Switching of Chiroptical Properties

Metamorphic Approaches for On-surface Switching of Chiroptical Properties

One great challenge nanoscience is facing is the difficulty to transpose molecular-scale phenomena into macroscopic properties finding application in everyday-life devices. A way to address this issue is to develop metamorphic molecular systems for which an external stimulus triggers a drastic structural reorganization. By controlling supramolecular self-assembly of metamorphic building blocks it is indeed possible to develop responsive materials for which properties at the macroscopic level can be modulated.

Based on this strategy in this project will bridge the gap between chiroptical properties observed in solution for Circularly Polarized Luminescence (CPL) switches and their use in device-like systems. Despite being crucial steps toward application in photonics and optoelectronics, modulation of CPL properties has rarely been achieved on-surface and switches responding to an electric stimulation remain almost unexplored.

The major breakthrough of this project relies on the hypothesis that metamorphic processes occurring in supramolecular assemblies can be used to achieve on-surface modulation of chiroptical properties. To succeed in this ambitious goal, the main objective of this project is to design responsive chiroptical switches whose supramolecular self-assembly and CPL properties on surfaces can be controlled with optical or electrical stimulations.

Knowledge acquired thanks to this project will serve the development of CPL devices with promising application for quantum cryptography, memory and computing apt to address the exponential growth of numerical data to be safely stored and processed.

This project is constructed around three axes of increasing difficulty and risk:

• The metamorphic processes in self-assembled monolayers of bis-viologen hinges will be investigated on-surface by Scanning Tunnelling Microscopy.
• CPL switches constituted of bis-viologen hinges and boron-based emitters featuring two intense CPL states will be studied in solution.
• On-surface CPL modulation will be achieved via metamorphic processes occurring in the self-assembled monolayers of CPL switches.