Electronic absorption spectra of antiviral aminophenol derivatives

Abstract

Electronic absorption spectra of aminophenol derivatives in solutions have been studied. A general property of the absorption spectra of these compounds, the dependence of the maximum of a long-wavelength absorption band on the solvent polarity, is revealed. As a rule, the absorption band maximum of compounds possessing pharmacological properties shows a greater shift to short wavelength with an increase in the medium polarity than that of inactive compounds. Absorption measurements of solutions of aminophenol derivatives can be used for a tentative estimation of their antiviral activity.Introduction. Aminophenols (APs) exhibited antiviral properties in experiments on cell cultures [1-6]. These properties correlated with their ability to affect the course of free-radical processes. Intramolecular hydrogen bonds (IHBs) involving the hydroxyls in APs were found to be important using steady-state radiolysis and IR spectroscopy [7-10]. However, molecular spectroscopy and quantum-chemical analysis have been somewhat neglected in studies of the electronic structure×biological activity relationship of APs.Various chromophores are present in AP derivatives. Structural features and molecular interaction mechanisms that are responsible for the radical-inhibiting properties of these molecules could be revealed by studying their absorption and luminescence spectra.Experimental. Herein we study the following AP derivatives, which exhibit various degrees of antiviral properties: N-(3,5-di-tert-butyl-2-hydroxyphenyl)acetamide (AP I), N-(3,5-di-tert-butyl-2-methoxyphenyl)acetamide (AP II), N-(3,5-di-tert-butyl-2-hydroxyphenyl)propanamide (AP III), N-(3,5-di-tert-butyl-2-hydroxyphenyl)butanamide (AP IV), N-(2-hydroxy-3,5-di-tert-butylphenyl)benzamide (AP V), and N-(3,5-di-tert-butyl-2-hydroxyphenyl)-2-(4-isobutylphenyl)propanamide (AP VI):

Infrared spectra and structure of molecular complexes of aromatic acids

“…Conditions for the formation of intramolecular HBs are created in phenols with several OH groups and electronegative atoms such as N and O located in the ortho-position to one of the hydroxyls [8][9][10][11][12]. Therefore, the AB with ν max = 3464 cm -1 in the IR spectrum of BA I in CCl 4 (Table 1) were observed in the IR spectrum of BA I crystal (Fig.…”

“…As a rule, vibrations of free OH groups in spectra of phenols appear in the range 3640-3600 cm -1 [12,13]. It is noteworthy that phenol hydroxyls are not involved in IeI that form HBs at concentrations ≤3⋅10 -3 M in neutral solvents [8][9][10][11][12].…”