460062-33-3Relevant academic research and scientific papers
Time-resolved EPR and laser photolysis investigations of photoinduced ω-bond dissociation in an aromatic carbonyl compound having triplet π,π* character
Yamaji, Minoru,Inomata, Susumu,Nakajima, Satoru,Akiyama, Kimio,Tero-Kubota, Shozo,Tobita, Seiji,Marciniak, Bronislaw
, p. 211 - 216 (2007/10/03)
Photochemical properties of photoinduced ω-bond dissociation in p-phenylbenzoylbenzyl phenyl sulfide (PPS) having the lowest triplet state (T1) of π,π* character in solution were investigated by time-resolved EPR and laser flash photolysis techniques. PPS was found to undergo photoinduced ω-bond cleavage in the excited lowest singlet state (S1(n,π*)) with a quantum yield (Φrad) of 0.15 for the radical formation, which was independent of excitation wavelengths. Based on the facts of the observation of the absorption spectrum of triplet PPS upon triplet sensitization of xanthone, and absence of CIDEP signal, ω-cleavage was shown to be absent in the T1(π,π*) state of PPS. Considering the electronic character of the excited and dissociative states of PPS, a schematic energy diagram for the ω-bond dissociation of PPS was shown.
Triplet energy distribution in photoinitiators containing two dissociable groups
Shah, Bipin K.,Neckers, Douglas C.
, p. 6117 - 6123 (2007/10/03)
Suitable probe molecules containing the benzophenone chromophore and one dissociable bond [perester 1 or C-X (4, 5)] or two such bonds (2, 3) have been synthesized and studied to examine intramolecular triplet energy dispersion. Triplet energies and phosphorescence quantum yields as well as quantum efficiencies of bond scissions have been studied, and the flow of triplet energy in such molecules is discussed. Upon irradiation at 350 nm in either benzene or methanol, the target peresters undergo dissociation of both cleavable groups, producing a pair of radicals. The presence of a benzylic chloride function has little influence on the efficiency of perester dissociation. However, the presence of a benzylic bromide function was found to decrease the quantum yield of decomposition of the perester function of 3. This can be explained by taking into account the effect of the heavy atom and the rate of cage geminate radical pair recombination. The nature of the heavy atom perturbation, however, was found to be different in 5 as compared with 3.
