Bistability between π -diradical open-shell and closed-shell states in indeno[1,2- a ]fluorene

Journal article

Indenofluorenes are non-benzenoid conjugated hydrocarbons that have received great interest owing to their unusual electronic structure and potential applications in nonlinear optics and photovoltaics. Here we report the generation of unsubstituted indeno[1,2-a]fluorene on various surfaces by the cleavage of two C–H bonds in 7,12-dihydroindeno[1,2-a]fluorene through voltage pulses applied by the tip of a combined scanning tunnelling microscope and atomic force microscope. On bilayer NaCl on Au(111), indeno[1,2-a]fluorene is in the neutral charge state, but it exhibits charge bistability between neutral and anionic states on the lower-workfunction surfaces of bilayer NaCl on Ag(111) and Cu(111). In the neutral state, indeno[1,2-a]fluorene exhibits one of two ground states: an open-shell π-diradical state, predicted to be a triplet by density functional and multireference many-body perturbation theory calculations, or a closed-shell state with a para-quinodimethane moiety in the as-indacene core. We observe switching between open- and closed-shell states of a single molecule by changing its adsorption site on NaCl.

Authors: Mishra, S; Vilas-Varela, M; Lieske, L; Ortiz, R; Fatayer, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Research
• Journal: Nature Chemistry
• Volume: 16
• Issue: 5
• Pages: 755-761
• Publication date: 2024-02-08
• Acceptance date: 2023-12-19
• DOI: 10.1038/s41557-023-01431-7
• EISSN: 1755-4349
• ISSN: 1755-4330
• Language: English