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Turkish Journal of Chemistry

DOI

10.3906/kim-1804-67

Abstract

Carbamates weaken the luminol-H$_{2}$O$_{2}$ chemiluminescence (CL) catalyzed by sodium copper chlorophyll (SCC). The capacity to inhibit the CL of three carbamates is in the order of carbaryl (CBL) \textgreater carbofuran (CBF) \textgreater metolcarb (MTC). Mechanisms of carbamates inhibiting SCC-luminol-H$_{2}$O$_{2}$ CL are investigated using fluorescence quenching and quantum chemistry simulations for the first time in this work. Carbamate-SCC interactions studied using fluorescence spectroscopy show that with the increasing concentration of the SCC, the fluorescence of carbamate is quenched regularly, and the quenching mechanism is a static quenching process. Binding constants ($K_{B})$ of the three carbamates with SCC are CBL (4.39 x 10$^{5})$ > CBF (1.46 x 10$^{4})$ > MTC (2.16 x 10$^{3}$ L/mol), which is completely harmonious with the capacity to inhibit CL of the carbamates. Furthermore, the carbamate-SCC interaction energies from quantum chemistry simulations are CBL-porphyrin copper (PPCu) (-30.1), CBF-PPCu (-21.0), and MTC-PPCu (-19.9 kJ/mol), which is also identical to their inhibiting capacity. This provides further evidence that the formation of carbamate-SCC complexes reduces the SCC catalytic activity and the CL intensity decreases. In addition, a novel flow injection chemiluminescence method for the determination of carbamate was established based on carbamate inhibiting CL of the SCC-luminol-H$_{2}$O$_{2}$ CL system under alkaline conditions. This work may contribute to the study of the mechanism of CL inhibition using fluorescence quenching and quantum chemistry calculation methods.

First Page

1566

Last Page

1576

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