Influence of Base Strength on the Proton-Transfer Reaction by Density Functional Theory

2017 ◽  
Vol 2017 (27) ◽  
pp. 3947-3956 ◽  
Author(s):  
Binfang Yuan ◽  
Rongxing He ◽  
Wei Shen ◽  
Ming Li
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Functional Theory ◽  
Base Strength

Protons Crossing Triple Phase Boundaries based on Pd and Barium Zirconate: A Density Functional Theory Study

2013 ◽  
Vol 1542 ◽  
Author(s):  
Massimo Malagoli ◽  
Angelo Bongiorno
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Transfer Reaction ◽  
Surface Region ◽  
Proton Transfer Reaction ◽  
Barium Zirconate ◽  
Phase Boundaries ◽  
Functional Theory ◽  
Electrolyte Interface

ABSTRACTDensity functional theory calculations are used to address the energetics of protons crossing “triple phase boundaries” based on Pd and barium zirconate. Our calculations show that the proton transfer reaction at these triple phase boundaries is controlled by the terminal layer of the electrolyte in contact with the metallic catalyst and gas phase. Hydrogen spilling onto the electrolyte surface is energetically favored at peripherical sites of the metal-electrolyte interface, and proton incorporation into the sub-surface region of the electrolyte involves energies of the order of 1 eV. At the triple phase boundary, the energy cost associated with the proton transfer reaction is controlled by both the nature of chemical contact and the Schottky barrier at the metal-electrolyte interface.

Investigation of excited-state intramolecular proton transfer coupled charge transfer reaction of paeonol

2014 ◽  
Vol 92 (4) ◽  
pp. 274-278 ◽  
Author(s):  
Shanshan Hu ◽  
Kun Liu ◽  
Yuanzuo Li ◽  
Qianqian Ding ◽  
Wei Peng ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Charge Transfer ◽  
Proton Transfer ◽  
Density Functional ◽  
Transfer Reaction ◽  
Intramolecular Proton Transfer ◽  
Ethanol Solution ◽  
Charge Transfer Reaction ◽  
Functional Theory

An excited-state intramolecular proton transfer (ESIPT) coupled charge transfer reaction of paeonol was investigated both experimentally and theoretically. The ESIPT reaction of paeonol was predicted based on the large Stokes shift, which is observed in steady-state absorption and fluorescence spectra in an ethanol solution. The steady-state spectra in some solutions, such as methanol, ethanol, propanol, dichloromethane, and n-hexane, illustrate that the ESIPT reaction of paeonol has no dependence on the solvent properties. Therefore, the excited-state intermolecular proton transfer cannot be generated in protic solvents. Using the density functional theory and time-dependent density functional theory methods, we make a subsequent theoretical calculation that indicates that the ESIPT reaction of paeonol occurs through the intramolecular hydrogen bond O−H···O=C. The excited-state potential energy curve of paeonol indicates that the ESIPT reaction is a barrierless process, and the fluorescence emission of paeonol at 493 nm in the ethanol solution was assigned to the keto isomer fluorescence. Additionally, we also found an intramolecular charge transfer in the excited state by analysing the frontier molecular orbitals of paeonol.

scholarly journals Minimal Optimized Effective Potentials for Density Functional Theory Studies on Excited-State Proton Dissociation

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 679
Author(s):  
Pouya Partovi-Azar ◽  
Daniel Sebastiani
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Proton Transfer ◽  
Density Functional ◽  
Photochemical Reactions ◽  
Transfer Energy ◽  
Functional Theory ◽  
Effective Potentials ◽  
Proton Dissociation ◽  
Dissociation Curves

Recently, a new method [P. Partovi-Azar and D. Sebastiani, J. Chem. Phys. 152, 064101 (2020)] was proposed to increase the efficiency of proton transfer energy calculations in density functional theory by using the T1 state with additional optimized effective potentials instead of calculations at S1. In this work, we focus on proton transfer from six prototypical photoacids to neighboring water molecules and show that the reference proton dissociation curves obtained at S1 states using time-dependent density functional theory can be reproduced with a reasonable accuracy by performing T1 calculations at density functional theory level with only one additional effective potential for the acidic hydrogens. We also find that the extra effective potentials for the acidic hydrogens neither change the nature of the T1 state nor the structural properties of solvent molecules upon transfer from the acids. The presented method is not only beneficial for theoretical studies on excited state proton transfer, but we believe that it would also be useful for studying other excited state photochemical reactions.

scholarly journals Influence of Varying Functionalization on the Peroxidase Activity of Nickel(II)–Pyridine Macrocycle Catalysts: Mechanistic Insights from Density Functional Theory

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 52
Author(s):  
Jerwin Jay E. Taping ◽  
Junie B. Billones ◽  
Voltaire G. Organo
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Stoichiometric Ratio ◽  
Functional Theory ◽  
Pendant Arm ◽  
Spin Singlet

Nickel(II) complexes of mono-functionalized pyridine-tetraazamacrocycles (PyMACs) are a new class of catalysts that possess promising activity similar to biological peroxidases. Experimental studies with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), substrate) and H2O2 (oxidant) proposed that hydrogen-bonding and proton-transfer reactions facilitated by their pendant arm were responsible for their catalytic activity. In this work, density functional theory calculations were performed to unravel the influence of pendant arm functionalization on the catalytic performance of Ni(II)–PyMACs. Generated frontier orbitals suggested that Ni(II)–PyMACs activate H2O2 by satisfying two requirements: (1) the deprotonation of H2O2 to form the highly nucleophilic HOO−, and (2) the generation of low-spin, singlet state Ni(II)–PyMACs to allow the binding of HOO−. COSMO solvation-based energies revealed that the O–O Ni(II)–hydroperoxo bond, regardless of pendant arm type, ruptures favorably via heterolysis to produce high-spin (S = 1) [(L)Ni3+–O·]2+ and HO−. Aqueous solvation was found crucial in the stabilization of charged species, thereby favoring the heterolytic process over homolytic. The redox reaction of [(L)Ni3+–O·]2+ with ABTS obeyed a 1:2 stoichiometric ratio, followed by proton transfer to produce the final intermediate. The regeneration of Ni(II)–PyMACs at the final step involved the liberation of HO−, which was highly favorable when protons were readily available or when the pKa of the pendant arm was low.

Barrierless Proton Transfer within Short Protonated Peptides in the Presence of Water Bridges. A Density Functional Theory Study

2011 ◽  
Vol 115 (6) ◽  
pp. 1485-1490 ◽  
Author(s):  
Po-Tuan Chen ◽  
Chia-Ching Wang ◽  
Jyh-Chiang Jiang ◽  
Hsi-Kai Wang ◽  
Michitoshi Hayashi
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Protonated Peptides ◽  
Water Bridges
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