A rational framework to estimate the chiroptical activity of [6]Helicene Derivatives

TL;DR

This paper combines experimental and computational methods to understand how different substituents affect the chiroptical properties of [6]helicene derivatives, enabling precise tuning of their optical activity for technological applications.

Contribution

It introduces a rational framework that integrates experimental data and ab-initio calculations to predict and tune the chiroptical properties of helicene derivatives.

Findings

Both electron withdrawing and donating groups cause redshift and decrease in optical activity.

Substituents influence pi-conjugation, affecting transition energy and intensity.

The computational setup effectively models the optical properties of helicene derivatives.

Abstract

Helicenes are a class of molecules potentially suitable in several technological applications with intrinsic structural chirality which makes them interesting scaffolds for chiroptical properties. As desirable is tuning chiroptical property by synthesis, we combine experimental optical characterization and ab-initio calculations to study how different substituents influence the optical properties of [6]helicene. We explore anchoring groups presenting a variety of sizes and chemical nature, finding that both electron withdrawing and donating groups redshift and dwindle the optical activity of the molecule. We suggest the observed dumping in transitions energy and intensity is connected to the strength of the perturbation induced by the substituent on the pi-conjugation of the aromatic rings. Such observations demonstrate how helicenes' chiroptical properties can be fine-tuned via stereochemical control of the substituents and validates a simple yet effective computational setup to model the optics of those systems.