O,N-Donor Ligands as Molecular Architects: Bridging Bioactive Metal Complexes and Advanced Materials

This doctoral thesis explores the design, synthesis, characterization, and application of acylpyrazolone-, pyrazolate-, and bipyrazolate-based coordination compounds and Metal-Organic Frameworks (MOFs) as multifunctional systems spanning biological, sensing, materials, and electrochemical applications. Integrating coordination chemistry, materials science, and biological evaluation, this work illustrates how rational ligand design and metal coordination can fine-tune stability, reactivity, and functional performance across both molecular and solid-state platforms. A comprehensive series of zinc(II) and silver(I) complexes was synthesized and fully characterized through single-crystal and powder X-ray diffraction, spectroscopic techniques, thermal analysis, and computational methods. Zinc(II) coordination was shown to enhance physicochemical robustness while enabling controlled metal release under physiological conditions, a balance that proved critical for biological activity. Several zinc–pyrazolone complexes exhibited anticancer properties, including reduction of mutant p53 protein levels, inhibition of tumor spheroid growth, and suppression of cell migration, while others displayed significant anti-inflammatory, antioxidant, and antibacterial activity. Structure–activity relationships were established through combined experimental and theoretical studies, highlighting the influence of ligand substitution, coordination mode, and hydrolytic stability. Pyrazolate- and bipyrazolate-based coordination polymers and MOFs based on Zn(II) and Cu(II) demonstrated strong antibacterial and antifungal activity against representative Gram+, Gram-, and postharvest fungal pathogens. In most cases, antimicrobial action occurred via contact-mediated mechanisms involving membrane disruption and reactive oxygen species generation, with minimal metal-ion release. Translation of these materials into composite systems, including chitosan and ethyl cellulose films as well as polysulfone beads, enabled the development of bioactive coatings, antimicrobial packaging materials, and air filtration prototypes suitable for food preservation and storage environments. Beyond biological applications, the thesis addresses functional materials for sensing, gas separation, and iontronics. Silver(I) bipyrazolate thin films were developed as the first Ag -based chemoresistive sensors capable of selective ethylene detection at room temperature, with demonstrated applicability to fruit ripening monitoring. Flexible MOFs exhibiting gate-opening behavior were shown to enable selective gas separation through molecular sieving. Finally, redox-active MOFs were integrated into unidirectional charging devices (CAPodes) and logic circuits, demonstrating stable electrochemical rectification and highlighting the potential of porous crystalline materials for iontronic applications.