# Enantiotopic-group-selective coupling for unified access to carbazole atropisomers as versatile chiral chromophores

## TL;DR

A new method enables efficient synthesis of chiral carbazole atropisomers, opening up new possibilities for advanced optical and electronic devices.

## Contribution

A unified strategy for enantioenriched synthesis of carbazole atropisomers with tailored π-functionalities and axial chirality.

## Key findings

- Enantiotopic-group-selective coupling achieves axial chirality with >99:1 enantiomeric ratio.
- Carbazole atropisomers show novel chiroptical functions including CPL and CP-TADF.
- An electrostatic steering strategy enables remote atroposelectivity in extended π-systems.

## Abstract

Chiral organic chromophores are foundational for advanced optical and electronic devices. Despite the widespread use of N-aryl carbazoles in visible-luminescent materials, chiroptical applications of their atropisomers have remained underdeveloped due to the synthetic challenge of achieving remote atroposelectivity necessitated by extended π-systems. Here, we present a unified strategy for the efficient synthesis of enantioenriched N–C and N–N carbazole atropisomers. By integrating 13C NMR-based ligand parameterization, we achieve enantiotopic-group-selective coupling reactions that simultaneously incorporate tailored π-functionalities and establish axial chirality (up to >99:1 er) using synthetic pathways established in carbazole chemistry. Through covalent modulation and noncovalent complexation, we investigate novel chiroptical functions of carbazole atropisomers, including circular dichroism (CD), circularly polarized luminescence (CPL), charge-transfer CPL (CT-CPL), and circularly polarized thermally activated delayed fluorescence (CP-TADF). By establishing an electrostatic steering strategy for remote atroposelectivity, our work paves the way for integrating multifunctional carbazoles into advanced optical and optoelectronic technologies.

Despite the widespread use of N-aryl carbazoles in visible-luminescent materials, chiroptical applications of their atropisomers have remained underdeveloped due to the synthetic challenge of achieving remote atroposelectivity necessitated by extended π-systems. Here, the authors report an enantiotopic-group-selective strategy to access enantioenriched N–C and N–N carbazole atropisomers and the investigate their functions as chiral chromophores.