J. Appl. Cryst.の発刊に際して

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

A chemosensor for the Al(3+) ion, 1-[(3-hydroxypyridin-2-ylamino)methylene]naphthalen-2(1H)-one (H2L), based on inhibited excited-state intramolecular proton transfer was synthesized. The experimental and theoretical calculations at B3LYP+PCM/6-31G(d) revealed that Al(3+) and H2L form a 1:1 complex, [AlL(OH)(H2O)]2, in dimethyl sulfoxide that exhibits two remarkably enhanced fluorescent emissions at 523 and 553 nm. It is confirmed that H2L could be used to detect Al(3+) ions in cells by bioimaging.

A Highly Selective Fluorescent Chemosensor for AlIII Ion and Fluorescent Species Formed in the Solution

During the last 50 years a vast number of structural studies on Schiff bases derived from hydroxyaryl aldehydes and their coordination compounds have been undertaken. In this review we present a systematic and brief overview of the most important discoveries and achievements accomplished in this field. The occurrence of Schiff bases (and their complexes) derived from nine most commonly used hydroxyaryl aldehydes in the Cambridge Structural Database (CSD) has been investigated. Keto-enol tautomerism and intramolecular hydrogen bonding in salicylaldimines and naphthaldimines is discussed, with a comment of the most common errors in determining the correct tautomeric form. Also, the interrelationship of crystal packing and the substituents on the Schiff base is studied. Finally, we give a short overview of conformational differences between free Schiff bases and Schiff bases bonded to metal ions as well as some structural characteristics of Schiff base metal complexes.

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Schiff bases derived from hydroxyaryl aldehydes: molecular and crystal structure, tautomerism, quinoid effect, coordination compounds

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 compounds, (E)-2-[(2-bromophenyl)iminomethyl]-4-methoxyphenol, C(14)H(12)BrNO(2), (I), (E)-2-[(3-bromophenyl)iminomethyl]-4-methoxyphenol, C(14)H(12)BrNO(2), (II), and (E)-2-[(4-bromophenyl)iminomethyl]-4-methoxyphenol, C(14)H(12)BrNO(2), (III), adopt the phenol-imine tautomeric form. In all three structures, there are strong intramolecular O-H...N hydrogen bonds. Compound (I) has strong intermolecular hydrogen bonds, while compound (III) has weak intermolecular hydrogen bonds. In addition to these intermolecular interactions, C-H...pi interactions in (I) and (III), and pi-pi interactions in (I), play roles in the crystal packing. The dihedral angles between the aromatic rings are 15.34 (12), 6.1 (3) and 39.2 (14) degrees for (I), (II) and (III), respectively.

Three (E)-2-[(bromophenyl)iminomethyl]-4-methoxyphenols.

The molecule of the title compound, C18H15NO2, is not completely planar. It adopts a keto–amine tautomeric form with an intramolecular N—H⋯O and an intermolecular O—H⋯O hydrogen bond. The mol­ecules are linked by O—H⋯O hydrogen bonds into a three-dimensional network.

1-((2-Hydroxy-5-methylphenylamino)methylene)naphthalen-2(1H)-one

The crystal structure of the title compound, C15H13NO2, has been redetermined with better precision and with the location and free refinement of all H atoms [previous report; Rekhlova, Furmanova, Chanturiya & Chikhladze (1991). Kristallografiya, 36, 117–120]. The mol­ecule is present as the phenol–imine tautomeric form with strong intramolec­ular O—H⋯N hydrogen bonds.

A redetermination of 1- 4-((2-hydroxybenzylidene)amino)phenyl ethanone

The mol­ecule of the title compound, C15H15NO2, adopts the enol–imine tautomeric form and has a strong intra­molecular O—H⋯N hydrogen bond as a result. The mol­ecule is almost planar, with a maximum deviation of 0.1038 (15) A for the meth­oxy C atom. A weak C—H⋯π inter­action and a weak C—H⋯O hydrogen bond are present in the crystal.

https://journals.iucr.org/e/issues/2010/02/00/is2517/is2517.pdf

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

The crystal structure of C14H12ClNO2 was determined by X-ray analysis. It crystallizes in the triclinic space group Pc with a = 12.5346(10) A, b = 4.5101(3) A, c = 12.0534(11) A, α = 90.00o, β = 113.669(6)o, γ = 90.00o, Z = 2, Dx = 1.393 mg/m3, μ (MoKα) = 0.298 mm−1. The title compound is photochromic and molecule is non-planar. It adopts a phenol–imine tautomeric form with a strong intramolecular O–H···N hydrogen bond and a strong intermolecular C–H···O hydrogen bond. Minimum energy conformations AM1 were calculated as a function of the three torsion angles θ1(C10–C9–N1–C8), θ2(C9–N1–C8–C1) and θ3(N1–C8–C1–C6), varied every 10°. As in the X-ray experiment results, molecule has an angle that makes it non-planar between two aromatic rings in AM1 optimized geometry. Molecular and crystal structure of [(E)-2-[(3-chlorophenylimino)methy])-4-methoxyphenol], C14H12ClNO2, have been determined by single crystal X-ray diffraction study, and conformational analysis of the title molecule with respect to the selected torsion angle has been achieved by AM1 semi-empirical calculations.

Arzu Özek

Papers

Three (E)-2-[(bromophenyl)iminomethyl]-4-methoxyphenols.

1-((2-Hydroxy-5-methylphenylamino)methylene)naphthalen-2(1H)-one

A redetermination of 1- 4-((2-hydroxybenzylidene)amino)phenyl ethanone

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

Crystallographic and Conformational Analysis of [( E )-2-[(3-Chlorophenylimino)methy])-4-methoxyphenol]