Transition metal based supramolecular systems: Synthesis, photophysics, photochemistry and their potential applications as luminescent chemosensors and switches

This dissertation research is primarily concerned with systematic design and study of transition metal mediated self-assembly supramolecules and their potential applications as molecular sensors and photoswitching materials. A number of self-assembly metallocyclophanes and cages have been prepared (chapters 2 to 8). We have found that the photophysical properties of these systems are highly dependent on the nature of the bridging ligands and that many of these metallocyclophanes and cages are capable of binding different guest molecules such as inorganic anions and a variety of aromatic compounds. Moreover, trinuclear (diimine) rhenium(I) tricarbonyl complexes linked by a stilbene-like ligand exhibit most interesting photoswitching features, where the luminescence from the complexes can be switched on and off by photoinduced ligand isomerization (chapter 9). We have also successfully synthesized two shape-persistent hexagonal phenylacetylenes and employed them as ligands to synthesize dinuclear transition-metal complexes. The photophysical properties of both phenylacetylenic ligands and their corresponding metal complexes are presented (chapter 10). In addition, a structurally simple and easily synthesized luminescent anion receptor has been recently developed and it displays outstanding sensitivity and selectivity toward a variety of anionic species (chapter 11). Some short chain conjugated pyridines have shown concentration-dependent emission and this property has been attributed to the formation excimeric species in the excited state (chapter 12). Finally, the photophysical and photochemical properties of W(0) and Re(I) metal carbonyl complexes incorporating end-capped ferrocenyl pyridine ligands are summarized (chapter 13).