scholarly journals Different types of biological proton transfer reactions studied by quantum chemical methods

2006 ◽  
Vol 1757 (8) ◽  
pp. 969-980 ◽  
Author(s):  
Margareta R.A. Blomberg ◽  
Per E.M. Siegbahn
Keyword(s):  
Proton Transfer ◽  
Quantum Chemical ◽  
Transfer Reactions ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Different Types ◽  
Proton Transfer Reactions

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1042-1049
Author(s):  
Wlodzimierz Galezowski ◽  
Iwona Grzeskowiak ◽  
Arnold Jarczewski
Keyword(s):  
Proton Transfer ◽  
Salt Effect ◽  
Ion Pairs ◽  
Order Rate Constant ◽  
Transfer Reactions ◽  
First Order ◽  
Organic Bases ◽  
Different Types ◽  
Proton Transfer Reactions ◽  
Guanidinium Cation

The rates of proton transfer reactions between C-acids of different types such as 1-(4-nitrophenyl)-1-nitroalkanes, 4-nitrophenylcyanomethanes, and 2,4,6-trinitrotoluene, and organic bases such as 1,1,3,3-tetrametylguanidine, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), and tri-n-butylamine have been measured in acetonitrile at pseudo-first-order conditions. A general equation for the rates of proton transfer reactions between C-acids and bases with product existing in two forms, ions and ion pairs, has been derived and its applicability tested. The equation works well except for reactions of 1-(4-nitrophenyl)-1-nitroalkanes with guanidines for which the second-order rate constant is diminished with concentration of guanidinium cation, while tetrabutylammonium salts accelerate the reactions. Possible reasons for this are discussed.Key words: proton transfer, kinetic study, ion pairs, C-acids, organic bases, acetonitrile, salt effect.

Quantum chemical treatments of metal clusters

2010 ◽  
Vol 368 (1915) ◽  
pp. 1245-1263 ◽  
Author(s):  
Florian Weigend ◽  
Reinhart Ahlrichs
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Metal Clusters ◽  
Potential Surface ◽  
A Priori ◽  
Chemical Methods ◽  
Functional Theory ◽  
Chemical Treatments ◽  
Quantum Chemical Methods ◽  
Different Types

This work focuses on finding and rationalizing the building principles of clusters with approximately 300 atoms of different types of metals: main group elements (Al, Sn), alkaline earth metals (Mg), transition metals (Pd) and clusters consisting of two different elements (Ir and Pt). Two tools are inevitable for this purpose: (i) quantum chemical methods that are able to treat a given cluster with both sufficient accuracy and efficiency and (ii) algorithms that are able to systematically scan the (3 n −6)-dimensional potential surface of an n -atomic cluster for promising isomers. Currently, the only quantum chemical method that can be applied to metal clusters is density functional theory (DFT). Other methods either do not account for the multi-reference character of metal clusters or are too expensive and thus can be applied only to clusters of very few atoms, which usually is not sufficient for studying the building principles. The accuracy of DFT is not known a priori , but extrapolations to bulk values from calculated series of data show satisfying agreement with experimental data. For scans of the potential surface, simulated annealing techniques or genetic algorithms were used for the smaller clusters (approx. 20–30 atoms), and for the larger clusters considerations were restricted to selected packings and shapes. For the mixed-metallic clusters, perturbation theory turned out to be efficient and successful for finding the most promising distributions of the two atom types at the different sites.

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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