Synthesis of photoactive compounds from 2H-pyran-2-ones and their photophysical properties.

2H-Pyran-2-ones and their derivatives constitute a versatile class of heterocycles that exhibit unique structural and electronic features, making them valuable building blocks for photoactive compounds. Their partial aromatic character, diverse reactivity, and inherent UV/visible absorption enable the construction of conjugated systems with tunable photophysical properties. This review highlights recent advances in the synthesis of photoactive compounds derived from 2H-pyran-2-ones and provides a detailed analysis of their photophysical properties. Particular emphasis is placed on structure-property relationships, light-induced transformations, and design principles that govern emission behaviour and stability. Case studies on metal ion sensors, ratiometric probes, and aggregation-induced emission luminogens are presented to illustrate the functional versatility of these scaffolds. In addition, the review underscores the relevance of pyranone-based systems in sustainable chemistry, as many of their photochemical transformations proceed under mild conditions. By consolidating current knowledge, this article aims to guide future efforts in the rational design of 2H-pyran-2-one-derived photoactive materials for emerging applications in optoelectronics, diagnostics, and responsive materials science.