# Investigation of the Chemiluminescent Reaction of a Fluorinated Analog of Marine Coelenterazine

## TL;DR

This study explores how a fluorinated version of a marine compound produces light more efficiently under basic conditions, shedding light on the underlying chemical processes.

## Contribution

The study reveals that an anionic intermediate contributes more to light emission efficiency than a neutral one, despite similar electron and charge transfer processes.

## Key findings

- CL efficiency is higher under basic conditions due to an anionic dioxetanone intermediate.
- Theoretical calculations show both species involve similar electron and charge transfer processes.
- Neither process alone explains the observed differences in chemiexcitation efficiency.

## Abstract

Bioluminescence (BL) and chemiluminescence (CL) are remarkable processes in which light is emitted due to (bio)chemical reactions. These reactions have attracted significant attention for various applications, such as biosensing, bioimaging, and biomedicine. Some of the most relevant and well-studied BL/CL systems are that of marine imidazopyrazine-based compounds, among which Coelenterazine is a prime example. Understanding the mechanisms behind efficient chemiexcitation is essential for the optimization and development of practical applications for these systems. Here, the CL of a fluorinated Coelenterazine analog was studied using experimental and theoretical approaches to obtain insight into these processes. Experimental analysis revealed that CL is more efficient under basic conditions than under acidic ones, which could be attributed to the higher relative chemiexcitation efficiency of an anionic dioxetanone intermediate over a corresponding neutral species. However, theoretical calculations indicated that the reactions of both species are similarly associated with both electron and charge transfer processes, which are typically used to explain efficiency chemiexcitation. So, neither process appears to be able to explain the relative chemiexcitation efficiencies observed. In conclusion, this study provides further insight into the mechanisms behind the chemiexcitation of imidazopyrazinone-based systems.