scholarly journals A Concise Synthesis of a Methyl Ester 2-Resorcinarene: A Chair-Conformation Macrocycle

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 627
Author(s):  
Michael R. Reynolds ◽  
Fraser S. Pick ◽  
John J. Hayward ◽  
John F. Trant
Keyword(s):  
Hydrogen Bond ◽  
Density Functional ◽  
Chair Conformation ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Functional Theory ◽  
Design And Synthesis ◽  
Hydrogen Bond Strength ◽  
Recognition Elements ◽  
Configurational Isomerism

Anions are important hydrogen bond acceptors in a range of biological, chemical, environmental and medical molecular recognition processes. These interactions have been exploited for the design and synthesis of ditopic resorcinarenes as the hydrogen bond strength can be tuned through the modification of the substituent at the 2-position. However, many potentially useful compounds, especially those incorporating electron-withdrawing functionalities, have not been prepared due to the challenge of their synthesis: their incorporation slows resorcinarene formation that is accessed by electrophilic aromatic substitution. As part of our broader campaign to employ resorcinarenes as selective recognition elements, we need access to these specialized materials. In this article, we report a straightforward synthetic pathway for obtaining a 2-(carboxymethyl)-resorcinarene, and resorcinarene esters in general. We discuss the unusual conformation it adopts and propose that this arises from the electron-withdrawing nature of the ester substituents that renders them better hydrogen bond acceptors than the phenols, ensuring that each of them acts as a donor only. Density Functional Theory (DFT) calculations show that this conformation arises as a consequence of the unusual configurational isomerism of this compound and interruption of the archetypal hydrogen bonding by the ester functionality.

scholarly journals A Concise Synthesis of a Methyl Ester 2-Resorcinarene: A Chair-Conformation Macrocycle

2021 ◽  
Author(s):  
Michael R. Reynolds ◽  
Fraser S. Pick ◽  
John Hayward ◽  
John F. Trant
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Methyl Ester ◽  
Chair Conformation ◽  
Selective Recognition ◽  
Aromatic Substitution ◽  
Design And Synthesis ◽  
Hydrogen Bond Strength ◽  
Recognition Elements ◽  
Configurational Isomerism

Anions are important hydrogen bond acceptors in a range of biological, chemical, environmental and medical molecular recognition processes.<sup> </sup>These interactions have been exploited for the design and synthesis of ditopic resorcinarenes as the hydrogen bond strength can be tuned through the modification of the substituent at the 2-position. However, many potentially useful compounds, especially those incorporating electron-withdrawing functionalities, have not been prepared due to the challenge of their synthesis: their incorporation slows resorcinarene formation that is accessed by electrophic aromatic substitution. As part of our broader campaign to employ resorcinarenes as selective recognition elements, we need access to these specialized materials, and in this article we report a straightforward synthetic pathway for obtaining a 2-(carboxymethyl)-resorcinarene, and resorcinarene esters in general. We discuss the unusual conformation it adopts, and propose that this arises from the electron-withdrawing nature of the ester substituents that renders them better hydrogen bond acceptors than the phenols, ensuring that each of those acts as a donor only. DFT calculations show that this conformation arises as a consequence of the unusual configurational isomerism of this compound and interruption of the archetypal hydrogen bonding by the ester functionality.

scholarly journals A Concise Synthesis of a Methyl Ester 2-Resorcinarene: A Chair-Conformation Macrocycle

2021 ◽  
Author(s):  
Michael R. Reynolds ◽  
Fraser S. Pick ◽  
John Hayward ◽  
John F. Trant
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Methyl Ester ◽  
Chair Conformation ◽  
Selective Recognition ◽  
Aromatic Substitution ◽  
Design And Synthesis ◽  
Hydrogen Bond Strength ◽  
Recognition Elements ◽  
Configurational Isomerism

Anions are important hydrogen bond acceptors in a range of biological, chemical, environmental and medical molecular recognition processes.<sup> </sup>These interactions have been exploited for the design and synthesis of ditopic resorcinarenes as the hydrogen bond strength can be tuned through the modification of the substituent at the 2-position. However, many potentially useful compounds, especially those incorporating electron-withdrawing functionalities, have not been prepared due to the challenge of their synthesis: their incorporation slows resorcinarene formation that is accessed by electrophic aromatic substitution. As part of our broader campaign to employ resorcinarenes as selective recognition elements, we need access to these specialized materials, and in this article we report a straightforward synthetic pathway for obtaining a 2-(carboxymethyl)-resorcinarene, and resorcinarene esters in general. We discuss the unusual conformation it adopts, and propose that this arises from the electron-withdrawing nature of the ester substituents that renders them better hydrogen bond acceptors than the phenols, ensuring that each of those acts as a donor only. DFT calculations show that this conformation arises as a consequence of the unusual configurational isomerism of this compound and interruption of the archetypal hydrogen bonding by the ester functionality.

Electrophilic aromatic substitution reactions of compounds with Craig-Möbius aromaticity

2021 ◽  
Vol 118 (39) ◽  
pp. e2102310118
Author(s):  
Yuanting Cai ◽  
Yuhui Hua ◽  
Zhengyu Lu ◽  
Qing Lan ◽  
Zuzhang Lin ◽  
...  
Keyword(s):  
Density Functional ◽  
Electronic Effect ◽  
Density Functional Theory Calculations ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Substitution Reactions ◽  
Electrophilic Attack ◽  
Functional Theory ◽  
Aromatic Species ◽  
Selective Formation

Electrophilic aromatic substitution (EAS) reactions are widely regarded as characteristic reactions of aromatic species, but no comparable reaction has been reported for molecules with Craig-Möbius aromaticity. Here, we demonstrate successful EAS reactions of Craig-Möbius aromatics, osmapentalenes, and fused osmapentalenes. The highly reactive nature of osmapentalene makes it susceptible to electrophilic attack by halogens, thus osmapentalene, osmafuran-fused osmapentalene, and osmabenzene-fused osmapentalene can undergo typical EAS reactions. In addition, the selective formation of a series of halogen substituted metalla-aromatics via EAS reactions has revealed an unprecedented approach to otherwise elusive compounds such as the unsaturated cyclic chlorirenium ions. Density functional theory calculations were conducted to study the electronic effect on the regioselectivity of the EAS reactions.

The hydrogen bond strength of the phenol–phenolate anionic complex: a computational and photoelectron spectroscopic study

2015 ◽  
Vol 17 (38) ◽  
pp. 25109-25113 ◽  
Author(s):  
Allyson M. Buytendyk ◽  
Jacob D. Graham ◽  
Kim D. Collins ◽  
Kit H. Bowen ◽  
Chia-Hua Wu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Bond Strength ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Negative Ion ◽  
Anionic Complex ◽  
Functional Theory ◽  
Hydrogen Bond Strength ◽  
193 Nm

The phenol–phenolate anionic complex was studied in vacuo by negative ion photoelectron spectroscopy using 193 nm photons and by density functional theory (DFT) computations at the ωB97XD/6-311+G(2d,p) level.

Theoretical Investigation on the Kinetics and Mechanism of the Synthesis of Fluorescent 3,8-Disubstituted-3H-Imidazo [4,5-a] Acridine-11-Carbonitriles

2016 ◽  
Vol 41 (4) ◽  
pp. 365-370 ◽  
Author(s):  
Fatemeh Zonozi ◽  
Mehdi Pordel ◽  
S. Ali Beyramabadi ◽  
Ali Morsali
Keyword(s):  
Theoretical Investigation ◽  
Density Functional ◽  
Theoretical Study ◽  
Fluorescent Dyes ◽  
Quantum Yields ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Dft Methods ◽  
Functional Theory ◽  
Plausible Mechanism

3,8-Disubstituted-3H-imidazo[4,5-a]acridine-11-carbonitriles show very interesting optical properties. In some cases, they have higher quantum yields compared to well-known fluorescent dyes such as fluorescein. Hitherto, no detailed theoretical study has been reported on the mechanism of the synthesis of the titled compounds, hence an accurate and detailed theoretical investigation on the synthesis of these dyes is desirable. In this paper, density functional theory (DFT) methods have been employed to investigate the most reasonable mechanism in formation of these fluorophores. All species and related transition states were optimised and the relative energies of all species and the activation energies for all proposed mechanisms were obtained. Comparing the Ea values of all pathways reveals that intramolecular electrophilic aromatic substitution is the most plausible mechanism for the cyclisation reaction in the preparation of these dyes. Also, the effects of substituents in positions 3 and 8 were investigated and the results show that electron-donor substituents can reduce the activation energy for formation of the σ complex in the electrophilic aromatic substitution.

scholarly journals Desulfination by 2′-hydroxybiphenyl-2-sulfinate desulfinase proceeds via electrophilic aromatic substitution by the cysteine-27 proton

2017 ◽  
Vol 8 (7) ◽  
pp. 5078-5086 ◽  
Author(s):  
Inacrist Geronimo ◽  
Shawn R. Nigam ◽  
Christina M. Payne
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Electrophilic Substitution ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Functional Theory ◽  
Rate Limiting

Density functional theory shows that the rate-limiting desulfination step in biodesulfurization involves concerted electrophilic substitution with the Cys-27 proton.

scholarly journals Chalcogen Bond versus Weak Hydrogen Bond: Changing Contributions in Determining the Crystal Packing of [1,2,5]-Chalcogenadiazole-Fused Tetracyanonaphthoquinodimethanes

2021 ◽  
Vol 03 (02) ◽  
pp. 090-096
Author(s):  
Yusuke Ishigaki ◽  
Kota Asai ◽  
Takuya Shimajiri ◽  
Tomoyuki Akutagawa ◽  
Takanori Fukushima ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Density Functional ◽  
Molecular Design ◽  
Crystal Packing ◽  
Cyano Group ◽  
Density Functional Theory Calculations ◽  
Weak Hydrogen Bond ◽  
Functional Theory ◽  
Chalcogen Bond ◽  
Thiadiazole Ring

The crystal structures of a series of tetracyanonaphthoquinodimethanes fused with a selenadiazole or thiadiazole ring revealed that their molecular packing is determined mainly by two intermolecular interactions: chalcogen bond (ChB) and weak hydrogen bond (WHB). ChB between Se and a cyano group dictates the packing of selenadiazole derivatives, whereas the S-based ChB is much weaker and competes with WHB in thiadiazole analogues. This difference can be explained by different electrostatic potentials as revealed by density functional theory calculations. A proper molecular design that weakens WHB can change the contribution of ChB in determining the crystal packing of thiadiazole derivatives.

scholarly journals Study on the interaction between catechin and cholesterol by the density functional theory

2020 ◽  
Vol 18 (1) ◽  
pp. 357-368
Author(s):  
Kaiwen Zheng ◽  
Kai Guo ◽  
Jing Xu ◽  
Wei Liu ◽  
Junlang Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Charge Transfer ◽  
Density Functional ◽  
Antioxidant Properties ◽  
Micelle Formation ◽  
Aromatic Rings ◽  
Hydrogen Bond Interaction ◽  
Functional Theory ◽  
The Density Functional Theory

AbstractCatechin – a natural polyphenol substance – has excellent antioxidant properties for the treatment of diseases, especially for cholesterol lowering. Catechin can reduce cholesterol content in micelles by forming insoluble precipitation with cholesterol, thereby reducing the absorption of cholesterol in the intestine. In this study, to better understand the molecular mechanism of catechin and cholesterol, we studied the interaction between typical catechins and cholesterol by the density functional theory. Results show that the adsorption energies between the four catechins and cholesterol are obviously stronger than that of cholesterol themselves, indicating that catechin has an advantage in reducing cholesterol micelle formation. Moreover, it is found that the molecular interactions of the complexes are mainly due to charge transfer of the aromatic rings of the catechins as well as the hydrogen bond interactions. Unlike the intuitive understanding of a complex formed by hydrogen bond interaction, which is positively correlated with the number of hydrogen bonds, the most stable complexes (epicatechin–cholesterol or epigallocatechin–cholesterol) have only one but stronger hydrogen bond, due to charge transfer of the aromatic rings of catechins.

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