Development of Photoswitchable Ruthenium Metathesis Catalysts

Abstract

Olefin metathesis has become a pervasive technique for creating carbon-carbon double bonds. The development of metathesis catalysts has contributed to their use in a variety of chemical disciplines. The usefulness of olefin metathesis has led to the development of switchable catalysts that go beyond high-efficiency. This thesis describes the attempt at an appropriate application of olefin metathesis, and novel photoswitchable olefin metathesis catalysts and catalysis. Chapter 2 explores the synthesis of a conjugated copolymer using acyclic diene metathesis for polymer light-emitting diode (PLED) applications. Various catalysts have been studied for the synthesis of the conjugated polymer poly(fluorenevinylene) by olefin metathesis. In addition, the copolymer was synthesized using comonomer tetravinylspirobifluorene, and PLED devices were fabricated. Chapter 3 describes azobenzene-bearing photoswitchable ruthenium catalysts. Photoswitching phenomena involving catalysts were observed in various types of olefin metathesis reactions, including ring-closing metathesis, ring-opening metathesis, cross-metathesis, and ethenolysis. The photoisomerization properties of the ligands and catalysts were examined by UV-vis spectroscopy, DFT calculation, and NMR spectroscopy. Chapter 4 details a photoswitchable olefin metathesis catalysis system using azobenzene additives. The cyclic(alkyl)(amino)carbene-ruthenium catalysts and azobenzene additive exhibited photoswitching characteristics in ring-closing metathesis, ring-opening metathesis, cross-metathesis, and ethenolysis. The relationship between cyclic(alkyl)(amino)carbene-ruthenium catalysts and azobenzene additives in the olefin metathesis reaction was also studied.