Formation of intramolecular dimer radical ions of diphenyl sulfones

Abstract

Dimer radical ions of aromatic molecules in which excess charge is localized in a pair of rings have been extensively investigated. While dimer radical cations of aromatics have been previously produced in the condensed phase, the number of molecules that form dimer anions is very limited. In this study, we report the formation of intramolecular dimer radical ions (cations and anions) of diphenyl sulfone derivatives (DPs) by electron beam pulse radiolysis in the liquid phase at room temperature. The density functional theory (DFT) calculations also showed the formation of the dimer radical ions. The torsion barrier of the phenyl ring of DPs was also calculated. It was found that the dimer radical ions show the larger barrier than the neutral state. Finally, stability of the dimer radical anion is dependent on not only the inductive effect of the sulfonyl group but the conjugation involving the d-orbital of the S atom and the phenyl rings.

Mechanistic Investigations into Amination of Unactivated Arenes via Cation Radical Accelerated Nucleophilic Aromatic Substitution

“…It is unclear whether the dimer itself or the free arene undergoes oxidation. Arene cation radical dimers have previously been observed in solution using time-resolved laser spectroscopy as an association between one neutral and one oxidized form of the relevant arene. − We were unable to observe cation radical dimer formation in solution; however, we believe this may serve to stabilize the oxidized intermediate and extend its lifetime by preventing premature back electron transfer with the reduced form of the photoredox catalyst. Ultimately, nucleophilic addition to the dissociated arene cation radical would lead to product formation.…”

Study on deprotonation from radiation-induced ionized acrylate polymers including acid-generation promoters for improving chemically amplified resists

“…Details have been provided elsewhere. 28,33) Polymers 1-4 (100 mM/unit conc.) in 1,2dichloroethane (DCE) solutions were used as the samples.…”

“…In this study, trioctylamine was used as a model for quencher. Table II shows the degree of polymerization of each polymer 36) The optimized structures of DTS 28) and PAG 41) were obtained from previous reports. The radial distribution function (RDF) was calculated from the MD results using GROMACS.…”

“…14,15) Furthermore, diphenyl sulfones react with electrons to produce radical anions. 28) Subsequently, electron transfer occurs from the radical anion to the PAG with high electron affinity, lowering the probability of the hole-electron recombination reaction and thus resulting in an increase in the acid yield of the resist polymer.…”

Sensitization of polymethacrylate resist with adding acid-generating promoters upon exposure to EUV light

“…We propose that diphenyl sulfone derivatives show promise as an AGP. Although diphenyl sulfones capture electrons to form radical anions, 31) the acid yield is not reduced by electron transfer from the radical anion to the PAG. 29) Moreover, in ArF lithography, the addition of di-p-tolyl sulfone (DTS) as an AGP to methacrylate polymers has been found to increase the initial acid yield.…”