Vibrational spectra and theoretical studies of tautomerism and hydrogen bonding in the violuric acid and 6-amino-5-nitrosouracil system

Bonacin, Juliano Alves; Formiga, André Luiz Barboza; Melo, Vitor H. S. de; Toma, Henrique E.

doi:10.1016/j.vibspec.2006.10.007

Cited by 37 publications

(23 citation statements)

References 33 publications

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“…Another interesting aspect of amidrazones is tautomerism. In recent years, study of tautomerism received renewed attention due to its effect on molecular behaviors and a lot of investigations about tautomerism have been reported especially about keto-enol [26,27], imine-enamine [28,29], purines [30], pyrimidines [31], and many other systems [32][33][34][35]. Despite the importance of tautomerism in amidrazones, any reports about the study of tautomerism in amidrazones have not been observed in the literatures.…”

Section: Introductionmentioning

confidence: 99%

DFT and MP2 study of simple and water-assisted tautomerism in amidrazones

Tavakol

2011

Struct Chem

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DFT and MP2 methods were used to calculate structural parameters, vibrational modes, solvent effect, and energetic properties of amidrazones. Amidrazones can be presented by three tautomeric forms and six isomers. All tautomers and transition states were optimized at the B3LYP/6-311??g** and MP2/6-311??G** levels of theory. The relative stabilities of amidrazone isomers in the gas phase were found to be as 1Z. The calculated energy differences between E and Z isomers are very low and between different tautomers are nearly low, but the energy barriers for tautomerism interconversions at the gas phase are high. The kinetic and thermodynamic data in solvents (chloroform, tetrahydrofuran, acetone, and water) are nearly similar to those in the gas phase but their rate constants are slightly less than those in the gas phase. Moreover, equilibrium and rate constants of intermolecular tautomerism in presence of 1-3 molecules of water were calculated. Computed energy barriers show that the barrier energy of water-assisted tautomerism is very lower than that in simple tautomerism and also calculated binding energies show that water can stabilize transition states more than tautomers. Therefore, this water-assisted tautomerism can be performed fast, especially with the assistance of two molecules of water.

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Section: Introductionmentioning

confidence: 99%

DFT and MP2 study of simple and water-assisted tautomerism in amidrazones

Tavakol

2011

Struct Chem

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“…A study of tautomerism, especially in biologically active molecules, has been one of the most interesting in computational researches because tautomerism plays an important role in the determination of compound application [22][23][24][25][26][27][28][29][30][31][32][33][34] , and different tautomers of each molecule behave differently in both chemical and biological systems. Thus, since the biological, chemical, and complexation properties of T are different in different tautomers, we have attempted a thorough analysis of this molecule in both the tautomery scheme and complexation properties in our study.…”

Section: T-i2(perp) T2-i2(planar)mentioning

confidence: 99%

Quantum mechanical investigation of 2,3-dihydro-1-methyl-2-thioxopyrimidin-4(1H)-one tautomers and their complexes with iodine.

Hadadi¹

2015

Orient. J. Chem

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DFT and AB initio theoretical methods were used to calculate the relative stability of tautomers and complexes with iodine in the 2,3-dihydro-1-methyl-2-thioxopyrimidin-4(1H)-one. This compound can be used to treat hyper thyroidism due to their ability to make complexes with iodine.All tautomers and complexes are optimized using the B3LYP Method with two different energies, the relative energies shows that in all tautomers and complexes. Thione forms are more stable than thieolforms.The NBO calculation is carried out for tautomers and complexes to obtain atomic charges and accept donor interactions. These result confirm the ability of T tautomers to form complexes and show that the planar complexes has more effective interaction than the perpendicular complex.The atom in molecule (AIM) analysis show that the charge density and its laplacian at the S-I bond critical point of the planar complex is greater than the perpendicular complex.

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“…For example, tautomerism in keto-enol [8,9], imineenamine [10,11], purines [12], pirimidines [13] and many other systems [14][15] have been studied during past two decades. Thereupon, compounds containing tautomers can be the subject of interest for the theoreticians.…”

Section: Introductionmentioning

confidence: 99%

Effect of Ring in Imines and Enamines Tautomerism in Gas Phase and Solution: A Computational Study

Mohamadi

Shabanian

Hajibeygi

et al. 2013

J. Chil. Chem. Soc.

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Tautomeric structures from imine-enamine equilibria with rings of different size were geometrically optimized at the B3LYP/6-311++G** level of theory. Then important molecular parameters, IR frequencies, NBO and dipole moment results in the gas phase and solution were extracted. The energetic results show that relative stability of enamine tautomer (versus imine tautomer) increases with the increase of ring size and polarity of solvent. Calculated frequencies show the effect on the C=N frequency (imine tautomer) is attributed to ring size. The effect of increasing ring stain by decreasing ring size is to increase the C=N frequency. In addition, variation of dipole moments and NBO charges on atoms in the solvents are studied.

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Vibrational spectra and theoretical studies of tautomerism and hydrogen bonding in the violuric acid and 6-amino-5-nitrosouracil system

Cited by 37 publications

References 33 publications

DFT and MP2 study of simple and water-assisted tautomerism in amidrazones

DFT and MP2 study of simple and water-assisted tautomerism in amidrazones

Quantum mechanical investigation of 2,3-dihydro-1-methyl-2-thioxopyrimidin-4(1H)-one tautomers and their complexes with iodine.

Effect of Ring in Imines and Enamines Tautomerism in Gas Phase and Solution: A Computational Study

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