ABSTRACT
Seven new 2,4,6-triarylpyrimidines were synthesized and their solvatofluorochromism investigated in 12 solvents and in an aqueous micellar solution of reduced Triton X-100. A multiparametric analysis of their emission band showed that the solvent dipolarity and basicity were mainly responsible for their solvatofluorochromism, which arose from an internal charge-transfer from a donor fragment to the pyrimidine acceptor, confirmed by theoretical calculations. In the micellar system, quenching of their fluorescence by addition of derivatives of 2,2,6,6-tetramethylpiperidinoxyl (TEMPO) radical was investigated and the results were consistent with the spectral changes brought about by the micro-heterogeneous system.
ABSTRACT
A simple protocol is described for locating the site of action of an antioxidant (AO) in a micro-heterogeneous mixture, based on the pattern of the reactivity curve towards the AO of a series of 4-alkanoyl TEMPO radicals. The resulting cut-off curves yield information regarding the hydrophobic microenvironment surrounding the reactive AO group, and its accessibility by the probe. Convex curves are an indication of an AO located in a more hydrophilic environment, while concave plots originate from AOs in a more hydrophobic location in the micro-heterogeneous system.
