# One‐Pot Incorporation of Quantum Defects into Single‐Walled Carbon Nanotubes with Arylazo Sulfonates

## TL;DR

Researchers developed a new method to create brighter carbon nanotubes using arylazo sulfonates, avoiding harmful side products and enabling better performance for photonic and sensing applications.

## Contribution

A novel photochemical strategy using arylazo sulfonates to create complex quantum defects in carbon nanotubes without purification.

## Key findings

- Arylazo sulfonates enable the incorporation of coumarin and other quantum defects into carbon nanotubes.
- NIR emission increases by over 90% without purification.
- Modified nanotubes retain photophysical properties and can sense dopamine and viscosity.

## Abstract

Single‐walled carbon nanotubes (SWCNTs) consist of a carbon monolayer and fluoresce in the near‐infrared (NIR, 800–2500 nm) region. Introduction of sp3 quantum defects (QDs) creates novel NIR emission features, which promise huge potential for (bio)photonics. However, so far defect chemistry based on diazonium salts is mainly limited to benzene derivatives. The reaction side products also quench SWCNT fluorescence and impair additional surface chemistry. Here, we introduce a photochemical strategy based on arylazo sulfonates to a) create more complex aromatic QDs and b) avoid side products that adsorb and quench. We show that this way coumarin and other QDs are incorporated, which increases overall NIR emission by more than 90% without purification. These materials can be non‐covalently modified with biocompatible polymers (polyethyleneglycoles, DNA) without a change in photophysical properties and we demonstrate mechanical (viscosity) and chemical (neurotransmitter dopamine) sensing. This one‐pot approach creates QDs in SWCNTs and provides access to advanced hybrid materials for photonic applications.

We present a photochemical strategy to create complex aromatic quantum defects in carbon nanotubes using arylazo sulfonates. It provides access to brighter carbon nanotubes without purification and simpler biofunctionalization.