Synthesis And Molecular Recognition Of Thioacetyl Functionalized Pillar[5]arene

Supramolecular chemistry is a new interdisciplinary subject.Researchers can construct many kinds of supramolecular systems with different forms and full functions through various weak interactions in supramolecular chemistry.The design and development of each macrocyclic compound promotes the continuous development and improvement of supramolecular chemistry.Japanese chemist Ogoshi first reported pillar[n]arenes in 2008.Due to its easy synthesis and modification,rigid electron-rich cavities and abundant action sites,this new generation of macrocyclic compounds has become a research hotspot in the field of supramolecular chemistry.It has been found that pillar[n]arenes can be functionalized and assembled into AIE systems.More importantly,pillar[n]arenes themselves can also act as AIE groups,which provides a reliable method for the synthesis of various AIE chemical sensors.This paper is divided into three parts:(1)We reviewed relevant literatures and summarized the studies based on AIE effect and weak interactions of pillar[n]arenes and its assemblies.In this part,we first introduce the AIE effect of pillar[n]arenes and its assemblies.Then,we summarize the weak interactions between pillar[n]arenes and various guests from the perspective of theoretical calculation.(2)Based on the strategy of"dual-site collaborative effect",we synthesized a pillar[5]arenes(SP5)with ethyl mercaptoacetate functionalization.The results showed that SP5 had AIE effect in DMF and H₂O binary solution with high fluorescence quantum yield.At the same time,the fluorescence sensor achieves high sensitivity and specificity for L-Met detection(LOD=2.84×10^-8 M)through the synergistic effect of the electron-rich cavities of pillar[5]arenes and the ester group.Other amino acids did not interfere with recognition.Meanwhile,the DFT calculation effectively supports the proposed recognition mechanism,and vividly shows the C-H··?and hydrogen bond interactions between SP5 and L-Met.(3)On the basis of previous work,we have designed and synthesized a pillar[5]arenes(SNP5)functionalized by N-(2-aminoethyl)-2-(hexylthio)acetamide.Interestingly,compared with SP5,which was able to detect L-Met in previous studies,SNP5 showed an efficient recognition ability for L-Trp in this work.These results indicate that changing the side chain modification group of the pillar[5]arenes to enrich the supramolecular interaction sites can adjust the selectivity of the pillar[5]arenes sensor to achieve the detection of different amino acids.Simultaneously,experimental and theoretical calculations show that L-Trp induces SNP5 to produce guest adaptive multiple supramolecular interactions.