Dependence of the optical absorption and Na+ binding energies of coumarin-crown ethers on the size and attachment position of ether ring: density functional investigation

2012 ◽  
Vol 19 (1) ◽  
pp. 173-178 ◽  
Author(s):  
Esra Kasapbasi ◽  
Mine Yurtsever
Keyword(s):  
Optical Absorption ◽  
Crown Ethers ◽  
Density Functional ◽  
Binding Energies ◽  
Ring Density ◽  
Functional Investigation

scholarly journals Organomagnesium Crown Ethers and Their Binding Affinities with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ Ions - a Theoretical Study

2021 ◽  
Author(s):  
Krishnan Thirumoorthy ◽  
Uday Kumar Padidela ◽  
Pothiappan Vairaprakash ◽  
Venkatesan Thimmakondu
Keyword(s):  
Metal Ions ◽  
Crown Ethers ◽  
Density Functional ◽  
Building Blocks ◽  
Binding Energies ◽  
Binding Affinities ◽  
Free Energies ◽  
Delta G ◽  
Cluster Methods ◽  
First Time

Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have<br>been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.

scholarly journals Organomagnesium Crown Ethers and Their Binding Affinities with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ Ions - a Theoretical Study

2021 ◽  
Author(s):  
Krishnan Thirumoorthy ◽  
Uday Kumar Padidela ◽  
Pothiappan Vairaprakash ◽  
Venkatesan Thimmakondu
Keyword(s):  
Metal Ions ◽  
Crown Ethers ◽  
Density Functional ◽  
Building Blocks ◽  
Binding Energies ◽  
Binding Affinities ◽  
Free Energies ◽  
Delta G ◽  
Cluster Methods ◽  
First Time

Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have<br>been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.

Density-Functional Investigation of Lun (n=2-14) Clusters

2011 ◽  
Vol 689 ◽  
pp. 74-84
Author(s):  
Chuan Hui Zhang ◽  
Qi Pen ◽  
Jiang Shen
Keyword(s):  
Fermi Level ◽  
Rare Earths ◽  
Magnetic Moment ◽  
Ground State ◽  
Density Functional ◽  
Chem Phys ◽  
Binding Energies ◽  
Icosahedral Structure ◽  
Ground State Structures ◽  
Functional Investigation

The binding energies, ground state geometries, and electronic properties of the rare earths metal neutral Lun(n=2–14) clusters, cations, and anions have been systematically investigated by using DFT. The ground state structures of the clusters with 4 and 11 atoms are found to be magic. We get some different property comparing with Lancluster [J. Chem. Phys. 120, 5104 (2004)], which belongs to lanthanide. Lu13cluster is an icosahedral structure with magnetic moment of 1μB, the occupied states of Lu13are highly degenerated. It has largep-dhybridization, which makesPDOSpeaks value below Fermi level moving to the Fermi level.

scholarly journals Tuning the electronic structure of Ag-Pd alloys to enhance performance for alkaline oxygen reduction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
José A. Zamora Zeledón ◽  
Michaela Burke Stevens ◽  
G. T. Kasun Kalhara Gunasooriya ◽  
Alessandro Gallo ◽  
Alan T. Landers ◽  
...  
Keyword(s):  
Metal Binding ◽  
Precious Metal ◽  
Metal Content ◽  
Density Functional ◽  
Binding Energies ◽  
Intrinsic Activity ◽  
Energy Technologies ◽  
Highly Active ◽  
Wide Range ◽  
Precious Metal Content

AbstractAlloying is a powerful tool that can improve the electrocatalytic performance and viability of diverse electrochemical renewable energy technologies. Herein, we enhance the activity of Pd-based electrocatalysts via Ag-Pd alloying while simultaneously lowering precious metal content in a broad-range compositional study focusing on highly comparable Ag-Pd thin films synthesized systematically via electron-beam physical vapor co-deposition. Cyclic voltammetry in 0.1 M KOH shows enhancements across a wide range of alloys; even slight alloying with Ag (e.g. Ag0.1Pd0.9) leads to intrinsic activity enhancements up to 5-fold at 0.9 V vs. RHE compared to pure Pd. Based on density functional theory and x-ray absorption, we hypothesize that these enhancements arise mainly from ligand effects that optimize adsorbate–metal binding energies with enhanced Ag-Pd hybridization. This work shows the versatility of coupled experimental-theoretical methods in designing materials with specific and tunable properties and aids the development of highly active electrocatalysts with decreased precious-metal content.

scholarly journals Nanotechnology-based approaches for targeting and delivery of drugs via Hexakis (m-PE) macrocycles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Samaneh Pasban ◽  
Heidar Raissi
Keyword(s):  
Drug Delivery ◽  
Density Functional ◽  
Water Solution ◽  
Decomposition Analysis ◽  
Binding Energies ◽  
Energy Decomposition Analysis ◽  
Partial Density ◽  
High Propensity ◽  
The Stability ◽  
Novel Applications

AbstractHexakis (m-phenylene ethynylene) (m-PE) macrocycles, with aromatic backbones and multiple hydrogen-bonding side chains, had a very high propensity to self-assemble via H-bond and π–π stacking interactions to form nanotubular structures with defined inner pores. Such stacking of rigid macrocycles is leading to novel applications that enable the researchers to explored mass transport in the sub-nanometer scale. Herein, we performed density functional theory (DFT) calculations to examine the drug delivery performance of the hexakis dimer as a novel carrier for doxorubicin (DOX) agent in the chloroform and water solvents. Based on the DFT results, it is found that the adsorption of DOX on the carrier surface is typically physisorption with the adsorption strength values of − 115.14 and − 83.37 kJ/mol in outside and inside complexes, respectively, and so that the essence of the drug remains intact. The negative values of the binding energies for all complexes indicate the stability of the drug molecule inside and outside the carrier's cavities. The energy decomposition analysis (EDA) has also been performed and shown that the dispersion interaction has an essential role in stabilizing the drug-hexakis dimer complexes. To further explore the electronic properties of dox, the partial density of states (PDOS and TDOS) are calculated. The atom in molecules (AIM) and Becke surface (BS) methods are also analyzed to provide an inside view of the nature and strength of the H-bonding interactions in complexes. The obtained results indicate that in all studied complexes, H-bond formation is the driving force in the stabilization of these structures, and also chloroform solvent is more favorable than the water solution. Overall, our findings offer insightful information on the efficient utilization of hexakis dimer as drug delivery systems to deliver anti-cancer drugs.

scholarly journals Tuning the optoelectronic properties of hematite with rhodium doping for photoelectrochemical water splitting using density functional theory approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdur Rauf ◽  
Muhammad Adil ◽  
Shabeer Ahmad Mian ◽  
Gul Rahman ◽  
Ejaz Ahmed ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Water Splitting ◽  
Density Functional ◽  
Formation Energy ◽  
Visible Region ◽  
Photoelectrochemical Water Splitting ◽  
Theory Approach ◽  
Functional Theory

AbstractHematite (Fe2O3) is one of the best candidates for photoelectrochemical water splitting due to its abundance and suitable bandgap. However, its efficiency is mostly impeded due to the intrinsically low conductivity and poor light absorption. In this study, we targeted this intrinsic behavior to investigate the thermodynamic stability, photoconductivity and optical properties of rhodium doped hematite using density functional theory. The calculated formation energy of pristine and rhodium doped hematite was − 4.47 eV and − 5.34 eV respectively, suggesting that the doped material is thermodynamically more stable. The DFT results established that the bandgap of doped hematite narrowed down to the lower edge (1.61 eV) in the visible region which enhanced the optical absorption and photoconductivity of the material. Moreover, doped hematite has the ability to absorb a broad spectrum (250–800) nm. The enhanced optical absorption boosted the photocurrent and incident photon to current efficiency. The calculated results also showed that the incorporation of rhodium in hematite induced a redshift in optical properties.

scholarly journals A Comparative Study of Oxygen and Hydrogen Adsorption on Strained and Alloy-Supported Pt(111) Monolayers

2021 ◽  
Vol 7 (7) ◽  
pp. 101
Author(s):  
Ian Shuttleworth
Keyword(s):  
Comparative Study ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Binding Energies ◽  
High Symmetry ◽  
Density Functionals ◽  
Functional Theory ◽  
Ligand Effects ◽  
Ferromagnetic Alloys ◽  
Depth Study

A comparative study of the unreacted and reacted uniaxially strained Pt(111) and the layered (111)-Pt/Ni/Pt3Ni and (111)-Pt/Ni/PtNi3 surfaces has been performed using density functional theory (DFT). An in-depth study of the unreacted surfaces has been performed to evaluate the importance of geometric, magnetic and ligand effects in determining the reactivity of these different Pt surfaces. An analysis of the binding energies of oxygen and hydrogen over the high-symmetry binding positions of all surfaces has been performed. The study has shown that O and H tend to bind more strongly to the (111)-Pt/Ni/Pt3Ni surface and less strongly to the (111)-Pt/Ni/PtNi3 surface compared to binding on the equivalently strained Pt(111) surfaces. Changes in the surface magnetisation of the surfaces overlaying the ferromagnetic alloys during adsorption are discussed, as well as the behaviour of the d-band centre across all surfaces, to evaluate the potential mechanisms for these differences in binding. An accompanying comparison of the accessible density functionals has been included to estimate the error in the computational binding energies.

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

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