Chemiluminogenic Features of 10-Methyl-9-(phenoxycarbonyl)acridinium Trifluoromethanesulfonates Alkyl Substituted at the Benzene Ring in Aqueous Media

Abstract

10-Methyl-9-(phenoxycarbonyl)acridinium trifluoromethanesulfonates bearing alkyl substituents at the benzene ring were synthesized, purified, and identified. In the reaction with OOH(-) in basic aqueous media, the cations of the compounds investigated were converted to electronically excited 10-methyl-9-acridinone, whose relaxation was accompanied by chemiluminescence (CL). The kinetic constants of CL decay, relative efficiencies of light emission, chemiluminescence quantum yields, and resistance toward alkaline hydrolysis were determined experimentally under various conditions. The mechanism of CL generation is considered on the basis of thermodynamic and kinetic parameters of the reaction steps predicted at the DFT level of theory. The chemiluminescence efficiency is the result of competition of the electrophilic center at C(9) between nucleophilic substitution by OOH(-) or OH(-) and the ability of the intermediates thus formed to decompose to electronically excited 10-methyl-9-acridinone. Identification of stable and intermediate reaction products corroborated the suggested reaction scheme. The results obtained, particularly the dependency of the "usefulness" parameter, which takes into account the CL quantum yield and the susceptibility to hydrolysis, on the cavity volume of the entity removed during oxidation, form a convenient framework within which to rationally design chemiluminescent 10-methyl-9-(phenoxycarbonyl)acridinium cations.

Molecular Basis of the Chemiluminescence Mechanism of Luminol

“…The involvement of intramolecular electron or charge transfer towards the peroxide bond in the chemiexcitation mechanism in not new, and constitutes the first step of the “chemically initiated electron‐exchange luminescence” (CIEEL) and “charge‐transfer‐induced luminescence” (CTIL) mechanisms, which have been proposed as general catalyzed chemiluminescence mechanisms in peroxide‐based systems. Intramolecular electron or charge transfer has been proposed to operate in various 1,2‐dioxetane systems containing phenolate or acridinium substituents . Such stabilization was also theoretically described recently in the intermolecular chemiluminescence mechanisms activated by aromatic compounds with low ionization potential .…”

On the use of acridinium indicators for the chemiluminescent determination of the total antioxidant capacity of dietary supplements

“…Optimal environments of AEs' CL emission were assessed within the framework of our earlier studies; however, due to high alkalinity (pH about 12.5) and low hydrogen peroxide concentration (below 0.1%), the latter conditions were not optimal in the context of the application proposed here. Therefore, new variants acridinium CL systems were developed, optimal for this application, characterized by a higher initial concentration of the oxidant and a lower pH, enabling moderate CL dynamics, as well as good sensitivity to the environment, while maintaining a relatively high emission efficiency and a broad range of kinetic changes.…”

“…According to the literature reports on the mechanisms of acridinium esters CL, the concentration of 10‐methylacridane‐9‐one – which is produced quantitatively as a result of AEs' oxidation – is proportional to the initial concentration of AE. Thus, the intensity of CL may be regulated by varying of its concentration.…”

Structure, formation, thermodynamics and interactions in 9-carboxy-10-methylacridinium-based molecular systems

“…As CMA makes one of the products secreted upon chemiluminescence of acridinium esters and sulphonamides, the structural study presented here may also shed some light on the course of this complicated process, that have been studied by us for a long time. 2,12,13 In this work we employed a broad set of experimental methods such as single crystal X-ray crystallography and spectroscopic techniques, including UV-VIS, 1 H and 13 C NMR and MALDI-TOF mass spectrometry.…”