es7b04510_si_001.pdf (3.97 MB)
Photooxidation of Aniline Derivatives Can Be Activated by Freezing Their Aqueous Solutions
journal contribution
posted on 2017-11-17, 20:46 authored by Pablo Corrochano, Dana Nachtigallová, Petr KlánA combined
experimental and computational approach was used to
investigate the spectroscopic properties of three different aniline
derivatives (aniline, N,N-dimethylaniline,
and N,N-diethylaniline) in aqueous
solutions and at the air–ice interface in the temperature range
of 243–298 K. The absorption and diffuse reflectance spectra
of ice samples prepared by different techniques, such as slow or shock
freezing of the aqueous solutions or vapor deposition on ice grains,
exhibited unequivocal bathochromic shifts of 10–15 nm of the
absorption maxima of anilines in frozen samples compared to those
in liquid aqueous solutions. DFT and SCS-ADC(2) calculations showed
that contaminant–contaminant and contaminant–ice interactions
are responsible for these shifts. Finally, we demonstrate that irradiation
of anilines in the presence of a hydrogen peroxide/O2 system
by wavelengths that overlap only with the red-shifted absorption tails
of anilines in frozen samples (while having a marginal overlap with
their spectra in liquid solutions) can almost exclusively trigger
a photochemical oxidation process. Mechanistic and environmental considerations
are discussed.