• Journal of the Korean Chemical Society
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• v.25 no.1
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• pp.13-20
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• 1981

Iminoxyl biradical may be useful biradical spin probe for the investigation of the dynamic distribution of the directors in some liquid crystal. The iminoxyl biradical has been synthesized by a new convenient method and the intermediate products of each step were identified by the measurement of melting point and spectroscopic methods such as IR, UV, NMR and Mass spectrometry. The final product, iminoxyl biradical, was identified by the electron paramagnetic resonance spectroscopy and the interaction between two spins of the radical was discussed based on the EPR peaks.

• Journal of Photoscience
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• v.4 no.1
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• pp.7-10
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• 1997

The structures of 8-membered azalactone isomers produced from photocyclization of 2-(N,N-dibenzylamino)ethyl benzoylacetate were determined by the X-ray structure analysis to clarify the stereochemical behavior of a 1,8-biradical. The remarkable stereoselectivity in cyclization of the 1,8-biradical to form cis- and trans-isomers of the azalactone was not observed. The ring conformations were boat-chair like and dihedral angles between C$_5$- and C$_6$- phenyl groups were ca 45$\circ$ in the both isomers. The 1,8-biradicals in the transition state for the cyclization would have nearly same boat-chair like conformation and twisted configuration with the dihedral angle of ca 45$\circ$ as the corresponding isomer, and this is responsible for luck of stereoselectivity in long-chain biradical cyclization.

• Bulletin of the Korean Chemical Society
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• v.29 no.11
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• pp.2140-2144
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• 2008

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3465-3468
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• 2011

• Journal of Photoscience
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• v.10 no.1
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• pp.49-60
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• 2003

How stereo selectivity in singlet and triplet photocycloaddition and photocyclization reactions, respectively, is linked to spin selectivity and how this link affects our understanding of photochemical reaction mechanisms, is described in this review. As illustrative examples, the Paterno-Buchi reaction and the Norrish-Yang cyclization are described with emphasis on triplet biradical structure and dynamics.

• Bulletin of the Korean Chemical Society
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• v.8 no.1
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• pp.27-30
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• 1987

Photocycloaddition of 1,4,5,8-tetraazaphenanthrene to olefins proceeds through a biradical triplet-state intermediate as proven by the photoproduct stereochemistry, quantum yield measurements, sensitization, quenching, and fluorescence and phosphorescence quenching studies.

• Journal of Photoscience
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• v.11 no.32
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• pp.75-76
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• 2004

${\alpha}$,${\alpha}$-Dibromovalerophenone and ${\alpha}$,${\alpha}$-dichlorovalerophenone were prepared and their photochemical behaviors were investigated. The former gives C-Br cleavage products and the latter gives mainly the Yang photocyclization products upon irradiation. The reactivity of the chlorine substituted ketone turned out to be quite different from that of ${\alpha}$,${\alpha}$-difluorovalerophenone which gives both the cyclization and elimination products from the 1,4-biradical intermediate.

• Journal of Photoscience
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• v.1 no.1
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• pp.67-68
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• 1994

INTRODUCTION : The photochemistry of nitro chromophore has been the subject of intense study only in recent years. Unlike the carbonyl functional group, of which the photochemistry has been quite extensively studied and fairly well understood, as a result of excellent work done by numerous physical and organic photochemists alike, the nature of photochemistry of nitro group has only recently been systematically explored. The photochemistry of nitro group exhibits general features of the photochemistry of the carbonyl groups such as hydrogen abstraction by the diradical species generated from the n-$\pi$$^*$ excited state of the nitro group. Other photochemical pathways common to the carbonyl group such as the biradical intermidiate formation, photocycloelimination, and cydoaddition reactions are also open for the nitro group. Of all the photochemical reactions of the nitro group mentioned above, hydrogen abstraction by the n-$\pi$$^*$ excited state of the nitro group has drawn much attention by synthetic organic chemists and polymer chemists. In the field of organic synthesis, above mintioned photochemical reaction has been utilized in the photoprotection-deprotection chemistry.

• Bulletin of the Korean Chemical Society
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• v.20 no.1
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• pp.76-80
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• 1999

The effects of zeolites on the intramolecular [2+2] photocycloadditions of 3-(3-butenyl)cyclohex-2-enone (la) and 3-(2-propenoxy)cyclohex-2-enone (lb) were investigated. When la adsorbed in cation-exchanged zeolites X and Y was irradiated through a Pyrex filter, the products from the 1,6-ring closure biradical increased compared to the results from the photoreaction in homogeneous solutions. In the intramolecular 1,5-ring closure photocycloaddition of la and lb, the products from the cis-fused intermediates increased in zeolites X and Y. The regiochemical and stereochemical outcomes of the photocycloadditions in the zeolites were interpreted by the binding of the guest molecules with the cations in the supercages.