Molecular structure, spectroscopic investigations, second-order nonlinear optical properties and intramolecular proton transfer of (E)-5-(diethylamino)-2-[(4-propylphenylimino)methyl]phenol: a combined experimental and theoretical study.

This work presents a combined experimental and theoretical study on an ortho-hydroxy Schiff base compound, (E)-5-(diethylamino)-2-[(4-propylphenylimino)methyl]phenol. The crystal structure and spectroscopic properties of the compound have been determined by using X-ray diffraction, IR and UV-vis spectroscopy techniques. The electronic structure, vibrational frequencies and electronic absorption spectra have been investigated from the calculative point of view.

Synthesis, spectroscopic characterizations and quantum chemical computational studies of (Z)-4-[(E)-p-tolyldiazenyl]-6-[(2-hydroxyphenylamino)methylene]-2-methoxycyclohexa-2,4-dienone.

In this study, the molecular structure and spectroscopic properties of title compound were characterized by X-ray diffraction, FT-IR and UV-vis spectroscopies. These properties of title compound were also investigated from calculative point of view. The X-ray diffraction and FT-IR analyses reveal the existence of keto form in the solid state.

(3aR,6S,7aR)-7a-Bromo-2-[(4-methyl-phen-yl)sulfon-yl]-1,2,3,6,7,7a-hexa-hydro-3a,6-ep-oxy-isoindole.

In the title compound, C(15)H(16)BrNO(3)S, the boat form of the six-membered ring is almost symmetrical with respect to the ep-oxy bridge. The two five-membered rings generated by the ep-oxy bridge of the six-membered ring adopt envelope conformations, whereas the N-containing five-membered ring adopts a twisted conformation. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds.

Spectroscopic investigations and quantum chemical computational study of (E)-4-methoxy-2-[(p-tolylimino)methyl]phenol.

In this work the electronic structure of (E)-4-methoxy-2-[(p-tolylimino)methyl]phenol has been characterized by the B3LYP/6-31G(d) level by using density functional theory. The experimental infrared and electronic absorption spectra have been obtained and compared with the theoretically obtained ones. Molecular electrostatic potential map has been evaluated; natural bond orbital and frontier molecular orbitals analysis have been performed from the optimized geometry.

(E)-2-Eth-oxy-6-[(4-ethoxy-phen-yl)imino-meth-yl]phenol.

In the asymmetric unit of the title compound, C(17)H(19)NO(3), there are three independent mol-ecules, which are align nearly parallel to each other and adopt the phenol-imine tautomeric form. In each mol-ecule, an intra-molecular 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 mol-ecules are 13.

(E)-4-Meth-oxy-2-(p-tolyl-imino-meth-yl)phenol.

The mol-ecule of the title compound, C(15)H(15)NO(2), adopts the enol-imine tautomeric form and has a strong intra-molecular O-H⋯N hydrogen bond as a result. The mol-ecule is almost planar, with a maximum deviation of 0.1038 (15) Å for the meth-oxy C atom.

(E)-2-[(4-Fluoro-phen-yl)imino-meth-yl]-5-methoxy-phenol.

In the mol-ecule of the title compound, C(14)H(12)FNO(2), the aromatic rings are oriented at a dihedral angle of 48.17 (1)°. An intra-molecular O-H⋯N hydrogen bond results in the formation of a six-membered ring.

(E)-5-Meth-oxy-2-(o-tolyl-imino-meth-yl)phenol.

In the title compound, C(15)H(15)NO(2), the phenol group make dihedral angles of 2.4 (2) and 24.1 (9)° with the imine linkage (-C=N-) and the phenyl group, respectively, and the mol-ecule adopts the enol-imine tautomeric form, so the mol-ecular structure is stabilized by a strong intra-molecular O-H⋯N hydrogen bond.

(E)-2-[(4-chlorophenyl)iminomethyl]-5-methoxyphenol and (E)-2-[(2-chlorophenyl)iminomethyl]-5-methoxyphenol: X-ray and DFT-calculated structures.

The crystal structures of the title 4-chlorophenyl, (I), and 2-chlorophenyl, (II), compounds, both C14H12ClNO2, have been determined using X-ray diffraction techniques and the molecular structures have also been optimized at the B3LYP/6-31 G(d,p) level using density functional theory (DFT). The X-ray study shows that the title compounds both have strong intramolecular O-H..

3-Hydroxy-6-[(4-hydroxyphenylamino)methylene]cyclohexa-2,4-dienone and 2-hydroxy-6-[(4-hydroxyphenylamino)methylene]cyclohexa-2,4-dienone.

The title compounds, both C(13)H(11)NO(3), exist as the keto-amine tautomers, and the formal hydroxyl H atoms, which display strong intramolecular hydrogen bonds, are located on the N atoms. This is a verification of the preference for the keto-amine tautomeric form in the solid state. The 2-hydroxy isomer has two independent molecules, with the molecules linked by intramolecular N-H.