Photolysis mechanism of Di(tert‐butylphenyl)iodonium salt using 2‐isopropylthioxanthone as a sensitizer.

Diaryliodonium salts (Ar2I+X−) are used as a photosensitive initiator that generates acid or radical species by ultraviolet light irradiation. Recently, sensitization of Ar2I+X− has gained importance owing to the escalating demand for high‐sensitive initiators with longer wavelength absorption such as 365 and 436 nm. However, the mechanism of photolysis of Ar2I+X− has not been strictly elucidated. This paper shows discussions of the details of its mechanism. Herein, we analyzed the photosensitization of Ar2I+X− with 2–isopropylthioxanthone (ITX) based on transient absorption techniques. As a result, it was revealed that electron transfer occurred from a triplet excited state of ITX to Ar2I+X− with an electron transfer rate constant of 4.2 × 109 s−1. Furthermore, high performance liquid chromatography measurements found the quantum yield of the photolysis was determined to be 0.48. [ABSTRACT FROM AUTHOR]