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Bistability between π-diradical open-shell and closed-shell states in indeno[1,2-a]fluorene
Shantanu Mishra1, Manuel Vilas-Varela2, Leonard-Alexander Lieske3
1IBM Research Europe - Zurich, Rüschlikon, Switzerland. SHM@zurich.ibm.com.
Nature Chemistry
|February 9, 2024
Summary
Researchers generated unsubstituted indeno[1,2-a]fluorene using voltage pulses. This molecule exhibits unique charge bistability and switches between open- and closed-shell states on surfaces.
Area of Science:
- Organic Chemistry
- Surface Science
- Quantum Chemistry
Background:
- Indenofluorenes are non-benzenoid conjugated hydrocarbons with unique electronic structures.
- They show potential in nonlinear optics and photovoltaics.
Purpose of the Study:
- To generate unsubstituted indeno[1,2-a]fluorene on surfaces.
- To investigate its electronic properties and charge states.
Main Methods:
- Voltage pulses applied by a scanning tunneling microscope-atomic force microscope tip.
- Surface preparation on Au(111), Ag(111), and Cu(111) with bilayer NaCl.
- Density functional and multireference many-body perturbation theory calculations.
Main Results:
- Successfully generated indeno[1,2-a]fluorene via C-H bond cleavage.
- Observed neutral charge state on Au(111) and charge bistability (neutral/anionic) on Ag(111) and Cu(111).
- Identified two ground states for neutral indeno[1,2-a]fluorene: a triplet diradical or a closed-shell para-quinodimethane state.
- Demonstrated switching between these states by altering adsorption site on NaCl.
Conclusions:
- Unsubstituted indeno[1,2-a]fluorene can be generated on surfaces.
- Its electronic properties, including charge state and ground state, are surface-dependent.
- Single-molecule state switching is achievable through controlled adsorption site manipulation.
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