Chiral Recognition of Carboxylate Anions by (R)-BINOL-Based Macrocyclic Receptors.

Tyszka-Gumkowska Tyszka-Gumkowska,Jurczak Jurczak,Pikus Pikus

doi:10.3390/molecules24142635

Tyszka-Gumkowska Tyszka-Gumkowska, Jurczak Jurczak + Show 1 more

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https://doi.org/10.3390/molecules24142635

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Abstract

Three (R)-BINOL-based macrocyclic receptors obtained via double-amidation reaction were used for chiral recognition of four anions derived from α-hydroxy and α-amino acids. The structural factors of hosts and guests that affect chiral recognition processes were also investigated, indicating that the proper geometry of both receptor and guest molecules plays a crucial role in effective enantio-discrimination.

Highlights

Molecular recognition has been a subject of intensive study for three decades including research into the synthesis and application of neutral receptors able to recognize neutral molecules as well as ions [1,2]
Differences in the binding of guest enantiomers are driven by the enthalpy and entropy effects, mainly attributed to the existence of numerous attractive and repulsive noncovalent interactions as well as distinct conformations of guest and host [4,5]. These phenomena can be better understood when host–guest interactions are investigated by means of model chiral recognition of hydroxy and amino acids, which are widely prevalent across various pharmaceuticals, and play crucial roles in numerous biological systems
We found that the optimum-sized host (R)-1 can pre-organize its chiral pocket, interacting much more effectively with only one enantiomer of guest molecules

Summary

Introduction

Molecular recognition has been a subject of intensive study for three decades including research into the synthesis and application of neutral receptors able to recognize neutral molecules as well as ions [1,2]. Differences in the binding of guest enantiomers are driven by the enthalpy and entropy effects, mainly attributed to the existence of numerous attractive and repulsive noncovalent interactions as well as distinct conformations of guest and host [4,5]. These phenomena can be better understood when host–guest interactions are investigated by means of model chiral recognition of hydroxy and amino acids, which are widely prevalent across various pharmaceuticals, and play crucial roles in numerous biological systems. Among the systems reported to date, macrocyclic chiral hosts have proved to have favorable enantio-discrimination properties as compared to their acyclic analogues due to increased steric repulsion, which allows for more efficient differentiation of enantiomers [7,8]

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