scholarly journals Harnessing Ionic Interactions and Hydrogen Bonding for Nucleophilic Fluorination

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 721 ◽  
Author(s):  
Young-Ho Oh ◽  
Hyoju Choi ◽  
Chanho Park ◽  
Dong Wook Kim ◽  
Sungyul Lee
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Strong Dependence ◽  
Ionic Species ◽  
Ionic Interactions ◽  
Solvent Engineering ◽  
Coulombic Interactions ◽  
Diaryliodonium Salts ◽  
Nucleophilic Fluorination

We review recent works for nucleophilic fluorination of organic compounds in which the Coulombic interactions between ionic species and/or hydrogen bonding affect the outcome of the reaction. SN2 fluorination of aliphatic compounds promoted by ionic liquids is first discussed, focusing on the mechanistic features for reaction using alkali metal fluorides. The influence of the interplay of ionic liquid cation, anion, nucleophile and counter-cation is treated in detail. The role of ionic liquid as bifunctional (both electrophilic and nucleophilic) activator is envisaged. We also review the SNAr fluorination of diaryliodonium salts from the same perspective. Nucleophilic fluorination of guanidine-containing of diaryliodonium salts, which are capable of forming hydrogen bonds with the nucleophile, is exemplified as an excellent case where ionic interactions and hydrogen bonding significantly affect the efficiency of reaction. The origin of experimental observation for the strong dependence of fluorination yields on the positions of -Boc protection is understood in terms of the location of the nucleophile with respect to the reaction center, being either close to far from it. Recent advances in the synthesis of [18F]F-dopa are also cited in relation to SNAr fluorination of diaryliodonium salts. Discussions are made with a focus on tailor-making promoters and solvent engineering based on ionic interactions and hydrogen bonding.

Understanding the role of hydrogen bonding in Brønsted acidic ionic liquid-catalyzed transesterification: a combined theoretical and experimental investigation

2016 ◽  
Vol 18 (48) ◽  
pp. 32723-32734 ◽  
Author(s):  
Kaixin Li ◽  
Yibo Yan ◽  
Jun Zhao ◽  
Junxi Lei ◽  
Xinli Jia ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Catalytic Activity ◽  
Ionic Liquids ◽  
Acidic Ionic Liquid ◽  
Brønsted Acidic Ionic Liquid ◽  
Acidic Ionic Liquids ◽  
Hydrogen Bonding Networks

The intra- and inter-hydrogen bonding networks that govern the catalytic activity of Brønsted acidic ionic liquids were identified.

The essential role of hydrogen-bonding interaction in the extractive separation of phenolic compounds by ionic liquid

AIChE Journal ◽  
2012 ◽  
Vol 59 (5) ◽  
pp. 1657-1667 ◽  
Author(s):  
Qiwei Yang ◽  
Huabin Xing ◽  
Baogen Su ◽  
Zongbi Bao ◽  
Jun Wang ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Phenolic Compounds ◽  
Essential Role ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction ◽  
Extractive Separation

scholarly journals A structural investigation of ionic liquid mixtures

2016 ◽  
Vol 18 (12) ◽  
pp. 8608-8624 ◽  
Author(s):  
Richard P. Matthews ◽  
Ignacio J. Villar-Garcia ◽  
Cameron C. Weber ◽  
Jeraime Griffith ◽  
Fiona Cameron ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Structural Investigation ◽  
Experimental Approach ◽  
Liquid Mixtures

The role of hydrogen bonding, π+–π+ stacking and anion–π+ interactions on the structure of ionic liquid mixtures has been elucidated through a combined theoretical and experimental approach.

scholarly journals Low molecular weight gelators (LMWGs) for ionic liquids: the role of hydrogen bonding and sterics in the formation of stable low molecular weight ionic liquid gels

2017 ◽  
Vol 19 (19) ◽  
pp. 4690-4697 ◽  
Author(s):  
Peter McNeice ◽  
Yingying Zhao ◽  
Jianxun Wang ◽  
Gerald F. Donnelly ◽  
Patricia C. Marr
Keyword(s):  
Molecular Weight ◽  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Low Molecular Weight ◽  
Diverse Range ◽  
Low Molecular Weight Gelators

3 sugar based low molecular weight gelators are shown to form ionic liquid gels with a diverse range of ionic liquids.

scholarly journals Revisiting the carbon mesopore contribution towards improved performance of ionic liquid–based EDLCs at sub-zero temperatures

Ionics ◽  
2021 ◽  
Author(s):  
V. Pavlenko ◽  
S. Kalybekkyzy ◽  
D. Knez ◽  
Q. Abbas ◽  
Z. Mansurov ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Room Temperature ◽  
Large Fraction ◽  
Perfect Match ◽  
Pore Wall ◽  
Average Diameter ◽  
Ionic Species ◽  
Graphene Layers ◽  
Coulombic Interactions ◽  
Improved Performance

AbstractThe important role of mesopores has been investigated in electric double-layer capacitors (EDLCs) operating from 24 °C down to − 40 °C by using two in-house synthesized carbons with hierarchical porosity. These carbons were prepared from colloidal nanoparticles of SiO2 as the template and d-glucose as the carbon source. A decrease in the average diameter of the nanoparticles from 12 to 8 nm results in increased surface area and offers a perfect match between ions of binary mixture of imidazolium-based fluorinated ionic liquids and the pores of carbon. Short-range graphene layers produced with 8-nm silica nanoparticles lead to the creation of transport channels which better accommodate ions. We explain these findings per coulombic interactions among the ions and between the pore wall and the ionic species under confinement and electrochemical polarization conditions. Further, it is shown that a microporous carbon (another in-house produced rice-husk carbon SBET = 1800 m2∙g−1) performs better than hierarchical carbons at room temperature; however, thanks to the large fraction of mesopores, the latter exhibit far higher capacitance down to − 40 °C. While the ordering of ions in confinement is more critical at room temperature and dictated by the micropores, low temperature performance of supercapacitors is determined by the mesopores that provide channels for facile ion movement and keep the bulk ionic liquid–like properties. Graphical abstract

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.

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