Photocatalysts based on Corrole complexes and development of fluorescent sensors for biologically important analytes

Abstract

Corroles are analogs of porphyrins, known as “contracted porphyrins”, because they lack one of the carbons connecting the four pyrrole rings. Through various functionalization of the carbon at the meso- position or the beta position of the pyrrole, the electronic systems of corroles can be altered, and this has attracted extensive research attention over the past two decades. Recently, research has expanded to a variety of applications, including corrole-based photocatalysts, solar cells, photodynamic therapy, chemical sensors, MRI contrast agents, and antiviral and antifungal drugs. This thesis covers the synthesis, analysis, and photophysical characterization of corrole derivatives containing meso- and beta- position substitutions and various central atoms, particularly with emphasis on their applications as photocatalysts. Fluorescent probes are small molecules that detect target substances, and the development of fluorescent chemical sensors has been widely used in the medical and life sciences for imaging cells and organs in vivo. Since they are easy to visualize, rapid, and non-invasive, a variety of fluorescent probes have been developed, but practitioners needs continuously improve their selectivity, sensitivity, and response-speed. Biological analytes include biothiols, reactive oxygen species, and metal ions, which are known as a significant factor for neurodegenerative diseases such as Alzheimer's and Parkinson's disease, depending on their presence and concentration of the molecular small molecule analytes. This thesis describes the synthesis, analysis, and cellular imaging of a fluorescent probe that can selectively detect cysteine, one of the most well-known biological biothiols. Chapter 1 provides an overview of the corrole systems, fluorescence mechanisms, and biothiols. Chapter 2 describes corrole complexes with non-metallic central atom as photocatalysts for the halogenation of aromatic compounds. In chapter 3, the synthesis and analysis of phosphorus(V)-corrole isomers and solvent effects on the phosphorescence of gold(III)-corrole complexes are presented. Finally, chapter 4 covers the AIE-ESIPT mechanism-based fluorescent probe for the selective detection of cysteines.