Visible Light-Mediated Metal-Free Photocatalytic Oxidative Reactions and Cycloadditions

Abstract

He always shares his ideas and discusses with me about the projects which sped up my projects a lot. I am very grateful to Prof. Dr. Konrad Koszinowski for his kindly accepting to be the second supervisor for my first two-year study and becomes my first supervisor in Göttingen during my joint PhD program study. He always gives me highly valuable suggestions and comments in last three years. I am also really appreciated for his kind corrections, suggestions, and polish of my thesis. I benefited and learned much from his rigorous spirit. I deeply thank my lab colleagues Daniel Riemer, Waldemar Schilling, Jiri Kollmann, Tong Zhang, Shaowei Qin, Nareh Hatami, Prakash Sahoo etc. for their kind help during my PhD study. I am also appreciated for the kind help of Prof. Dr. Maes and all ORSY members during the study in the University of Antwerp. I would like to thank the analytical departments especially the Dr. Michael John and Dr. Holm Frauendorf at the IOBC, for their strong support and offered possibility to operate several machines by myself. I gratefully acknowledge China Scholarship Council (CSC) and BOF International Joint PhD Fellowships for the financial support during my research stay in Germany and Belgium. Special thanks should give to my wife, Mrs. Na Zhang who always encourages me to face and overcome challenges. She is always there for me. At last, I will thank my parents, sister and other families for their continuous support and encouragement. I love you all forever. Contents VIII UCNF nitrogen deficient carbon nitride VB valence band wt% weight by volume total solar irradiance is about 1366.1 W m -2 which provides roughly 4.3x10 20 J energyonly in 1 h. [4] Therefore, if it is harvested and utilized in organic transformations, could bring a vision to solve the sustainable issues.As a key factor in the recent rapid growth of this field has been recognized the fact that readily accessible metal complexes and organic dyes can facilitate the conversion of visible light into chemical energy under exceptionally mild conditions. Among them, ruthenium-and iridium-based organometallic complexes stand at the forefront of this class. These species are mostly employed as radical sources: they exhibit excellent visible-light absorption and long-lived excited states (Scheme 1.1). [5] Scheme 1.1 Chemical structures of typical homogeneous photocatalysts. [4a][6a] Even though these species are not strong oxidants or reductants in their ground states, in their excited state they are potent single electron transfer reagents with suitable redox potentials. The redox potential is a measure of the tendency of a chemical species to gain electrons from an electrode and thereby get reduced. In principle, a higher positive value of the redox potential signifies a greater affinity for electrons to be gained, thereby a higher tendency to be reduced. Hence, the redox potential of the photocatalyst must be matched to the reagents of the reaction. Compared to the transition metal complexes, metal-free organic dyes (e.g. eosin ...