Nonionic Photoinitiators Based on Coumarin Derivatives of Bis-Oxime Esters

Photoinitiators (PIs), as essential components of photosensitive materials, are widely used in photolithography, photocuring, and other photochemical reactions. Coumarin derivatives, known for their excellent optical properties, exhibit significant potential for application in the design and synthesis of photoinitiators. This study focuses on bis-sulfonic acid oxime esters based on coumarin derivatives, aiming to develop green, low-toxicity, and highly efficient PIs. By systematically modifying the molecular structure of coumarin derivatives, the effects of different substituents on photoacid generation efficiency were investigated to provide theoretical and experimental support for optimizing PIs performance. Six PIs were synthesized and their photoinitiating and photoacid generation capabilities were evaluated using ultraviolet–visible (UV–vis) spectroscopy, fluorescence spectroscopy, and real-time infrared spectroscopy (RT-IR); their reaction mechanisms were analyzed. The results demonstrate that these coumarin-based bis-sulfonic acid oxime ester PIs possess excellent photosensitizing properties and efficiently generate sulfonic acid under UV irradiation. This study not only enriches PI synthesis strategies but also provides avenues for their industrial application, holding considerable theoretical and practical significance.