scholarly journals Theoretical Study on the Extraction of Alkaline Earth Salts by 18-Crown-6: Roles of Counterions, Solvent Types and Extraction Temperatures

2014 ◽  
Vol 14 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Saprizal Hadisaputra ◽  
Lorenz R Canaval ◽  
Harno Dwi Pranowo ◽  
Ria Armunanto
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Alkaline Earth ◽  
Theoretical Study ◽  
Polar Solvent ◽  
Density Functional Method ◽  
Nitrate Anion ◽  
Interaction Energies ◽  
Free Energies ◽  
Solvent Phase

The roles of counterions, solvent types and extraction temperatures on the selectivity of 18-crown-6 (L) toward alkaline earth salts MX2 (M = Ca, Sr, Ba; X = Cl-, NO3-) have been studied by density functional method at B3LYP level of theory in gas and solvent phase. In gas phase, the chloride anion Cl- is the preference counterion than nitrate anion NO3-. This result is confirmed by the interaction energies, the second order interaction energies, charge transfers, energy difference between HOMO-LUMO and electrostatic potential maps. The presence of solvent reversed the gas phase trend. It is found that NO3- is the preference counterion in solvent phase. The calculated free energies demonstrate that the solvent types strongly change the strength of the complex formation. The free energies are exothermic in polar solvent while for the non polar solvent the free energies are endothermic. As the temperature changes the free energies also vary where the higher the temperatures the lower the free energy values. The calculated free energies are correlated well with the experimental stability constants. This theoretical study would have a strong contribution in planning the experimental conditions in terms of the preference counterions, solvent types and optimum extraction temperatures.

scholarly journals Theoretical study on the binding selectivity of 18-membered azacrown ethers with alkaline earth metal species

2018 ◽  
Vol 1 (1) ◽  
pp. 17
Author(s):  
Saprini Hamdiani ◽  
Lalu Rudyat Telly Savalas ◽  
Agus Abhi Purwoko ◽  
Saprizal Hadisaputra
Keyword(s):  
Density Functional ◽  
Alkaline Earth ◽  
Theoretical Study ◽  
Earth Metal ◽  
Metal Species ◽  
Stable Complex ◽  
Alkaline Earth Metal ◽  
Interaction Energies ◽  
Binding Selectivity ◽  
Azacrown Ethers

The binding selectivity of 18-membered azacrown ethers (monoaza- N1, diaza- N2, triaza- N3, tetraaza- N4, pentaaza- N5, and hexaaza-18-crown-6 N6) with Ca2+, Sr2+, Ba2+ have been studied by density functional theory (DFT) calculations. The complex binding selectivity was analyzed in term of interaction energies, thermodynamic properties, second order interaction energies, and charge transfer effects. The geometrical study shows that Ca2+ and azacrown complexes acquire envelope like structure, leading to shorter bond lengths. As a result, these complex systems have the highest interaction energies. Theoretical study also showed that N6 complex with alkaline earth metal ion were shown to be more stable complex than those ligand with lower nitrogen number. The interaction energy order is N0 < N1 < N2 < N3 < N4 < N5 < N6. This trend shows that the presence of more nitrogen on the crown ether cavity increases the interaction energies by approx. 7.3 % in going from N0 to N6. It is clearly showed that the contribution of the number of nitrogen play a dominant role in the binding selectivity of these systems.  

Intrinsic Stacking Interactions of Natural and Artificial Nucleobases

2019 ◽  
Author(s):  
Drew P. Harding ◽  
Laura J. Kingsley ◽  
Glen Spraggon ◽  
Steven Wheeler
Keyword(s):  
Gas Phase ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Molecular Descriptors ◽  
Stacking Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Binding Partner ◽  
Heavy Atoms ◽  
Wide Range

The intrinsic (gas-phase) stacking energies of natural and artificial nucleobases were explored using density functional theory (DFT) and correlated ab initio methods. Ranking the stacking strength of natural nucleobase dimers revealed a preference in binding partner similar to that seen from experiments, namely G > C > A > T > U. Decomposition of these interaction energies using symmetry-adapted perturbation theory (SAPT) showed that these dispersion dominated interactions are modulated by electrostatics. Artificial nucleobases showed a similar stacking preference for natural nucleobases and were also modulated by electrostatic interactions. A robust predictive multivariate model was developed that quantitively predicts the maximum stacking interaction between natural and a wide range of artificial nucleobases using molecular descriptors based on computed electrostatic potentials (ESPs) and the number of heavy atoms. This model should find utility in designing artificial nucleobase analogs that exhibit stacking interactions comparable to those of natural nucleobases. Further analysis of the descriptors in this model unveil the origin of superior stacking abilities of certain nucleobases, including cytosine and guanine.

Structure, stability and intramolecular interaction of M(N5)2(M = Mg, Ca, Sr and Ba) : a theoretical study

RSC Advances ◽  
2015 ◽  
Vol 5 (28) ◽  
pp. 21823-21830 ◽  
Author(s):  
Xueli Zhang ◽  
Junqing Yang ◽  
Ming Lu ◽  
Xuedong Gong
Keyword(s):  
Energetic Materials ◽  
Density Functional ◽  
Alkaline Earth ◽  
Theoretical Study ◽  
Intramolecular Interaction ◽  
Earth Metal ◽  
Structure Stability ◽  
Alkaline Earth Metal ◽  
Functional Theory ◽  
The Density Functional Theory

The potential energetic materials, alkaline earth metal complexes of the pentazole anion (M(N5)2, M = Mg2+, Ca2+, Sr2+and Ba2+), were studied using the density functional theory.

Theoretical study of gas and solvent phase stability and molecular adsorption of noncanonical guanine bases on graphene

2017 ◽  
Vol 19 (25) ◽  
pp. 16819-16830 ◽  
Author(s):  
Nabanita Saikia ◽  
Shashi P. Karna ◽  
Ravindra Pandey
Keyword(s):  
Density Functional Theory ◽  
Phase Stability ◽  
Density Functional ◽  
Theoretical Study ◽  
Molecular Adsorption ◽  
Functional Theory ◽  
Solvent Phase

The gas and solvent phase stability of noncanonical (Gua)n nucleobases is investigated in the framework of dispersion-corrected density functional theory (DFT).

4s to 5s and 4p photoexcitation dynamics of K atoms from the surface of helium nanodroplets: a theoretical study

2019 ◽  
Vol 21 (7) ◽  
pp. 3626-3636 ◽  
Author(s):  
Maxime Martinez ◽  
François Coppens ◽  
Manuel Barranco ◽  
Nadine Halberstadt ◽  
Martí Pi
Keyword(s):  
Superfluid Helium ◽  
Density Functional ◽  
Theoretical Study ◽  
Density Functional Method ◽  
Potassium Atom ◽  
Functional Method ◽  
Time Dependent ◽  
Spin Orbit ◽  
Helium Nanodroplets

We study the photodissociation of the potassium atom from a superfluid helium nanodroplet upon 5s 2S or 4p 2P excitation using the time-dependent helium density functional method (He-TDDFT). The results show possible K spin–orbit relaxation.

A theoretical study of weak interactions in phenylenediamine homodimer clusters

2016 ◽  
Vol 18 (42) ◽  
pp. 29249-29257 ◽  
Author(s):  
Chengqian Yuan ◽  
Haiming Wu ◽  
Meiye Jia ◽  
Peifeng Su ◽  
Zhixun Luo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Intermolecular Interactions ◽  
Density Functional ◽  
Theoretical Study ◽  
Natural Bond Orbital ◽  
Weak Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Weak Intermolecular Interactions

Utilizing dispersion-corrected density functional theory (DFT) calculations, we demonstrate the weak intermolecular interactions of phenylenediamine dimer (pdd) clusters, emphasizing the local lowest energy structures and decomposition of interaction energies by natural bond orbital (NBO) and atoms in molecule (AIM) analyses.

THEORETICAL STUDY ON POTENCY AND SELECTIVITY OF NOVEL NONPEPTIDE INHIBITORS OF MATRIX METALLOPROTEINASES MMP-2 AND MMP-9

2009 ◽  
Vol 08 (03) ◽  
pp. 491-506 ◽  
Author(s):  
DAI-LIN LI ◽  
QING-CHUAN ZHENG ◽  
XUE-XUN FANG ◽  
HAI-TAO JI ◽  
JIN-GANG YANG ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Density Functional ◽  
Theoretical Study ◽  
Zinc Binding ◽  
Hydroxyl Group ◽  
Interaction Energies ◽  
Binding Modes ◽  
Functional Theory ◽  
Total Interaction ◽  
Binding Affinity Calculations

Two novel matrix metalloproteinase (MMP) inhibitors, myricetin (m) and kaempferol (k), were found and the inhibitory activity is both in decreased order towards MMP-2 and MMP-9. To understand the mechanism during the processes when inhibitors bind to MMP-2 and MMP-9, molecular modeling, docking, and density functional theory (DFT) calculations were performed. The calculated results indicated that the hydroxyls on benzene ring of the inhibitors control the binding modes between inhibitors and MMPs, thus play an important role on the potency and selectivity. Besides coordinating with the N atoms of three His residues, Zn also interacts with a hydroxyl group of inhibitors by O – Zn distances of 2.66–2.78 Å in all of the docked complexes, so that the hydroxyl acts as a weak zinc binding group (ZBG). The DFT calculated results support the above analysis. The binding affinity calculations between inhibitors and MMPs present the total interaction energies in the m-MMP < k-MMP order and the solvation energy of myricetin is less than that of kaempferol, which reflect the experimental inhibitory activity.

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