The Role of the Lone Pairs in Hydrogen Bonding

2016 ◽  
pp. 53-68
Author(s):  
Ivar Olovsson
Keyword(s):  
Hydrogen Bonding ◽  
Lone Pairs

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.

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

The role of hydrogen bonding in alginate/poly(acrylamide-co-dimethylacrylamide) and alginate/poly(ethylene glycol) methyl ether methacrylate-based tough hybrid hydrogels

RSC Advances ◽  
2015 ◽  
Vol 5 (71) ◽  
pp. 57678-57685 ◽  
Author(s):  
Zhi Wei Low ◽  
Pei Lin Chee ◽  
Dan Kai ◽  
Xian Jun Loh
Keyword(s):  
Hydrogen Bonding ◽  
Elastic Modulus ◽  
Ethylene Glycol ◽  
Methyl Ether ◽  
Poly Ethylene Glycol ◽  
Hybrid Hydrogels ◽  
Poly Ethylene ◽  
Glycol Methyl Ether ◽  
Poly Acrylamide

Hybrid hydrogels, with an elastic modulus and compressive toughness of 350 kPa and 70 J m−3, was synthesized and reported here.

scholarly journals Role of hydrogen bonding in hysteresis observed in sorption-induced swelling of soft nanoporous polymers

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Mingyang Chen ◽  
Benoit Coasne ◽  
Robert Guyer ◽  
Dominique Derome ◽  
Jan Carmeliet
Keyword(s):  
Hydrogen Bonding ◽  
Nanoporous Polymers
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