Title: Hexa-Branched Nanographenes with Large Two-Photon Absorption

Authors: Xin-Jing Zhao, Yang-Yang Ju, Yu-Ming Su, Chun Tang, Qi Zeng, LiuBin Feng, Cheng Wang*, Klaus Müllen, and Yuan-Zhi Tan*

Abstract: The conventional approach toward molecules with large two-photon absorption (TPA) involves donor–acceptor conjugation. Herein we show a new strategy involving the use of hexa-branched nanographenes. We synthesized two hexa-branched nanographenes, one with six benzoaceanthrylene arms fused to the coronene core and the other with six pyrenyl arms fused to the coronene core. Neither of these hexa-branched nanographenes has a donor–acceptor structure, yet they exhibited high TPA values of 3.6 × 10³ and 1.9 × 10⁴ GM, respectively, which are the highest values recorded for heteroatom-free hydrocarbon molecules. Theoretical analysis suggests that the fused branched structures are responsible for the large TPA cross-section. These findings illustrate the importance of the topology of the fused conjugated skeleton in TPA and provide an alternative structural design toward large TPA.

Full-Link: https://pubs.acs.org/doi/10.1021/jacs.3c05662