A DFT Approach on Tioguanine: Exploring Tio-Tiol Tautomers, Frontier Molecular Orbitals, IR and UV Spectra, and Quadrupole Coupling Constants

2021 ◽  
pp. 116018
Author(s):  
Kun Harismah ◽  
Adil Muala Dhumad ◽  
Heba Salman Ibraheem ◽  
Hasan Zandi ◽  
Hatem Jameel Majeed
Keyword(s):  
Uv Spectra ◽  
Molecular Orbitals ◽  
Coupling Constants ◽  
Frontier Molecular Orbitals ◽  
Quadrupole Coupling ◽  
Ir And Uv Spectra

scholarly journals Barbituric Acid Tautomers: DFT Computations of Keto-Enol Conversions, Frontier Molecular Orbitals and Quadrupole Coupling Constants

2021 ◽  
Vol 12 (1) ◽  
pp. 244-252
Keyword(s):  
Density Functional ◽  
Barbituric Acid ◽  
Molecular Orbitals ◽  
Coupling Constants ◽  
Atomic Scale ◽  
Model Systems ◽  
Frontier Molecular Orbitals ◽  
Hydrogen Atoms ◽  
Dft Computations ◽  
Quadrupole Coupling

In this work, density functional theory (DFT) computations were performed to investigate tautomeric formation processes of barbituric acid (BA). Ten tautomers were totally investigated for the purpose based on the movement of hydrogen atoms among nitrogen and oxygen atoms providing one pure keto form (BA1) and nine other keto-enol forms. The structures were optimized, and BA1 was found to be the most stable one, and both BA3 and BA7 were found to be the most unstable ones. The point was that the ring structure was broken for both BA3 and BA7, but the structure's stability was still approved. Indeed, such serious tautomeric conversion with breaking the structure warns for using such BA bio-organic molecules for further applications, especially in pharmacy-related ones, in which side effects or byproduct synthesis might appear. Further analyses of frontier molecular orbitals features indicated the effects of such tautomerism processes on all model systems, in which more details were obtained by atomic-scale quadrupole coupling constant (Qcc). All obtained results approved significant changes of tautomers regarding molecular and atomic scale features with more or less significant effects regarding the original BA1 reference model.

Prediction of Antiglycation Activity by Calculating the Energies of Frontier Molecular Orbitals for New 4-Hydroxy-1,4-Dihydroazolo[5,1-c]-1,2,4-Triazines Used as an Example

2020 ◽  
Vol 46 (6) ◽  
pp. 1278-1284
Author(s):  
R. A. Litvinov ◽  
R. A. Drokin ◽  
D. D. Shamshina ◽  
M. Yu. Kalenova ◽  
L. E. Usmianova ◽  
...  
Keyword(s):  
Molecular Orbitals ◽  
Frontier Molecular Orbitals

Syntheses, spectral properties and pesticide activity of O-ethyl-S-propyl-O-(1-alkyl, phenyl-5-chloro, alkoxy-6-oxo-1H-pyridazine-4-yl)esters of dithiophosphoric acid

1980 ◽  
Vol 45 (8) ◽  
pp. 2247-2253 ◽  
Author(s):  
Václav Konečný ◽  
Štefan Varkonda ◽  
Vojtech Kubala
Keyword(s):  
Spectral Properties ◽  
Uv Spectra ◽  
Dithiophosphoric Acid ◽  
Insecticide Activity ◽  
Ir And Uv Spectra

Syntheses of O-ethyl-S-propyl-O-(1-alkyl, phenyl-5-chloro, alkoxy-6-oxo-1H-pyridazine-4-yl) esters of dithiophosphoric acid are described. The compounds were investigated for their IR and UV spectra and for their contact and system activities as insecticides, acaricides, ovicides, fungicides and herbicides. Some of the compounds proved efficient acaricides; compound VIII also had an insecticide activity.

Thermal cyclocondensations of 3-N(4- and 5-benzimidazolyl and benztriazolyl)amino derivatives of 2-propenoic acid

1987 ◽  
Vol 52 (12) ◽  
pp. 2918-2925 ◽  
Author(s):  
Viktor Milata ◽  
Dušan Ilavský
Keyword(s):  
Uv Spectra ◽  
Propenoic Acid ◽  
Amino Derivatives ◽  
Derivatives Of ◽  
C Nmr ◽  
Ir And Uv Spectra

The cyclization of 3-N(4- and 5-benzimidazolyl and benztriazolyl)amino-2-cyano- and 2-ethoxycarbonyl-2-propenoate esters Ia, b-IVa, b under the conditions of the Gould-Jacobs reaction leads to angularly ring-fused substituted imidazo or triazolo[4,5-f] (V, VI) and [4,5-h] (VII, VIII) quinolines, respectively. The esters Vb-VIIIb have been transformed into the corresponding chloroderivatives Vc-VIIIc. 3-N(5-Benzimidazolyl and 5-benztriazolyl)amino-2-cyano-2-propenenitriles are cyclized in the presence of aluminium(III) chloride to give the aminoquinolines Vd, VId. The structure of the products has been characterized by their 1H, 13C NMR, IR, and UV spectra.

19F Nuclear Quadrupole Coupling in some Halomethanes

1986 ◽  
Vol 41 (1-2) ◽  
pp. 171-174 ◽  
Author(s):  
M. Frank ◽  
F. Gubitz ◽  
W. Ittner ◽  
W. Kreische ◽  
A. Labahn ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Simple Model ◽  
Temperature Dependence ◽  
Coupling Constants ◽  
Temperature Dependent ◽  
Distribution Method ◽  
Quadrupole Coupling ◽  
Time Differential ◽  
Nuclear Quadrupole

The 19F quadrupole coupling constants in CF4, CHF3, CClF3 and CHClF2 are reported. The measurements were carried out temperature dependent using the time differential perturbed angular distribution method (TDPAD). The temperature dependence can be satisfactorily described in the framework of the Bayer-Kushida theory. A simple model is used to explain the appearance of H-F and Cl-F coupling constants in CHF3/CHClF2 and CClF3, respectively.

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