Date of Award

Fall 12-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

Guijun Wang

Committee Member

John Cooper

Committee Member

Richard Gregory

Committee Member

Jingdong Mao

Committee Member

Yuan Zhang

Abstract

Low molecular weight gelators (LMWGs) are small molecules that self-assemble in appropriate solvents to form three dimensional networks that immobilize the solvent, creating a supramolecular gel. The self-assembly of LMWGs occurs through non-covalent interactions such as hydrogen bonding, aromatic interactions, donor-acceptor interactions, Van der Waals interactions, hydrophobic forces, halogen bonding, etc. Due to self-assembly occurring through reversible non-covalent interactions, supramolecular gels can undergo a gel to solution transformation. Because of this, these materials can be sensitive to external stimuli such as temperature changes, pH changes, and other stimuli that effect non-covalent interactions. This makes the synthesis of LMWG’s an appealing target for the synthesis of smart materials.

Carbohydrates are an appealing feedstock for the synthesis of LMWGs because of their natural abundance, renewability, biocompatibility, biological activity, biodegradability, structural diversity, and a capacity for chiral self-assembly. The biocompatibility and bioactivity of carbohydrate based LMWGs make them enticing materials for biomedical applications such as drug delivery and tissue engineering. The abundance and renewability make them attractive materials for larger uses, such as environmental remediation. Carbohydrates are an optimal starting material for exploring the gelation-structure relationship because of their structural diversity. Previously, we have had great success in designing carbohydrate based LMWGs via tuning the gelation properties through changing functional groups at various positions on various carbohydrates.

In this research, the structure to gelation properties relationship was explored through the synthesis and characterization of various 4,6-protected glucosamine derivatives and branched glycoclusters. These include 4,6-(1-naphthylidene) protected glucosamine (amide, urea and carbamate) derivatives, 4,6-(4-chlorobenzylidene) protected glucosamine amide derivatives and triazole linked Janus glycoclusters. Preparation of the glucosamine derivatives were carried out using readily available N-acetyl-D-glucosamine and the preparation of the branched glycoconjugates were carried out using both D-glucose and N-acetyl-D-glucosamine, using commercially available pentaerythritol as central scaffold. The design, synthesis, and analysis of the self-assembling properties of the 4,6-protected glucosamine derivatives and Janus glycoclusters will be discussed in Chapters 2, 3, and Chapter 4. A final conclusion and future perspectives are given in Chapter 5.

DOI

10.25777/2qz8-7v97

ISBN

9798780600848

ORCID

0000-0003-3845-8116

Available for download on Friday, January 19, 2024

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