Unraveling the Nature of Interaction between Substituted Phenol and Amiodarone

Abstract

A comprehensive study of the interaction between nitrophenols (π-acceptors) and amiodarone (AM) was performed using electronic absorption spectra. The key point is to clarify the erroneous interpretation of the interaction between nitrophenols and one of the basic organic drugs. Matching of the experimental UV-vis spectra and the theoretical ones obtained by DFT calculations revealed that the tertiary amino group of AM reacts with the phenol compounds under investigation via proton-transfer but not charge-transfer (C.T.) mechanisms, unlike what is commonly known about this type of interaction. The interaction was carried out in solutions of different basic pH values to study the effect of hydrogen ion concentration on the reaction. The results show that the reaction is a simple acid-base reaction. As a result, this reaction cannot be used by analytical chemists for determination of one of the studied compounds due to its very low selectivity. TD-DFT as well as geometry optimization of the nitrophenols were calculated with the B3LYP functional, using aug-cc-pvDZ and LanL2DZ as basis sets for ionic and neutral compounds, respectively. The theoretical spectra of possible interactions between AM and nitrophenols result in the same spectra of ionized nitrophenols alone, indicating no possibility for the formation of charge-transfer complexes.