scholarly journals DFT-D4 Insight into the Inclusion of Amphetamine and Methamphetamine in Cucurbit[7]uril: Energetic, Structural and Biosensing Properties

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7479
Author(s):  
Abdelkarim Litim ◽  
Youghourta Belhocine ◽  
Tahar Benlecheb ◽  
Monira Galal Ghoniem ◽  
Zoubir Kabouche ◽  
...  
Keyword(s):  
Density Functional ◽  
Hydrophobic Interactions ◽  
Decomposition Analysis ◽  
Atomic Charge ◽  
Density Functional Theory Calculations ◽  
Frontier Molecular Orbital ◽  
Recognition Mechanism ◽  
Water Solvent ◽  
Charge Decomposition Analysis ◽  
Molecular Orbital Analysis

The host–guest interactions of cucurbit[7]uril (CB[7]) as host and amphetamine (AMP), methamphetamine (MET) and their enantiomeric forms (S-form and R-form) as guests were computationally investigated using density functional theory calculations with the recent D4 atomic-charge dependent dispersion corrections. The analysis of energetic, structural and electronic properties with the aid of frontier molecular orbital analysis, charge decomposition analysis (CDA), extended charge decomposition analysis (ECDA) and independent gradient model (IGM) approach allowed to characterize the host–guest interactions in the studied systems. Energetic results indicate the formation of stable non-covalent complexes where R-AMP@CB[7] and S-AMP@CB[7] are more stable thermodynamically than R-MET@CB[7] and S-MET@CB[7] in gas phase while the reverse is true in water solvent. Based on structural analysis, a recognition mechanism is proposed, which suggests that the synergistic effect of van der Waals forces, ion–dipole interactions, intermolecular charge transfer interactions and intermolecular hydrogen bonding is responsible for the stabilization of the complexes. The geometries of the complexes obtained theoretically are in good agreement with the X-ray experimental structures and indicate that the phenyl ring of amphetamine and methamphetamine is deeply buried into the cavity of CB[7] through hydrophobic interactions while the ammonium group remains outside the cavity to establish hydrogen bonds with the portal oxygen atoms of CB[7].

A Density Functional Theory Study on the Ring-Opening Polymerization of D-Lactide Catalyzed by a Bifunctional-Thiourea Catalyst

2009 ◽  
Vol 62 (2) ◽  
pp. 157 ◽  
Author(s):  
Rong-Xiu Zhu ◽  
Ruo-Xi Wang ◽  
Dong-Ju Zhang ◽  
Cheng-Bu Liu
Keyword(s):  
Density Functional Theory ◽  
Ring Opening ◽  
Density Functional ◽  
Population Analysis ◽  
Density Functional Theory Calculations ◽  
Ring Opening Polymerization ◽  
Acyl Transfer ◽  
Frontier Molecular Orbital ◽  
Functional Theory ◽  
Elimination Pathway

The thiourea-catalyzed methanolysis of d-lactide, a model system for the initiation and propagation of the organocatalyzed ring-opening polymerization (ROP) of lactide, has been studied by performing density functional theory calculations. Both the catalyzed and uncatalyzed reactions are explored along two possible pathways: one involves the stepwise addition–elimination pathway and the other is related to the concerted pathway. It is found that the reaction without the presence of the catalyst is difficult because the barrier involved is as high as 176 kJ mol–1. With the aid of a thiourea catalyst, the barrier is reduced to 88 kJ mol–1 with a preference for the stepwise addition–elimination mechanism over the concerted one. The role of the catalyst has been rationalized by analyzing the frontier molecular orbital interactions between the catalyst and substrates and by performing natural population analysis. Finally, another mechanism involving acyl transfer is discussed for the thiourea-catalyzed ROP.

scholarly journals The ANI-1ccx and ANI-1x Data Sets, Coupled-Cluster and Density Functional Theory Properties for Molecules

2020 ◽  
Author(s):  
Justin S. Smith ◽  
Roman Zubatyuk ◽  
Benjamin T. Nebgen ◽  
Nicholas Lubbers ◽  
Kipton Barros ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Atomic Charge ◽  
Density Functional Theory Calculations ◽  
Coupled Cluster ◽  
Data Sets ◽  
Data Set ◽  
Functional Theory ◽  
Energy Surfaces

<p>Maximum diversification of data is a central theme in building generalized and accurate machine learning (ML) models. In chemistry, ML has been used to develop models for predicting molecular properties, for example quantum mechanics (QM) calculated potential energy surfaces and atomic charge models. The ANI-1x and ANI-1ccx ML-based eneral-purpose potentials for organic molecules were developed through active learning; an automated data diversification process. Here, we describe the ANI-1x and ANI-1ccx data sets. To demonstrate data set diversity, we visualize them with a dimensionality reduction scheme, and contrast against existing data sets. The ANI-1x data set contains multiple QM properties from 5M density functional theory calculations, while the ANI-1ccx data set contains 500k data points obtained with an accurate CCSD(T)/CBS extrapolation. Approximately 14 million CPU core-hours were expended to generate this data. Multiple QM properties from density functional theory and coupled cluster are provided: energies, atomic forces, multipole moments, atomic charges, and more. We provide this data to the community to aid research and development of ML models for chemistry.</p>

scholarly journals The transition metal to ligand bonding nature: A quantum chemical study of π-allyl-ruthenacycle molecule

2018 ◽  
Vol 58 (3) ◽  
Author(s):  
Aušra Vektarienė
Keyword(s):  
Transition Metal ◽  
Physical Properties ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Decomposition Analysis ◽  
Computational Procedure ◽  
Chemical Study ◽  
Hartree Fock ◽  
Charge Decomposition Analysis ◽  
The Density Functional Theory

Understanding of the transition metal (TM) to ligand (L) bonding nature is important for characterization of experimental observations. One of the methods to explain the TM to L interactions is the Dewar–Chatt–Duncanson (DCD) model. However, in most applications the validity of the DCD model is based on assumptions in order to explain trends in vibrational spectroscopy or other physical properties of TM complexes. In this paper the computational methodology for treatment of the π-allyl-ruthenacycle complex based on the density functional theory, restricted Hartree–Fock method, natural bond orbital and charge decomposition analysis is reported. It is shown how the DCD model emerges from the presented calculation scheme and how it relates with the physical properties and stability of this complex. It is important to note that in this work the determination of the DCD model operation is based on the defined computational procedure, not postulated beforehand. The calculated geometry parameters, vibrational frequencies and electron density arrangement for the π-allyl-ruthenacycle complex are in good agreement with the experiment and support the DCD model.

scholarly journals Molecular Modeling of Interactions between N-(Carboxymethyl)-N-tetradecylglycine and Fluorapatite

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 278 ◽  
Author(s):  
Nan Nan ◽  
Yimin Zhu ◽  
Yuexin Han ◽  
Jie Liu
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Service Condition ◽  
Frontier Molecular Orbital ◽  
Adsorption Ability ◽  
Functional Theory ◽  
Molecular Orbital Analysis ◽  
Theory Calculation ◽  
Orbital Analysis ◽  
Flotation Collector

In this study, a flotation collector N-(carboxymethyl)-N-tetradecylglycine (NCNT) was introduced for the purpose of energy-saving, and its adsorption ability on a fluorapatite (001) surface was investigated by density functional theory calculation. The results of frontier molecular orbital analysis of NCNT and adsorption energy between NCNT and fluorapatite (FAp) showed that NCNT possessed better activity and stronger interactions in the reagent–FAp system than oleic acid (OA). A simulation model revealed that the adsorption positions of NCNT on the fluorapatite surface are calcium atoms, at which NCNT chemisorbed on (001) fluorapatite surface via a bidentate geometry involving the formation of two Ca–O bonds. Flotation experiments verified that NCNT had a good recovery of 92.27% on FAp at pH 3.5, which was slightly lower than OA. Moreover, NCNT was used at 16 °C, which was much lower than the OA’s service condition (25 °C).

scholarly journals DFT calculations as an efficient tool for prediction of Raman and infra-red spectra and activities of newly synthesized cathinones

2020 ◽  
Vol 18 (1) ◽  
pp. 185-195
Author(s):  
Maja Vujović ◽  
Venkatesan Ragavendran ◽  
Biljana Arsić ◽  
Emilija Kostić ◽  
Milan Mladenović
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Minimum Energy ◽  
Density Functional Theory Calculations ◽  
Maximum Energy ◽  
Monoamine Transporters ◽  
Good Tool ◽  
Molecular Orbital Analysis ◽  
Experimental Values

AbstractInitially made for medical treatment for Parkinsonism, obesity, and depression, cathinones have become illegal drugs for the “recreational use”. The mechanism of action of synthetic cathinones consists of the inhibition of monoamine transporters. DFT (Density Functional Theory) calculations on the selected cathinones (3-FMC, 4-FMC, 4-MMC, Buphedrone, Butylone, Ethylone, MDPV, Methcathinone, and Methylone) were performed using B3LYP level of the Gaussian 09 program suite. The unscaled B3LYP/6–31G vibrational wavenumbers are in general larger than the experimental values, so the use of selective scaling was necessary. The calculated spectra of selected cathinones are in good correlation with the experimental spectra which demonstrates that DFT is a good tool for the prediction of spectra of newly synthesized and insufficiently experimentally characterised cathinones. Also, HOMO-LUMO (Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital) analysis shows that 3-FMC possesses the minimum energy gap of 3.386 eV, and the molecule 4-FMC possesses the maximum energy gap of 4.205 eV among the investigated cathinones. It indicates that 3-FMC would be highly reactive among all the cathinones under investigation.

scholarly journals Zinc-Doped Boron Phosphide Nanocluster as Efficient Sensor for SO2

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Shahid Hussain ◽  
Shahzad Ali Shahid Chatha ◽  
Abdullah Ijaz Hussain ◽  
Riaz Hussain ◽  
Muhammad Yasir Mehboob ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Frontier Molecular Orbital ◽  
Functional Theory ◽  
Global Indices ◽  
Boron Phosphide ◽  
Adsorption Energies ◽  
Molecular Orbital Analysis ◽  
Orbital Analysis ◽  
Optimized Geometries

Adsorption of SO2 on pure B12P12 and Zn-doped B12P12 is investigated through density functional theory methods. Zn adsorption on BP delivers four optimized geometries: B-Top, P-top, b64, and ring-enlarged geometry with adsorption energies of −57.12 kJ/mol, −14.50 kJ/mol, −22.94 kJ/mol, and −14.83 kJ/mol, respectively. The adsorption energy of SO2 on pristine boron phosphide is −14.92 kJ/mol. Interaction of SO2 with Zn-doped boron phosphide gives four different geometries with adsorption energies of −69.76 kJ/mol, −9.82 kJ/mol, −104.92 kJ/mol, and −41.87 kJ/mol. Geometric parameters such as dipole moment, QNBO, frontier molecular orbital analysis, PDOS, and global indices of reactivity are performed to visualize the changes in electronic properties of B12P12 after Zn and SO2 adsorption.

scholarly journals Spectroscopic Examination using Density Functional Theory Calculations on 3-chloro-5-methoxyphenol

2020 ◽  
Vol 8 (4S4) ◽  
pp. 113-118
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
Density Functional Theory Calculations ◽  
Nbo Analysis ◽  
Computational Method ◽  
Frontier Molecular Orbital ◽  
Functional Theory ◽  
Charge Delocalization ◽  
Raman Spectral Data

The complete vibrational assignment of 3-chloro-5-methoxyphenol (CMOP) has been identified by the observed IR and Raman spectral data and vibrational frequencies were calculated by density functional theory method. The ability of the computational method for describing the vibrational modes can be understood by comparing experimental and theoretical spectra. Besides, frontier molecular orbital, Mulliken’s charge analyses and molecular electrostatic potential (MEP) surfaces have been computed. The natural bond orbital (NBO) analysis has been studied to analyze the charge delocalization and molecular hyperconjugative interactions

scholarly journals Molecular orbital analysis of the hydrogen bonded water dimer

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Bo Wang ◽  
Wanrun Jiang ◽  
Xin Dai ◽  
Yang Gao ◽  
Zhigang Wang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Functional Materials ◽  
Water Dimer ◽  
Energy Decomposition Analysis ◽  
Functional Theory ◽  
Hartree Fock ◽  
Molecular Orbital Analysis ◽  
Negligible Contribution

Abstract As an essential interaction in nature, hydrogen bonding plays a crucial role in many material formations and biological processes, requiring deeper understanding. Here, using density functional theory and post-Hartree-Fock methods, we reveal two hydrogen bonding molecular orbitals crossing the hydrogen-bond’s O and H atoms in the water dimer. Energy decomposition analysis also shows a non-negligible contribution of the induction term. Our finding sheds light on the essential understanding of hydrogen bonding in ice, liquid water, functional materials and biological systems.

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