There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

J. Appl. Cryst.の発刊に際して

Structure and mechanism in organic chemistry

Theoretical analysis (NBO, NPA, Mulliken Population Method) and molecular orbital studies (hardness, chemical potential, electrophilicity and Fukui function analysis) of (E)-2-((4-hydroxy-2-methylphenylimino)methyl)-3-methoxyphenol

The Schiff base compound (E)-2-[(2-chlorophenyl)iminomethyl]-4-trifluoromethoxyphenol has been synthesized and characterized by IR, UV–vis, and X-ray single-crystal determination. The molecular geometry from X-ray experiment in the ground state has been compared using the density functional theory (DFT) with the 6-311++G(d,p) basis set. The calculated results show that the DFT can well reproduce the structure of the title compound. Using the TD-DFT method, electronic absorption spectra of the title compound have been predicted, and a good agreement is determined with the experimental ones. To investigate the tautomeric stability, optimization calculations at the B3LYP/6-311++G(d,p) level were performed for the enol and keto forms of the title compound. Calculated results reveal that its enol form is more stable than its keto form. The predicted nonlinear optical properties of the title compound are much greater than those of urea. The changes of thermodynamic properties for the formation of the title comp...

Crystal structure, spectroscopy, and quantum chemical studies of (E)-2-[(2-chlorophenyl)iminomethyl]-4-trifluoromethoxyphenol.

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.

https://journals.iucr.org/e/issues/2009/09/00/fl2259/fl2259.pdf

2-[(2,4-Dimethyl­phen­yl)imino­meth­yl]-6-methyl­phenol

The molecular and crystal structure of the title compound, C14H11Cl2NO, has been determined by X-ray single crystal diffraction technique. The compound crystallizes in the orthorhombic, space group Pbca with unit cell dimensions a = 7.5537(10) A, b = 11.5518(13) A, c = 29.760(4) A, M
 r
  = 280.14, V = 2596.8(6) A3, Z = 8, R
 1 = 0.065 and wR
 2 = 0.191. The title compound exists in the enol–imine tautomeric form with a strong intramolecular O–H···N hydrogen bond. The dihedral angle between the two benzene rings is 37.66(15)°. The asymmetric unit in the crystal structure contains only one neutral molecule. Calculational studies were performed by using AM1, PM3, PM6 semi-empirical and DFT methods. Geometry optimizations of compound have been carried out by using three semi-empirical methods and DFT method and bond lengths, bond and torsion angles of title compound have been determined. Dipole moments (Debye) and the energy parameters of compound (kcal/mol) were calculated by using above mentioned calculation methods. Atomic charge distribution has been obtained from AM1, PM3, PM6 and DFT. In order to determine conformational flexibility on the molecule, molecular energy profile of the title compound was obtained with respect to the selected torsion angle T(N1–C7–C1–C2), which is varied from −180° to +180° in every 10 via PM3 semi-empirical method. A new crystal of (E)-2-[(2,4-Dichlorophenylimino) methyl]-p-cresol with orthorhombic space group Pbca [unit cell dimensions a = 7.5537(10) A, b = 11.5518(13) A, c = 29.760(4) A, V = 2596.8(6) A3, Z = 8, R
 1 = 0.065] has been determined by single crystal X-ray diffraction study and theoretical calculations were performed by using AM1, PM3, PM6 semi-empirical and DFT methods.

Experimental and Semi-Empirical and DFT Calculational Studies on ( E )-2-[(2,4-Dichlorophenylimino) methyl]- p -cresol

The title Schiff base compound, C14H12N2O4, is in an inter­mediate state between NH and OH tautomers. Apart from the intra­molecular O—H⋯N hydrogen bond, there are inter­molecular C—H⋯O hydrogen bonds, generating centrosymmetric R22(18) and R22(14) dimers.

https://journals.iucr.org/e/issues/2009/04/00/bt2883/bt2883.pdf

2-[(4-Methoxy­phen­yl)imino­meth­yl]-4-nitro­phenol

The title compound, C16H18N2O, a Schiff base, crystallizes in the phenol–imine tautomeric form, with a strong intra­molecular O—H⋯N hydrogen bond which forms an almost planar ring.

/pdf/e-2-4-dimethylamino-phenyliminomethyl-6-methylphenol-524xuyqow6.pdf

(E)-2-[4-(Dimethylamino)phenyliminomethyl]-6-methylphenol

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).

https://journals.iucr.org/e/issues/2009/04/00/bt2917/bt2917.pdf

Ferda Erşahin

Papers

2-[(2,4-Dimethylphenyl)iminomethyl]-6-methylphenol

Experimental and Semi-Empirical and DFT Calculational Studies on ( E )-2-[(2,4-Dichlorophenylimino) methyl]- p -cresol

2-[(4-Methoxyphenyl)iminomethyl]-4-nitrophenol

(E)-2-[4-(Dimethylamino)phenyliminomethyl]-6-methylphenol

2-[(4-Ethylphenyl)iminomethyl]-3,5-dimethoxyphenol

Ferda Erşahin

Papers

2-[(2,4-Dimethyl­phen­yl)imino­meth­yl]-6-methyl­phenol

Experimental and Semi-Empirical and DFT Calculational Studies on ( E )-2-[(2,4-Dichlorophenylimino) methyl]- p -cresol

2-[(4-Methoxy­phen­yl)imino­meth­yl]-4-nitro­phenol

(E)-2-[4-(Dimethylamino)phenyliminomethyl]-6-methylphenol

2-[(4-Ethyl­phen­yl)imino­meth­yl]-3,5-dimethoxy­phenol

2-[(2,4-Dimethylphenyl)iminomethyl]-6-methylphenol

2-[(4-Methoxyphenyl)iminomethyl]-4-nitrophenol

2-[(4-Ethylphenyl)iminomethyl]-3,5-dimethoxyphenol