HDR Seminar: Lyndon Hall, D’Alessandro and Lakhwani groups
Monday, 3 March 2025 4:00pm – 5:00pm
This seminar will be delivered in Chemistry Lecture Theatre 4
Speaker: Lyndon Hall
Host: Prof. Girish Lakhwani
Title: Harnessing Redox and Temperature as Stimuli for High-Performance Chiroptical Switches
Abstract: Chiroptical switches are devices comprising of chiral molecules or materials whose chiroptical signal can be reversibly and controllably converted between two (or more) states which have different chiroptical signals. Chiroptical switches exhibiting good reversibility over many switching cycles and high sensitivity to the applied stimulus are highly desirable, with potential applications in electronic devices, optical displays, and chiral sensing. [1]
Electrical potential is an ideal stimulus for chiroptical switching due to its versatility and effectiveness. Here, I’ll describe the synthesis and characterisation of a novel chiroptical switch based on a chiral 1,1′-binaphthylene scaffold, appended with redox-active 1,8-naphthalimide groups. [2] Electrochemical reduction of the naphthalimide moieties to their radical anion state leads to significant changes in their spectra, which are monitored in situ by UV-vis, circular dichroism (CD), and electron paramagnetic resonance (EPR) spectroelectrochemistry (SEC) techniques. Excellent reversibility is demonstrated through successive reduction and oxidation cycles.
Dual-responsive chiroptical switches respond to two different stimuli and are of great interest due to their high degree of functionality and tunability. I’ll also present the development of a chiral ferrocene amino acid bioconjugate, which operates as a dual-responsive chiroptical switch. In this molecule, the chirality arises from intramolecular hydrogen bonding between amino acid residues, which forces the molecule to adopt an axially chiral conformation. Temperature-modulated chiroptical switching was achieved by exploiting the relative lability of these hydrogen bonding interactions. Additionally, redox-modulated chiroptical switching was demonstrated through oxidation of the ferrocene core. The influence of analyte concentration on electrochemical reversibility is also explored.
References
- Hall, L. A.; D’Alessandro, D. M.; Lakhwani, G. Soc. Rev. 2023, 52, 3567-3590.
- Hall, L. A.; Windsor, H. J.; Chan, B.; D’Alessandro, D. M.; Lakhwani, G. Phys. Chem. Lett. 2025, 1529-1534.