scholarly journals Benchmark ab initio proton affinity of glycine

2021 ◽  
Author(s):  
Andras B. Nacsa ◽  
Gabor Czako
Keyword(s):  
Ab Initio ◽  
Proton Affinity ◽  
Conformational Search

A systematic conformational search reveals three N- (amino) and eight O- (carbonyl) protonated glycine conformers with benchmark equilibrium(adiabatic) relative energies in the 0.00−7.51(0.00−7.37) and 25.91−31.61(24.45−30.28) kcal/mol ranges, respectively. Benchmark ab...

Ab Initio-Rechnungen zur Protonenaffinität unverzweigter primärer aliphatischer Amine / Ab Initio-Calculations on the Protonaffinity of Unbranched Primary Aliphatic Amines

1984 ◽  
Vol 39 (6) ◽  
pp. 593-595
Author(s):  
Eberhard Heyne ◽  
Gerhard Raabe ◽  
Jörg Fleischhauer
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Proton Affinity ◽  
Positive Charge ◽  
Semiempirical Calculations ◽  
Aliphatic Amines ◽  
Semiempirical Methods ◽  
Satisfactory Correlation ◽  
Primary Aliphatic Amines

Recently we reported the results of semiempirical calculations (MNDO, MINDO/3) which led us to the conclusion, that the proton-affinity of molecules R-NH2 (R = H, CH3, C2H5, n-C3H7 and n-C4H9) is determined by the ability of the groups R to carry positive charge in the corresponding cations R-NH3+. We did extend our investigations concerning the protonaffinities of primary aliphatic amines including NH3 and performed ab initio calculations with an STO-3G basis. The results qualitatively parallel those obtained by the semiempirical methods mentioned above. In contrast to the semiempirical results we found that there is a satisfactory correlation between the Mulliken-charges of the nitrogen-atoms and of the NH2-groups and the experimental protonaffinities if NH3 is excluded.

Methyl Cation Affinity vs Proton Affinity in Substituted Benzenes:  An ab Initio Study

1998 ◽  
Vol 102 (17) ◽  
pp. 2981-2987 ◽  
Author(s):  
Zvonimir B. Maksić ◽  
Mirjana Eckert-Maksić ◽  
Andrea Knežević
Keyword(s):  
Ab Initio ◽  
Proton Affinity ◽  
Ab Initio Study ◽  
Substituted Benzenes ◽  
Cation Affinity ◽  
Methyl Cation

Thermokinetic Proton Transfer and Ab Initio Studies of the [2H,S,O]+System. The Proton Affinity of HSO

2000 ◽  
Vol 104 (19) ◽  
pp. 4636-4647 ◽  
Author(s):  
Brian K. Decker ◽  
Nigel G. Adams ◽  
Lucia M. Babcock ◽  
T. Daniel Crawford ◽  
Henry F. Schaefer
Keyword(s):  
Proton Transfer ◽  
Ab Initio ◽  
Proton Affinity

scholarly journals Ab Initio Metadynamics Calculations of Dimethylamine for Probing pKb Variations in Bulk vs. Surface Environments

2020 ◽  
Author(s):  
Sohag Biswas ◽  
Hyuna Kwon ◽  
Kelley Barsanti ◽  
Nanna Myllys ◽  
James N. Smith ◽  
...  
Keyword(s):  
Free Energy ◽  
Ab Initio ◽  
Proton Affinity ◽  
Particle Surface ◽  
Physical Property ◽  
Basicity Constant ◽  
Aqueous Environment ◽  
Energy Profiles ◽  
Atomic Interactions ◽  
Air Water Interface

The basicity constant, or pK<sub>b</sub>, is an intrinsic physical property of bases that gives a measure of its proton affinity in macroscopic environments. While the pKb is typically defined in reference to the bulk aqueous phase, several studies have suggested that this value can differ significantly at the air-water interface (which can have significant ramifications for particle surface chemistry and aerosol growth modeling). To provide mechanistic insight into surface proton affinity, we carried out <i>ab initio</i> metadynamics calculations to (1) explore the free-energy profile of dimethylamine and (2) provide reasonable estimates of the pKb value in different solvent environments. We find that the free-energy profiles obtained with our metadynamics calculations show a dramatic variation, with interfacial aqueous dimethylamine pK<sub>b</sub> values being significantly lower than in the bulk aqueous environment. Furthermore, our metadynamics calculations indicate that these variations are due to reduced hydrogen bonding at the air-water surface. Taken together, our quantum mechanical metadynamics calculations show that the reactivity of dimethylamine is surprisingly complex, leading to pK<sub>b</sub> variations that critically depend on the different atomic interactions occurring at the microscopic molecular level.

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