Results 261 to 270 of about 464,016 (298)

Entropy barriers to proton transfer

Journal of the American Chemical Society, 1991
Proton transfer between sterically hindered pyridines and amines proceeds through locked-rotor, low-entropy intermediates. The reactions exhibit slow kinetics (efficiencies of 0.1-0.0001) and large negative temperature coefficients (up to k=CT − 8 .7 ).
Meotner, M, Smith, SC
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Dynamics of Proton Transfer in Solution

1977
Proton transfer reactions in principle belong to the simplest possible chemical processes, since only a naked proton is exchanged between the two molecules concerned.
P, Schuster, P, Wolschann, K, Tortschanoff   +2 more
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Proton Transfer in Dissociative Protonation Processes

The Journal of Physical Chemistry A, 1998
Proton transfer in dissociative protonation processes involving fluoroadamantane and other smaller model compounds with different reference bases has been studied, through the use of B3LYP density ...
Leticia González, Otilia Mó, Manuel Yáñez   +2 more
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Proton Assisted Electron Transfer

2000
Likely mechanisms for long range electron transfer coupled to proton transfer are investigated. It is shown that, in model systems closely resembling realistic biochemical sequences, the injection of an electron on one end of the H-bonded chain can activate a sequential hopping of protons, which localizes the electronic charge on the opposite end of ...
BORRELLI, Raffaele, M. DI DONATO, A. CAPOBIANCO, R. IMPROTA, G. MONACO, M. BRAHIMI, A. PELUSO   +6 more
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Proton-Transfer Dynamics in Protonated Benzene

Bulletin of the Chemical Society of Japan, 2016
Abstract The proton-transfer reaction mechanism in protonated benzene was examined using ab initio molecular dynamics, paying special attention to cooperative motions. We first examined the lifetime of each stable state of protonated benzene, taken as equal to the time lag between proton-transfer reactions.
Ayaka Kuroki, Hiroshi Ushiyama, Koichi Yamashita   +2 more
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Gas‐phase proton‐transfer pathways in protonated histidylglycine

Rapid Communications in Mass Spectrometry, 2008
Abstract Pathways for proton transfer in the histidylglycine cation are examined in the gas‐phase environment with the goal of understanding the mechanism by which protons may become mobile in proteins with basic amino acid residues. An extensive search of the potential energy surface is performed using density functional theory (DFT)
Brandon I, Macdonald, Mark, Thachuk
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The Problem of Proton Transfer in Membranes

Journal of Theoretical Biology, 2002
Proton (H(+)) transfer has been examined in many molecular systems for more than 50 years. General mechanistic possibilities including tunnelling have been recognized for proton movement from local base-to-base centres. An especially fast mechanism over considerable distances, the Grotthus mechanism, has been described in water.
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Influence of stereochemistry on proton transfer in protonated tripeptide models

Journal of Molecular Modeling, 2011
Vectorial proton transfer among carbonyl oxygen atoms was studied in two models of tripeptide via quantum chemical calculations using the hybrid B3LYP functional and the 6-31++G basis set. Two principal proton transfer pathways were found: a first path involving isomerization of the proton around the double bond of the carbonyl group, and a second ...
Namat Ali, Soliman, Petr, Kulhánek, Jaroslav, Koča   +2 more
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Vibrational Spectroscopy and Proton Transfer Dynamics in Protonated Oxalate

The Journal of Physical Chemistry A, 2017
The dynamics and infrared spectroscopic signatures of proton transfer in protonated oxalate (p-Oxa) are studied using classical and quantum dynamics. The intermolecular interactions are described by a force field suitable to follow proton transfer.
Zhen-Hao Xu, Markus Meuwly
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Proton transfer reactions and dynamics in protonated water clusters

Physical Chemistry Chemical Physics, 2011
Proton transfer reactions and dynamics were theoretically studied using the hydrogen-bond (H-bond) complexes formed from H(3)O(+) and nH(2)O, n = 1-4, as model systems. The investigations began with searching for characteristics of transferring protons in the gas phase and continuum aqueous solution using DFT method at the B3LYP/TZVP level, followed by
Charoensak, Lao-Ngam, Prapasri, Asawakun, Sornthep, Wannarat, Kritsana, Sagarik   +3 more
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