-aqua-tetra-kis-(1H-imidazole-κN (3))magnesium dichloride.

In the title compound, [Mg(C3H3N2)4(H2O)2]Cl2, the Mg(II) cation lies on a crystallographic inversion centre and is coordinated by two water mol-ecules and four N-atom donors from monodentate imidazole ligands, giving a slightly distorted octa-hedral stereochemistry. In the crystal, water O-H⋯Cl and imidazole N-H⋯Cl hydrogen bonds give rise to a three-dimensional structure.

(E)-N'-(4-Meth-oxy-benzyl-idene)pyridine-3-carbohydrazide dihydrate.

In the title compound, C14H13N3O2·2H2O, the hydrazone mol-ecule adopts an E conformation with respect to the C=N bond. The dihedral angle between the benzene and pyridine rings is 8.55 (10)°. The methyl-idene-hydrazide [-C(=O)-N-N=C-] fragment is essentially planar, with a maximum deviation of 0.0375 (13) Å. The mean planes of the benzene and pyridine rings make dihedral angles of 2.71 (14) and 11.25 (13)°, respectively, with mean plane of the methyl-idene-hydrazide fragment. In the crystal, the benzohydrazide and water mol-ecules are linked by N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds into a three-dimensional network.

N-(4,4'-Dibromo-[1,1'-biphen-yl]-2-yl)benzamide.

In the title compound, C(19)H(13)Br(2)NO, the dihedral angle between the rings of the biphenyl group is 53.59 (14)°. The ring of the benzamide group is inclined to the phenyl rings of the biphenyl group by 23.87 (15) and 75.89 (15)°. There are no significant inter-molecular inter-actions in the crystal structure.

rac-4a,10b-cis,10b,5c-trans-5-(7-Methyl-2-oxo-2H-chromen-4-yl)-3,4,4a,5,6,10b-hexa-hydro-2H-pyrano[3,2-c]quinoline.

In the racemic title compound, C(22)H(21)NO(3), the nitro-gen-containing ring of the pyran-oquinoline moiety adopts a slightly distorted half-chair conformation and the oxygen-containing ring adopts a slightly distorted chair conformation. The benzene rings make a dihedral angle of 84.97 (8)°. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into chains extending along the a-axis direction.

7-[(Morpholin-4-yl)(phen-yl)meth-yl]quinolin-8-ol.

In the title compound, C20H20N2O2, the quinoline ring system makes dihedral angles of 81.05 (4) and 61.16 (5)° with the mean planes of the benzene and morpholine rings, respectively; the mean planes of the latter two rings make a dihedral angle of 83.59 (4)°. In the crystal, pairs of O-H⋯N hydrogen bonds link neighbouring mol-ecules related by a twofold rotation axis, generating R2(2)(10) motifs.

4-(4-Meth-oxy-pheneth-yl)-3,5-diphenyl-4H-1,2,4-triazole.

In the title compound, C(23)H(21)N(3)O, the dihedral angles formed by the mean plane of the triazole ring [maximum deviation = 0.007 (1) Å] and the three phenyl rings are 51.13 (8), 52.84 (8) and 47.04 (8)°. In the crystal, mol-ecules are linked by weak C-H⋯N inter-actions, forming infinite chains propagating along the b-axis direction.

3-Chloro-methyl-6,7-dimethyl-1,2-benz-oxazole.

In the title compound, C(10)H(10)ClNO, the benzoisoxazole ring is almost planar (r.m.s. deviation = 0.0121 Å) and the chloro substituent in the side chain is anti-clinal relative to the N-C bond of the isoxazole ring. In the crystal, adjacent mol-ecules are linked via a pair of weak C-H⋯N hydrogen bonds, forming dimers through a cyclic R(2) (2)(8) association.

4-Bromo-N-(4-hy-droxy-benzyl-idene)-aniline.

In the title compound, C(13)H(10)BrNO, the benzene ring planes are inclined at an angle of 48.85 (17)°, resulting in a nonplanar mol-ecule. A characteristic of aromatic Schiff bases with N-aryl substituents is that the terminal phenyl rings are twisted relative to the HC=N plane. In this case, the HC=N unit makes dihedral angles of 11.1 (4) and 38.5 (3)° with the hy-droxy-benzene and bromo-benzene rings, respectively. In the crystal, the molecules are linked by O-H⋯N hydrogen bonds to form infinite (C8) chains along the b axis.

4-[(E)-(4-Methyl-phen-yl)imino-meth-yl]phenol.

In the title compound, C(14)H(13)NO, the two rings show significant deviation from coplanarity, with a dihedral angle between the two planes of 49.40 (5)°. The hy-droxy group is involved in an inter-molecular O-H⋯N hydrogen bond, forming an extended one-dimensional zigzag chain along (001).

4,4'-Dibromo-2-nitro-biphen-yl.

The title compound, C(12)H(7)Br(2)NO(2), a biphenyl derivative, displays a twisted conformation with the two benzene rings making a dihedral angle of 55.34 (14)°. The dihedral angle between the nitro group and its parent benzene ring is 26.8 (2)°. The crystal structure is stabilized by inter-molecular C-H⋯Br and C-H⋯O inter-actions, which lead to the formation of chains propagating along the c-axis direction.

12-(4-Meth-oxy-benzo-yl)-2-methyl-benzo[f]pyrido[1,2-a]indole-6,11-dione.

In the title compound, C(25)H(17)NO(4), the indolizine fused naphthaquinone unit is approximately planar [r.m.s deviation = 0.0678 Å] and makes a dihedral angle of 57.82 (5)° with the benzene ring of the meth-oxy-benzene group. The naphtho-quinone O atoms deviate, in the same sense, from the mean plane of the fused six-membered rings by 0.2001 (14) and 0.0516 (14) Å. In the crystal there is π-π stacking of inversion-related pairs of mol-ecules [inter-planar spacing = 3.514 (2) Å].

2,3,6,7-Tetra-bromo-9-butyl-9H-carbazole.

In he title compound, C(16)H(13)Br(4)N, the carbazole skeleton is nearly planar [maximum deviation = 0.026 (4) Å] and makes a dihedral angle of 73.8 (4)° with the butyl chain. The butyl chain adopts a trans conformation. In the crystal, mol-ecules are linked by π-π stacking inter-actions [centroid-centroid distance = 3.559 (2) Å].

2,2'-Bithio-phene-3,3'-dicarbonitrile.

The complete mol-ecule of the title compound, C(10)H(4)N(2)S(2), is generated by an inversion center situated at the mid-point of the bridging C-C bond. The bithio-phene ring system is planar [maximum deviation = 0.003 (2) Å] and the central C-C bond length is 1.450 (2) Å. There are no significant inter-molecular inter-actions in the crystal structure, which is stabilized by van der Waals inter-actions.

(Z)-4-{1-[(2-Hy-droxy-ethyl)-amino]-ethyl-idene}-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one.

In the title compound C(14)H(17)N(3)O(2), the dihedral angle between the rings is 16.68 (13)°. Although the compound crystallizes in the keto form, the possibility of keto-enamine-enol-imine tautomerism is explained by a strong intra-molecular N-H⋯O hydrogen bond.

3-[Chloro-(phen-yl)meth-yl]-6-methyl-1,2-benzoxazole.

The title compound, C(15)H(12)ClNO, is a functionalized 1,2-benzoxazole with a chloro-(phen-yl)methyl substituent. The mol-ecule is V-shaped, the dihedral angle between the mean plane of the 1,2-benzoxazole system [maximum deviation = 0.023 (3) Šfor the N atom] and the phenyl ring being 70.33 (14)°. There are no hydrogen-bonding inter-actions in the crystal structure, which is stabilized by van der Waals inter-actions only.