Decafluorinated and Perfluorinated Warped Nanographenes: Synthesis, Structural Analysis, and Properties

Fluorination is a useful approach for tailoring the physicochemical properties of nanocarbon materials. However, owing to the violent reactivity of fluorination, achieving edge-perfluorination of nanographene while maintaining its original π-conjugated structure is challenging. Instead of using traditional fluorination, here, we employed a bottom-up strategy involving fluorine preinstallation and synthesized decafluorinated and perfluorinated warped nanographenes (<b>DFWNG</b> and <b>PFWNG</b>, respectively) through a 10-fold Suzuki-Miyaura coupling followed by a harsh Scholl reaction, whereby precisely edge-perfluorinated nanographene with an intact π-conjugated structure was achieved for the first time. X-ray crystallography confirmed the intact π-conjugated structure and more twisted saddle-shaped geometry of <b>PFWNG</b> compared to that of <b>DFWNG</b>. Dynamic study revealed that the 26-ring carbon framework of <b>PFWNG</b> is less flexible than that of <b>DFWNG</b> and the pristine <b>WNG</b>, enabling chirality resolution of <b>PFWNG</b> and facilitating the achievement of CD spectra at -10 °C. The edge-perfluorination of <b>PFWNG</b> resulted in improved solubility, lower lowest unoccupied molecular orbital, and a surface electrostatic potentials/dipole moment direction opposite those of the pristine <b>WNG</b>. Likely owing to its intact π-conjugated structure, <b>PFWNG</b> exhibits comparable electron mobility with well-known PC₆₁BM. Furthermore, perfluorination improves thermal stability and hydrophobicity, making <b>PFWNG</b> suitable for use as a thermostable/hydrophobic <i>n</i>-type semiconductor material. In the future, this fluorination strategy can be used to synthesize other perfluorinated nanocarbon materials, such as perfluorinated graphene nanoribbons and porous nanocarbon.