Low‐Symmetry Macrocycles and Cages for Carbohydrate Recognition

Abstract

The recognition of carbohydrate plays a key role in numerous biological processes. Thus, artificial receptors have been synthesized to mimic these biological systems. To date, most of the receptors reported for carbohydrate complexation present highly symmetrical cavities, probably because their syntheses require less synthetic efforts and are easier to achieve and control. However, carbohydrates display complex, asymmetrical structures suggesting that hosts with low symmetry might be more adapted to recognize these guests. Here, we described the strategies that have been used to complex carbohydrates with macrocycles and cages presenting low symmetry and the potential of this approach. Self-assembled cages are first described, then covalent macrocycles and cages are presented and for each example the binding properties of low-symmetry systems are compared to those of their higher-symmetry counterparts.

Stepwise Synthesis of Low-Symmetry Hexacationic Pyridinium Organic Cages

“…24−28 Therefore, it is essential for developing more efficient methods for synthesizing lowsymmetry organic cages, considering the benefits of their robustness, porosity, solubility, and enzyme-like inner cavity. 7,23,29 Macrocycles and frameworks containing pyridinium, along with organic cages and self-assembled coordination cages, have been extensively utilized in the realm of molecular receptors, mechanically interlocked molecules (MIMs), and functional materials. 30−37 These applications take advantage of the rich redox and photochromic properties inherent to pyridinium units.…”

“…Various synthetic approaches have been utilized to construct molecular cages with low symmetry, governed by either thermodynamic or kinetic control . Dynamic strategies that permit error correction based on reversible coordinative and dynamic covalent bonds have proven to be effective in fabricating low-symmetry cages under thermodynamic control in high yields. − However, creating purely organic cages with asymmetric cavities is notably challenging . This process requires complex, multi-step irreversible organic transformations and labor-intensive workup and purification steps, often resulting in low overall yields.…”

“…18−22 However, creating purely organic cages with asymmetric cavities is notably challenging. 23 This process requires complex, multi-step irreversible organic transformations and labor-intensive workup and purification steps, often resulting in low overall yields. Despite the arduous and timeintensive nature of this process, stepwise organic synthesis remains the predominant method for creating a variety of synthetic cage molecules.…”

“…This process requires complex, multi-step irreversible organic transformations and labor-intensive workup and purification steps, often resulting in low overall yields. Despite the arduous and time-intensive nature of this process, stepwise organic synthesis remains the predominant method for creating a variety of synthetic cage molecules. − Therefore, it is essential for developing more efficient methods for synthesizing low-symmetry organic cages, considering the benefits of their robustness, porosity, solubility, and enzyme-like inner cavity. ,, …”