We
report here a simple and cost-effective technique for classification
of the samples of writing inks based on their digital color analysis
(DCA). The dynamics of artificial aging of writing inks under UV irradiation
was studied by means of DCA for the first time. The color of ballpoint
pen marks was recorded over time using an ordinary consumer DSLR camera.
The inks were classified according to the parameters of their color
degradation curves with precision superior to conventional Raman scattering
method, which serves as a proof-of-concept of the proposed approach.
The reported approach has broad prospects for implementation by criminalists
for document investigation when document forgery is suspected. The
proposed technique can be of interest not only in the field of forensic
science but also for those who deal with dyes and dye-containing materials
and their degradation over time as well as for the study of any processes,
the evolution of which is reflected in a color change.
A one-step synthesis of cytotoxic 2-aroylpyrimidines by the denitrogenative reaction of 1-tosyl-1,2,3-triazoles with isoxazoles under rhodium catalysis has been developed. According to the density functional theory calculations and control experiments, the disclosed reaction proceeds via the rearrangement of an oxadiazatetraene intermediate involving a cascade of intramolecular aza-Diels−Alder and retro-aza-Diels−Alder reactions. The presence of a substituent at C4 of the isoxazole is a prerequisite for the formation of the pyrimidines.
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