Synthesis and Application of New Coumarin‐Based UV Absorbers

ABSTRACT A series of coumarin‐based UV absorbers with different conjugated structures are synthesized from 4‐methylesculetin or 7‐hydroxycoumarin via efficient nucleophilic reactions with acyl chlorides, sulfonyl chlorides, and halogenated derivatives. The products are characterized by NMR and HRMS, and their optical properties are evaluated. All the compounds exhibit strong UV absorption in the 220–360 nm range. When incorporated into UV‐curable coatings, they significantly improve photostability and extend storage time, resulting in films that are smooth, transparent, and show good hardness and adhesion after curing. This work presents a simple and efficient synthetic approach for coumarin‐based UV absorbers, providing a new strategy for developing structurally diverse and tunable UV‐absorbing materials.