Mustafa Odabaşoğlu

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. 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.

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

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.

Probing the compound (E)-5-(diethylamino)-2-[(4-methylphenylimino)methyl]phenol mainly from the point of tautomerism in solvent media and the solid state by experimental and computational methods

In this study, the molecular structure and spectroscopic properties of (E)-5-(diethylamino)-2-[(4-methylphenylimino)methyl]phenol were characterized experimentally by X-ray diffraction, FT-IR and UV-vis spectroscopic techniques and computationally by DFT method. It is concluded on the basis of X-ray diffraction and FT-IR analyses that the title compound exists in enol form in the solid state. UV-vis spectra of the title compound were recorded in different organic solvents to investigate the dependence of tautomerism on solvent types. The tautomerism-solvent relation was also studied by computational methods to have more insight on structural properties. The geometry optimization of the title compound in gas phase was performed by using DFT (B3LYP) method with 6-311G(d,p) basis set. The geometry optimizations in solvent media were carried out at the same theory level by the polarizable continuum model (PCM). In the calculation of excitation energies, TD-DFT calculations were carried out in both gas and solution phases. The computational investigation of non-linear optical properties indicates that the title compound has a good second order nonlinear optical property. The thermodynamic properties were obtained in the range of 100-500 K.

The prototropic tautomerism and substituent effect through strong electron-withdrawing group in (E)-5-(diethylamino)-2-[(3-nitrophenylimino)methyl]phenol.

The prototropic tautomerism in o-Hydroxy Schiff bases results in two forms called phenol-imine and keto-amine. The preference of a particular form by the compound changes in the solid and solvent media. The choice can also be regulated by a substituent with a different electron-donating or withdrawing group. In the present study, the above-mentioned factors are considered in the investigation of (E)-5-(diethylamino)-2-[(3-nitrophenylimino)methyl]phenol compound (an o-Hydroxy Schiff basis) by experimental (XRD, FT-IR and UV-vis) and computational (DFT and TD-DFT) methods. The results show that the title compound adopts only phenol-imine form in the solid and solvent media. This was attributed to the substituent effect through strong electron-withdrawing nitro group.

Electrochemical and spectroscopic study of 4-(Phenyldiazenyl)-2-{[tris-(hydroxymethyl)methyl] aminomethylene}cyclohexa-3,5-dien-1(2H)-one: mechanism of the azo and imine electroreduction

Newly synthesized 4-(phenyldiazenyl)-2-{[tris(hydroxymethyl)methyl]aminomethylene} cyclohexa-3,5-dien-1(2H)-one was characterized by elemental analysis, FT-IR, NMR, electronic spectra, voltammetry. Tautomeric equilibrium of 4-(phenyldiazenyl)-2-{[tris(hydroxymethyl) methyl]aminomethylene}cyclohexa-3,5-dien-1(2H)-one in DMSOd is supported by 1H NMR data. The nature of electrochemical process of 4-(phenyldiazenyl)-2-{[tris(hydroxymethyl) methyl]aminomethylene}cyclohexa-3,5-dien-1(2H)-one in Britton-Robinson buffer (pH 2-9) was studied on the HMDE by square-wave (SWV), adsorptive stripping square-wave (AdSWV) and cyclic voltammetry (CV). The electrochemical parameters (Ip/Ep, Ip/v, Ip/pH, Ip/tacc) of the compound were determined.

Synthesis, spectroscopic characterizations and quantum chemical computational studies of (Z)-4-[(E)-(4-fluorophenyl)diazenyl]-6-[(3-hydroxypropylamino)methylene]-2-methoxycyclohexa-2,4-dienone.

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.

Propynylferrocene and (phenyl­ethyn­yl)­ferrocene

The title compounds, propynylferrocene, [Fe(C 5 H 5 )(C 8 H 7 )], (I), and (phenylethynyl)ferrocene, [Fe(C 5 H 5 )(C 13 H 9 )], (II), are stabilized by weak C-H···π interactions. The C≡C bond distances in these molecules are in the range 1.182 (3)-1.192 (3) A. In (II), the ferrocenyl and phenyl groups are perpendicular, making an angle of 89.06 (13)°, which is a rare occurrence.

2-Aminopyridinium-succinate-succinic acid (2/1/1).

In the title compound, 2C(5)H(7)N(2)(+).C(4)H(4)O(4)(2-).C(4)H(6)O(4), cyclic eight-membered hydrogen-bonded rings exist involving 2-aminopyridinium and succinate ions. The succinic acid and succinate moieties lie on inversion centres. Succinic acid molecules and succinate ions are linked into zigzag chains by O-H.O hydrogen bonds, with O.O distances of 2.6005 (16) A.

2-aminopyridinium benzoate.

Cyclic eight-membered hydrogen-bonded rings exist in the title compound, C(5)H(7)N(2)(+).C(7)H(5)O(2)(-), involving the 2-aminopyridinium and benzoate ions. Each benzoate ion has two intramolecular hydrogen bonds. 2-Aminopyridinium benzoate ion pairs are linked by N-H...O hydrogen bonds, with an N...O distance of 2.8619 (14) A.

Existence of a resonance hybrid structure as a result of proton tautomerism in (±)-(E)-4-Bromo-2-[(2,3-dihydroxypropylimino) methyl]phenol racemate

o-Hydroxy Schiff bases have two tautomers known as phenol-imine and keto-amine forms. In the present work, the tautomerism in (E)-4-Bromo-2-[(2,3-dihydroxypropylimino)methyl]phenol compound has been investigated by experimental (XRD, FT-IR and UV-vis) and computational (DFT and TD-DFT) methods. The X-ray diffraction (XRD) study reveals that the title compound favors a resonance hybrid structure of phenol-imine and keto-amine forms in the solid state rather than having these forms separately or jointly. Experimental UV-vis study of proton transfer process in solvent media (Benzene, DMSO and EtOH) shows the preference of phenol-imine form in benzene while both phenol-imine and keto-amine characteristics are present in EtOH and DMSO.