1,10-Phenanthroline-5,6-dione as Workable Platform to Build Drug Candidates with Antimicrobial Action: Advances to Date

1,10-Phenanthroline-5,6-dione (phendione) is a functionalized derivative of 1,10-phenanthroline bearing two carbonyl groups at the 5,6-positions, which enhance its electron-accepting ability, polarity and coordination versatility. These structural features enable phendione to act as a bidentate ligand for a variety of transition metals, forming stable coordination compounds (or complexes) widely explored in coordination chemistry, catalysis, materials science and redox systems. In addition, phendione and its metal complexes have demonstrated relevant biological activities, including antibacterial, antifungal and antiprotozoal effects, attributed to DNA interaction, redox cycling, inhibition of key enzymes and interference with essential microbial processes such as protein synthesis. In the context of the escalating global burden of antimicrobial resistance, the discovery and development of innovative therapeutic strategies have become an urgent priority. In this scenario, phendione-based complexes have emerged as promising candidates owing to their remarkable structural diversity, versatile coordination chemistry, tunable physicochemical properties and ability to engage multiple and distinct mechanisms of action that differ from those of currently available clinical antimicrobial drugs. These characteristics provide opportunities for overcoming existing therapeutic limitations and expanding the arsenal of antimicrobial agents, particularly against clinically relevant pathogenic microorganisms, including multidrug- and pan-resistant strains for which effective treatment options remain critically limited. The present review provides a comprehensive and critical analysis of the current literature concerning the synthesis, structural features and antimicrobial properties of phendione-containing complexes, highlighting their potential as promising next-generation antimicrobial agents and exploring their mechanisms of action, biological relevance and future perspectives in the development of innovative therapies.