Keto–iminol tautomerism in acetohydroxamic and formohydroxamic acids

Sałdyka, Magdalena; Mielke, Zofia

doi:10.1016/j.vibspec.2007.06.003

Cited by 15 publications

(14 citation statements)

References 46 publications

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“…Since HU displays strong biochemical activity, it seemed reasonable to perform a detailed study of the most stable keto isomers of HU. It has been shown in our earlier papers [26][27][28] that the MP2 method and the level of ab initio calculations used in this study reproduce well the experimental data of simple hydroxamic acids. Full geometry optimizations of the four keto isomers of HU have been performed with the MP2/6-311++G(2d,2p) method.…”

Section: Geometries and Energeticssupporting

confidence: 68%

“…See DOI: 10.1039/c0cp00709a our research group 26,27 we have shown that formohydroxamic and acetohydroxamic acids trapped from the gas-phase into solid argon or nitrogen exist in matrices mainly in the keto form with an intramolecular hydrogen bond. Recent Møller-Plesset perturbation theory (MP2) 28,29 and density functional theory (DFT) 30,31 calculations performed for acetohydroxamic acid indicated the Z-keto structure to be the lowest energy isomer. The two methods however differed in the order of stability of the 2Z and 1E isomers.…”

Section: Introductionmentioning

confidence: 99%

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Isomerical and structural determination of N-hydroxyurea: a matrix isolation and theoretical study

Sałdyka

2010

Phys. Chem. Chem. Phys.

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The structure, isomerization pathways and vibrational spectra of the important N-hydroxyurea (HU) molecule were studied by matrix isolation FT-IR spectroscopy and molecular orbital calculations undertaken at the MP2/6-311++G(2d,2p) level of theory. In agreement with theoretical predictions, 1Ea represents the most stable keto isomer in the gas-phase, being the dominant species trapped in argon matrices, while the 1Za isomer also contributes to the spectrum of isolated HU molecules. According to the calculated abundance values at the temperature of evaporation of the compound (393 K), the 1Ea and 1Za isomers together with a small contribution of 1Eb are expected to appear in the experimental spectra. Since the barrier for interconversion 1Ea↔ 1Eb is only ∼2 kJ mol(-1), these two isomers are in equilibrium in the matrices and, at low temperature, the population of the less stable 1Eb form is too small to be observed. Full assignment of the observed spectra of N-hydroxyurea and its deuterium analogue was undertaken on the basis of comparison with theoretical data.

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Section: Geometries and Energeticssupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Isomerical and structural determination of N-hydroxyurea: a matrix isolation and theoretical study

Sałdyka

2010

Phys. Chem. Chem. Phys.

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“…Based on previous reports that confirm the existence of acyl and aroylhydrazones in polar solvents (such as DMSO solutions) up to 100% as E -isomers [ 56 ], the Z -isomers are excluded in this study. On the other hand, many reports have studied the amide-amidic acid tautomerism of amides and anilides [ 57 , 58 , 59 , 60 , 61 ]. However, to the best of our knowledge, there are no literature reports studying amido-amidic acid tautomerism for acylhydrazones.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, DFT Molecular Geometry and Anticancer Activity of Symmetrical 2,2′-(2-Oxo-1H-benzo[d]imidazole-1,3(2H)-diyl) Diacetate and Its Arylideneacetohydrazide Derivatives

et al. 2022

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To identify new candidate anticancer compounds, we here report the synthesis of benzimidazole derivatives: diethyl 2,2′-(2-oxo-1H-benzo[d]imidazole-1,3(2H)-diyl) diacetate and its arylideneacetohydrazide derivatives, using ultrasonic irradiation and conventional heating. The compounds were confirmed by Nuclear magnetic resonance (NMR) (JEOL, Tokyo, Japan) and Fourier transform infrared spectroscopy (FTIR) spectroscopy (Thermoscientific, Waltham, MA, USA). The molecular structure and electronic properties of the studied compounds were predicted for the acetohydrazide hydrazones. These compounds exist as a mixture of configurational and conformational isomerism as well as amido-amidic acid tautomerism. The NMR spectral data proved the predominance of syn-E amido isomers. In addition, density functional theory (DFT) predicted stability in the gas phase and showed that syn-E amido isomers are the most stable in the presence of an electron donating group, while the anti-isomer is the most stable in the presence of electron-attracting substituents. The anticancer activity of these synthetic compounds 6a, 6b and 6c towards both colon cancer (HCT-116) and cervical cancer (HeLa) cells was examined by MTT assay and DAPI staining. The MTT assay revealed a strong antiproliferative effect against the cancer cells at low concentrations, and interestingly, no significant inhibitory action against the non-cancerous cell line, HEK-293. The IC50 values for HCT-116 were 29.5 + 4.53 µM, 57.9 + 7.01 µM and 40.6 + 5.42 µM for 6a, 6b, and 6c, respectively. The IC50 values for HeLa cells were 57.1 + 6.7 µM, 65.6 + 6.63 µM and 33.8 + 3.54 µM for 6a, 6b, and 6c, respectively. DAPI staining revealed that these synthesized benzimidazole derivatives caused apoptotic cell death in both the colon and cervical cancer cells. Thus, these synthetic compounds demonstrate encouraging anticancer activity as well as being safe for normal human cells, making them attractive candidates as anticancer agents.

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“…The relative abundances were calculated in the same way as described in Ref. [26]. The most abundant conformer in the gas phase at this temperature is PL HB 1 (ca.…”

Section: Resultsmentioning

confidence: 99%

Conformational isomerism of pyridoxal. Infrared matrix isolation and theoretical studies

Kwiatek¹,

Mielke²

2015

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Keto–iminol tautomerism in acetohydroxamic and formohydroxamic acids

Cited by 15 publications

References 46 publications

Isomerical and structural determination of N-hydroxyurea: a matrix isolation and theoretical study

Isomerical and structural determination of N-hydroxyurea: a matrix isolation and theoretical study

Synthesis, DFT Molecular Geometry and Anticancer Activity of Symmetrical 2,2′-(2-Oxo-1H-benzo[d]imidazole-1,3(2H)-diyl) Diacetate and Its Arylideneacetohydrazide Derivatives

Conformational isomerism of pyridoxal. Infrared matrix isolation and theoretical studies

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