Survey of conformational isomerism in (E)-2-[(4-bromophenylimino)methyl]-5-(diethylamino)phenol compound from structural and thermochemical points of view

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• 作者：Ç ; i臒dem Albayrak^a ; ^{calbayrak@sinop.edu.tr} ; Gö ; khan Ka艧ta艧^b ; Mustafa Odaba艧o臒lu^c ; René ; Frank^d
• 关键词：Schiff base ; Intramolecular hydrogen bond ; DFT ; Conformational analysis ; Isomerism ; IR and UV&ndash ; Vis spectroscopies
• 刊名：Spectrochimica Acta Part A ; Molecular and Biomolecular Spectroscopy
• 出版年：2012
• 期刊代码：99_13861425
• 类别：ch
• 出版时间：September, 2012
• 卷：95
• 期：Complete
• 页码：664-669
• 文件大小：510 K

摘要

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鈰疊r and C-H鈰€ interactions. The combination of these interactions is resulted in fused and 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.