Synthesis and properties of ionic photoacid generators based on iodonium salts†

Abstract

This paper presents the design and synthesis of nine ionic photoacid generators (PAGs) based on iodonium salts. The compounds were characterized using ¹H NMR, ¹³C NMR, ¹⁹F NMR and UV, and the structures and properties of 9 PAG molecules were determined. The maximum ultraviolet absorption wavelength of each PAG is in the range of 200–250 nm, with a wide absorption domain, making it highly applicable. In addition, using the uneven discoloration of rhodamine B (RB) in the presence of acid, the acid production efficiency of 9 PAGs under 254 nm ultraviolet irradiation was quantitatively measured in acetonitrile. It was found that all 9 PAGs underwent I–C cleavage and generated specific acids and other photolysis products. At the same time, the mechanism for the heterolytic cleavage of the I–C bond to generate acid in extreme ultraviolet (EUV) and electron beam (EB) lithography was calculated using time-dependent density functional theory (TD-DFT).