The development of highly sensitive and selective devices for the rapid screening of polycyclic aromatic hydrocarbons (PAHs) in water is nowadays a crucial challenge owing to their alarming abundance in the environment and adverse health effects. Herein, inspired by the unique π-stacking interactions taking place between identical small aromatic molecules, a novel, generic and straightforward methodology to electrochemically determine and discriminate such pollutants is described. Such method is focused on covalently anchoring different PAHs on an Indium Tin Oxide (ITO) electrode surface by means of self-assembled monolayers (SAMs). The surface anchored PAHs act as recognition units to selectivity interact with a specific PAH target of the same nature. By tailoring the recognition platform with four different model PAH molecules (naphthalene, anthracene, pyrene and fluoranthene) and carrying out an electronic tongue approximation, the selective discrimination and quantification of the selected PAHs in aqueous samples at ultra-low concentrations was achieved impedimetrically, which was also validated using a certified reference PAH mixture.
The functionalization of substrates with radical species
has been
shown to be a promising strategy to confer novel physical and chemical
properties to a surface. Urazole radicals are persistent nitrogen-centered
radicals that are insensitive to oxygen, making them desirable targets
for the functionalization of surfaces. Here, we succeed in the preparation
of self-assembled monolayers (SAMs) of a 1-arylurazole radical on
Au surfaces using two different approaches. In the first approach,
a SAM of a radical precursor on the gold surface is prepared followed
by its chemical oxidation to generate the active urazole radical.
In the second route, the radical is generated in solution and subsequently
grafted on the Au surface. In both cases, the SAMs exhibit active
radical behavior, but the SAM prepared by the first approach demonstrates
greater surface coverage of the electroactive urazole radical species.
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