Six methyl-substituted triaryl phosphates (TAPs) were synthesized for application as acid generators for thermodeveloping type photosensitive materials [(Aryl-O)3PO; Aryl group, 2-tolyl (ToTP), 3-tolyl (TmTP), 4-tolyl (TpTP), 2,6-xylenyl (TooXP), 2,4-xylenyl (TopXP), and 3,4-xylenyl (TmpXP)]. The TAPs yielded a bisaryl compound and a phosphoric acid monoaryl ester equivalently after photoirradiation with 254-nm radiation. Among these compounds, TmpXP was the most reactive yielding 3,3′,4,4′-tetramethylbiphenyl (78%) after only 4-h irradiation. During the photoirradiation of TAP, strong emissions were detected. Each spectrum had two emission maxima. The shorter wavelength maximum was assigned to monomer fluorescence and the longer one to excimer fluorescence. Emission quenching was carried out by using oxygen. The photosensitivities of thin films of poly(4-trimethylsiloxystyrene) (PSSt) and TAP were studied. Among the films, the PSST-TmpXP thin film was the most sensitive (35 mJ cm−2).
Ikuo Naito, Yoshinori Sugao, Kosuke Sugiyama, Keito Kobayashi, "Application of Triaryl Phosphate to Photosensitive Materials (III): Structure and Reactivity of Methyl-Substituted Triaryl Phosphate" in Journal of Imaging Science and Technology, 1998, pp 163 - 168, https://doi.org/10.2352/J.ImagingSci.Technol.1998.42.2.art00012