Quinone based fluorescent compounds: synthesis, characterization, and investigation of photophysical/electrochemical properties

This study focuses on quinones and their derivatives, particularly 1,4-naphthoquinone and its derivatives. Quinones are aromatic compounds widely found in nature and can be obtained from fungi, algae, bacteria, and various plants. These compounds are present in some cancer treatment drugs and exhibit cytotoxic properties through DNA topoisomerase inhibition. 1,4-naphthoquinone is used as a raw material in the production of pharmaceuticals, agrochemicals, and other valuable compounds. The synthesis of 1,4-naphthoquinone is achieved through various oxidation methods of naphthalene. For example, the oxidation of naphthalene with chromic trioxide in acetic acid or the oxidation of 4-Amino-1-naphthol with potassium dichromate yields this product. Additionally, electrochemical oxidation methods are also used. 2-hydroxy-1,4-naphthoquinone (Lawsone) is a natural compound found in the Lawsonia inermis plant and is traditionally used as a dye for skin and hair. Its synthesis involves various chemical reactions, such as the Thiele-Winter reaction. The synthesis of halogenated 1,4-naphthoquinone derivatives is also examined in this study. For example, 2,3-dichloro-1,4-naphthoquinone is obtained by chlorination of 1,4-naphthoquinone with potassium perchlorate and hydrochloric acid. Similarly, 2-bromo-1,4-naphthoquinone is synthesized using NBS in the presence of CuBr2. 1,4-naphthoquinone derivatives undergo nucleophilic substitution reactions with electron-rich nucleophiles. These reactions are used to synthesize new biologically active molecules. This study also obtained 2-hydroxy-1,4-naphthoquinone derivatives through the Mannich reaction. Mannich bases are used in the synthesis of biologically important drug candidates and are obtained by reacting with various amine compounds and aldehydes. In this thesis study, Mannich reactions were performed with 2-hydroxy-1,4-naphthoquinone, hexylamine, and eight different benzaldehyde derivatives. Additionally, 1,4-naphthoquinone was brominated in acetic acid to yield 2,3-dibromo-1,4-naphthoquinone with high efficiency. This dibromo-1,4-naphthoquinone was subjected to nucleophilic substitution reactions with various nitrogen and oxygen-containing nucleophiles. These compounds, together with 1,4-naphthoquinone, contain pharmaceutically important structures such as carbazole, thiadiazole, tacrine, and BODIPY. The structures of all compounds were determined by 1H, 13C, and 19F NMR methods. The structures of the final products were characterized by HPLC-MS and FT-IR in addition to these methods, and their melting points were determined. The photophysical properties of all 1,4-naphthoquinone derivatives were determined by UV-vis and fluorescence spectroscopy. Their electrochemical properties were investigated using cyclic voltammetry.