Singlet molecular oxygen trapping by the fluorescent probe diethyl-3,3′-(9,10-anthracenediyl)bisacrylate synthesized by the Heck reaction

Abstract

Singlet molecular oxygen O₂(¹Δ_g) is a potent oxidant that can react with different biomolecules, including DNA, lipids and proteins. Many polycyclic aromatic hydrocarbons have been studied as O₂(¹Δ_g) chemical traps. Nevertheless, a suitable modification in the polycyclic aromatic ring must be made to increase the yield of O₂(¹Δ_g) chemical trapping. With this goal, an anthracene derivative, diethyl-3,3′-(9,10-anthracenediyl)bisacrylate (DADB), was obtained from the reaction of 9,10-dibromoanthracene and ethyl acrylate through the Heck coupling reaction. The coupling of ethyl acrylate with the anthracene ring produced a new lipophilic, esterified, fluorescent probe reactive toward O₂(¹Δ_g). This compound reacts with O₂(¹Δ_g) at a rate of k_r = 1.69 × 10⁶ M⁻¹s⁻¹ forming a stable endoperoxide (DADBO₂), which was characterized by UV-Vis, fluorescence, HPLC/MS and ¹H and ¹³C NMR techniques. The photophysical, photochemical and thermostability features of DADB were also evaluated. Furthermore, this compound has the potential for great application in biological systems because it is easily synthetized in large amount and generates specific endoperoxide (DADBO₂), which can be easily detected by HPLC tandem mass spectrometry (HPLC/MS/MS).