Nicotine as a Catalyst for Chlorination Promoted by Hypochlorous Acid: Experimental and Theoretical Studies

Author(s)

Ximenes, Valdecir F. ; Pavan, Nathalia M. ; de Souza, Aguinaldo R. ; Barros, Gabriel A. ; Morgon, Nelson H.

• Document type: Journal article
• Source: Journal of the Brazilian Chemical Society; v. N/A, p. 6-pg., 2022-06-27.

Abstract

There is robust evidence of the hypochlorous acid (HClO)-mediated damage in biomolecules, and nicotine boosts the chlorination potency of HClO. We present experimental and theoretical evidence of the mechanism by which nicotine catalyzes the chlorination of pyranine. The rate constants for chlorination of pyranine by HClO were measured in the presence (5.3 x 10(5) mol(-1) L s(-1)) and absence of nicotine (4.2 x 10(3) mol(-1) L s(-1)), revealing the catalytic effect of the alkaloid. Density functional theory (DFT) calculations, based on B3LYP-GD3(BJ)/6-311++G(3df,2p)/SMD(Water)//B3LYP-GD3(BJ)/6-311++G(2d,p)/SMD(Water) level of theory, were performed and showed a decreased activation energy for chlorine transfer and hydrogen abstraction when nicotine chloramine intermediated the reaction. The atomic polar tensor (APT) charges on the chlorine atom of HClO (+0.084) were lower than the chlorine of nicotine chloramine (+0.149), revealing the higher electrophilic character of nicotine chloramine. In conclusion, the increased electrophilic nature of HClO provoked by nicotine explains its catalytic effect. (AU)

• FAPESP's process: 19/18445-5 - Synthesis, studies and applications of fluorescent and circular dichroic probes for characterization of interactions with proteins, DNA and determination of enzymatic activity
• Grantee: Valdecir Farias Ximenes
• Support Opportunities: Regular Research Grants
• FAPESP's process: 19/12294-5 - Theoretical calculations of electronic spectra (UV-Vis, fluorescence and circular dichroism) of molecules of pharmacological and applied interest
• Grantee: Nelson Henrique Morgon
• Support Opportunities: Regular Research Grants