scholarly journals High throughput virtual screening of 230 billion molecular solar heat battery candidates

2021 ◽  
Vol 3 ◽  
pp. e16
Author(s):  
Mads Koerstz ◽  
Anders S. Christensen ◽  
Kurt V. Mikkelsen ◽  
Mogens Brøndsted Nielsen ◽  
Jan H. Jensen
Keyword(s):  
Free Energy ◽  
Energy Barrier ◽  
Density Functional ◽  
Storage Capacity ◽  
Chemical Reactivity ◽  
Methodological Approach ◽  
Parent Compound ◽  
High Energy ◽  
Back Reaction ◽  
Free Energy Barrier

The dihydroazulene/vinylheptafulvene (DHA/VHF) thermocouple is a promising candidate for thermal heat batteries that absorb and store solar energy as chemical energy without the need for insulation. However, in order to be viable the energy storage capacity and lifetime of the high energy form (i.e., the free energy barrier to the back reaction) of the canonical parent compound must be increased significantly to be of practical use. We use semiempirical quantum chemical methods, machine learning, and density functional theory to virtually screen over 230 billion substituted DHA molecules to identify promising candidates. We identify a molecule with a predicted energy density of 0.38 kJ/g, which is significantly larger than the 0.14 kJ/g computed for the parent compound. The free energy barrier to the back reaction is 11 kJ/mol higher than the parent compound, which should correspond to a half-life of about 10 days—4 months. This is considerably longer than the 3–39 h (depending on solvent) observed for the parent compound and sufficiently long for many practical applications. Our paper makes two main important contributions: (1) a novel and generally applicable methodological approach that makes screening of huge libraries for properties involving chemical reactivity with modest computational resources, and (2) a clear demonstration that the storage capacity of the DHA/VHF thermocouple cannot be increased to >0.5 kJ/g by combining simple substituents.

scholarly journals High Throughput Virtual Screening of 230 Billion Molecular Solar Heat Battery Candidates

2020 ◽  
Author(s):  
Mads Koerstz ◽  
Anders S. Christensen ◽  
Kurt V. Mikkelsen ◽  
Mogens Brøndsted Nielsen ◽  
Jan H. Jensen
Keyword(s):  
Free Energy ◽  
Energy Barrier ◽  
Storage Capacity ◽  
Chemical Reactivity ◽  
Methodological Approach ◽  
Parent Compound ◽  
High Energy ◽  
Back Reaction ◽  
Free Energy Barrier ◽  
Practical Applications

<div> <div> <div> <div> <p>The dihydroazulene/vinylheptafulvene (DHA/VHF) thermocouple is a promising candidate for thermal heat batteries that absorb and store solar energy as chemical energy without the need for insulation. However, in order to be viable the energy storage capacity and lifetime of the high energy form (i.e. the free energy barrier to the back reaction) of the canonical parent compound must be increased significantly to be of practical use. We use semiempirical quantum chemical methods, machine learning, and density func- tional theory to virtually screen over 230 billion substituted DHA molecules to identify promising candidates. We identify a molecule with a predicted energy density of 0.38 kJ/g, which is significantly larger than the 0.14 kJ/g computed for the parent compound. The free energy barrier to the back reaction is 11 kJ/mol higher than the parent com- pound, which should correspond to a half-life of about 10 days - 4 months. This is considerably longer than the 3-39 hours (depending on solvent) observed for the parent compound and sufficiently long for many practical applications. Our paper makes two main important contributions: 1) a novel and generally applicable methodological approach that makes screening of huge libraries for properties involving chemical reactivity with modest computational resources, and 2) a clear demonstration that the storage capacity of the DHA/VHF thermocouple cannot be increased to >0.5 kJ/g by combining simple substituents. </p> </div> </div> </div><br></div>

scholarly journals High Throughput Virtual Screening of 230 Billion Molecular Solar Heat Battery Candidates

2020 ◽  
Author(s):  
Mads Koerstz ◽  
Anders S. Christensen ◽  
Kurt V. Mikkelsen ◽  
Mogens Brøndsted Nielsen ◽  
Jan H. Jensen
Keyword(s):  
Free Energy ◽  
Energy Barrier ◽  
Density Functional ◽  
Parent Compound ◽  
High Energy ◽  
Back Reaction ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Practical Applications ◽  
Quantum Chemical Methods

<div>The dihydroazulene/vinylheptafulvene (DHA/VHF) thermocouple is a promising can- didate for thermal heat batteries that absorb and store solar energy as chemical energy without the need for insulation. However, in order to be viable the energy storage capacity and lifetime of the high energy form (i.e. the free energy barrier to the back reaction) of the canonical parent compound must be increased significantly to be of practical use. We use semiempirical quantum chemical methods, machine learning, and density functional theory to virtually screen over 230 billion substituted DHA molecules to identify promis- ing candidates. We identify a molecule with a predicted energy density of 0.38 kJ/g, which is significantly larger than the 0.14 kJ/g computed for the parent compound. The free energy barrier to the back reaction is 11 kJ/mol higher than the parent compound, which should correspond to a half-life of about 10 days - 4 months. This is considerably longer than the 3-39 hours (depending on solvent) observed for the parent compound and sufficiently long for many practical applications. However, the main conclusion of this study is that there are no molecules among the 230 billion with a storage density approaching 1 kJ/g.<br></div>

scholarly journals High Throughput Virtual Screening of 230 Billion Molecular Solar Heat Battery Candidates

2020 ◽  
Author(s):  
Mads Koerstz ◽  
Anders S. Christensen ◽  
Kurt V. Mikkelsen ◽  
Mogens Brøndsted Nielsen ◽  
Jan H. Jensen
Keyword(s):  
Free Energy ◽  
Energy Barrier ◽  
Density Functional ◽  
Parent Compound ◽  
High Energy ◽  
Back Reaction ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Practical Applications ◽  
Quantum Chemical Methods

<div>The dihydroazulene/vinylheptafulvene (DHA/VHF) thermocouple is a promising can- didate for thermal heat batteries that absorb and store solar energy as chemical energy without the need for insulation. However, in order to be viable the energy storage capacity and lifetime of the high energy form (i.e. the free energy barrier to the back reaction) of the canonical parent compound must be increased significantly to be of practical use. We use semiempirical quantum chemical methods, machine learning, and density functional theory to virtually screen over 230 billion substituted DHA molecules to identify promis- ing candidates. We identify a molecule with a predicted energy density of 0.38 kJ/g, which is significantly larger than the 0.14 kJ/g computed for the parent compound. The free energy barrier to the back reaction is 11 kJ/mol higher than the parent compound, which should correspond to a half-life of about 10 days - 4 months. This is considerably longer than the 3-39 hours (depending on solvent) observed for the parent compound and sufficiently long for many practical applications. However, the main conclusion of this study is that there are no molecules among the 230 billion with a storage density approaching 1 kJ/g.<br></div>

High Throughput Virtual Screening of 200 Billion Molecular Solar Heat Battery Candidates

2019 ◽  
Author(s):  
Mads Koerstz ◽  
Anders S. Christensen ◽  
Kurt V. Mikkelsen ◽  
Mogens Brøndsted Nielsen ◽  
Jan H. Jensen
Keyword(s):  
Free Energy ◽  
Density Functional ◽  
Parent Compound ◽  
High Energy ◽  
Back Reaction ◽  
Free Energy Barrier ◽  
Promising Candidate ◽  
Functional Theory ◽  
Practical Applications ◽  
Quantum Chemical Methods

<div>The dihydroazulene/vinylheptafulvene (DHA/VHF) thermocouple is a promising candidate for thermal heat batteries that absorb and store solar energy as chemical energy without the need for insulation. However, in order to be viable the energy storage capacity and stability of the high energy form (the free energy barrier to the back reaction) must be increased significantly. We use semiempirical quantum chemical methods, machine learning, genetic algorithms, and density functional theory to virtually screen roughly 200 billion substituted DHA molecules to identify promising candidates for further study. We identify three molecules with predicted energy densities of (0.34-0.36 kJ/g), which is significantly larger than the 0.14 kJ/g computed for the parent system. The free energy barriers to the back reaction are between 6.8 and 7.7 kJ/mol higher than the parent compound, which should correspond to half-lives of days - sufficiently long for many practical applications.</div>

DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

2018 ◽  
Vol 17 (08) ◽  
pp. 1850050 ◽  
Author(s):  
Qiuhan Luo ◽  
Gang Li ◽  
Junping Xiao ◽  
Chunhui Yin ◽  
Yahui He ◽  
...  
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Carbonyl Group ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Metsulfuron Methyl ◽  
Catalytic Role ◽  
Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

scholarly journals Prebiotic Peptide Bond Formation Through Amino Acid Phosphorylation. Insights from Quantum Chemical Simulations

Life ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 75 ◽  
Author(s):  
Berta Martínez-Bachs ◽  
Albert Rimola
Keyword(s):  
Free Energy ◽  
Quantum Chemical ◽  
Density Functional ◽  
Bond Formation ◽  
Building Blocks ◽  
Peptide Bond ◽  
High Energy ◽  
Free Energy Barrier ◽  
Peptide Bond Formation ◽  
Condensation Reactions

Condensation reactions between biomolecular building blocks are the main synthetic channels to build biopolymers. However, under highly diluted prebiotic conditions, condensations are thermodynamically hampered since they release water. Moreover, these reactions are also kinetically hindered as, in the absence of any catalyst, they present high activation energies. In living organisms, in the formation of peptides by condensation of amino acids, this issue is overcome by the participation of adenosine triphosphate (ATP), in which, previous to the condensation, phosphorylation of one of the reactants is carried out to convert it as an activated intermediate. In this work, we present for the first time results based on density functional theory (DFT) calculations on the peptide bond formation between two glycine (Gly) molecules adopting this phosphorylation-based mechanism considering a prebiotic context. Here, ATP has been modeled by a triphosphate (TP) component, and different scenarios have been considered: (i) gas-phase conditions, (ii) in the presence of a Mg2+ ion available within the layer of clays, and (iii) in the presence of a Mg2+ ion in watery environments. For all of them, the free energy profiles have been fully characterized. Energetics derived from the quantum chemical calculations indicate that none of the processes seem to be feasible in the prebiotic context. In scenarios (i) and (ii), the reactions are inhibited due to unfavorable thermodynamics associated with the formation of high energy intermediates, while in scenario (iii), the reaction is inhibited due to the high free energy barrier associated with the condensation reactions. As a final consideration, the role of clays in this TP-mediated peptide bond formation route is advocated, since the interaction of the phosphorylated intermediate with the internal clay surfaces could well favor the reaction free energies.

THEORETICAL STUDY ON CUI-CATALYZED LIGAND-FREE N-ARYLATION OF IMIDAZOLE WITH BROMOBENZENE

2012 ◽  
Vol 11 (05) ◽  
pp. 1135-1147 ◽  
Author(s):  
HAN GUO ◽  
YING XUE
Keyword(s):  
Free Energy ◽  
Energy Barrier ◽  
Density Functional ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Free Energy Barrier ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Ligand Free ◽  
Rate Limiting

The density functional theory (DFT) is used to investigate the mechanism of ligand-free CuI -catalyzed N -arylation of imidazole with aryl halide. The oxidative addition/reductive elimination mechanism is adopted via two different pathways to form the same Cu(III) intermediate. Comparing two pathways, the path 1 in which the imidazolyl coordination occurs prior to the oxidative addition is more favorable, because the free energy barrier of the rate-limiting step of path 1 is lower than the barrier of the other. In addition, it leads to a relative stable intermediate which can promote the reaction to process via path 1. And the overall free energy barrier of oxidative addition to imidazole-ligated Cu(I) complex is not high enough when comparing with the diamine-promote process, which can further prove that the N -arylation of imidazole is feasible in the absence of additional ligands. Nucleophile coordination and reductive elimination steps are facile, while the oxidative addition is the rate-limiting step.

scholarly journals Thermodynamic Insights of Base Flipping in TNA Duplex: Force Fields, Salt Concentrations, and Free Energy Simulation Methods

2020 ◽  
Author(s):  
Zhaoxi Sun ◽  
John Z. H. Zhang
Keyword(s):  
Free Energy ◽  
Phase Space ◽  
Force Field ◽  
Energy Barrier ◽  
Force Fields ◽  
Computational Modelling ◽  
High Energy ◽  
Energy Simulation ◽  
Free Energy Barrier ◽  
Base Flipping

<p>Threofuranosyl nucleic acid (TNA) is an analogue of DNA. Its inter-nucleotide linkages are shifted from the wild-type 5'-to-3' one to the 3'-to-2' one. As a result, the number of covalent bonds between consecutive phosphates is reduced from 6 to 5. This leads to higher chemical stability, less reactive groups, and lower conformational flexibility. Experimental observations indicate that the interaction network is perturbed at the minimal level and the thermodynamic stability of the duplex is unaltered upon the TNA mutation. Whether computational modelling could reproduce this result will be studied in the base flipping of the middle T (DNA) residue or its T-to-TFT mutation (TNA). We applied the equilibrium free energy simulation and the nonequilibrium stratification method proposed previously in the base flipping case, proving the applicability of alternative free energy simulation protocols. As the force field is the main accuracy-limiting factor when converged phase space sampling is obtained, we benchmarked three popular AMBER force fields for nucleotides. The last-generation force fields include bsc1 and OL15, both of which perform similarly in reproducing the structures near the crystal conformation in previous benchmark studies. Our results indicate that all these three force fields provide similar descriptions of the base-paired state. However, with free energy simulation constructing the free energy profiles along the conformational change pathway, high-energy regions are explored and these three force fields behave differently. The bsc1 force field is found to perform best in reproducing the similarity of stabilities of DNA and TNA duplexes. The free energy barrier of base flipping under the OL15 force field is lowered modestly in TNA, and thus this force field is also usable. However, the bsc0 force field provides wrong results. The TNA duplex is significantly less stable than the DNA duplex. Therefore, the bsc0 force field is not recommended in any application in modern nucleotide simulations. The salt concentration in nucleotide simulations is another factor influencing the thermodynamics of the system. Previous reports conclude that the net-neutral and excess-salt simulations provide similar results. However, the simulation method limits the phase space region explored in previous computational modelling. Our free energy simulation explores high-energy regions, where the excess salt does affect the thermodynamic stability. The free energy barrier along the base flipping pathway is generally elevated upon the addition of excess salts, but the relative height of the free energy barriers in DNA and TNA duplexes is not significantly changed. This phenomenon emphasizes the importance of adding sufficient salts to reproduce the experimental condition. </p>

Effect of Substitution for Insertion of CO2 into Epoxides and Aziridines: An Ab Initio Study

2020 ◽  
Vol 73 (1) ◽  
pp. 30
Author(s):  
Yunhan Yang ◽  
Fenji Li ◽  
Cuicui Yang ◽  
Lijuan Jia ◽  
Lijuan Yang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Free Energy ◽  
Reaction Mechanism ◽  
Ab Initio ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Concerted Mechanism

The insertion of CO2 into epoxides and aziridines has been studied using density functional theory (B3LYP) and ab initio (MP2) methods, and the effect of substitution for the two reactions are further explored. It is found that the reactivity of epoxides and aziridines are similar, and insertion of CO2 proceeds through a concerted mechanism. The substitutions of methyl and phenyl does not change the reaction mechanism, but the transition state for the substitution on the attacking position becomes loose with a lower free energy barrier. The substitutions of methyl and phenyl decrease the free energy barrier, with phenyl substitution having a greater affect. The results also show that the free energy barriers for the insertions of CO2 into aziridines are ~10kcalmol−1 lower than the corresponding reactions of CO2 with epoxides.

scholarly journals Computational Prediction of Chiral Iron Complexes for Asymmetric Transfer Hydrogenation of Pyruvic Acid to Lactic Acid

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1892
Author(s):  
Wan Wang ◽  
Xinzheng Yang
Keyword(s):  
Free Energy ◽  
Formic Acid ◽  
Pyruvic Acid ◽  
Energy Barrier ◽  
Density Functional ◽  
Iron Complexes ◽  
Computational Prediction ◽  
Transfer Hydrogenation ◽  
Free Energy Barrier ◽  
Asymmetric Transfer Hydrogenation

Density functional theory calculations reveal a formic acid-assisted proton transfer mechanism for asymmetric transfer hydrogenation of pyruvic acid catalyzed by a chiral Fe complex, FeH[(R,R)-BESNCH(Ph)CH(Ph)NH2](η6-p-cymene), with formic acid as the hydrogen provider. The rate-determining step is the hydride transfer from formate anion to Fe for the formation and dissociation of CO2 with a total free energy barrier of 28.0 kcal mol−1. A series of new bifunctional iron complexes with η6-p-cymene replaced by different arene and sulfonyl groups were built and computationally screened as potential catalysts. Among the proposed complexes, we found 1g with η6-p-cymene replaced by 4-isopropyl biphenyl had the lowest free energy barrier of 26.2 kcal mol−1 and excellent chiral selectivity of 98.5% ee.

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