Kiyoshi Mutai

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.

Photochemistry of chain molecules containing 4-nitro-1-naphthoxyl and anilino chromophores. Switching of reaction pathways due to methylene chain length and magnetic field effects

Abstract Photochemistry of N-[ω-(4-nitro-1-naphthoxyl)alkyl] anilines depends on the chain length. Species with six or fewer methylene groups undergo the photo-Smiles rearrangement, while higher homologues ( n ⩾ 8) yield photo-redox reaction products. Magnetic fields cause large effects on the product distribution of the photo-redox reaction and can be used for the selection of reaction pathways.

Thermal and photochemical rearrangements of 1,4-dithiin sulfoxides

Abstract Thermolysis of 2,5-diphenyl-1,4-dithiin-1-oxide afforded 2-formyl-2,4-diphenyl-1,3-dithiole, which was obtained also in photolysis along with another rearranged product, 2-benzoyl-4-phenyl-1,3-dithiole.

Intramolecular N-H ⋯ O hydrogen bonding in N- (ω-phenoxyalkyl) anilines

Abstract In order to compare the characteristics and spectral behaviours of the N-H group acting as a proton donor in the intramolecular N-H ⋯ π interaction (observed in the system Ar(CH2)nNHPh) with intramolecular hydrogen bond, the N-H stretching absorption of a system, ArO(CH2nNHPh (N-H ⋯ O hydrogen bond), was measured. The band due to the hydrogen bonding was detected from the change of its intensity caused by varying the substituent in Ar group. The limitation of the chain length to the bond formation was found to be n =5 or eight-membered ring as is also the case in the N-H ⋯ π interaction. In this respect, it can be said that the N-H ⋯ π interaction resembles the rather general type of intramolecular hydrogen bonding. Some spectral behaviours of the N-H group in both cases, especially peak displacement Δvmax by the interaction, are discussed. In the compound p-O2NC6H4O(CH2)3-NHPh, an unusually low value of Ab/Af (a measure of the equilibrium constant between the bonded and the free forms) was observed.

Magnetic field effects upon photoredox reactions of bifunctional chain molecules containing anilino and nitro-aromatic chromophores

Abstract Bichromophoric chain molecules, p-O2NC6H4O(CH2)12NBzC6H5 (Bz=*CX2C6H5, *C=12C or 13C, X=H or D), undergo two different intramolecular photoreactions involving the benzylic and methylene chain oxidations. The end product ratio for two competitive processes depends upon the magnetic field strength and nuclear magnetic moments within biradical intermediates.

The rearranged products in thermal decomposition of 2,5-diaryl-1,4-dithiin. Evidence for valence isomerization of 1,4-dithiin system.

Bis(2,4-diaryl-3-thienyl) disulfide was isolated in the thermal decomposition of 2,5-diaryl-1,4-dithiin. The formation of the rearranged product as well as the kinetic data suggest strongly the valence isomerization of 2,5-diaryl-1,4-dithiin in the course of the decomposition.

A stable triplet non-Kekulé molecule; m-phenylene-2,2′-bis(1,1:3,3-di-2,2′-biphenylenepropenyl)

Abstract Esr experiments of the titled non-Kekule molecule in an MTHF matrix between 7 and 85 K show that a triplet ( |D|/hc = 0.00494, and |E|/hc: ≤ 0.00019 cm−1) is the ground-state (or both the triplet and a singlet lie within 20 cal/mol).

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.

(3-Nitrenophenyl)methylene: a ground state quintet molecule having both carbenic and nitrenic atoms

(3-Nitrenophenyl)methylene (1), a non-Kekule molecule with quintet ground state, has been generated photochemically from (3-azidophenyl)diazomethane in organic matrix at cryogenic temperatures.