Luminescent transition metal complexes for functional food quality and safety: Analysis of bioactive constituents and contaminants

As public awareness of food safety and functional foods grows, there is increasing demand for rapid, sensitive, and reliable detection technologies. Conventional analytical methods, while accurate, often suffer from laborious sample preparation, long processing times, and limited adaptability to diverse food matrices. Luminescent transition metal complexes—including Ru(II), Ir (III), Pt (II), Re(I), Au(I) and Au(III)—have emerged as versatile platforms to overcome these challenges. They combine tunable photophysical properties, predictable excited-state behavior, and selective biomolecular recognition, enabling sensitive detection of bioactive constituents such as thiols, carboxylate metabolites, as well as food contaminants including pesticides, heavy metals, antibiotic residues, and mycotoxins. Beyond sensing, these complexes support antimicrobial applications inspired by food-relevant ligands and phytochemical scaffolds. Their structural and electronic adaptability allows signal amplification, real-time monitoring, and compatibility with diverse optical and catalytic transduction pathways. This review systematically summarizes recent advances in the design principles, sensing mechanisms, and multifunctional applications of luminescent transition metal complexes, providing a comprehensive perspective on their role in modern food quality, safety, and functional evaluation.