On the Role of Hydrogen Bonding in Gas-Phase SN2 Reactions at Silicon

2021 ◽  
Author(s):  
Malte Fugel ◽  
Anneke Dittmer ◽  
Florian Kleemiss ◽  
Simon Grabowsky
Keyword(s):  
Hydrogen Bonding ◽  
Gas Phase ◽  
Sn2 Reactions

Hydrogen-Bonding Mediated Reactions of Criegee Intermediates in the Gas Phase: Competition between Bimolecular and Termolecular Reactions and the Catalytic Role of Water

2019 ◽  
Vol 123 (39) ◽  
pp. 8336-8348 ◽  
Author(s):  
Wen Chao ◽  
Cangtao Yin ◽  
Kaito Takahashi ◽  
Jim Jr-Min Lin
Keyword(s):  
Hydrogen Bonding ◽  
Gas Phase ◽  
Phase Competition ◽  
Criegee Intermediates ◽  
Catalytic Role

Dynamical Bifurcation in Gas-Phase XH−+ CH3Y SN2 Reactions: The Role of Energy Flow and Redistribution in Avoiding the Minimum Energy Path

2016 ◽  
Vol 22 (45) ◽  
pp. 16220-16229 ◽  
Author(s):  
Yaicel G. Proenza ◽  
Miguel A. F. de Souza ◽  
Ricardo L. Longo
Keyword(s):  
Gas Phase ◽  
Energy Flow ◽  
Minimum Energy ◽  
Minimum Energy Path ◽  
Sn2 Reactions

scholarly journals Deciphering the Role of π-Interactions in Polyelectrolyte Complexes Using Rationally Designed Peptides

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2074
Author(s):  
Sara Tabandeh ◽  
Cristina Elisabeth Lemus ◽  
Lorraine Leon
Keyword(s):  
Hydrogen Bonding ◽  
Phase Separation ◽  
Liquid Phase ◽  
Charge Density ◽  
Secondary Structures ◽  
Liquid Phase Separation ◽  
Polyelectrolyte Complexes ◽  
Π Interactions ◽  
Liquid Liquid Phase Separation

Electrostatic interactions, and specifically π-interactions play a significant role in the liquid-liquid phase separation of proteins and formation of membraneless organelles/or biological condensates. Sequence patterning of peptides allows creating protein-like structures and controlling the chemistry and interactions of the mimetic molecules. A library of oppositely charged polypeptides was designed and synthesized to investigate the role of π-interactions on phase separation and secondary structures of polyelectrolyte complexes. Phenylalanine was chosen as the π-containing residue and was used together with lysine or glutamic acid in the design of positively or negatively charged sequences. The effect of charge density and also the substitution of fluorine on the phenylalanine ring, known to disrupt π-interactions, were investigated. Characterization analysis using MALDI-TOF mass spectroscopy, H NMR, and circular dichroism (CD) confirmed the molecular structure and chiral pattern of peptide sequences. Despite an alternating sequence of chirality previously shown to promote liquid-liquid phase separation, complexes appeared as solid precipitates, suggesting strong interactions between the sequence pairs. The secondary structures of sequence pairs showed the formation of hydrogen-bonded structures with a β-sheet signal in FTIR spectroscopy. The presence of fluorine decreased hydrogen bonding due to its inhibitory effect on π-interactions. π-interactions resulted in enhanced stability of complexes against salt, and higher critical salt concentrations for complexes with more π-containing amino acids. Furthermore, UV-vis spectroscopy showed that sequences containing π-interactions and increased charge density encapsulated a small charged molecule with π-bonds with high efficiency. These findings highlight the interplay between ionic, hydrophobic, hydrogen bonding, and π-interactions in polyelectrolyte complex formation and enhance our understanding of phase separation phenomena in protein-like structures.

Mechanisms on the stability and instability of water-in-oil emulsion stabilized by interfacially active asphaltenes: Role of hydrogen bonding reconstructing

Fuel ◽  
2021 ◽  
Vol 297 ◽  
pp. 120763
Author(s):  
Jun Ma ◽  
Yongli Yang ◽  
Xingang Li ◽  
Hong Sui ◽  
Lin He
Keyword(s):  
Hydrogen Bonding ◽  
Oil Emulsion ◽  
Stability And Instability ◽  
The Stability ◽  
Water In Oil Emulsion

scholarly journals The role of radiolysis in the modelling of C2H4O2 isomers and dimethyl ether in cold dark clouds

2020 ◽  
Vol 500 (3) ◽  
pp. 3414-3424
Author(s):  
Alec Paulive ◽  
Christopher N Shingledecker ◽  
Eric Herbst
Keyword(s):  
Gas Phase ◽  
Dimethyl Ether ◽  
Recent Observation ◽  
Cosmic Ray ◽  
Thermal Method ◽  
Dark Clouds ◽  
Ice Surface ◽  
Dust Grain ◽  
Complex Organic

ABSTRACT Complex organic molecules (COMs) have been detected in a variety of interstellar sources. The abundances of these COMs in warming sources can be explained by syntheses linked to increasing temperatures and densities, allowing quasi-thermal chemical reactions to occur rapidly enough to produce observable amounts of COMs, both in the gas phase, and upon dust grain ice mantles. The COMs produced on grains then become gaseous as the temperature increases sufficiently to allow their thermal desorption. The recent observation of gaseous COMs in cold sources has not been fully explained by these gas-phase and dust grain production routes. Radiolysis chemistry is a possible non-thermal method of producing COMs in cold dark clouds. This new method greatly increases the modelled abundance of selected COMs upon the ice surface and within the ice mantle due to excitation and ionization events from cosmic ray bombardment. We examine the effect of radiolysis on three C2H4O2 isomers – methyl formate (HCOOCH3), glycolaldehyde (HCOCH2OH), and acetic acid (CH3COOH) – and a chemically similar molecule, dimethyl ether (CH3OCH3), in cold dark clouds. We then compare our modelled gaseous abundances with observed abundances in TMC-1, L1689B, and B1-b.

The role of hydrogen bonding on tuning hard-soft segments in bio-based thermoplastic poly(ether-urethane)s

2020 ◽  
Vol 274 ◽  
pp. 122678
Author(s):  
Paulina Kasprzyk ◽  
Hynek Benes ◽  
Ricardo Keitel Donato ◽  
Janusz Datta
Keyword(s):  
Hydrogen Bonding ◽  
Soft Segments
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