Intramolecular through-space charge-transfer in naphthalene-based compounds and development of an efficient heterogeneous catalytic method for the aerobic C-H oxidation of alkylarenes

Abstract

The transfer of electrons between two molecules or between different groups attached to a molecule is known as charge transfer. Electronic communication can take place either through chemical bonds or through space. Intramolecular through-space charge transfer occurs between donor and acceptor parts of a molecule depending on the electron density difference, the distance between them, and their relative positions. The main objective of the project is to study the phenomenon of intramolecular through-space charge transfer in naphthalene-based organic materials. We investigated the charge transfer in 1,8-substituted naphthalene derivatives and the effect of different electron-donating and electron-withdrawing groups. To investigate the role of these groups, a variety of control substrates which have different electronic structures were synthesized. Subsequently, it was determined which substances possess a charge transfer band by examining the UV-Vis spectra of these substances. Additionally, it was found that substances with charge transfer bands in UV-Vis absorption spectroscopy had multiple emission values when fluorescence spectra were analyzed. In addition, to observe the effect of different solvents on charge transfer, the substance with observed charge transfer was dissolved in different solvents and examined in terms of color, absorption, and emission values. A key objective of the second part is to develop an environmentally friendly and efficient earth-abundant metal hydroxide catalyst that can be used in aerobic C-H activation reactions for a variety of organic compounds. Metal hydroxides are used for this purpose because of their ability to operate at relatively low temperatures and it allows metal hydroxides to act as highly effective catalysts for oxidation reactions. As an earth-abundant metal-containing catalyst, FexMn(1-x)(OH)y has been prepared by the Özensoy research group with different elemental ratios. In addition, the concentration of NaOH was systematically investigated during the synthesis of the catalyst. The catalytic activities of all catalysts were studied in the aerobic oxidation of fluorene to fluorenone as a model reaction. The optimized conditions were used for the oxidation of diphenylmethane to benzophenone. Subsequently, diphenylmethanes functionalized with electron-donating and electron-withdrawing groups were synthesized, and the yields of oxidation reactions were determined. Finally, the results of the kinetic isotope effect experiment were combined with the yields of the previous experiments to shed light on the mechanism of oxidation.