Rational Synthesis of non-classical Nanographenes via Cyclodehydrofluorination Algorithm

• Applicant: Professor Dr. Konstantin Amsharov
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 264409058

The exploding interest in non-classical nanographenes (extra-large PAHs containing non-hexagonal rings, multihelical and/or porous systems) originates from enormous expectations about the possible applications of these materials in the next generation technologiesand future electronics. However the investigation and widespread application have remained elusive since facile access to this class of molecules is still lacking. Therefore the development of new effective synthetic approaches to this unique class of materials appears to be the central task in the field. The aim of this project is to develop facilesynthetic routes to non-classical NGs based on the C-F bond activation approach. The proposed strategy is rely on highly effective Aryl-Aryl coupling technique via cyclodehydrofluorination (CDHF) developed in our group. Previously we have found that intramolecular Aryl-Aryl coupling can be realized effectively under mild conditions via C-F bond activation on thermally activated aluminum oxide. During the first period we have successfully demonstrated the feasibility of our approach for the synthesis of nanographenes and strained geodesic systems including functional buckybowls and fullerenes. Among the high selectivity and frequently quantitative Transformation the CDHF provides the possibility to perform a domino-like coupling(HF-zipping) via execution of the rationally built into a precursor coupling algorithm. This provides essential flexibility in the design of the precursor and allow superseding the conventional step-by-step construction of the carbon-skeleton by the one-pot intramolecularassembly. Because of our big success in the synthesis of nanostructures implementing multiple CDHF algorithm we intend to investigate this reaction further and to develop a general syntheticapproach to various non-classical NGs. Our preliminary results Show that facile incorporation of non-hexagonal rings and construction of multihelical NGs is feasible. This points the way to the preparative fabrication of these unique materials in a fully controllable manner. In this project the synthesis of helical, bowl-shaped (Pentagon containing) and saddle-shaped (heptagon/octagon containing) NGs via C-F bond activation is intended. This includes the synthesis of rationally fluorinated precursors followed by zipping to the desired nanostructures. The respective non-classical NGs are planned to be investigated with spectroscopic and electrochemical methods. Among many further interesting aspects of this project it is intended to investigate the mechanism of metal-oxide mediated condensationfurther. The unprecedentedly high efficiency of CDHF demonstrates the high potential and provides strong basis for achieving the objectives of this proposal. The preliminary work opens up promising vistas for tackling the challenge of facile synthesis of elusive nonclassicalNGs.

• DFG Programme: Research Grants