• Journal of Photoscience
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• 제9권3호
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• pp.57-63
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• 2002

A homopolymer containing anthracene groups, poly[6-(9-anthryloxy)hexyl methacrylate] (PAn) was prepared and the effect of oxygen on its photochemical reaction was studied by UV and IR absorption spectroscopy in order to understand its photochemical behavior. Photochemical reaction of the PAn in THF solution under an atmosphere of air resulted in the formation of endoperoxide at the beginning stage of reaction followed by photodimerization reaction after all the oxygen was consumed, whereas photodimerization and endoperoxide formation took place concomitantly in the film state. The photoreversible reaction of the anthracene photodimer groups in the polymer by photolysis with 254 nm UV light was not efficient. The IR absorption spectral changes of the PAn film upon irradiation indicate that various photooxidation products were produced in the atmosphere of air.

• Journal of Photoscience
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• 제6권3호
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• pp.145-151
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• 1999

The use of O-carbamoyloximes as photobase generators was investigated. $\alpha$-Meth-ylbenzilydeneamino phenylcarbamate(2a) and $\alpha$-methyl benzilydeneamino cyclohexylcarbamate(2b) were prepared by the reaction of phenyl or cyclohexyl isocyanates with acetophenone oxime , respectively. Aniline, phenylhydrazine and N, N'-diphenylhydrazine were detected in thephotolysis of 2a and cyclohexylamine and cyclohexylhydrazine in the photolysis of 2b. A monomer having pendant carbamoyloxyimino groups (BGM) was prepared by the reaction fo methancryloyloxyethyl iocyanate with acetophenone oxime, and copolymerized with styrene. The BGM copolymer films turned insoluble on UV irradiation, and the degree of insolubilizationwas increased by post-baking. The photocrosslinking was thought to be due to coupling of resulting pendant aminyl radicals, and the thermal crosslinking was due to association of resulting amino and hydrazino groups by hydrogen bonding. The introduction of epoxy groups into polymer increased the degree of thermal crosslinking by post-baking.

• Bulletin of the Korean Chemical Society
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• 제3권3호
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• pp.110-115
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• 1982

Thermochemistry and photochemistry of picolyl chlorides were studied. The thermal reaction of 2-picolyl chloride in benzene afforded intermolecular condensation product. In the case of 3-picolyl chloride, this type of the reaction did not occur, but polymers were obtained. A cyclic hexamer, suggested by a molecular model, was not formed because of the steric strain and low reactivity. The thermal reaction of 4-picolyl chloride gave a cyclic hexamer as well as a polymer. The cyclic hexamer, identified by NMR spectrum, showed ${\lambda}_{max}$ at 460 nm. The cyclic hexamer was cloven to the linear structure. Photolysis of 2-picolyl chloride at 253.7 nm gave a para-isomer followed by polymerization. When a methyl hydrogen of 2-methylpyridine is substituted by $CH_3O$, iso-PrO, and EtO group, the photoisomerization to the corresponding anilines or para-substituted pyridines did not occur within the range of the time used for 2-picolyl chloride. Thermolysis of picolyl chlorides in an acidic methanol solution did not afford any product.

• Bulletin of the Korean Chemical Society
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• 제9권2호
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• pp.84-87
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• 1988

The Photophysical and photochemical properties of Ruthenium bipyridine with two long hydrocarbon chains, $[Ru(bipy)_2(dhbipy)]^{2+}$ and transient phenothiazine derivative cation radical $(PTD^+)$ in the cationic vesicle were studied. Transient absorption spectra of cation radical of phenothiazine derivative in the vesicle system containing the $Ru^{2+}$ complex, $[Ru(bipy)_2(dhbipy)]^{2+}$, (1) as sensitizer and phenothiazine derivative as electron donor was observed by XeCl excimer laser photolysis system. Thus the excited ruthenium complex would be quenched by phenothiazine derivative(PTD) reductively in the vesicle system. The quenching rate constant($K_Q$) of $Ru^{2+}$ with two long hydrocarbon chains in the vesicle by PTD was $9.6{\times}10^8M^{-1}S^{-1}$. The absorption decay kinetics showed that lifetime of phenothiazine derivative cation radical is a value in the 4-8m sec range.

• Bulletin of the Korean Chemical Society
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• 제13권6호
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• pp.684-688
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• 1992

Three photocyclodimers of 5,7-dimethoxycoumarin (DMC) were isolated and characterized from the photolysis of DMC in acetonitrile. The configuration of the dimers was found to be anti head-to-head, syn head-to-head and syn head-to-tail, respectively. The number and the ratio of the products are solvent dependent. The anti head-to-head dimer is favored in nonpolar solvents and the preference decreases as the solvent polarity increases giving almost 100${\%}$ syn dimers and less than 1${\%}$ anti dimer from methanol solution. The overall yields of dimers also increase with the solvent polarity. From sensitization and quenching experiments, anti dimer was found to be formed via excited singlet state while syn dimers were formed via both excited singlet and triplet states.

• 방사선산업학회지
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• 제12권4호
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• pp.333-336
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• 2018

Natural lacquer was cured at room temperature at a relative humidity of 60% at $27^{\circ}C$ to obtain a lacquer film. Photolysis of lacquer was investigated by irradiating 1~75 kGy of gamma ray to this lacquer film. No significant changes were observed in the range of 1~10 kGy radiation. As the radiation doses were increased, the white spots were increased in the scanning electron microscope photographs. The increase of the white dots of the lacquer surface shows that the lacquer is degradation by radiation. As a result of IR spectral analysis of the lacquer surface with increasing irradiation dose, there was no significant change in $3,445cm^{-1}$ hydroxide group, $2,900cm^{-1}$ hydrocarbon group, and $993cm^{-1}$ triene group. However, the $1,745cm^{-1}$ carbonyl group was found to increase, and the $1,715cm^{-1}$ unsaturated hydrocarbon group and the $1,463cm^{-1}$ methylene group showed a tendency to decrease.

• Mass Spectrometry Letters
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• 제12권3호
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• pp.118-124
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• 2021

Many previous studies have focused on revealing the harmfulness of microplastic particles, whereas very few studies have focused on the effects of chemicals, particularly photooxidation product. In this study, products of photodegradation from expanded polystyrene (EPS), compounds produced by photolysis by ultraviolet (UV) light, were investigated. EPS was directly irradiated and photolyzed using a UV lamp, and then the extracted sample was analyzed using high-resolution mass spectrometry (HRMS). Multiple ionization techniques, including electrospray ionization, atmospheric pressure chemical ionization, and atmospheric pressure photoionization, were used. In total, >300 compounds were observed, among which polystyrene monomer, dimer, and oxidized products were observed. In this work, the data presented clearly demonstrate that it is necessary to identify and monitor oxidized plastic compounds and assess their effect on the environment.

• Bulletin of the Korean Chemical Society
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• 제5권5호
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• pp.194-198
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• 1984

The UV action spectra and quantum yields for photodestruction of tryptophan (Trp) in peptide such as N-acetylphenylalanyl-L-tryptophan (NAPT) and 3-methyl indole (scatole) were determined in aerated aqueous and organic solvents. The photodestruction of aqueous NAPT was shown to be initiated by photoionization without requirement of threshold energy, as demonstrated by the similarity of fluence effect curves obtained for the action at various wavelengths and the wavelength dependence of quantum yield comparable to that reported for the photoionization of L-Trp. N-formylkynurenine (NFK)-type photoproduct, which is a photodynamic sensitizer, was not found to be involved in the photodestruction of Trp in NAPT in aqueous solution. In contrast, the action spectra of NAPT and scatole in organic solvents have revealed evidences for the significant role of internal photosensitization by NFK-type photoproduct in photolysis of Trp in peptide.

• Bulletin of the Korean Chemical Society
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• 제16권3호
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• pp.202-204
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• 1995

The ultraviolet photochemistry of N,N'-bis(salicylidene)ethylenediamine copper(II), Cu(sal)2en, was investigated with low pressure mercury lamp. Redution of Cu(Ⅱ) and formation of Cl- were shown on 254 nm irradiation both for aerated and deaerated chlorinated hydrocarbon solvent such as CH2Cl2, chloroform, and 1,2-dichloroethane. Relatively long lived $({\tau}=100{\mu}sec)$ intermediate was detected by flash photolysis. Overall photo-process can be described as the formation of Cl- and new copper complex, product(1) by chlorohydrocarbon mediation, photoinduced reduction by abstraction of halogen from solvent, followed by redox induced substitution of axial ligand with chlorine. Product(1) is possibly Cu(III) chlorosalicylaldeimido complex and cyclic -CH2CH2- moiety is absent in the structure. 247nm band of Cu(sal)2en should contain ligand to metal charge transfer character.

• Bulletin of the Korean Chemical Society
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• 제6권3호
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• pp.153-157
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• 1985

A diacetylene compound, 1,4-diphenyl-1,3-butadiyne, was photolyzed with 2,3-dimethyl-2-butene, 1,4-cyclohexadiene, dimethyl fumarate, and methyl crotonate, as a model reaction of the phototoxic conjugated polyynes with DNA or RNA and [2 + 2] photocycloadducts were obtained except for 1,4-cyclohexadiene. In the photoreaction of 1,4-diphenyl-1,3-butadiyne with 2,3-dimethyl-2-butene, a [2 + 2 + 2] photoadduct was additionally obtained. The photolysis of 1,4-di-t-buyl-1,3-butadiyne with 2,3-dimethyl-2-butene also yielded a [2 + 2] photoadduct. Fluorescence was observed from all the photoadducts while the reactants did not show any fluorescence.