Investigating Functionalization Impacts on Structural Features of Barbituric Acid Derivatives: DFT Approach

2021 ◽  
pp. 1-9
Author(s):  
Narjes Hajali ◽  
Afshin Taghva Manesh ◽  
Ahmad Seif
Keyword(s):  
Density Functional ◽  
Barbituric Acid ◽  
Minimum Energy ◽  
Structural Features ◽  
Coupling Constants ◽  
Atomic Scale ◽  
Functional Theory ◽  
Quadrupole Coupling ◽  
Homo And Lumo ◽  
Characteristic Features

Density functional theory (DFT) calculations were performed to investigate electronic and structural properties of barbituric acid (BA) and sixtheen of its derivatives to show impacts of structural functionalization on the features of parent BA. The models were optimized and the minimum energy structures were confirmed by frequency calculations. Molecular and atomic descriptors were evaluated for the optimized models, in which the results of formation binding strength and molecular orbital features indicated significance of such functionalization processes on the observed properties. The highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) and their related parameters all indicated magnitudes of changes from one molecule to another one. Furthermore, atomic scale quadrupole coupling constants (Cq) were evaluated for the nitrogen and oxygen atoms of BA compounds showing significance of structural functionalization impacts on the atomic properties of parent BA. As a consequence, such structural analyses of BA compounds could show their characteristic features for further developments especially for their efficient pharmaceutical applications.

Structural analysis of an iron-assisted carbon monolayer for delivery of 2-thiouracil

2021 ◽  
pp. 1-9
Author(s):  
Azar Asgari Pari ◽  
Mohammad Yousefi ◽  
Susan Samadi ◽  
Mohammad Reza Allahgholi Ghasri ◽  
Maryam Bikhof Torbati
Keyword(s):  
Drug Delivery ◽  
Molecular Orbital ◽  
Density Functional ◽  
Dominant Role ◽  
Structural Features ◽  
Coupling Constants ◽  
Functional Theory ◽  
Quadrupole Coupling ◽  
Atomic Descriptors

An idea of employing an iron-assisted carbon (FeC) monolayer for delivery of 2-thiouracil (2TU) was examined in this work by analyzing structural features for singular and bimolecular models. Density functional theory (DFT) calculations were performed for optimizing the structures and evaluating molecular and atomic descriptors for analyzing the models systems. Two bimolecular models were obtained assigning by S-FeC and O-FeC models, in which each of S and O atom of 2TU was relaxed towards the Fe region of FeC surface in the mentioned models, respectively. The results indicated that both models were achievable with slightly more favorability for formation of S-FeC model. The obtained molecular orbital properties revealed the dominant role of FeC monolayer for managing future interactions of attached 2TU, which is indeed a major role for employing nanomaterials for targeted drug delivery purposes. In addition to energies and molecular orbital features, atomic quadrupole coupling constants indicated the benefit of employing FeC monolayer for drug delivery of 2TU.

Non-Covalent Functionalisation of C30 Fullerene by Pyrrole-n-Carboxylic Acid (n=2, 3): Density Functional Theory Studies

2017 ◽  
Vol 73 (1) ◽  
pp. 51-56
Author(s):  
Kun Harismah ◽  
Mahmoud Mirzaei ◽  
Nahid Ghasemi ◽  
Mohammad Nejati
Keyword(s):  
Density Functional Theory ◽  
Carboxylic Acid ◽  
Density Functional ◽  
Spherical Shape ◽  
Density Functional Theory Calculations ◽  
Coupling Constants ◽  
Atomic Scale ◽  
Functional Theory ◽  
Quadrupole Coupling ◽  
Non Covalent Interactions

AbstractFor functionalisation of a representative C30 fullerene nanostructure by pyrrole-n-carboxylic acid (PnCA; n=2, 3) their stabilities and properties were investigated based on density functional theory calculations. Parallel calculations were also done for C60 fullerene as evidence for comparing the results. Non-covalent interactions are considered to make the functionalised structures. In contrast with the spherical shape of C60, the shape of C30 fullerene is elliptical; therefore, the functionalisation processes were done for both axial and equatorial elliptical positions (AC30 and EC30). The results indicated that both the positions of C30 have almost equivalent chances to be functionalised by PnCA; but functionalisation by P2CA is slightly more favourable than P3CA, either for C60. The illustrated molecular orbitals’ distributions indicated that the direction of charge transfer could be considered from PnCA counterparts to fullerene counterparts. The molecular properties indicated more reactivity for C30 than for C60 fullerene. Finally, the atomic scale quadrupole coupling constants indicated different roles for N and O atoms of PnCA in the functionalised models.

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.

Density Functional Theory Studies of Bonding in Complexes H3N···XY of Ammonia and Dihalogen Molecules: A Comparison with Experimental Results from Rotational Spectroscopy

2002 ◽  
Vol 57 (6-7) ◽  
pp. 537-543 ◽  
Author(s):  
O. Kh. Poleshchuk ◽  
A. C. Legona
Keyword(s):  
Density Functional ◽  
Natural Bond Orbital ◽  
Coupling Constants ◽  
Rotational Spectroscopy ◽  
Charge Redistribution ◽  
Functional Theory ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Experimental Values

The electron density and nuclear quadrupole coupling constants (NQCC) of the H3N...XY (n a type in Mulliken notation) complexes, (X, Y = F, Cl, Br and I), are analyzed with the aid of density functional calculations. To demonstrate the quality of the calculations, various bond lengths and NQCCs obtained by using the hybrid Becke-Lee-Perdew-Yang functional are compared with the corresponding experimental values determined from rotational spectroscopy. An analysis of the NQCC values and various quantities derived fromthe natural bond orbital approach reveals that the molecular interaction is mainly electrostatic, with probably only a small extent of intermolecular electric charge redistribution on complex formation

A boroxol ring doped zigzag boron nitride nanotube: a computational DFT study of the quadrupole coupling constant

2009 ◽  
Vol 87 (6) ◽  
pp. 647-652 ◽  
Author(s):  
Asadollah Boshra ◽  
Ahmad Seif
Keyword(s):  
Density Functional Theory ◽  
Boron Nitride ◽  
Density Functional ◽  
Quadrupole Coupling Constant ◽  
Coupling Constants ◽  
Boron Nitride Nanotube ◽  
Coupling Constant ◽  
Functional Theory ◽  
Quadrupole Coupling ◽  
Dopant Atoms

Based upon density functional theory, we investigate the influence of oxygen dopant atoms that make a boroxol ring on the electrostatic properties of a zigzag (10, 0) boron nitride nanotube in which three of the nitrogen atoms are replaced by oxygen dopant atoms. The electric field gradient (EFG) tensors at the sites of 11B and 14N nuclei were calculated and converted to quadrupole coupling constants (CQ) in the two models of a perfect and a boroxol ring O-doped (10, 0) single-walled boron nitride nanotube (BNNT). Our calculations showed that the CQ values of the boron and nitrogen nuclei along the length of a perfect BNNT are divided into layers. Among the layers the mouth layers have the largest CQ magnitudes. In the doped model, in addition to the mouth layers, the CQ values of those nitrogen nuclei which directly bond to the boroxol ring are increased. However, the CQ values of the boron nuclei that make the boroxol ring and directly bond to the boroxol ring are decreased.

scholarly journals First Principle Study on Atomic Scale Structures of Cathode in Aluminium-ion Battery Using Various van der Waals Corrections

2020 ◽  
Vol 213 ◽  
pp. 01023
Author(s):  
Kaihao Geng ◽  
Haining Cao ◽  
Meng-Chang Lin
Keyword(s):  
Density Functional ◽  
Van Der Waals ◽  
Structural Features ◽  
Atomic Scale ◽  
First Principle ◽  
Functional Theory ◽  
Principle Calculation ◽  
First Principle Calculation ◽  
Aluminium Ion ◽  
Scale Structures

There is still controversy on the atomistic configuration of aluminium-ion batteries (AIB) cathode when using first principle calculation based on density functional theory (DFT). We examined the relevant cathodic structures of Al/graphite battery by employing several van der Waals (vdW) corrections. Among them, DFT-TS method was determined to be a better dispersion correction in correctly rendering structural features already found through experiment investigations. The systematic comparison paved the way to the choice of vdW parameters in first principle calculation of graphitic electrode.

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