Synthetic and Structural Studies on the Effect of Non-Covalent Interactions on N(sp2)-Heterocyclic Molecules

Abstract

The thesis herein describes the synthesis and characterization of compounds designed to be utilized as acceptor molecules in non-covalent interactions. The non-covalent interactions are applied in fluorescence modulation and construction of novel halogen-bonded complexes. In the literature part, an introduction to supramolecular chemistry and non-covalent interactions is given. It presents the concepts of light absorption and emission and discusses host-guest chemistry of larger supramolecular structures. At the end of the literature part, some common N(sp2)-heterocyclic molecules as hydrogen and halogen bond acceptor molecules are reviewed, highlighting the target compounds most relevant to the thesis work. The results and discussion part of the thesis describes the synthesis and characterization of imidazole- and carbazole-derived small-molecules as fluorescence emitters and hydrogen and halogen bond acceptors. The acceptor molecules were further utilized in the synthesis of larger tripodal N-donor ligands which were employed in the construction of halogen-bonded iodine(I) capsular assemblies manifesting three [N‒I‒N]+ three-center four-electron bonds through the intermediate silver(I) metallocage formation. The publication I focuses on the fundamentals of protonation and its potential in fluorescence modulation for simple, commercially available N(sp2)-heterocyclic molecules, viz. quinoline derivatives. This work was broadened in the publication II to carbazole derivatives. The publications III and IV focused on the development of small symmetric halogen-bonded iodine(I) carbazole complexes (publication III) and tris-imidazole based cage complexes (publication IV).