Pillar[5]arene Based [1]rotaxane Systems With Redox-Responsive Host-Guest Property: Design, Synthesis and the Key Role of Chain Length

Abstract

Pillar[ n ]arenes are a new type of macrocyclic compounds, which were first reported in 2008 by Ogoshi. They not only have cylindrical, symmetrical, and rigid structures, but also have many advantages, including easy functionalization and rich host-guest properties. On the other hand, mechanically interlocked molecules (MIMs) exist extensively in nature which have been artificially synthesized and widely applied in the fields of nanotechnology and biology. Although pillar[5]arene-based MIMs have been investigated much over recent years, pillar[5]arene-based [1]rotaxanes are very limited. In this report, we synthesized a series of amide-linked pillar[5]arene-based [1]rotaxanes with ferrocene unit as the stopper. Under the catalysis of HOBT/EDCL, the mono-amido-functionalized pillar[5]arenes were amidated with ferrocene carboxylic acid to constructed ferrocene-based [1]rotaxanes, respectively. The structure of the [1]rotaxanes were characterized by 1 H NMR, 13 C NMR, 2D NMR, mass spectroscopy, and single-crystal X-ray structural determination. In the experiment, the monofunctionalized pillar[5]arene was synthesized with a self-inclusion property, which allows for forming a pseudo-rotaxane. The key role is the length of the imine chain in this process. The formation of a rotaxane was realized through amidation of ferrocene dicarboxylic acid, which acted as a plug. In addition, due to the ferrocene units, the pillar[5]arene-based [1]rotaxanes perform electrochemically reversible property. Based on this nature, we hope these pillar[5]arene-based [1]rotaxanes can be applied in battery devices in the future.

A p-tert-Butyldihomooxacalix[4]arene Based Soft Gel for Sustained Drug Release in Water

“…The designed and prepared macrocyclic hosts [mainly including crown ethers (Liu et al, 2017;Morrison et al, 2017), cyclodextrins Larsen and Beeren, 2019), calixarenes (Wang et al, 2015;Tian et al, 2019), cucurbiturils (Kim et al, 2007;Wu et al, 2018;Xiao B. et al, 2019), and pillar[n]arenes (Xue et al, 2012;Sun et al, 2018;Ogoshi et al, 2019;Xiao T. et al, 2019)] and the investigations of their host-guest properties are the foundation of the development of supramolecular chemistry (Zheng et al, 2012;Yao et al, 2018;Zhang et al, 2019). As the third generation of macrocyclic compounds in supramolecular chemistry, calixarenes process several advantages, such as excellent flexibility, improved conformational mobility, and easy modification (Kim et al, 2012;Nimse and Kim, 2013).…”

GSH/ROS Dual-Responsive Supramolecular Nanoparticles Based on Pillar[6]arene and Betulinic Acid Prodrug for Chemo–Chemodynamic Combination Therapy

“…Moreover, they are sensitive to stimuli, with notable responsiveness [ 29 , 30 ]. Pillararenes, the fifth generation of supramolecule, can serve as hosts and bind with the specific functional group of various guests via hydrogen bonding, covalent bonding, π–π stacking interaction, electrostatic interaction, and ionic interaction [ 31 , 32 , 33 , 34 ], showing better stability and bioactivity [ 35 , 36 , 37 , 38 , 39 , 40 ].…”

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

“…Macrocycles with converging binding sites and functional groups hold a key position in supramolecular chemistry, which has been repeatedly confirmed by classic macrocyclic molecules, such as crown ethers, cyclodextrins, calixarenes, cucurbiturils and their homologues [1]. For the past decades, numerous intriguing macrocycles have come into our sight, cycloparaphenylenes [2][3][4][5][6][7][8], pillararenes [9][10][11][12], tiaraarenes [13,14], coronaarenes [15][16][17], heteracalixaromatics [18,19], and hemicucurbiturils [20] for instance, and these modified macrocycles have been applied into practical domains, such as chemosensors [21], drug delivery [22], and nano materials preparation [23].…”