Controlled synthesis of functionalized oligomers and polymers: Development of methods for the solid supported synthesis of quinoxalin-based oligomers using 1,2-diketosynthons for their investigation and application in materials science.

• Applicants: Professor Dr. Stefan Bräse; Dr. Nicole Jung
• Subject Area: Preparatory and Physical Chemistry of Polymers ; Solid State and Surface Chemistry, Material Synthesis ; Synthesis and Properties of Functional Materials ; Organic Molecular Chemistry - Synthesis and Characterisation ; Polymer Materials
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 367274963

Quinoxalinones and quinoxalines are related substance classes whose investigations in synthetic, biological and materials science are of great interest. In addition to numerous pharmaceutically relevant properties, quinoxaline-containing structures are extensively studied in the field of materials science. In particular, compounds which can be described by more than one quinoxaline moiety are of great interest due to various electronic and structural properties. Quinoxalines are investigated as ligands in charge-transfer complexes, new magnetic materials, the basis for organic semiconductors, battery electrodes, electrodes for storage media, or novel OLED components and solar cells. The self-assembly of dichinoxalinophenazines or their fiber formation has also been described as well as the formation of helical structures, which can be used for the development of new functional materials, e.g. for the preparation of optically active polymers. The aim of this project is to develop methods that enable the formation and derivatization of oligo-quinoxalines on solid phases. The use of the polymeric support is intended to permit the abolition of previous synthetic limitations and, as a consequence, the generation of new classes of oligo- and later poly-quinoxalines. The newly developed methods are intended to provide methods by which a flexible combination of individual quinoxaline modules can be used in a controlled manner for the formation of oligo-quinoxalines. The modules differ in the way of their incorporation into the oligomer and additional diversity is generated by the use of different quinoxaline building blocks. For this purpose, four types of modules are to be constructed on the solid support, which lead in linear combination to four different oligomeric structures. The different constitution of the oligomers will have a significant influence on the overall structure of the oligomer, on its three-dimensional shape as well as on the material properties. The findings from the oligomeric syntheses for homogeneous oligomers are intended to enable the synthesis of further oligomeric structural variants, hitherto completely unknown. Thus, diverse variations within the oligomers, metal coordination and covalent bond formation between the individual modules, as well as the introduction of additional linker groups will be pursued. In addition to the synthesis of oligomers, the formation of quinoxalines on the solid phases is to be used for the cleavage of trimeric quinoxalines, which can be aromatized to give hexaazatrinaphthalene derivatives. The developed methods are used in the last step to test the transferability of the syntheses to other surfaces. The aim is to demonstrate an application on planar surfaces in order to allow syntheses of polymers by controlled linkage of single modules.

• DFG Programme: Research Grants