Study of topological formation of lanthanide luminescent supramolecular edifices

Abstract

Lanthanide supramolecular self-assembly is an emerging technological advancement not only in fundamental science but also with wide range of applications such as drug-delivery system, medical imaging and batteries. The unique photophysical properties and coordination chemistry provide researchers a great opportunity to devise new supramolecular system. The control in topological formation in supramolecular edifices has become particularly crucial in developing biomedical and daily-life application. This thesis, therefore, aims at studying the correlation between the ligand structure and their supramolecular self-assembling behaviors. To introduce the area of supramolecular chemistry, chapter 1 encompasses general chemistry in lanthanide and the development in lanthanide supramolecular chemistry. Chapter two focuses on reviewing various pyridine-dicarboxamide (pcam) with different offsetting and spacing properties and their correlation to their ultimate supramolecular structure upon complexation to lanthanide. The offsetting angle and distance are found to be one of deciding parameter in ultimate topologies while the first lanthanide chiral supramolecular cubes are reported. Additionally, the solvent-induced self-assembling and transformation is also included. Supramolecular self-assembly is known to be a collective result from various weak non-covalent interaction. The thermodynamic stability from lanthanide-ligand coordination bonds have played an important role to maintain the entropically disfavored ordered supramolecular architectures. The functionalization of luminescence and stable 1,2-di-Hydroxypyridinones (HOPO) ligands are, therefore, included in Chapter 3. This chapter encompasses the detailed synthetic work on functionalizing HOPO units and basic photophysical properties. Meanwhile, the investigation on incorporating the HOPO building blocks to ultimate assembly is also included. In the view of intrinsic instability and ineffectiveness in lanthanide sensitization of pcam chromophores, chapter 4 investigate the synthesis in new class of chiral hydroxyquinoline (HQ) based chromophores while the detailed synthetic attempts are included. With the new class of chromophores, the effect of chelating strength towards final supramolecular self-assembling can be studied.