(Invited) Synthetic Exploration of Functional Nanographenes for Photonic Applications

Abstract

Nanographenes, or large polycyclic aromatic hydrocarbons (PAHs), have been attracting renewed attentions for their unique optical, electronic, and magnetic properties [1]. Nanographenes can also be considered as atomically precise graphene quantum dots (GQDs), which are promising as an environmentally friendly alternative of semiconductor quantum dots, especially for photonic applications ranging from light-emitting devices to bioimaging. To this end, we have been exploring the synthesis and functionalization of dibenzo[hi,st]ovalene (DBOV) as a nanographene with zigzag and armchair edges, which demonstrated high stability, strong red emission, and optical gain properties [1,2]. For example, the functionalization of DBOV with two fluoranthene imide (FAI) groups induced red-shift of the absorption and emission bands, increase of the Stokes shift, and enhancement of the stimulated emission (SE) signals with significantly reduced excited state absorption, allowing the efficient lasing at 720 nm [3]. More recently, we have synthesized dibenzo[a,m]dinaphtho[3,2,1-ef:1',2',3'-hi]coronene (DBDNC) with armchair, zigzag, and fjord edges, which also showed high stability and red emission [4]. Notably, DBDNC has a nonplanar structure around the fjord edges, as revealed by the single-crystal X-ray analysis, and displayed a SE signal at 710 nm with a longer lifetime than that of DBOV, presumably due to the suppression of intermolecular interactions. These results provide a further insight into the relationship between the PAH structures and their photophysical properties, paving the way toward their photonic applications.[1] Paternò, G. M.; Goudappagouda, Chen, Q.; Lanzani, G.; Scotognella, F; Narita A., Adv. Optical Mater. 2021, 9, 2100508.[2] Paternò, G. M.; Chen, Q.; Wang, X.-Y.; Liu, J.; Motti, S. G.; Petrozza, A.; Feng, X.; Lanzani, G.; Müllen, K.; Narita, A.; Scotognella, F., Angew. Chem. Int. Ed. 2017, 56, 6753–6757.[3] Paternò, G. M.; Chen, Q.; Muñoz-Mármol, R.; Guizzardi, M.; Bonal, V.; Kabe, R.; Barker, A. J.; Boj, P. G.; Chatterjee, S.; Ie, Y.; Villalvilla, J. M.; Quintana, J. A.; Scotognella, F.; Müllen, K.; Díaz-García, M. A.; Narita, A.; Lanzani, G., Mater. Horiz. 2022,9, 393–402.[4] Xu, X.; Serra, G.; Villa, A.; Muñoz-Mármol, R.; Vasylevskyi, S.; Gadea, M.; Lucotti, A.; Lin, Z.; Boj, P. G.; Kabe, R.; Tommasini, M.; Díaz-García, M. Á.; Scotognella, F.; Paternò, G. M.; Narita, A., Chem. Sci. 2022, 13, 13040–13045