Tuning Sugar‐Based Chiral and Flower‐Like Microparticles

Abstract

Unique supermolecular structures as chiral and flower‐like microparticles and the precise tuning of the morphologies hold immense promise for a variety of applications. Examples of such structures deriving from monosaccharides are still rare, and a general understanding is also lacking. Herein, it is shown that chiral, flower‐like, or solid microparticles can be tuned by only using monosaccharide esters without external stimuli. Chiral “left‐handed” (counterclockwise) and “right‐handed” (clockwise) morphologies can be induced by d‐ and l‐glucose stearoyl esters. In comparison, other monosaccharides, i.e., galactose, mannose, and xylose, cannot formed chiral particles and generated diverse other morphologies of the supermolecular microparticles based on their distinct molecular configurations. Due to the numbers of side chains and the bond orientations, microparticles with solid and porous flower‐like morphologies can be obtained. While glucose and xylose esters only lead to solid microparticles, mannose and galactose generate porous flower‐like particles. These findings suggest a general method to design and control the superstructures by using monosaccharide backbones with diverse molecular configurations.

Tuning the Chiral Structures from Self‐Assembled Carbohydrate Derivatives

“…The stearoyl esters have been introduced on different monosaccharides and their enantiomer under mild conditions. [ 23 ] In another study, six synthetic oligosaccharides ranging from dimers to hexamers carrying benzyl ethers, methylated analogue or acetylated analogue can self‐assemble into nanostructures of varying morphologies, such as vesicles and fibers ( Figure a). [ 37 ] The introduced groups helped with the encountered poor solubility and low reactivity issues.…”

“…Yao et al reported the formation of chiral microparticles by using monosaccharide stearoyl esters (MSSEs) without using external stimuli. [23] Four types of MSSEs including glucose stearoyl ester (GlcSE), xylose stearoyl ester (XylSE), galactose stearoyl ester (GalSE), and mannose stearoyl ester (ManSE) were compared. It was shown that only GlcSE with a certain α/β ratio (GlcSE20/80) can form chiral microparticles (Figure 4a-c).…”

“…Reproduced with permission. [ 23 ] Copyright 2021, Wiley‐VCH. d) Chemical structure of oligosaccharide derivatives and e) corresponding SEM images showing helical fibers.…”

“…[5] monosaccharide, oligosaccharide, and polysaccharide derivatives. [23][24][25][26][27] It has been reported that the possible mechanism of chiral superstructures includes chirality transfer, chirality amplification, and asymmetry breaking, where diverse interactions such as van der Waals force, electrostatic interactions, π-π stacking, and hydrogen-bonding are vital for the formation of chiral superstructures. [20] Despite growing efforts to create the chirality, how to obtain the carbohydrate derivatives and use them to fabricate chiral superstructures, precise control and manipulate the morphologies and functions of specific superstructures for diverse applications still challenge us.…”

“…Figure 4. a) Chemical structures of monosaccharide stearoyl esters and b,c) corresponding SEM images of chiral microparticles. Reproduced with permission [23]. Copyright 2021, Wiley-VCH.…”