# Donor–Acceptor-Substituted 5‑Azaazulenes

## TL;DR

Scientists synthesized new 5-azaazulene compounds with donor and acceptor groups, which could be useful for organic photonics.

## Contribution

A novel synthetic route to donor–acceptor-substituted 5-azaazulenes via ring expansion is introduced.

## Key findings

- Regioisomeric 5-azaazulenes were successfully synthesized and characterized.
- Computational studies revealed insights into the transformation mechanism and excited state energy levels.
- The compounds show potential as chromophores for organic photonics applications.

## Abstract

The synthesis of
5-azaazulenes with both donor and acceptor substituents
on their seven-membered rings is reported through the ring expansion
of stable azapentalene derivatives upon reaction with dimethyl acetylenedicarboxylate.
Regioisomeric products were obtained and characterized. The mechanism
of the transformation and the excited state energy levels of the products
were studied computationally, suggesting that these structures can
be entry points to chromophore design for organic photonics applications.