Electron configuration, binding energy, and nature of the bands in absorption spectra of tautomeric forms

1972 ◽  
Vol 15 (12) ◽  
pp. 1743-1746
Author(s):  
V. I. Danilova ◽  
A. G. Turovets ◽  
B. G. Plyaskin
Keyword(s):  
Binding Energy ◽  
Absorption Spectra ◽  
Electron Configuration ◽  
Tautomeric Forms

The interactions of tensides with calconalide I

1991 ◽  
Vol 56 (10) ◽  
pp. 2100-2106
Author(s):  
Irena Němcová ◽  
Oldřich Valcl ◽  
Jiří Makovička
Keyword(s):  
Dissociation Constant ◽  
Absorption Spectra ◽  
Tautomeric Forms

A study was made of the effect of cationogenic, anionogenic and nonionogenic tensides on the absorption spectra and dissociation constant of calconalide I. It was found that the changes in the absorption spectra are a result of influences on the dissociation of the dye and a shift in the equilibrium between the tautomeric forms. The mechanism of the effect of the tenside on dye dissociation was also discussed.

SYNTHETIC AND SPECTROMETRIC STUDIES OF SOME PYRAZOLONES

1949 ◽  
Vol 27b (4) ◽  
pp. 190-204 ◽  
Author(s):  
Paul E. Gagnon ◽  
R. Norman Jones ◽  
Jean L. Boivin
Keyword(s):  
Hydrochloric Acid ◽  
Absorption Spectra ◽  
Chemical Reactions ◽  
Ultraviolet Absorption ◽  
Tautomeric Forms ◽  
Single Form ◽  
First Time

Fourteen pyrazolones were synthesized from the corresponding mono or disubstituted cyanoacethydrazides or cyanoacetphenylhydrazides and evidence concerning their constitution was obtained from chemical reactions and ultraviolet absorption spectra determinations. A mixture of two tautomeric forms was obtained when 4-benzyl-3-amino-5-pyrazolone was prepared; it was converted to a single form by treatment with hydrochloric acid. The following compounds, as far as the authors are aware, have been prepared for the first time: 4-methyl-3-amino-5-pyrazolone, 4-methyl-2-phenyl-3-amino-5-pyrazolone, 4-ethyl-3-amino-5-pyrazolone, 4-ethyl-2-phenyl-3-amino-5-pyrazolone, 4-(2-phenoxyethyl)-3-amino-5-pyrazolone, 4-(2-phenoxyethyl)-2-phenyl-3-amino-5-pyrazolone, 4-(3-phenoxypropyl)-3-amino-5-pyrazolone, 4-(3-phenoxypropyl)-2-phenyl-3-amino-5-pyrazolone, 4-phenyl-3-amino-5-pyrazolone, 4-benzyl-3-amino-5-pyrazolone, 4-benzyl-2-phenyl-3-amino-5-pyrazolone, 4,4-dibenzyl-3-amino-5-pyrazolone, 4, 4-dibenzyl-2-phenyl-3-imino-5-pyrazolone, 4,4-(2,2-spiro-indanyl)-3-amino-5-pyrazolone.

scholarly journals Spectral and quantum chemical study of tautomeric and ion transformations of 2-(2-(2-hydroxy-5-sulfamoylphenyl)- hydrazono)-3-oxo-N-phenylbutanamide

2019 ◽  
Vol 60 (11) ◽  
pp. 106-113
Author(s):  
Anh Thi Ngoc Vu ◽  
◽  
Mikhail A. Ryabov ◽  
Olga V. Kovalchukova ◽  
Dmitry S. Gusarov ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Quantum Chemical ◽  
Electronic Absorption Spectra ◽  
Bathochromic Shift ◽  
Stable Form ◽  
Ionic Form ◽  
Absorption Bands ◽  
Tautomeric Forms ◽  
The Stability

In this paper, using the method DFT/B3LYP of quantum chemical modeling, the stability of tautomeric, conformer, and anionic forms of 2-(2-(2-hydroxy-5-sulfamoylphenyl)hydrazone-3-oxo-N-phenylbutanamide (H2L) was studied and the geometric, electronic structure and bond lengths of molecules in various tautomeric forms were determined. It was shown that the stability of tautomeric molecules H2L as anionic forms was determined by the number of existing intermolecular hydrogen bonds (closing six-membered and five-membered cycles). The most stable tautomeric and conformal forms of an organic molecule and its dianion are proposed. The interatomic distances, angles, charges on atoms, IR and electronic absorption spectra of tautomeric forms of the molecule and dianion (H2L and L2-) were calculated. In this work, we studied the electronic absorption spectra in an aqueous-alcoholic solution and found that in an alkaline medium the molecule transforms into the ionic form with a bathochromic shift of 47 nm, corresponding to the results of the shift of the long-wavelength band electronic absorption spectra upon transition from the hydrazotautomer (form a) to the dianion form (form b’’) at 92 nm obtained by TD-DFT. The calculated results for the distance and angles between atoms are in good agreement with the experimental data of the molecule by X-ray diffraction analysis. It was shown that the IR spectrum of the stable form appears two absorption bands in the region of 1690 and 1655 cm–1, which are attributed to stretching vibrations of carbonyl groups (C=O), bound by a strong intramolecular hydrogen bond and the presence of the NH-hydrazone fragment of the 1H NMR spectrum confirmed the most stable for a neutral molecule is the hydrazone form.

Interplay between conformational and solvent effects in UV-visible absorption spectra: curcumin tautomers as a case study

2019 ◽  
Vol 21 (28) ◽  
pp. 15504-15514 ◽  
Author(s):  
Alessandra Puglisi ◽  
Tommaso Giovannini ◽  
Liudmil Antonov ◽  
Chiara Cappelli
Keyword(s):  
Aqueous Solution ◽  
Experimental Study ◽  
Absorption Spectra ◽  
Solvent Effects ◽  
Visible Absorption ◽  
Tautomeric Forms ◽  
Uv Visible

We present a combined theoretical and experimental study on the UV-vis spectra of enol–keto (EK) and keto–keto (KK) tautomeric forms of curcumin dissolved in aqueous solution.

Electronic absorption spectra and structure of hydroxycoumarin derivatives and their ionized forms

1997 ◽  
Vol 75 (4) ◽  
pp. 365-376 ◽  
Author(s):  
Valery F. Traven ◽  
Larisa I. Vorobjeva ◽  
Tatjana A. Chibisova ◽  
Edward Andrew Carberry ◽  
Noelle Jean Beyer
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Bathochromic Shift ◽  
Hydroxyl Group ◽  
Absorption Bands ◽  
Pyrone Ring ◽  
Tautomeric Forms ◽  
Wavelength Absorption ◽  
Carbonyl Function

Electronic absorption spectra of 18 hydroxycoumarin derivatives and their ionized forms have been studied. Close agreement between experimental and the PPP CI calculated electron absorption band energies has been found in most cases. Strong polarization of the carbonyl function of the pyrone ring in the 7-hydroxycoumarin derivatives, H-bonding between the hydroxyl group and neighboring substituent in the ortho-substituted hydroxycoumarins, as well as their tautomeric transformations, have been suggested in the discussion of the electronic absorption spectra of the hydroxycoumarin derivatives. In accord also with calculational results, ionization of the hydroxyl function leads to a bathochromic shift of the longest-wavelength absorption bands in the spectra of 7-hydroxycoumarin derivatives. The ionization has no effect on the electronic absorption of the 4-hydroxycoumarin derivatives. Relative stabilities of the tautomeric forms of hydroxycoumarin derivatives and their ionized forms have also been compared by MNDO calculations. Keywords: hydroxycoumarins, intramolecular H-bonding, ionization, electronic absorption spectra, keto–enol tautomerism.

ABSORPTION SPECTRA OF 2,5-DIMERCAPTO-1,3,4-THIADIAZOLE AND ITS METHYL DERIVATIVES

1960 ◽  
Vol 38 (9) ◽  
pp. 1439-1444 ◽  
Author(s):  
G. D. Thorn
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Region ◽  
Hypsochromic Shift ◽  
Tautomeric Forms ◽  
Methyl Derivatives

The absorption spectra of the three tautomeric forms of 2,5-dimercapto-1,3,4-thiadiazole have been determined by using the N- and S-methyl derivatives. In the ultraviolet region, a hypsochromic shift in absorption maxima is shown in the change from the dithionic to the thionic–thiolic and to the dithiolic forms. Strong bands in the infrared at 1508–1475 cm−1 and 1435–1415 cm−1 have been assigned to [Formula: see text]respectively.

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