Authors Wu, F. ; Ma, J. ; Lombardi, F. ; Fu, Y. ; Liu, F. ; Huang, Z. ; Liu, R. ; Komber, H. ; Alexandropoulos, D.I. ; Dmitrieva, E. ; Lohr, T.G. ; Isreal, N. ; Popov, A. A. ; Liu, J. ; Bogani, L. ; Feng, X.
Title Benzo-extended cyclohepta[def]fluorene derivatives with very low-lying triplet states
Date 15.03.2022
Number 60141
Abstract Open-shell non-alternant polycyclic hydrocarbons (PHs) are attracting increasing attention due to their promising applications in organic spintronics and quantum computing. Herein we report the synthesis of three cyclohepta[def]fluorene-based diradicaloids (1–3), by fusion of benzo rings on its periphery for the thermodynamic stabilization, as evidenced by multiple characterization techniques. Remarkably, all of them display a very narrow optical energy gap (Egopt=0.52–0.69 eV) and persistent stability under ambient conditions (t1/2=11.7–33.3 h). More importantly, this new type of diradicaloids possess a low-lying triplet state with an extremely small singlet–triplet energy gap, as low as 0.002 kcal·mol-1, with a clear dependence on the molecular size. This family of compounds thus offers a new route to create non-alternant open-shell PHs with high-spin ground states, and opens up novel possibilities and insights into understanding the structure–property relationships.
Publisher Angewandte Chemie - International Edition
Citation Angewandte Chemie - International Edition (2022) early view

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