Novel promising antibacterial agents and carbon dioxide capture and valorization materials based on pyrazolate Coordination Polymers and Metal-Organic Frameworks

Coordination Polymers (CPs) and Metal-Organic Frameworks (MOFs) have emerged in the last thirty years, due to their hybrid organic/inorganic nature and incredible versatility, which has allowed their wide use in various fields: catalysis, sensing, luminescence, magnetism, conductivity, antimicrobial activity etc. Crystallinity and porosity of MOFs, in addition, open to other interesting applications such as gas storage and conversion, separation and drug delivery. The thesis work has focused on two main aspects: the antibacterial activity of CPs and MOFs exploring the simultaneous activity of the metal center and the organic molecules, and the capture and conversion of carbon dioxide in useful chemicals within MOFs pores. In detail, eight Cu(II) CPs based on 4-X-pyrazolate linkers (X= H, Cl, Br, I and NO2) have been investigated as antibacterial agents against S. aureus, E. coli and P. aeruginosa, whereas six MOFs consisting of zinc or copper metal centers and three different bipyrazolate linkers (4,4'-bipyrazole, 1,4-bis(1H-pyrazol-4-yl-3,5-dimethyl)benzene and 3-amino-4,4'-bipyrazole) have been tested against S. aureus and E. coli. Bacterial growth inhibition, antibacterial rate (%), ROS and PI assays and metal ions release tests revealed the action mechanism which is expressed in the interaction between the CP/MOF surface with the bacterial cell in combination with metal ions release, and in the production of ROS damaging the bacterial cell content. The second issue deals with CO2 trapping and its conversion by two distinct techniques: i) fixation by reaction with activated epoxides and ii) electroreduction. In the first case, two Zn(II) MOFs based on isomeric forms of diamino-4,4’-bipyrazole linkers have been synthesized, solid-state characterized (PXRD, TGA, IR, porosimetry) and tested as heterogeneous catalysts in the conversion of carbon dioxide and epibromohydrin or epichlorohydrin into the corresponding cyclic carbonates in solvent-free conditions, at 393K and 5 bar of CO2 pressure. Lastly, four mixed-metal MOFs with formula unit [CuxNi1-x(3,5- diamino-4,4’-bipyrazolate)] (CuxNi1-x, x = 0.05, 0.1, 0.2, 0.5) were synthesized, characterized (PXRD, TGA, IR, porosimetry, SEM, EDX, ICP, XPS) and employed for carbon dioxide electroreduction to produce methane and carbon monoxide.