Inverting substitution patterns on amphiphilic cyclodextrins induces unprecedented formation of hexagonal columnar superstructures

Abstract

Inverting the substitution patterns of amphiphilic cyclodextrins has uncovered their unprecedented abilities to form hexagonal columnar mesophases.

Amphiphilic Cyclodextrin-Based Liquid Crystals for Proton Conduction

“…The optimized molecular structure of compound 9 exhibits a truncated cone shape composed of a low-volume, nonpolar end consisting of the alkyl chains and a high-volume, polar end consisting of the CD scaffold and the TEG chains (Figure 2d). To satisfy the requirements of phase-segregation and efficient space filling, which are known to be key factors driving the self-assembly of macromolecular materials, 22,23 we propose that molecules are aligned in alternating directions in a "zipper-like fashion" within each layer (Figure 2b), which also gives a layer spacing consistent with experimental results. This ordered macromolecular array generates 2D ion channels composed of fluid TEG chains, which should allow for ion transport (Figure 2c).…”

“…For example, amphiphilic CDs with long n- octadecyl chains introduced to the primary face were found to form stable smectic phases over wide temperature ranges (∼51−235 °C), 22 while inverting the substitution patterns of amphiphilic CDs results in the formation of columnar mesophases. 27 Both types of mesophases could be suitable for the design of materials with enhanced ion conductivity, as they provide highly efficient 1D or 2D pathways for ion conduction. Herein, we report the first example of liquid crystalline CD (9) exhibiting fast proton conductivity.…”

“…Over the past few years, we have been developing a group of supramolecular liquid crystals based on biodegradable cyclodextrins (CDs), a family of macrocyclic carbohydrates based on nontoxic glucose. − CDs were found to be excellent scaffolds to design liquid crystalline materials, due to their polyfunctionalities and the presence of a unique face-to-face pseudosymmetry that originates from the placement of all primary hydroxyl groups at one end of the macrocycle (primary face) and all secondary hydroxyl groups at the opposite end (secondary face). These features allow for efficient regioselective derivatization through which multiple copies of incompatible functionalities such as hydrophobic/hydrophilic groups can be grafted to each face of the macrocycle.…”

“…These features allow for efficient regioselective derivatization through which multiple copies of incompatible functionalities such as hydrophobic/hydrophilic groups can be grafted to each face of the macrocycle. For example, amphiphilic CDs with long n -octadecyl chains introduced to the primary face were found to form stable smectic phases over wide temperature ranges (∼51–235 °C), while inverting the substitution patterns of amphiphilic CDs results in the formation of columnar mesophases . Both types of mesophases could be suitable for the design of materials with enhanced ion conductivity, as they provide highly efficient 1D or 2D pathways for ion conduction.…”

Multicharged cyclodextrin supramolecular assemblies

“…[41][42][43][44] However, since the C-6 hydroxy groups on the primary face are more reactive than the C-2 and C-3 hydroxyl groups on the secondary face, most reports are on the modification of the C-6 hydroxy groups to obtain mono-and per-substituted CDs, as well as site-selective poly-heterofunctionalized CDs, [45][46][47][48][49] although C-2 and C-3 hydroxy modifications are also used in the derivation of CDs. [50][51][52][53][54] Therefore, the regioselective modification of CDs is a very challenging issue that can further enrich the CD supramolecular assemblies and their applications in various fields. The inner cavity is typically used to encapsulate size-matched guest molecules to form complexes through host-guest interactions.…”