45 research outputs found
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埮现çžäºäœçšã«åºã¥ãã¹ãã³æ Œåç·©åã«ãã説æã§ãããWe have investigated photochemical behavior of bichromophoric chain species containing hydrogen-donor and acceptor moieties. This type of chain molecules undergo intramolecular hydrogen abstraction reactions. Apparent magnetic field and magnetic isotope effects have been observed on photoredox reaction yields of a 4-nitro-1-naphthoxy derivative containing anilino moiety. This is one of few cases where the unimolecular cage reaction predominates in the zero-field and the bimolecular escape process becomes a major reaction pathway on application of external magnetic fields. On the other hand, conspicuous magnetic isotope effects (MIEs) have been detected on lifetimes of biradicals derived from bifunctional chain molecules consisting of aromatic carbonyl compounds and hydrogen-donor groups.Some aspects of bifunctional photochemistry of nitroaryloxy and aromatic carbonyl species are summarized as follows : [1] magnetic field effects on photoredox product yields derived from the bichromophoric parent compounds containing nitro-aromatic moieties,[2] magnetic field and magnetic isotope effects on decay profiles of biradical species,[3] disappearance of heavy carbon magnetic isotope effects in a very high field region.The third phenomenon is explained by taking account of the anisotropic magnetic interactions which contribute to the spin-lattice relaxation. The MIEs are observed when the anisotropic hyperfine interaction is of dominant importance. The MIEs disappear in the presence of very high fields (> 6T) where the anisotropic Zeeman interaction predominates.ç 究課é¡/é åçªå·:13555218, ç 究æé(幎床):1996-1997åºå
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Photochemistry of large ring 2-phenylcycloalkanone in the presence of molecular oxygen
é沢倧åŠè¬åŠéšé沢倧åŠå€§åŠé¢èªç¶ç§åŠç 究ç§çç掻æ§ç©è³ªç§åŠPhotolysis of 2-phenylcyclododecanone (2PCDD, ring size: C12) has been investigated in an air-saturated solution. The ïŸïœ±-photocleavage of 2PCDD (Norrish type I) has led to the formation of triplet acyl-benzyl biradical (3BR) which reacts with O2 to produce a peroxyester intermediate. A major photoproduct of 2-phenyl-1-oxacyclododecane is formed by a stepwise decarboxylation from the peroxyester intermediate. The peroxyester is also a common intermediate for minor products of benzaldehyde, cyclodecane, and acetophenone. 1-Phenylcycloundecane is produced from decarbonylation of 3BR. On the other hand, 3BR undergoes intersystem crossing to the singlet biradical which in turn recombines to form the parent 2PCDD or to afford a cage product of cyclophane. The recombination yield to the starting species is estimated to be 0.5 by measuring a time evolution of enantiomer concentration of 2PCDD starting from one optically pure enantiomer. Photolysis mechanism of 2PCDD in the presence of molecular oxygen has been proposed and discussed. © 2006 Elsevier B.V. All rights reserved