POLYAMINE-BASED FLUORESCENT RECEPTORS FOR EMERGING POLLUTANTS

Emerging Pollutants (EPs) are synthetic or naturally occurring chemical substances whose environmental concern is recently emerged and often not yet regulated by the Italian or European rules. Their wide use and release in the environment, as a consequence of the development of human activities (industry, agriculture, medicine) can lead to a continuous intake from living beings, with possible long- and medium-term toxic effects on human health. In this scenario, the development of economically viable, highly sensitive, easily manageable, and rapid response sensors to protect ecosystems and human health represent a compelling challenge. Luminescent polyamine-based chemosensors have been proven to perfectly fit these requirements. This PhD thesis is focused on the development of different fluorescent polyamine-based molecular systems for the recognition and sensing of representative target analytes of four different classes of EPs, such as ketoprofen (KP), perfluoroctanoic acid (PFOA), glyphosate (Gly) and glufosinate (Glu), and the main metabolite of Gly, aminomethylphosphonic acid, and bisphenol A (BPA), in aqueous media. The receptors herein proposed are based on linear triamine chains or cyclic polyamine scaffolds ([9]aneN3 and [12]aneN4) containing pendant fluorogenic units, including anthracene, pyrene, quinoline and a Ru(II)(phen)2bpy core. Protonated polyamines are able to interact with the anionic functions of the substrates via hydrogen bonding and/or salt bridging. The presence of the Zn(II) ion can be exploited as an additional anchor point for the carboxylate, phenolate or phosphate groups of the substrate, thanks to its ability to easily change or expand its coordination sphere. In both cases, multiple forces are involved in receptor-substrate adduct stabilization, including hydrogen bonding, coordinative interactions with the metal, and hydrophobic interactions. The binding of the substrate leads to modifications in the electronic characteristics of the receptor, causing changes of its emission properties, which can be used to optically detect the target analyte in solution.