Polimero basato su complessi triazolici di cationi divalenti per la potenziale cattura di fluorochinoloni

Abstract Click-chemistry is a synthetic approach born to create substances by joining modular blocks with heteroatom links. To be defined “click-chemistry”, a process must follow some criteria: the reaction must be wide in scope, give high yield, generate non-toxic byproducts and be stereospecific. This approach is really useful for Huisgen 1,3-dipolar cycloadditions, a class of reactions that unites two unsaturated compounds to gives five-membered heterocycles. Cycloadditions between a terminal alkyne and an azide lead to a mixture of 1,4- and 1,5- disubstituted triazole. In order to head the reaction to the 1,4-disubstituted product, Cu(I) can be used as catalyst. This type of reaction, the so called Copper-catalysed azide–alkyne cycloaddition (or CuAAC reaction), involves an alkyl or aryl azide and a terminal alkyne to give the 1,4-disubstituted [1,2,3]-triazole. Cu(I) is thermodynamically instable, and is generated in situ from a Cu(II) salt and sodium ascorbate as reductant. It is common to use a ligand for the copper, in order to protect the so obtained Cu(I) from oxidation. Tris(benzyltriazolylmethyl)amine (TBTA) is the most used ligand in click-chemistry: it a tripodal tetradentate ligand, that binds Cu atom using N-3 of the triazoles and the amine. CuAAC reactions have been applied to polymers synthesis, too, giving access to different types of materials: linear polymers, Hyper-Cross-linked Polymers, Porous Organic Polymers. These types of materials find application in different fields, ranging from gas adsorption to heterogeneous catalysis. The polymer target of my internship was prepared through a click-chemistry approach, using TBTA as monomer unit. It was then loaded with metal cations (Cu(II) and Mg(II)) and tests for fluoroquinolones uptake were performed. Fluoroquinolones (a class of antibiotics) are an emerging threat: because of their excessive use, started to develop drug-resistance and also they are found in the environment as pollutants. Therefore, materials capable to separate these antibiotics from water would be a starting point in the fight against pollution. To understand the interactions between tris-triazoles located in the polymer and Cu(II) cations, TBTA was synthesized and used as model compound. Potentiometric, spectrophotometric and pH-spectrophotometric titration were performed, in order to determine the equilibrium constants. During this study, we observed that the complex Cu(II)-triazole is not stable at pH>8. The polymer synthesized, named POP-Click, was characterized with solid-phase analysis methods (thermogravimetric analysis, differential scanning calorimetry, SEM-EDX, elemental analysis CHN). The polymer was then loaded with metal cations (Cu(II) and Mg(II)), by stirring a known quantity of polymer in a solution of the metal salt (we used Cu(CF3SO3)2 for Cu(II) uptake and Mg(NO3)2 for Mg(II) uptake). The characterization of the loaded polymer included also ICP analysis after mineralization of the sample, in order to determine the weight % of metal in the polymer. The loaded polymer was tested with enoxacin, to determine the efficiency of adsorption of the antibiotic.