Pillar[n]arene-Mimicking/Assisted/Participated Carbon Nanotube Materials

Abstract

The recent progress in pillar[n]arene-assisted/participated carbon nanotube hybrid materials were initially summarized and discussed. The molecular structure of pillar[n]arene could serve different roles in the fabrication of attractive carbon nanotube-based materials. Firstly, pillar[n]arene has the ability to provide the structural basis for enlarging the cylindrical pillar-like architecture by forming one-dimensional, rigid, tubular, oligomeric/polymeric structures with aromatic moieties as the linker, or forming spatially "closed", channel-like, flexible structures by perfunctionalizing with peptides and with intramolecular hydrogen bonding. Interestingly, such pillar[n]arene-based carbon nanotube-resembling structures were used as porous materials for the adsorption and separation of gas and toxic pollutants, as well as for artificial water channels and membranes. In addition to the art of organic synthesis, self-assembly based on pillar[n]arene, such as self-assembled amphiphilic molecules, is also used to promote and control the dispersion behavior of carbon nanotubes in solution. Furthermore, functionalized pillar[n]arene derivatives integrated carbon nanotubes to prepare advanced hybrid materials through supramolecular interactions, which could also incorporate various compositions such as Ag and Au nanoparticles for catalysis and sensing.

Keywords: application; carbon nanotube; hybrid materials; pillar[n]arene; synthesis.

Chart 1

Schematic presentation of structures of pillar[n]arene (left), as well as single-walled (middle) and multi-walled carbon nanotubes (right).

Scheme 1

Chemical structures of pillar[5]arene-based polymers P1–P7.

Scheme 2

Chemical structures of pillar [5]arene derivative P8 [65].

Scheme 3

Chemical structures of pillar[6]arene derivative P9, guests such as pyrene derivatives G1–G3, as well as functional molecules F1 and F2 [76,83].

Figure 1

Illustration of dispersing multi-walled carbon nanotube by using amphiphilic host–guest inclusion P9 ⸧ G2 in aqueous solution [76].

Scheme 4

Chemical structures of polymer F3, pillar[5]arene P10, pillar[5]arene-based polymer P11 and PEG derivative G4 [85].

Figure 2

Illustration of dispersing and gelating carbon nanotube by using host–guest inclusion P11 ⸧ G4 in 1,2-dichlorobenzene [85].

Figure 3

Photographs of pillar[5]arene-based polymer-carbon nanotube-complexed organogels in 1,2-dichlorobenzene via noncovalent interactions (right), compared to those phenomena in the presence of P11 ⸧ G4 (middle), as well as physical mixture of P11 and PEG600 [85]. Copyright © 2022 by American Chemical Society.

Scheme 5

Chemical structures of pillar[6]arene P12 and pillar[5]arene P13, as well as guests such as G5–G8 [86,87].

Figure 4

Illustration of the fabrication of hybrid materials Ag@(P12 non-covalently interacting with carbon nanotubes) [86].

Figure 5

TEM (left) and high-resolution TEM images (middle and right) of hybrid materials Ag@(P12 noncovalently interacting with carbon nanotubes), where the average diameter of Ag nanoparticles is around 3–4 nm [86]. Copyright © 2022 by Elsevier.

Figure 6

Upper (left) and side view (middle), as well as packing model (right) of X-ray single-crystal structures of (a) pillar[8]arene, (b) pillar[9]arene and (c) pillar[10]arene. The hydrogen atoms were omitted for clarity [94]. Copyright © 2012 by The Royal Society.