Π-Π İstiflenmesinin Mekanistik Etkileri ve Olefin Metatezde Katalitik Uygulamaları

Abstract

π–π stacking phenomenon is one of the topics that has attracted increasing attention from researchers in recent years. However, only a few studies have been published on this subject in literature. Olefin metathesis, on the other hand, has been an efficient synthetic method, and has become a key tool in organic synthesis and polymerizations. In this thesis work, a ligand containing a polyaromatic structure pyrene was synthesized and characterized using 1H-NMR, 13C-NMR, and GC-MS. Its electronic transitions were analyzed using UV-Vis and fluorescence spectroscopy. To examine the effect of varying degrees of π–π stacking on the electronic and structural properties of coordination compounds, a compound was synthesized using the synthesized ligand and Grubbs First Generation Catalyst. To demonstrate the catalytic applications in olefin metathesis, in-situ catalyst systems were also prepared. These catalyst systems were analyzed using 1H-NMR, 31P{1H}-NMR, and MALDI-MS. The results supported each other and illuminated the structures. In addition, graphene oxide nanoplatelets (GONP) were synthesized from graphene nanoplatelets (GNP), and its structure was characterized using X-ray photoelectron (XPS) spectroscopy and Fourier Transform Infrared (FT-IR) spectroscopy. GNP and GONP were used as heterogeneous support materials to be compared with homogeneous counterparts in catalytic activities, and their stacking properties were examined using UV-Vis spectroscopy to enable the separation of catalyst systems involving π–π stacking from the reaction medium at the end of the reaction. The catalytic activities of the synthesized catalyst systems were evaluated through ringclosing metathesis of diethyl diallylmalonate and ring-opening metathesis polymerization of cyclooctene which have been previously used as testing substrates in olefin metathesis. In these experiments, additional compounds capable of π–π stacking such as graphene nanoplatelets (GNP), graphene oxide nanoplatelets (GONP), and pyrene, as well as the 31P{1H}-NMR’s of the catalyst systems with varying acid ratios which are different from those of literature were used to examine both catalytic performance and mechanistic effects. Due to the results of these experiments, this thesis presents, to the best of our knowledge, for the first time the mechanistic and catalytic impact of π–π stacking to literature.