Design, Synthesis and Self-assembly of Amphiphilic Cyclodextrin-Based Materials for Enhanced Ion Conduction and Drug Encapsulation

Supramolecular chemistry, often referred to as ‘chemistry beyond the molecule,’ explores the intricate world of non-covalent interactions that govern the assembly, recognition, and function of complex chemical systems. Supramolecular systems enable the design of highly functional materials with applications spanning many fields including drug delivery, catalysis, and nanotechnology. This thesis explores the synthesis, characterization, and potential applications of several new families of cyclodextrin (CD) derivatives. These novel derivatives were designed to investigate their supramolecular assembly, aiming to develop innovative alternatives in energy applications. To prepare readers with the required background to understand the topics of this thesis, Chapter 1 is dedicated to introducing the fundamental aspects of CDs, crown ethers, liquid crystal materials and their associated mesophases commonly formed in solid states as well as characterization methods. A brief review on amphiphilic CD-based liquid crystalline materials during recent years has also been provided. Following the introduction, Chapter 2 details the synthesis of family of amphiphilic β-CD derivatives. This chapter presents an effective strategy for introducing 12-benzocrown-4 and 15-benzocrown-5 functionalities at the termini of seven oligoethylene glycol (OEG) chains, which are conjugated to the primary face of the β-CD scaffold. In combination with fourteen stearoyl chains on the secondary face, these new amphiphilic CD derivatives have shown unprecedented ability to form bicontinuous cubic mesophases. Chapter 3 builds upon the findings of the previous chapter by enhancing the synthetic efficiency and investigating the ‘open’ crown-ether concept, achieved by incorporating linear OEG chains onto a benzene ring in place of a closed crown structure. To capitalize on the potential for enhanced lithium-ion mobility within the 3D bicontinuous cubic mesophase, these molecules are further evaluated for lithium conduction, confirming their superior transport properties compared to previous systems. Chapter 4 leverages epichlorohydrin chemistries to develop a novel family of amphiphilic β-CD-based liquid crystalline materials that are polyesterified with 14 varying lengths of aliphatic chains at the secondary face and 14 oligoethylene glycol (OEG) chains at the primary face, likely approaching a nearly ‘cylindrical’ geometry. By varying the lengths of the aliphatic chains, we present a more systematic investigation in which the lengths of the hydrophobic chains were methodically varied to produce a series of amphiphilic β-CD derivatives with different hydrophilic-to-hydrophobic volume ratios. This systematic approach enabled the identification of an optimal ratio range for the formation of bicontinuous cubic mesophases. Chapter 5 focuses on the molecules that did not form liquid crystalline materials from the previous chapter. Instead, they were tested for micelles and their effectiveness for potential application in host-guest inclusion studies with APIs (active pharmaceutical ingredients). Overall, this work advances CD research by addressing synthetic challenges, expanding mesophase design principles, and explore applications in ion conduction and molecular encapsulation.