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The title compound, C16H17NO, is a Schiff base which adopts the phenol–imine tautomeric form in the solid state. The mol­ecule is almost planar, with a dihedral angle of 4.61 (4)° between the aromatic rings. The molecular structure is stabilized by an intramolecular O—H⋯N hydrogen bond which generates a six membered ring.

X-ray analysis reveals that the title Schiff base compound, C17H19NO3, possesses both OH and NH tautomeric character in its mol­ecular structure. The occupancies of the enol and keto tautomers are 0.62 (3) and 0.38 (3), respectively. The presence of the minor keto form could not be confirmed from the IR spectrum. The mol­ecule is approximately planar, the dihedral angle between the planes of the two aromatic rings being 6.97 (8)°. The mol­ecular structure of the major component is stabilized by an intra­molecular O—H⋯N hydrogen bond, which generates an S(6) ring motif (N—H⋯O hydrogen bond in the minor component).

The mol­ecule of the title compound, C16H16N2O4, exists in the E configuration with respect to the central C=N double bond. The dihedral angle between the two benzene rings is 2.17 (9) Å. In the crystal, mol­ecules are linked via O—H⋯N hydrogen bonds into chains that propagate along the b-axis direction. There is also π–π stacking of inversion-related mol­ecules, with inter­planar spacings of 3.479 (5) Å and ring centroid–centroid distances of 3.876 (4) Å.

The title mol­ecule, C13H8Cl3NO, exists in a trans configuration with respect to the C=N bond [1.278 (2) Å]. The benzene rings form a dihedral angle of 24.64 (11)°. The mol­ecular structure is stabilized by an intra­molecular O—H⋯N hydrogen bond, which generates an S(6) ring motif. In the crystal, π–π stacking inter­actions [centroid–centroid distances = 3.6893 (14) Å] are observed.

There are two symmetry-independent mol­ecules in the asymmetric unit of the title compound, C16H16N2O, that differ in conformation. The dihedral angles between the benzene rings in the two mol­ecules are 44.35 (19) and 48.14 (17)°, but the rings twist in opposite directions. The acetamide groups make nearly equal dihedral angles of 25.4 (3) and 25.7 (3)° with the parent benzene rings. An S(6) ring motif is formed in each mol­ecule by intra­molecular C—H⋯O close contacts. In the crystal, strong N—H⋯O hydrogen bonds between acetamide groups generate a C(4) chain motif arranging the mol­ecules into two symmetry-independent polymeric structures extending along [010].

In the asymmetric unit of the title compound, C17H19NO3, there are three independent mol­ecules, which are align nearly parallel to each other and adopt the phenol-imine tautomeric form. In each mol­ecule, an intra­molecular O—H⋯N hydrogen bond results in the formation of an S(6) ring motif. The dihedral angles between the aromatic rings in the three independent mol­ecules are 13.55 (2), 21.24 (2) and 46.26 (1)°. C—H⋯π inter­actions are also observed in the crystal structure.

The mol­ecule of the title compound, C17H21N3O, displays a trans configuration with respect to the C=N double bond. The dihedral angle between the planes of the two benzene rings is 50.96 (11)° and a strong intra­molecular O—H⋯N hydrogen bond is present. An inter­molecular N—H⋯O hydrogen-bonding inter­action stabilizes the crystal structure.

The crystal structure of the title compound, C14H12N2O4, contains four crystallographically independent mol­ecules in the asymmetric unit. All the mol­ecules have similar conformations; the dihedral angles between the aromatic rings are 33.1 (1), 33.76 (9), 31.41 (9) and 32.56 (10)°. Intra­molecular O—H⋯N hydrogen bonds form S(6) ring motifs in each molecule. In the crystal, there are two pairs of pseudo-inversion-related mol­ecules. Along the c axis, mol­ecules are stacked with π–π inter­actions between the 2-hy­droxy­phenyl and 4-meth­oxy-2-nitro­phenyl rings [centroid–centroid distances = 3.5441 (12)–3.7698 (12) Å].

There are two independent mol­ecules in the asymmetric unit of the title compound, C15H14BrNO3, with very similar geometrical parameters. Each mol­ecule adopts the phenol–imine tautomeric form, with strong intra­molecular O—H⋯N hydrogen bonds. The two mol­ecules are non-planar, the dihedral angles between the two aromatic rings being are 24.6 (2) and 30.30 (13)°.

In the mol­ecule of the title compound, C16H17NO3, the aromatic rings are oriented at a dihedral angle of 29.25 (8)°. An intra­molecular O—H⋯N hydrogen bond results in the formation of a nearly planar [maximum deviation 0.034 (13) Å] six-membered ring, which is oriented at dihedral angles of 0.91 (1) and 28.91 (12)° with respect to the aromatic rings. The title mol­ecule is a phenol–imine tautomer, as evidenced by C—O, C—N and C—C bond lengths. In the crystal, mol­ecules are linked by inter­molecular C—H⋯O hydrogen bonds that generate C(8) chains.

In the title compound, C15H14BrNO, the dihedral angle between the aromatic rings is 4.10 (11)° and the mol­ecule is close to planar (r.m.s. deviation for the non-H atoms = 0.053 Å). An intra­molecular O—H⋯N hydrogen bond closes an S(6) ring. In the crystal, very weak C—H⋯π inter­actions are observed.

In the mol­ecule of the title compound, C14H12FNO2, the aromatic rings are oriented at a dihedral angle of 48.17 (1)°. An intra­molecular O—H⋯N hydrogen bond results in the formation of a six-membered ring. The title mol­ecule is a phenol–imine tautomer, as evidenced by the C—O [1.351 (3) Å], C—N [1.282 (3) Å], and C—C [1.416 (3)–1.445 (3) Å] bond lengths. In the crystal, mol­ecules are linked by inter­molecular C—H⋯π inter­actions.

The title compound, C16H18N2O, an N-benzyl­ideneaniline derivative with substituents on both aromatic rings, crystallizes with two independent mol­ecules (A and B) in the asymmetric unit. Both mol­ecules exist in the E configuration. The dihedral angle between the two aromatic rings is 8.20 (5)° for mol­ecule A and 12.52 (6)° for mol­ecule B, and the imino C—N torsion angle (τ) is 7.1 (2)° for mol­ecule A and −14.7 (2)° for mol­ecule B. In the crystal structure, mol­ecules are arranged in stacks which propagate along the a-axis direction. The crystal structure is stabilized by a number of weak C—H⋯π inter­actions.

The title compound, C13H8BrCl2NO, was obtained by reaction of 3-bromo-5-chloro­salicylaldehyde and 2-chloro­benzenamine in methanol. The mol­ecule displays an E configuration with respect to the imine C=N double bond. The dihedral angle between the two benzene rings is 4.57 (11)°. The mol­ecular conformation is stabilized by an intra­molecular O—H⋯N hydrogen bond. In the crystal structure, mol­ecules are linked by inter­molecular C—H⋯O hydrogen-bonding inter­actions into zigzag chains running parallel to the b axis. Inter­molecular Br⋯Cl [3.5289 (11) Å] and Cl⋯Cl [3.5042 (12) Å] inter­actions are present.

The title compound, C15H15NO3, adopts the enol–imine tautomeric form. The two rings are twisted with respect to each other, making a dihedral angle of 44.08 (5)°. The 3-methoxy-2-[(E)-(4-methoxyphenyl)-iminomethyl]phenol unit is almost planar, the largest deviation from the mean plane being 0.047 (2) Å. Such a planar conformation might be related to the occurrence of an intra­molecular O—H⋯N hydrogen bond. In the crystal, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into sheets parallel to (010). These sheets are inter­connected by weak C—H⋯π inter­actions.

The asymmetric unit of the title Schiff base compound, C30H38N4O2, comprises two crystallographically independent mol­ecules, A and B. The structure is non-merohedrally twinned with a refined BASF ratio of 0.219 (6):0.701 (6). Mol­ecule B shows both phenol–imine and keto–amine tautomeric forms in a single structure. The dihedral angles between the central ring and the two outer rings are 5.9 (3) and 48.4 (3)° in mol­ecule A, and 48.3 (3) and 6.9 (3)° in mol­ecule B. Strong intra­molecular O—H⋯N and N—H⋯O hydrogen bonds generate S(6) ring motifs. The crystal structure is further stabilized by inter­molecular C—H⋯O, C—H⋯π and π–π inter­actions [centroid–centroid distances = 3.870 (4)–3.871 (4) Å].

The title compound, C14H9ClF3NO2, crystallizes in a phenol–imine tautomeric form, with a strong intra­molecular O—H⋯N hydrogen bond. The dihedral angle between the two benzene rings is 47.62 (9)°. In the crystal, mol­ecules are linked into chains along the c axis by C—H⋯O hydrogen bonds, and weak C—H⋯π inter­actions involving both benzene rings are also observed.

The mol­ecule of the title compound, C16H17NO2, adopts the phenol–imine tautomeric form with a strong intra­molecular O—H⋯N hydrogen bond and an E conformation with respect to the azomethine C=N bond. The dihedral angle between the aromatic rings is 21.23 (9)°. The ethyl group is disordered over two orientations with occupancies of 0.598 (6) and 0.402 (6). In the crystal, the mol­ecules are linked into chains along the b axis by C—H⋯π inter­actions.

The asymmetric unit of title compound, C19H22INO, contains two independent mol­ecules. Classical intra­molecular O—H⋯N hydrogen bonds stabilize the mol­ecular structures. The crystal structure is stabilized by weak inter­molecular C—H⋯π and π–π [centroid–centroid = 3.8622 (18) Å] inter­actions. In both mol­ecules, the aromatic rings are nearly perpendicular to each other [dihedral angles = 84.26 (17) and 86.69 (15)°].

In the title compound, C15H15NO, the almost planar 2,3-dimethyl­aniline unit and the salicyl­aldehyde group (r.m.s. deviations of 0.0156 and 0.0109 Å, respectively) are oriented at a dihedral angle of 43.69 (9)° with respect to each other. An S(6) ring motif is formed due to intra­molecular O—H⋯N hydrogen bonding. In the crystal, C—H⋯π inter­actions occur between the 2,3-dimethyl­aniline unit and the salicyl­aldehyde group, where the CH is from the o-methyl group.

The title anilide–imine compound, C24H26N2O, features an intra­molecular N—H⋯N hydrogen bond involving the imine and anilide groups to generate an S(6) ring motif. The mol­ecule displays an E configuration about the imine C=N double bond, with the dihedral angle between the two benzene rings being 86.5°. The packing is stabilized by three different C—H⋯π inter­actions.

The title Schiff base compound, C16H14N2O2, has been synthesized by the reaction of 5-amino-3,4-dimethyl­isoxazole and 2-hydr­oxy-1-naphthaldehyde. The dihedral angle between the isoxazole ring and the napthyl ring system is 3.29 (7)°. The mol­ecule adopts an E configuration about the central C=N double bond. Intra­molecular O—H⋯N hydrogen bonding generates an S(6) ring motif. In the crystal structure, π–π inter­actions are observed involving the isoxazole ring and the substituted benzene ring of the naphthyl unit, with centroid–centroid distances of 3.5200 (10) Å.

The asymmetric unit of the title compound, C22H21NO, consists of two crystallographically independent mol­ecules (A and B). Each mol­ecule contains two benzene rings and one dimethyl­benzene ring. The dihedral angle between the two benzene rings is 87.75 (16)° in mol­ecule A and 89.25 (16)° in mol­ecule B. In mol­ecule A, the dimethyl­benzene ring forms dihedral angles of 89.65 (8) and 42.98 (11)° with the two benzene rings, whereas the corresponding angles are equal to 63.15 (7) and 58.67 (10)° in mol­ecule B. An intra­molecular C—H⋯O hydrogen bond generates an S(6) ring motif in each mol­ecule. In the crystal, mol­ecules are linked by bifurcated (N,C)—H⋯O hydrogen bonds, generating R 2 1(6) ring motifs and forming infinite chains along the a axis. The crystal is further stabilized by C—H⋯π and π–π inter­actions with centroid–centroid distances of 3.8543 (18) and 3.930 (2) Å.

The title compound, C14H12INO, adopts the phenol–imine tautomeric form. The dihedral angle between the aromatic rings is 20.6 (3)°. The mol­ecular conformation is stabilized by an intra­molecular O—H⋯N hydrogen bond while in the crystal, weak inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into a zigzag chain parallel to the b axis.

In the title compound, C14H11BrN2O2, the mean planes of the two benzene rings are almost parallel to each other, making a dihedral angle of 4.09 (1)°. An intra­molecular O—H⋯N hydrogen bond occurs. In the crystal, inter­molecular O—H⋯N and C—H⋯O hydrogen bonds link the mol­ecules into a chain-like supra­molecular structure.