title: Stepwise photocleavage of two C-O bonds of 1,8-bis[(4-benzoylphenoxy)-methyl]naphthalene with three-step excitation using three-color, three-laser flash photolysis.
abstract: Stepwise photocleavage of two naphthylmethyl-oxygen bonds of 1,8-bis[(4-benzoylphenoxy)methyl]naphthalene (1,8-(BPO-CH2)2Np, 1) was observed during three-color, three-laser flash photolysis at room temperature. The mechanism from 1 to the final product, acenaphthene (2), was clearly elucidated. The first (308 nm, 5 mJ pulse-1) XeCl laser excited 1 to the lowest triplet excited state 1(T1), in which the excited energy was localized in the naphthalene moiety, but the C-O bond cleavage did not occur. The second (430 nm, 7 mJ pulse-1) OPO laser excited 1(T1) to the higher triplet excited states 1(Tn) in which the excited energy is delocalized in the naphthalene moiety and C-O bonds, and one C-O bond cleavage occurred. The third (355 nm, 10 mJ pulse-1) YAG laser excited the carbon-centered radical in the ground state 1-(BPO-CH2)NpCH2*(D0) to its excited states 1-(BPO-CH2)NpCH2*(Dn), from which the second C-O bond cleavage occurred to give 2 as the final product. This is a successful example of stepwise cleavage of two equivalent C-O bonds in a molecule using three-color three-laser photolysis method.
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Xichen
authors.initials: X
authors.lastname: Cai
authors.forename: Masanori
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Michihiro
authors.initials: M
authors.lastname: Hara
authors.forename: Sachiko
authors.initials: S
authors.lastname: Tojo
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ouchi
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Kawai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Endo
authors.forename: Mamoru
authors.initials: M
authors.lastname: Fujitsuka
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Majima