Multistate Switching of Spin Selectivity in Electron Transport through Light-Driven Molecular Motors.

Qirong Zhu,Sidney R Cohen,Francesco Tassinari,Wojciech Danowski,G Henrieke Heideman,Ron Naaman,Ben L Feringa,Carlijn L F Van Beek,Amit Kumar Mondal,Kakali Santra

doi:10.1002/advs.202101773

Abstract

It is established that electron transmission through chiral molecules depends on the electron's spin. This phenomenon, termed the chiral‐induced spin selectivity (CISS), effect has been observed in chiral molecules, supramolecular structures, polymers, and metal‐organic films. Which spin is preferred in the transmission depends on the handedness of the system and the tunneling direction of the electrons. Molecular motors based on overcrowded alkenes show multiple inversions of helical chirality under light irradiation and thermal relaxation. The authors found here multistate switching of spin selectivity in electron transfer through first generation molecular motors based on the four accessible distinct helical configurations, measured by magnetic‐conductive atomic force microscopy. It is shown that the helical state dictates the molecular organization on the surface. The efficient spin polarization observed in the photostationary state of the right‐handed motor coupled with the modulation of spin selectivity through the controlled sequence of helical states, opens opportunities to tune spin selectivity on‐demand with high spatio‐temporal precision. An energetic analysis correlates the spin injection barrier with the extent of spin polarization.

Highlights

In the case of (R,R)-(P,P)-E-1 (Figure 1e), a μm-sized layered structure is formed with thickness of 2–3 nm
This work presents the dependence of the spin selective conduction on structural changes of the molecular motors as a result of photoisomerization followed by thermal relaxation (THI)
High spin selectivity was observed in the photostationary state mixture of isomers obtained by photoisomerization, as compared to the initial structures

Summary

Introduction

This phenomenon, termed the chiral-induced spin selectivity (CISS), effect has been observed in chiral molecules, supramolecular structures, polymers, and metal-organic films. The authors found here multistate switching of spin selectivity in electron transfer through first generation molecular motors based on the four accessible distinct helical configurations, far, the CISS effect was observed in a wide range of helically chiral biological and synthetic organic molecules including oligopeptides,[4] DNA,[5] helicenes,[6] and more recently in helical covalent[7]. An energetic are based on molecules with fixed handedness, limiting the spin of the transported electrons to that defined by the molecular chirality.[2] A major challenge is the development of switchable organic spinanalysis correlates the spin injection barrier with the extent of spin filters, capable of inversion of the spin polarpolarization. This would allow for the construction of responsive spintronic devices and represents a major step forward in the field of organic spintronics

Results

Discussion

Conclusion