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ABSTRACT: In this study, (E)-2-[(4-bromophenylimino)methyl]-5-(diethylamino)phenol compound was investigated by mainly focusing on conformational isomerism. For this purpose, molecular structure and spectroscopic properties of the compound were experimentally characterized by X-ray diffraction, FT-IR and UV-Vis spectroscopic techniques, and computationally by DFT method. The X-ray diffraction analysis of the compound shows the formation of two conformers (anti and eclipsed) related to the ethyl groups of the compound. The two conformers are connected to each other by non-covalent C-H⋯Br and C-H⋯π interactions. The combination of these interactions is resulted in fused R(2)(2)(10) and R(2)(4)(20) synthons which are responsible for the tape structure of crystal packing arrangement. The X-ray diffraction and FT-IR analyses also reveal the existence of enol form in the solid state. From thermochemical point of view, the computational investigation of isomerism includes three studies: the calculation of (a) the rate constants for transmission from anti or eclipsed conformations to transition state by using Eyring equation, (b) the activation energy needed for isomerism by using Arrhenius equation, (c) the equilibrium constant from anti conformer to eclipsed conformer by using the equation including the change in Gibbs free energy. The dependence of tautomerism on solvent types was studied on the basis of UV-Vis spectra recorded in different organic solvents. The results showed that the compound exists in enol form in all solvents except ethyl alcohol.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 04/2012; 95:664-9. · 2.10 Impact Factor
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ABSTRACT: In this study, (E)-5-(diethylamino)-2-[(4-iodophenylimino)methyl]phenol compound was investigated from the point of stacking interactions assembling the supramolecular network, conformational isomerism and tautomerism. For this purpose, X-ray diffraction, FT-IR and UV/Vis spectroscopic techniques were used, giving the following structural and spectroscopic properties of the compound: The title compound has two conformers (anti and eclipsed) in the crystal structure resulting from rotation about C-N single bond of ethyl group. Both conformers prefer enol form in the solid state, adopting E configuration about the CN double bond. The supramolecular architecture of the compound is constructed by two non-covalent interactions as C-H⋯π and halogen-halogen interactions. The repetition of C-H⋯π interactions is resulted in a single-stranded helical structure. The helical structures are further connected by C-I⋯I-C interactions of Type I to construct the two dimensional supramolecular network defined as (6,3)-net in Wells nomenclature. The title compound adopts both enol and keto forms in EtOH (a polar and protic solvent) while enol form is preferred in the solid state.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2012; 94:200-4. · 2.10 Impact Factor
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ABSTRACT: 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°. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis, and thermodynamic properties were described from the computational process. In addition to these calculations, we were investigated solvent effects on the nonlinear optical properties (NLO) of the title compound.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2012; 93:208-13. · 2.10 Impact Factor
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ABSTRACT: 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. A relaxed potential energy surface scan has been performed based on the optimized geometry of OH tautomeric form to describe the potential energy barrier belonging to intramolecular proton transfer and to observe the effects of transfer on the molecular geometry. The second-order nonlinear optical properties have been investigated based on the first static hyperpolarizability (β) by using the density functional theory.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2012; 93:1-9. · 2.10 Impact Factor
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ABSTRACT: 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. UV-vis spectra were recorded in different organic solvents. The results show that title compound exists in both keto and enol forms in DMSO, EtOH but it exists in enol form in benzene. In addition, the title compound in DMSO showed new absorption band at 436 nm due to the high ionizing effect of this solvent. The geometry optimization of title compound in gas phase was performed using DFT method with B3LYP applying 6-311G(d,p) basis set. TD-DFT calculations starting from optimized geometry were carried out in gas phase to calculate excitation energies of title compound. The non-linear optical properties were computed with the same level of theory and title compound showed a good second order nonlinear optical property. In addition, thermodynamic properties were obtained in the range of 100-500 K.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2012; 92:357-64. · 2.10 Impact Factor
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ABSTRACT: In this study, the molecular structure and spectroscopic properties of the title compound were characterized by X-ray diffraction, FT-IR and UV-vis spectroscopies. These properties were also investigated using DFT method. The most convenient conformation of title compound was firstly determined. The geometry optimizations in gas phase and solvent media were performed by DFT methods with B3LYP adding 6-31G(d) basis set. The differences between crystal and computational structures are due to crystal packing in which hydrogen bonds play an important role. UV-vis spectra were recorded in different organic solvents. The results show that title compound exists in both keto and enol forms in DMSO, EtOH but it tends to shift towards enol form in benzene. The polar solvents facilitate the proton transfer by decreasing the activation energy needed for Transition State. The formation of both keto and enol forms in DMSO and EtOH is due to decrease in the activation energy. TD-DFT calculations starting from optimized geometry were carried out in both gas and solution phases to calculate excitation energies of the title compound. The non-linear optical properties were computed at the theory level and the title compound showed a good second order non-linear optical property. In addition, thermodynamic properties were obtained in the range of 100-500K.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 01/2012; 85(1):85-91. · 2.10 Impact Factor
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ABSTRACT: 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)°. In the mol-ecule, an intra-molecular O-H⋯O hydrogen bond generates an S(6) ring motif.
Acta Crystallographica Section E Structure Reports Online 01/2011; 67(Pt 3):o640. · 0.35 Impact Factor
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ABSTRACT: 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 19.06 (2)° in the other. Each of the independent mol-ecules has an intra-molecular O-H⋯O hydrogen bond. In the crystal, mol-ecules are stacked along [100].
Acta Crystallographica Section E Structure Reports Online 01/2011; 67(Pt 3):o639. · 0.35 Impact Factor
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ABSTRACT: The title compound, C(19)H(24)N(2)O(2), adopts the phenol-imine tautomeric form. An intra-molecular O-H⋯N hydrogen bond results in the formation of a six-membered ring. The aromatic rings are oriented at a dihedral angle of 17.33 (16)°. Inter-molecular C-H⋯π inter-actions occur in the crystal.
Acta Crystallographica Section E Structure Reports Online 01/2011; 67(Pt 3):o599-600. · 0.35 Impact Factor
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ABSTRACT: In the mol-ecule of the title compound, C(17)H(20)N(2)O(2), the aromatic rings are oriented at a dihedral angle of 6.23 (22)°. Intra-molecular N-H⋯O hydrogen bonding involving the amine H atom and the carbonyl O atom affects the conformation of the mol-ecule. One of the ethyl arms is disordered over two conformations, with occupancies of 0.59 (2) and 0.41 (2). The crystal packing is stabilized by inter-molecular C-H⋯O and O-H⋯O hydrogen bonds, and weak C-H⋯π inter-actions.
Acta Crystallographica Section E Structure Reports Online 01/2010; 66(Pt 12):o3138-9. · 0.35 Impact Factor
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ABSTRACT: 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 13.55 (2), 21.24 (2) and 46.26 (1)°. C-H⋯π inter-actions are also observed in the crystal structure.
Acta Crystallographica Section E Structure Reports Online 01/2010; 66(Pt 3):o684. · 0.35 Impact Factor
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ABSTRACT: 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)°. There is a strong intra-molecular O-H⋯O hydrogen bond. Geometrical parameters, determined using X-ray diffraction techniques, are compared with those calculated by density functional theory (DFT), using hybrid exchange-correlation functional, B3LYP and semi-empirical (PM3) methods.
Acta Crystallographica Section E Structure Reports Online 01/2010; 66(Pt 3):o559-60. · 0.35 Impact Factor
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ABSTRACT: 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. A weak C-H⋯π inter-action and a weak C-H⋯O hydrogen bond are present in the crystal.
Acta Crystallographica Section E Structure Reports Online 01/2010; 66(Pt 2):o469. · 0.35 Impact Factor
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ABSTRACT: 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)°. An intra-molecular N-H⋯O hydrogen bond generates an S(6) ring motif. In the crystal structure, pairs of mol-ecules are linked into centrosymmetric R(2) (2)(10) dimers by pairs of O-H⋯O hydrogen bonds. Aromatic π-π inter-actions are observed between the benzene rings of adjacent dimers [centroid-centroid distance = 3.4808 (7) Å].
Acta Crystallographica Section E Structure Reports Online 01/2010; 66(Pt 2):o449. · 0.35 Impact Factor
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ABSTRACT: 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. The title mol-ecule 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, mol-ecules are linked by inter-molecular C-H⋯π inter-actions.
Acta Crystallographica Section E Structure Reports Online 01/2010; 66(Pt 2):o315. · 0.35 Impact Factor
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ABSTRACT: 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. The crystal structure features a weak C-H⋯π inter-action.
Acta Crystallographica Section E Structure Reports Online 01/2010; 66(Pt 2):o311. · 0.35 Impact Factor
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ABSTRACT: 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)°. The ethyl group is disordered over two orientations with occupancies of 0.598 (6) and 0.402 (6). In the crystal, the mol-ecules are linked into chains along the b axis by C-H⋯π inter-actions.
Acta Crystallographica Section E Structure Reports Online 01/2010; 66(Pt 2):o287. · 0.35 Impact Factor
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ABSTRACT: The title compound, C(14)H(12)ClNO(3)·0.25H(2)O, exists in the keto-amine form, and the aromatic rings are oriented at a dihedral angle of 7.24 (7)°. Bifurcated intra-molecular N-H⋯(O,O) hydrogen bonds result in the formation of planar six- and five-membered rings. In the crystal structure, inter-molecular O-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules into chains. π-π contacts between benzene rings [centroid-centroid distance = 3.5065 (9) Å] may further stabilize the structure. There also exists a weak C-H⋯π inter-action.
Acta Crystallographica Section E Structure Reports Online 01/2009; 65(Pt 5):o1104. · 0.35 Impact Factor
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ABSTRACT: The title compound, C(15)H(15)NO(2), adopts the enol-imine tautomeric form. The dihedral angle between the two benzene rings is 48.1 (1)°. Intra-molecular O-H⋯N and O-H⋯O hydrogen bonds generate S(6) and S(5) ring motifs, respectively. In the crystal, mol-ecules are linked into centrosymmetric R(2) (2)(10) dimers via pairs of O-H⋯O hydrogen bonds and the dimers may interact through very weak by π-π inter-actions [centroid-centroid distance = 4.150 (1) Å]. The ethyl group is disordered over two orientations, with occupancies of 0.587 (11) and 0.413 (11).
Acta Crystallographica Section E Structure Reports Online 01/2009; 65(Pt 8):o2055. · 0.35 Impact Factor
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ABSTRACT: The title compound, C(17)H(19)NO(2), exists as an enol-imine tautomer. The dihedral angle between the two benzene rings is 4.6 (2)°. The mol-ecular structure is stabilized by intramol-ecular O-H⋯O and O-H⋯N hydrogen bonds which generate S(5) and S(6) ring motifs, respectively. In the crystal, mol-ecules are linked into centrosymmetric dimers by pairs of O-H⋯O hydrogen bonds. In addition, C-H⋯π inter-actions involving both benzene rings are observed.
Acta Crystallographica Section E Structure Reports Online 01/2009; 65(Pt 8):o2022. · 0.35 Impact Factor
