Authors: Wijesekera, Gamage Isuri Pramodya
Source: Scholar Commons (University of South Carolina) (article, 2025-07-01)
Field: Chemistry — Organic Chemistry

Exploring the Self-Assembly of Functional Bis-Urea Macrocycles: M-Terphenyl Bis Urea Macrocycles and Triphenylamine Bis-Urea Macrocycles Porous materials have gained significant attention due to their diverse applications in catalysis, separation, and molecular storage. Among them, self-assembled macrocycles represent a unique class of functional materials that leverage non-covalent interactions to form well-defined architectures with pores of controlled size. This thesis explores the design, synthesis, and self-assembly of bis-urea macrocycles in both solid-state and solution-phase environments, with a particular focus on supramolecular polymerization mechanisms and the emergence of kinetically trapped states. The first chapter of this thesis presents a detailed overview of self-assembled porous materials, categorizing them based on pore dimensions and discussing their significance in catalysis, separation, and molecular storage. The role of bis-urea moieties as assembly scaffolds is explored, emphasizing their structural versatility. Additionally, the chapter highlights the significance of self-assembly in solution, introducing key mechanisms that govern this process. A particular focus is placed on kinetically controlled supramolecular polymerization, underscoring its impact on the formation of well-defined supramolecular architectures. The second chapter of this thesis focuses on the synthesis of a novel m-terphenyl bis-urea macrocycle, which demonstrates pathway complexity and kinetic trapping in THF/water solutions. Spectroscopic and microscopic techniques are employed to elucidate the self-assembly mechanism. Electronic structure calculations reveal the formation of metastable intermediates before transitioning to thermodynamically stable structures. These findings provide fundamental insights into controlling supramolecular polymerization through kinetic pathways. In the third chapter, machine learning techniques are applied to predict photoinduced radical (PIR) generation in crystalline triphenylamine derivatives. A Random Forest model is developed to correlate structural and electronic features with experimental PIR yields, enabling a data-driven approach for pre-synthesis screening of photoactive materials. This computational framework offers a predictive tool for designing novel radical-generating materials with tailored properties. The fourth chapter presents a new synthesis strategy for m-terphenyl bis-urea macrocycles utilizing dynamic covalent chemistry. This approach affords high-yielding macrocycles with improved synthetic efficiency compared to conventional high-dilution methods. Structural and functional characterization of these macrocycles highlights their potential for self-assembly into porous frameworks with tunable host-guest interactions. Supramolecular chemistry ; Triphenylamine ; Polymerization ; Supramolecular polymers ; Supramolecular assembly ; Cucurbituril Advanced Polymer Synthesis and Characterization ; Covalent Organic Framework Applications ; Surface Chemistry and Catalysis