Experimental and quantum chemical computational study of (E)-1-[5-(3,4-dimethylphenyldiazenyl)-2-hydroxyphenyl]ethanone.

In this work, the azo dye, (E)-1-[5-(3,4-dimethylphenyldiazenyl)-2-hydroxyphenyl]ethanone, has been synthesized and characterized by IR, and X-ray single-crystal determination. In the theoretical calculations, the stable structure geometry of the isolated molecule in gas phase was investigated under the framework of the density functional theory (B3LYP) with 6-31G (d, p). To designate lowest energy molecular conformation of the title molecule, the selected torsion angle was varied every 10° and the molecular energy profile was calculated from -180° to +180°.

1-{5-[(E)-(4-Propyl-phen-yl)diazen-yl]-2-hy-droxy-phen-yl}ethanone.

The mol-ecular geometry of the title compound, C(17)H(18)N(2)O(2), displays an E configuration with respect to the azo group. The dihedral angle between the aromatic rings is 10.39 (4)°.

1-{5-[(E)-(2-Fluoro-phen-yl)diazen-yl]-2-hy-droxy-phen-yl}ethanone.

Theere are two independent mol-ecules in the asymmetric unit of the title compound, C(14)H(11)FN(2)O(2), each with a trans configuration with respect to the azo double bond. The dihedral angle between the aromatic rings is 17.21 (2)° in one mol-ecule and 19.

(E)-2-Acetyl-4-[(3-methyl-phenyl-)diazen-yl]phenol: an X-ray and DFT study.

The title compound, C(15)H(14)N(2)O(2), an azo dye, displays a trans configuration with respect to the N=N bridge. The dihedral angle between the aromatic rings is 0.18 (14)°.

(E)-2-[(2-Ethyl-phen-yl)iminiometh-yl]-6-hydroxy-phenolate.

The mol-ecule of the title compound, C(15)H(15)NO(2), crystallizes in a zwitterionic form, and displays an E configuration about the C=N bond. The dihedral angle between the two aromatic rings is 5.59 (6)°.

(E)-2-[(2-Ethyl-phen-yl)imino-meth-yl]-6-methoxy-phenol.

The mol-ecule of the title compound, C(16)H(17)NO(2), adopts the phenol-imine tautomeric form with a strong intra-molecular 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)°.

4-{2-Meth-oxy-6-[(4-methyl-phen-yl)imino-meth-yl]phen-oxy}phthalonitrile.

In the mol-ecule of the title compound, C(23)H(17)N(3)O(2), the methoxy-phenyl ring is oriented at dihedral angles of 13.34 (12) and 88.83 (12)° with respect to the methyl-phenyl and phthalonitrile rings, respectively; the dihedral angle between methyl-phenyl and phthalonitrile rings is 89.

2-[(4-Chloro-phen-yl)imino-meth-yl]hydro-quinone.

The title compound, C(13)H(10)ClNO(2), exists in the phenol-imine form in the crystal, and the aromatic rings are oriented at a dihedral angle of 2.82 (9)°. An intra-molecular O-H⋯N hydrogen bond results in the formation of a planar six-membered ring.

(E)-2-Hydr-oxy-6-[(4-propyl-phenyl)-iminiometh-yl]phenolate.

The title compound, C(16)H(17)NO(2), crystallizes with three crystallographically independent zwitterionic mol-ecules in the asymmetric unit which differ significantly in the orientations of the propyl side chains. The dihedral angles between the two benzene rings in the three mol-ecules are 6.17 (7), 6.