Conformational studies of aminomethylene-malonic acid dimethylester and its N-methyl derivatives using vibrational spectroscopy, X-ray analysis and ab initio calculations

Gróf, Martin; Gatial, A.; Matějka, Pavel; Kožı́šek, Jozef; Milata, Viktor; Prónayová, Nadežda

doi:10.1016/j.molstruc.2008.10.051

Cited by 3 publications

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“…In accordance with Table 4, the EZa:ZZa Boltzmann ratio of P2 in vacuo is approximately 1:4, while in CHCl 3 and DMSO, the ratios change to 2:3 and 1:1, respectively. 30 The major difference in the geometry of P1, P2, and P3 compounds is found for the intramolecular hydrogen N−H…”

Section: ■ Computational Detailsmentioning

confidence: 99%

“…The πconjugation prefers a planar structure of the push−pull systems. The planar structure is furthermore stabilized by the hydrogen bond between the amino hydrogen and the carbonyl oxygen from the acetyl 29 or methyl/ethyl ester 30 group. On the other hand, sp 3 hybridization of the amino nitrogen and the hydrogen−hydrogen repulsion prefer different nonplanar geometries.…”

Section: ■ Introductionmentioning

confidence: 99%

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Conformational, Spectroscopic, and Molecular Dynamics DFT Study of Precursors for New Potential Antibacterial Fluoroquinolone Drugs

et al. 2014

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Biological activity, functionality, and synthesis of (fluoro)quinolones is closely related to their precursors (for instance 3-fluoroanilinoethylene derivatives) (i.e., their functional groups, conformational behavior, and/or electronic structure). Herein, the theoretical study of 3-fluoroanilinoethylene derivatives is presented. Impact of substituents (acetyl, methyl ester, and ethyl ester) on the conformational analysis and the spectral behavior is investigated. The B3LYP/6-311++G** computational protocol is utilized. It is found that the intramolecular hydrogen bond N-H···O is responsible for the energetic preference of anti (a) conformer (anti position of 3-fluoroanilino group with respect to the C═C double bond). The Boltzmann ratios of the conformers are related to the differences of the particular dipole moments and/or their dependence on the solvent polarity. The studied acetyl, ethyl ester, and methyl ester substituted fluoroquinolone precursors prefer in the solvent either EZa, ZZa, or both conformers equally, respectively. In order to understand the degree of freedom of rotation of the trans ethyl ester group, B3LYP/6-311G** molecular dynamic simulations were carried out. Vibrational frequencies, electron transitions, as well as NMR spectra are analyzed with respect to conformational analysis, including the effect of the substituent. X-ray structures of the precursors are presented and compared with the results of the conformational analysis.

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Section: ■ Computational Detailsmentioning

confidence: 99%