Recognition Selectivities of Lasso-Type Pseudo[1]rotaxane Based on a Mono-Ester-Functionalized Pillar[5]arene

Abstract

Two types of mono-ester-functionalized pillar[5]arenes, P1 and P2, bearing different side-chain groups, were synthesized. Their host–guest complexation and self-inclusion properties were studied by 1H NMR and 2D nuclear overhauser effect spectroscopy (NOESY) NMR measurements. The results showed that the substituents on their phenolic units have a great influence on the self-assembly of both pillar[5]arenes, although they both could form stable pseudo[1]rotaxanes at room temperature. When eight bulky 4-brombutyloxy groups were capped on the cavity, instead of methoxy groups, pseudo[1]rotaxane P1 became less stable and its locked ester group in the inner space of cavity was not as deep as P2, leading to distinctly different host–guest properties between P1 and P2 with 1,6-dibromohexane. Moreover, pillar[5]arene P1 displayed effective molecular recognition toward 1,6-dichlorohexane and 1,2-bromoethane among the guest dihalides. In addition, the self-complex models and stabilities between P1 and P2 were also studied by computational modeling and experimental calculations.

A pH-Responsive Supramolecular Drug Delivery System Constructed by Cationic Pillar[5]arene for Enhancing Antitumor Activity

“…pillar [n]arenes, as a new class of macrocycle first synthesized by Ogoshi et al (2008), have recently been widely used in many fields including molecular recognition (Yakimova et al, 2016;Yuan et al, 2017), mechanical interlocking molecules (Chen et al, 2013a;Zhang et al, 2019c), artificial transmembrane channels (Chen et al, 2013b;Xin et al, 2017), metal ion separation (Xia et al, 2017), chemical sensors (Wu et al, 2014;Stepanova et al, 2017;Wei et al, 2017;Hua et al, 2018;Sun et al, 2018), and supramolecular polymers (Strutt et al, 2012;Zhou et al, 2014a;Nierengarten et al, 2016;Zhang et al, 2018). At present, researchers are more focusing on the study of watersoluble pillar [n]arenes (Hu et al, 2016;Yang et al, 2016;Yu et al, 2016;Zhou et al, 2017b;Li et al, 2019;Zhong et al, 2019) because they can effectively bind different types of molecules into their cavities to construct a series of stimulus-responsive supramolecular amphiphiles for the application in DDSs.…”

Noncovalently bound and mechanically interlocked systems using pillar[n]arenes

“…This selectivity was tuned by changing the competing side chain 111 or the eight substituents on the rims of pillar[5]arenes ( P18 ). 112…”