PMID- 15570395
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20050428
LR  - 20041130
IS  - 1474-905X (Print)
IS  - 1474-905X (Linking)
VI  - 3
IP  - 11-12
DP  - 2004 Nov-Dec
TI  - Mechanism of photoacid generation for an arylcycloalkylsulfonium salt by ring 
      opening and aryl cleavage.
PG  - 1052-7
AB  - The photochemistry of 1-(4-tert-butylphenyl)-tetrahydro-thiopyranium triflate 
      (1), an arylcycloalkylsulfonium salt, was investigated in acetonitrile and 
      methanol at low conversion in order to understand the reaction mechanism and its 
      efficiency as photoacid generator. Both types of C-S bond in 1 are cleaved from 
      the excited state. The heterolytic cleavage of the methylene C-S bond produces 
      4-t-BuC(6)H(4)S(CH(2))(4)CH(2)(+) by ring opening. The carbocation generates acid 
      and arylalkenylsufides by elimination or 1,2 hydride shift and elimination. The 
      predominantly homolytic cleavage of the aryl C-S bond yields 4-t-BuC(6)H(4)* and 
      c-C(5)H(10)S(+)* as the fragmentation products. The radicals react with the 
      solvent forming acid, pentamethylene sulfide and tert-butylbenzene. In methanol, 
      the formation of 4-tert-butylanisole indicates a contribution of solvolysis in 
      the excited state of 1 or a competing formation of free aryl cation by 
      heterolytic fragmentation. The acid generation efficiency of 1 in solution 
      (acetonitrile or methanol) is lower than that corresponding to triphenylsulfonium 
      triflate (TPS OTf) under the same conditions. This suggests a pathway for the 
      regeneration of 1 after photocleavage. The photochemistry of 1 is discussed in 
      terms of the contribution of fragmentation and ring opening reaction paths to its 
      overall acid generation efficiency, a key property in terms of its applications 
      in resist formulations.
FAU - Sanrame, Carlos N
AU  - Sanrame CN
AD  - Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa ON, K1N 
      6N5, Canada.
FAU - Brandao, Mariette S B
AU  - Brandao MS
FAU - Coenjarts, Christopher
AU  - Coenjarts C
FAU - Scaiano, J C
AU  - Scaiano JC
FAU - Pohlers, Gerd
AU  - Pohlers G
FAU - Suzuki, Yasuhiro
AU  - Suzuki Y
FAU - Cameron, James F
AU  - Cameron JF
LA  - eng
PT  - Journal Article
DEP - 20041005
PL  - England
TA  - Photochem Photobiol Sci
JT  - Photochemical & photobiological sciences : Official journal of the European 
      Photochemistry Association and the European Society for Photobiology
JID - 101124451
EDAT- 2004/12/01 09:00
MHDA- 2004/12/01 09:01
CRDT- 2004/12/01 09:00
PHST- 2004/12/01 09:00 [pubmed]
PHST- 2004/12/01 09:01 [medline]
PHST- 2004/12/01 09:00 [entrez]
AID - 10.1039/b408992h [doi]
PST - ppublish
SO  - Photochem Photobiol Sci. 2004 Nov-Dec;3(11-12):1052-7. doi: 10.1039/b408992h. 
      Epub 2004 Oct 5.