Mechanistic Investigation of H₂O₂‐dependent Chemiluminescence from Tetrabromo‐1,4‐Benzoquinone

Abstract

As a H2O2‐dependent bioluminescent substrate, tetrabromo‐1,4‐benzoquinone (TBBQ) was first isolated from acorn worm. The mechanism of chemiluminescence (CL) corresponding to the bioluminescence (BL) of acorn worm is largely unknown, let alone the mechanism of BL. In this article, we firstly studied the chemical and physical processes, and mechanism of H2O2‐dependent CL from TBBQ by theoretical and experimental methods. The research results indicate: the CL process is initiated by a nucleophilic substitution reaction, which leads to the formation of an anionic dioxetane through five consecutive reactions; the anionic dioxetane decomposes to the first singlet excited state (S1) via a conical interaction of the potential energy surfaces (PESs) between the ground (S0) and S1 state; the anionic S1‐state changes to its neutral form by a proton transfer from the solvent and this neutral product is assigned as the actual luminophore. Moreover, the experimental detection of CL, .OH and the identifications of 2,3‐dibromo maleic acid and 2‐bromo malonic acid as the major final products provide direct evidence of the theoretically suggested mechanism. Finally, this study proves that the activity of the H2O2‐dependent CL from TBBQ is significantly lower than the one from tetrachloro‐1,4‐benzoquinone (TCBQ), which is caused by the weaker electron withdrawing effect and the stronger heavy atomic effect of bromine.

Theoretical study on oxidation mechanism of fluorescent probe, coumarin‐7‐pinacolboronate by various reactive oxygen species

“…The energy barrier is 25.21 kcal/mol lower than that of the reaction of CBU and H 2 O 2 . This conclusion is in agreement with other H 2 O 2 probe 45,46 . Next, the S 0 → S 1 interplay during the decomposition reaction is investigated.…”

“…This conclusion is in agreement with other H 2 O 2 probe. 45,46 Next, the S 0 ! S 1 interplay during the decomposition reaction is investigated.…”

AuFe3@Pd/γ-Fe2O3 Nanosheets as an In Situ Regenerable and Highly Efficient Hydrogenation Catalyst

“…In final, the reaction between OH radicals and the S atom in the S poisoned AuFe 3 @Pd/γ-Fe 2 O 3 NSs was stimulated with Born–Oppenheimer molecular dynamics (BOMD) simulations (Figure S40, Supporting Video). , The adsorption of •OH onto the S atoms and their reaction are almost energy-barrier free, with the only exception a strong electronic repulsion between the preadsorbed two •OH radicals and the third. This indicates the oxidative regeneration of S poisoned AuFe 3 @Pd/γ-Fe 2 O 3 NSs is a energetically favorable one.…”

“…After vortexing for 30 s, the ESR spectra were recorded on a Bruker EMX-plus X-band ESR spectrometer. 5% (v/v) ethanol or dimethyl sulfoxide (DMSO) was also added to confirm the observed ESR signal is from •OH radical …”

“…5% (v/v) ethanol or dimethyl sulfoxide (DMSO) was also added to confirm the observed ESR signal is from •OH radical. 48 S Poisoning and Oxidative Regeneration. The S poisoning experiment was performed by reacting AuFe 3 @Pd/γ-Fe 2 O 3 NSs with Na 2 S for 30 min under stirring.…”