Recognition of Hydrophilic Cyclic Compounds by a Water-Soluble Cavitand.

Yun-Hui Wan,Julius Rebek,Yang Yu,Yu-Jie Zhu

doi:10.3390/molecules26071922

Yun-Hui Wan, Julius Rebek + Show 2 more

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https://doi.org/10.3390/molecules26071922

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Abstract

A water-soluble deep cavitand bearing amides on the upper rim and trimethyl ammonium groups on the feet was synthesized. The open-ended cavity is stabilized by the intramolecular hydrogen bonds formed between the adjacent amides, and the introduction of trimethylammonium imparts to the cavitand good solubility in water. The cavitand exhibits high binding affinity and selectivity to hydrophilic molecules in water. With certain guests, such as cyclohexyl alcohols, amines and acids, the recognition involves the synergistic action of hydrogen bonding with hydrophobic effects. The binding phenomena are interpreted in terms of a fixed solvent cage presented by the host to the guest.

Highlights

Molecular recognition [1] is a central topic of supramolecular chemistry and provides a basis for numerous life processes [2], such as signal transduction, cell recognition and so on
The effective solvation of hydrophilic molecules thwarts their attraction to synthetic receptors since the recognition process involves a desolvation penalty that needs to be compensated
Name came from the intramolecular hydrogen bonds that maintain the vase shape as opposed to the kite shape which features larger exposure to the solvents [17]

Summary

Introduction

Molecular recognition [1] is a central topic of supramolecular chemistry and provides a basis for numerous life processes [2], such as signal transduction, cell recognition and so on. In the past few decades, a number of synthetic molecular receptors, such as crown ethers [3], cyclodextrins [4], calixarenes [5], cucurbiturils [6] and pillararenes [7], have been synthesized and extensively studied. Their readily accessible macrocyclic structures and promising applications in molecular recognition have attracted synthetic, physical organic and supramolecular chemists. The effective solvation of hydrophilic molecules thwarts their attraction to synthetic receptors since the recognition process involves a desolvation penalty that needs to be compensated Natural receptors solve this problem cleverly by combining hydrophobic effects with well-positioned non-covalent interactions, such as hydrogen bonding. Supramolecular chemists have designed such inwardly directed functions to imitate such biomimetic receptors, but few examples have been successful [15,16]

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