scholarly journals Investigation of hydrogen bonding between nitrosamine and sulfuric acid using Density Functional Theory

2014 ◽  
Vol 25 (1) ◽  
pp. 5-10
Author(s):  
Sadeghali Bavafa ◽  
Mona Mahboubi
Keyword(s):  
Hydrogen Bonding ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Nbo Analysis ◽  
Basis Sets ◽  
Stable Complex ◽  
Antibonding Orbital ◽  
Functional Theory ◽  
Hydrogen Bonding Interactions ◽  
Density Transfer

Abstract DFT calculations were performed to analyze those interactions; B3LYP and B3PW91 methods were applied and the following basis sets were used: 6-311++G(2d, 2p), 6-311++G(3df, 3pd) and aug-cc-pVDZ. The natural bond orbital (NBO) analysis and atom in molecules (AIM) theory were applied to understand the nature of the interactions. The most stable complex NS1 with an eight-membered cyclic structure contains two O- H· ··O and N-H·· ·O hydrogen bonding interactions. From the values of r(r) at O·· ·H critical points, it can be concluded that the H-boding in eight-membered cyclic NS1 is stronger than other. The elongation of the O-H bond length is caused by the electron-density transfer to the O-H antibonding orbital.

scholarly journals Tipping the balance: theoretical interrogation of divergent extended heterolytic fragmentations

2020 ◽  
Vol 11 (8) ◽  
pp. 2231-2242 ◽  
Author(s):  
Croix J. Laconsay ◽  
Ka Yi Tsui ◽  
Dean J. Tantillo
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Electric Field ◽  
Ab Initio ◽  
External Electric Field ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Nbo Analysis ◽  
Functional Theory

We interrogate a type of heterolytic fragmentation called a ‘divergent fragmentation’ using density functional theory (DFT), natural bond orbital (NBO) analysis, ab initio molecular dynamics (AIMD), and external electric field (EEF) calculations.

THE ORIGIN OF THE ROTATIONAL BARRIER IN DIMETHYL ETHER AND DIMETHYL SULFIDE: A THEORETICAL STUDY

2007 ◽  
Vol 06 (03) ◽  
pp. 421-434 ◽  
Author(s):  
JÍMENEZ-FABIAN ◽  
A. F. JALBOUT
Keyword(s):  
Dimethyl Ether ◽  
Density Functional ◽  
Dimethyl Sulfide ◽  
Nbo Analysis ◽  
Rotational Barrier ◽  
Basis Sets ◽  
Functional Theory ◽  
Hartree Fock ◽  
Torsional Potential ◽  
Methyl Rotation

The torsional potential function for methyl rotation in dimethyl ether (DME) and dimethyl sulfide (DMS) has been determined by utilizing ab initio (Hartree–Fock and MP2) and density functional theory (B3LYP, B3P86, and B3PW91) methods along with several basis sets. Natural bond orbital (NBO) analysis was also applied to investigate the origin of the rotational barrier.

THEORETICAL STUDY ON INTERACTION BETWEEN IONIC LIQUIDS AND AROMATIC SULFUR COMPOUNDS

2011 ◽  
Vol 10 (01) ◽  
pp. 31-40 ◽  
Author(s):  
YI NIE ◽  
XIANGAI YUAN
Keyword(s):  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Density Functional ◽  
Sulfur Compound ◽  
Ion Pairs ◽  
Benzene Molecule ◽  
Sulfur Compounds ◽  
Functional Theory ◽  
Hydrogen Bonding Interactions ◽  
Bonding Interaction

It is important to understand how ionic liquids interact with aromatic sulfur compounds in view of ionic liquids application in desulfurization from fuels. Ion pairs of N, N-dialkylimidazolium dialkylphosphate ionic liquids were optimized at the Becke3LYP level of density functional theory. The most stable geometries were obtained. The stable ion pairs indicate there exist hydrogen bonding interactions between them. The calculated interaction energies of ion pairs were found to increase in magnitude with decreasing alkyl chain length, and with decreasing anionic radius. Furthermore, the interactions between the IL and aromatic sulfur compound, and benzene molecule were investigated. The results indicate that there exist hydrogen bonds between them. The calculated interaction energy between IL and sulfur compound is larger than that between IL and benzene. The aromatic ring π - π interaction and hydrogen bonding interaction may be the dominant factors to influence the trend of interaction between ILs and aromatic sulfur compounds.

scholarly journals 2-Substituted agelasine analogs: Synthesis and biological activity, and structure and reactivity of synthetic intermediates

2011 ◽  
Vol 83 (3) ◽  
pp. 645-653 ◽  
Author(s):  
Heidi Roggen ◽  
Lars Bohlin ◽  
Robert Burman ◽  
Colin Charnock ◽  
Jenny Felth ◽  
...  
Keyword(s):  
Significant Variation ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Nbo Analysis ◽  
Atomic Charges ◽  
Functional Theory ◽  
Methyl Group ◽  
H Nmr ◽  
Nmr Techniques ◽  
Synthetic Intermediates

2-Substituted N-methoxy-9-methyl-9H-purin-6-amines were synthesized either from their corresponding 6-chloro-9-methyl-9H-purines or 2-chloro-N-methoxy-9-methyl-9H-purin-6-amine. Great diversity in the amino/imino tautomeric ratios was observed and calculated based on 1H NMR. The tautomers were identified by 1D and 2D 1H, 13C, and 15N NMR techniques, and showed significant variation both in 13C and 15N shift values. Comparison of the tautomeric ratios with Hammett F values revealed that as the field/inductive withdrawing abilities of the 2-substituent increased, the ratio of amino:imino tautomers was shifted toward the amino tautomer. Computational chemistry exposed the significance of hydrogen bonding between solvent and the compound in question to reach accurate predictions for tautomeric ratios. B3LYP/def2-TZVP density functional theory (DFT) calculations resulted in quantitatively more accurate predictions than when employing the less expensive BP86 functional. N-7-Alkylation of the 2-substituted N-methoxy-9-methyl-9H-purin-6-amines showed that when the field/inductive withdrawing ability of the 2-substituent reached a certain point the reactivity drastically dropped. This correlated with the atomic charges on N-7 calculated using a natural bond orbital (NBO) analysis. Biological screening of the final 2-substituted agelasine analogs indicated that the introduction of a methyl group in the 2-position is advantageous for antimycobacterial and antiprotozoal activity, and that an amino function may improve activity against several cancer cell lines.

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