Polycyclic aromatic molecules are promising functional materials for a wide range of applications, especially in organic electronics. However, their largely hydrophobic nature has impeded further applications. As such, imparting high solubility/hydrophilicity to polycyclic aromatic molecules leads to a breakthrough in this research field. Herein, we report the synthesis of diazapentabenzocorannulenium, a cationic nitrogen-embedded buckybowl bearing a central imidazolium core, by a bottom-up strategy from polycyclic aromatic azomethine ylide. X-ray crystallography analyses have revealed a bowl-shaped molecular structure that is capable of forming charge-segregated one-dimensional columns by bowl-in-bowl packing. In addition to its fluorescence capabilities and high dispersibility in water, the molecule was found to selectively localize in the mitochondria of various tumor cells, showing potential as viable mitochondriaselective fluorescent probes.Polycyclic aromatic molecules are one of the most important class of organic molecules owing to their widespread applications in various scientific fields. [1][2][3][4][5] The significant progress and application of polycyclic aromatic molecules in material sciences, especially in organic electronics, are mainly based on their intrinsic hydrophobic properties. [6,7] In order to further extend possible applications, for example in biological or medicinal research, the development of highlysoluble/hydrophilic molecules is desirable. [8,9] The most conventional method to achieve water-soluble polycyclic aromatic molecules is to add hydrophilic substituents at their peripheral positions (Figure 1a). [10][11][12][13][14][15][16] However, the method may not be ideal in terms of step economy as it requires some additional steps for functionalization. It is therefore essential to develop more efficient methods in introducing hydrophilicity to polycyclic aromatic molecules by other methods than introducing hydrophilic substituents. A possible solution would be to change the framework of polycyclic aromatic molecules. Firstly, the introduction of curvature to Angewandte Chemie

A compound with a highly twisted CC bond in the intermediate bond dissociation region was isolated, and its biradicaloid nature was experimentally demonstrated. A bianthrone derivative substituted with long-chain alkoxy groups was synthesized, and its twisted conformer was assembled into crystals through hydrophobic intermolecular interactions of the introduced alkoxy chains. X-ray crystallography revealed that the CC bond connecting the two anthrone rings has a long bond length (1.429 Å) and a large torsional angle (57.33°). In addition, ESR studies revealed that the twisted bianthrone has biradicaloid character with a small singlet–triplet energy gap of 23.8 kJ mol–1. The thermally excited triplet species were observed in the ESR spectrum as distinct fine structures along with a ΔM S = ±2 forbidden transition.

The designed and synthesized tetramethoxy-substituted bianthrone exists as an equilibrium mixture of the folded and twisted conformers in solution.