Mitsuo Hiramatsu

Photochemistry of bichromophoric chain molecules containing electron donor and acceptor moieties: External magnetic field effects upon the photochemistry of N-[ω-(p-nitrophenoxy]alkyl]anilines

Abstract Magnetic field effects upon the photochemistry of chain molecules, A-(CH2) n-D, where A is a p-nitrophenoxy group and D an anilino or p-fluoroanilino group, have been studied by steady-state photolysis. Magnetic field effects due to the hyperfine coupling mechanism are observed when the chain length n is larger than 8.

Photochemistry of bichromophoric chain molecules containing electron donor and acceptor moieties. Dependence of reaction pathways on the chain length and mechanism of photoredox reaction of N-|ω-(p-nitrophenoxy)alkyl|anilines

Abstract Switching of photochemical reaction pathways was found for a series of bichromophoric species. D(CH 2 ) n A, consisting of electron donor and acceptor moieties by changing the number of methylene groups linking two chromophores. Long-chain molecules ( n ⩾ 8) show a photoredox reaction, while short-chain compounds ( n ⩽ 6) exhibit the photo-Smiles rearrangement when D  anilino and A  p -nitrophenoxy group.

Magnetic field effects on photoionization of N,N,N′,N′-tetramethyl-p-phenylenediamine in 2-propanol

Abstract Magnetic field effects on the photoionization yield of N,N,N′,N′-tetramethyl- p -phenylenediamine in deaerated 2-propanol have been studied by transient photoconductivity measurements. The photocurrent increases by about 15% in the presence of a magnetic field (720 mT). The results are interpreted in terms of a radical pair model.

Intramolecular photo-oxidation of triphenylphosphine and 10-alkylphenothiazine by nitro-aromatic moieties: Magnetic field effects and long-range oxygen transfer

Abstract Magnetic field effects have been observed for the photo-redox reaction of chain molecules containing an electron donor (triphenylphosphine or phenothiazine chromophore) and an acceptor (nitro-aromatic moiety). The yield of a cage product (nitroso compound) is reduced by 8–9% under a magnetic field of 0.64 T.

Photo-Smiles Rearrangement (IV) Electron-Transfer Mechanism of an Intra-Molecular Aromatic Nucleophilic Substitution

Abstract The mechanism of the photo-Smiles rearrangement involves formation of an intra-molecular radical ion-pair and a spiro-type Meisenheimer complex. The complete reaction pathways can be qualitatively described by the use of potential energy surfaces for the ground, the charge-transfer, and the locally-excited states. This can be regarded as an extention of the charge-transfer theory for aromatic substitution reactions developed by Nagakura to photochemical reactions.