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A red star is born

A Large Starphene Comprising Pentacene Branches

by Guy Molénat - published on , updated on

Starphenes, planar molecules comprising three acenes branches, show promising optoelectronic properties. Notably, HOMO-LUMO energy gap presumably decreases with their increasing size, making larger homologues extremely desirable. Unfortunately, with the size, their instability and insolubility also increase, challenging classical synthetic ways. A new method has been developed, enabling synthesis of large starphenes in a quantity sufficient for their full characterization and further applications,

Researchers from the NanoSciences Group at CEMES have been able to solve this problem by designing chemically stable, non-planar and soluble precursors which allows their synthesis and characterization by classical methods of organic chemistry (in fifteen synthesis steps in total).

These precursors can be converted to starphene simply by heating either in the solid phase or on an ultra-high vacuum surface or by irradiating in ultra-violet in a solvent frozen at a few degrees Kelvin. The electronic structure and optical properties of these molecules have been studied in collaboration with teams of microscopists from the DIPC in San Sebastian (Spain), photophysicists from the Academy of Sciences in Warsaw (Poland) and a theorist from the university. from Hokkaido (Japan).

Caption: (a) High-Resolution Scanning Tunneling Microscopy image (tip functionalized with a CO Molecule-STM image of a starphene. (b) dI/dV point spectra on starphene showing various resonances marked with dashed lines. The inset marks the positions at which each of the spectra are taken, two on the molecule and one on the substrate as reference. (c) and (d) Constant height dI/dV images of a starphene recorded with a Cl tip at the energy of the lowest unoccupied and highest occupied states, respectively. (e) and (f) Calculated wavefunctions of the HOMO and LUMO of free-standing starphene.

 

Contact: André Gourdon, andre.gourdon [at] cemes.fr

Publication: A Large Starphene Comprising Pentacene Branches

Jan Holec, Beatrice Cogliati, James Lawrence, Alejandro Berdonces-Layunta, Pablo Herrero, Yuuya Nagata, Marzena Banasiewicz, Boleslaw Kozankiewicz, Martina Corso, Dimas G. de Oteyza, Andrej Jancarik* and André Gourdon*

Angew. Chem. Int. Ed.Eng. (2021) https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202016163