Safranine-T triplet-state quenching by modified silica nanoparticles

Abstract

Modified silica nanoparticles (NPs) were obtained by esterification of the silanol groups of fumed silica nanoparticles with 4-hydroxymethyl-N,N- dimethylbenzenamine. These particles were characterized by Fourier transform infrared spectroscopy, 13C and 29Si nuclear magnetic resonance, thermogravimetry, X-ray photoelectron spectroscopy, transmission electron microscopy with energy-dispersive spectroscopy, and measurement of the specific surface area. Laser flash photolysis experiments at the excitation wavelength of 532 nm were performed with safranine-T and NP suspensions in acetonitrile. Comparative experiments of safranine-T with solutions of 4-hydroxymethyl-N,N-dimethylbenzenamine and two other related alcohols were performed. Evidence for the triplet safranine-T H-abstraction from the organic group of the particles is obtained. The electron transfer from the organic group to the triplet excited states of safranine-T also takes place, as shown by the absorption traces obtained at 50 μs after the laser shot.