Deciphering the exceptional selectivity of semipinacol rearrangements in cis-fused β-lactam diols using high-level quantum chemical methods

2019 ◽  
Vol 6 (6) ◽  
pp. 725-731 ◽  
Author(s):  
Abdulkader Baroudi ◽  
Amir Karton
Keyword(s):  
Quantum Chemical ◽  
Acyl Migration ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Rearrangement Mechanism ◽  
Semipinacol Rearrangement ◽  
High Level ◽  
In Cis

The semipinacol rearrangement mechanism in cis-fused β-lactam diols has been found to kinetically and thermodynamically favor acyl migration. The semipinacol rearrangement was also investigated for trans-fused β-lactam diol, in which the reversed selectivity that favors the alkyl migration was observed.

Comprehensive theoretical study of all 1812 C60 isomers

2017 ◽  
Vol 19 (22) ◽  
pp. 14296-14305 ◽  
Author(s):  
Rebecca Sure ◽  
Andreas Hansen ◽  
Peter Schwerdtfeger ◽  
Stefan Grimme
Keyword(s):  
Quantum Chemical ◽  
Theoretical Study ◽  
Stability Criteria ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
High Level

All 1812 C60 isomers are investigated with high-level quantum chemical methods to benchmark semiempirical approaches and find appropriate stability criteria.

scholarly journals Toward a computational photobiology

2005 ◽  
Vol 77 (6) ◽  
pp. 977-993 ◽  
Author(s):  
Adalgisa Sinicropi ◽  
Tadeusz Andruniow ◽  
Luca De Vico ◽  
Nicolas Ferré ◽  
Massimo Olivucci
Keyword(s):  
Molecular Mechanism ◽  
Quantum Chemical ◽  
Chemical Methods ◽  
Photochemical Processes ◽  
Quantum Chemical Methods ◽  
High Level

In this paper, we discuss the results of our recent studies on the molecular mechanism, which stand at the basis of the photochemical processes occurring in photobiological systems. These results are obtained using modern, robust, and fairly accurate high-level quantum chemical methods.

scholarly journals Sulfate radical oxidation of aromatic contaminants: a detailed assessment of density functional theory and high-level quantum chemical methods

2017 ◽  
Vol 19 (3) ◽  
pp. 395-404 ◽  
Author(s):  
Sangavi Pari ◽  
Inger A. Wang ◽  
Haizhou Liu ◽  
Bryan M. Wong
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Sulfate Radical ◽  
Chemical Methods ◽  
Functional Theory ◽  
Radical Oxidation ◽  
Quantum Chemical Methods ◽  
Detailed Assessment ◽  
High Level

DFT and high-level quantum methods are utilized to explore sulfate radical-driven oxidation.

scholarly journals The INV24 test set: how well do quantum-chemical methods describe inversion and racemization barriers?

2016 ◽  
Vol 94 (12) ◽  
pp. 1133-1143 ◽  
Author(s):  
Lars Goerigk ◽  
Rahul Sharma
Keyword(s):  
Quantum Chemical ◽  
Computational Study ◽  
Basis Sets ◽  
Generalized Gradient ◽  
Chemical Methods ◽  
Generalized Gradient Approximation ◽  
Quantum Chemical Methods ◽  
London Dispersion ◽  
High Level ◽  
Jacob's Ladder

For years, there has been ongoing interest in experimentally and theoretically understanding inversion and racemization processes. However, to the best of our knowledge, there has been no computational study that systematically investigated how well low-level quantum-chemical methods predict inversion barriers. Herein, we provide an answer to this question and we present the INV24 benchmark set of 24 high-level, ab initio inversion barriers. INV24 covers inversion in triatomics, in pyramidal molecules, in one cyclic system, and in various helical and bowl-shaped compounds. Our results indicate that previously applied DFT approximations combined with small basis sets are not reliable enough and that at least a triple-ζ basis is needed for meaningful results. Moreover, we show that intramolecular London dispersion influences the barriers by 2 kcal/mol or more and that dispersion corrections should always be applied to DFT results. With our analysis of 34 DFT approximations, we can reproduce the well-known Jacob’s Ladder scheme with (meta-)generalized-gradient-approximation methods underestimating barriers and global-hybrid DFT functionals performing better. Range-separated hybrids or Minnesota-type hybrids are not particularly superior to more conventional methods, such as B3LYP-D3. The by far best results are achieved with dispersion-corrected double hybrids, which give results below the chemical accuracy target of 1 kcal/mol. They also outperform wave-function second-order perturbation theory approaches and we recommend using them whenever possible. Given that our systematic study of INV24 is the first of its kind, our findings have the potential to change common practice in this field and they will guide future investigations of inversion processes.

scholarly journals Energetics of LOHC: Structure-Property Relationships from Network of Thermochemical Experiments and in Silico Methods

Hydrogen ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 101-121
Author(s):  
Sergey P. Verevkin ◽  
Vladimir N. Emel’yanenko ◽  
Riko Siewert ◽  
Aleksey A. Pimerzin
Keyword(s):  
In Silico ◽  
Quantum Chemical ◽  
Structure Property ◽  
Chemical Methods ◽  
Key Technology ◽  
Structure Property Relationships ◽  
Quantum Chemical Methods ◽  
Dehydrogenation Reactions ◽  
Storage Technologies ◽  
In Silico Methods

The storage of hydrogen is the key technology for a sustainable future. We developed an in silico procedure, which is based on the combination of experimental and quantum-chemical methods. This method was used to evaluate energetic parameters for hydrogenation/dehydrogenation reactions of various pyrazine derivatives as a seminal liquid organic hydrogen carriers (LOHC), that are involved in the hydrogen storage technologies. With this in silico tool, the tempo of the reliable search for suitable LOHC candidates will accelerate dramatically, leading to the design and development of efficient materials for various niche applications.

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