# Regioselective Halogenation of BOPPY Fluorophores and Subsequent Diversification via Cross-Coupling and Aromatic Nucleophilic Substitution Strategies

## TL;DR

This paper describes a method to selectively modify BOPPY dyes with bromine and then use chemical reactions to create new fluorescent compounds with altered light properties.

## Contribution

The study introduces regioselective bromination and diversification strategies for BOPPY fluorophores through cross-coupling and nucleophilic substitution.

## Key findings

- Brominated BOPPYs undergo efficient cross-coupling with boronic acids and organotin reagents.
- Nucleophilic substitution reactivity varies with bromine position on the BOPPY molecule.
- Functionalized BOPPY derivatives show significant bathochromic shifts and altered fluorescence quantum yields.

## Abstract

The regioselective mono- and tribromination of a BOPPY
dye followed
by its reactivity under Pd-catalyzed cross-coupling and nucleophilic
substitution reactions are reported. The brominated BOPPYs undergo
Pd(0)-catalyzed cross-couplings with a variety of boronic acids and
organotin reagents to give the corresponding products in good-to-excellent
yields. Nucleophilic aromatic substitutions occur both on the mono-
and tribromo-BOPPYs. The reactivity order of the latter is C3-Br >
C1-Br > C2-Br, while in the cross-coupling reactions using Pd­(PPh3)4, it is C1-Br > C3-Br > C2-Br, likely due
to
steric interaction upon Pd­(PPh3)2 insertion
into the C3-Br bond and the slightly longer and weaker C1-Br bond.
The functionalized BOPPY derivatives showed pronounced bathochromic
shifts in their absorption and emission bands compared with the starting
compound, and fluorescence quantum yields depend on the nature and
position of the substituent.