The Role of Charge Transfer in the Hydrogen Bond Cooperative Effect ofcis-N-Methylformamide Oligomers

2005 ◽  
Vol 109 (28) ◽  
pp. 6303-6308 ◽  
Author(s):  
Hongwei Tan ◽  
Wenwen Qu ◽  
Guangju Chen ◽  
Ruozhuang Liu
Keyword(s):  
Hydrogen Bond ◽  
Charge Transfer ◽  
Cooperative Effect

The Nature of the Hydrogen Bond in DNA Base Pairs: The Role of Charge Transfer and Resonance Assistance

1999 ◽  
Vol 5 (12) ◽  
pp. 3581-3594 ◽  
Author(s):  
Célia Fonseca Guerra ◽  
F. Matthias Bickelhaupt ◽  
Jaap G. Snijders ◽  
Evert Jan Baerends
Keyword(s):  
Hydrogen Bond ◽  
Charge Transfer ◽  
Base Pairs ◽  
Dna Base ◽  
Dna Base Pairs

scholarly journals On the Role of Hydrogen Bond Strength and Charge Transfer of a Diels-Alder Reaction On-Water: Semiempirical and Free Energy Calculations.

2021 ◽  
Author(s):  
Andrés Henao Aristizàbal ◽  
Yomna Gohar ◽  
René Whilhelm ◽  
Thomas D. Kühne
Keyword(s):  
Hydrogen Bond ◽  
Free Energy ◽  
Charge Transfer ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Alder Reaction ◽  
Free Energy Calculations ◽  
Diels Alder ◽  
Diels Alder Reaction

Accelerated chemistry at the interface with water has received increasing attention. The mechanisms behind the enhanced reactivity On-Water are not yet clear. In this work we use a Langevin scheme in the spirit of second generation Car-Parrinello to accelerate the second-order density functional Tight-Binding (DFTB2) method in order to investigate the free energy of two Diels-Alder reaction On-Water: the cycloaddition between cyclopentadiene and ethyl cinnamate or thionocinnamate. The only difference between the reactants is the substitution of a carbonyl oxygen for a thiocarbonyl sulfur, making possible the distinction between them as strong and weak hydrogen-bond acceptors. We find a different mechanism for the reaction during the transition states and uncover the role of hydrogen bonds along with the reaction path. Our results suggest that acceleration of Diels-Alder reactions do not arise from an increased number of hydrogen bonds at the transition state and charge transfer plays a significant role. However, the presence of water and hydrogen-bonds is determinant for the catalysis of these reactions.

Hydrogen bonding from a valence bond theory perspective: the role of covalency

2018 ◽  
Vol 20 (32) ◽  
pp. 20963-20969 ◽  
Author(s):  
Coleen T. Nemes ◽  
Croix J. Laconsay ◽  
John Morrison Galbraith
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Charge Transfer ◽  
Bond Energy ◽  
Valence Bond ◽  
Hydrogen Bond Energy ◽  
Valence Bond Theory ◽  
Bond Theory

Valence bond structures that explicitly include charge transfer account for more than 50% of hydrogen bond energy.

scholarly journals Role of hydrogen bond alternation and charge transfer states in photoactivation of the Orange Carotenoid Protein

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Igor A. Yaroshevich ◽  
Eugene G. Maksimov ◽  
Nikolai N. Sluchanko ◽  
Dmitry V. Zlenko ◽  
Alexey V. Stepanov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Charge Transfer ◽  
Electric Field ◽  
Quantum Chemical ◽  
Time Resolved ◽  
Bond Alternation ◽  
Orange Carotenoid Protein ◽  
The Impact

AbstractHere, we propose a possible photoactivation mechanism of a 35-kDa blue light-triggered photoreceptor, the Orange Carotenoid Protein (OCP), suggesting that the reaction involves the transient formation of a protonated ketocarotenoid (oxocarbenium cation) state. Taking advantage of engineering an OCP variant carrying the Y201W mutation, which shows superior spectroscopic and structural properties, it is shown that the presence of Trp201 augments the impact of one critical H-bond between the ketocarotenoid and the protein. This confers an unprecedented homogeneity of the dark-adapted OCP state and substantially increases the yield of the excited photoproduct S*, which is important for the productive photocycle to proceed. A 1.37 Å crystal structure of OCP Y201W combined with femtosecond time-resolved absorption spectroscopy, kinetic analysis, and deconvolution of the spectral intermediates, as well as extensive quantum chemical calculations incorporating the effect of the local electric field, highlighted the role of charge-transfer states during OCP photoconversion.

scholarly journals On the Role of Hydrogen Bond Strength and Charge Transfer of a Diels-Alder Reaction On-Water: Semiempirical and Free Energy Calculations.

2021 ◽  
Author(s):  
Andrés Henao Aristizàbal ◽  
Yomna Gohar ◽  
René Whilhelm ◽  
Thomas D. Kühne
Keyword(s):  
Hydrogen Bond ◽  
Free Energy ◽  
Charge Transfer ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Alder Reaction ◽  
Free Energy Calculations ◽  
Diels Alder ◽  
Diels Alder Reaction

Accelerated chemistry at the interface with water has received increasing attention. The mechanisms behind the enhanced reactivity On-Water are not yet clear. In this work we use a Langevin scheme in the spirit of second generation Car-Parrinello to accelerate the second-order density functional Tight-Binding (DFTB2) method in order to investigate the free energy of two Diels-Alder reaction On-Water: the cycloaddition between cyclopentadiene and ethyl cinnamate or thionocinnamate. The only difference between the reactants is the substitution of a carbonyl oxygen for a thiocarbonyl sulfur, making possible the distinction between them as strong and weak hydrogen-bond acceptors. We find a different mechanism for the reaction during the transition states and uncover the role of hydrogen bonds along with the reaction path. Our results suggest that acceleration of Diels-Alder reactions do not arise from an increased number of hydrogen bonds at the transition state and charge transfer plays a significant role. However, the presence of water and hydrogen-bonds is determinant for the catalysis of these reactions.

Nature and role of the weak intermolecular bond in enantiomeric conformations of H2O2–noble gas adducts: a chiral prototypical model

2021 ◽  
Author(s):  
Alan Leone de Araujo Oliveira ◽  
Luiz Guilherme Machado de Macedo ◽  
Yuri Alves de Oliveira Só ◽  
João Batista Lopes Martins ◽  
Fernando Pirani ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Charge Transfer ◽  
Noble Gas ◽  
Intermolecular Hydrogen Bond ◽  
Intermolecular Bond ◽  
Prototypical Model ◽  
Weak Intermolecular Hydrogen Bond

The role and nature of the weak intermolecular bond in the H2O2–noble gas enantiomeric conformations are presented. Charge transfer associated with the formation of a weak intermolecular hydrogen bond tends to stabilize the cis-barrier conformation.

Dynamic adjustment of emission from both singlets and triplets: the role of excited state conformation relaxation and charge transfer in phenothiazine derivates

2021 ◽  
Author(s):  
Weidong Qiu ◽  
Xinyi Cai ◽  
Mengke Li ◽  
Liangying Wang ◽  
Yanmei He ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Dynamic Adjustment ◽  
Twisted Intramolecular Charge Transfer

Dynamic adjustment of emission behaviours by controlling the extent of twisted intramolecular charge transfer character in excited state.

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