• Macromolecular Research
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• 제13권3호
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• pp.180-186
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• 2005

A novel bifunctional dye composed of spirobenzopyran and a cinnamoyl moiety was prepared and its photochromic behavior under the illumination of monochromatic UV light was investigated. This colorless bifunctional dye exhibits typical photochromism in both the film and in solution, through the structural and geometrical transformation from spirobenzopyran to merocyanine accompanied by a photocrosslinking reaction between the cinnamoyl moieties. Two kinds of photochemical reaction were selectively achieved by irradiation with monochromatic UV light at wavelengths of 275 and 365 nm, respectively. The effect of the selective photochemical reaction on the photochromism of the dye and its decaying behavior was investigated.

• 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.

• 생약학회지
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• 제11권3_4호통권43호
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• pp.181-187
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• 1980

• Bulletin of the Korean Chemical Society
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• 제29권4호
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• pp.869-872
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• 2008

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.3053-3056
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• 2009

The title compound, ${\alpha},{\alpha}$-dichloro-o-methylacetophenone, was prepared and its photochemical behavior was investigated. Addition of an extra chlorine at alpha position to the carbonyl showed many different features from photochemical reactivities of mono chloro analogue, 2,5-dimethylphenacyl chloride. In benzene, a rearrangement product with a formal 1,5-Cl shift and a reduction product were formed beside indanone. In methanol, solvolysis and cyclization of a common dienol intermediate occurred at comparable reaction rates.

• Journal of Photoscience
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• 제1권1호
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• pp.39-45
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• 1994

Haloarene in which the phenyl group and halophenyl group are connected by alkyl groups were synthesized to study the photochemical behavior. The photochemical reactions of 1-halo-2-(phenylalkyl)enzenes (1 and 2) were studied in several aerated or unaerated solvents. In the case of 2-benzyl-1-halobenzene photoreduced product (biphenyl) is major in acetonitrile or benzene. In cyclohexane or acetonitrile with triethylamine, photoreduced product is obtained exclusively, while in acetonitrile with toluene, xylene, or sodium hydroxide photocyclized product (fluorene) is mainly obtained. In the case of 1-halo-2-phenethylbenzenes (5 and 6), photocyclized product (9,10-dihydrophenanthrene and phenanthrene) are major in acetonitrile or benzene. While the haloarenes 1 or 2 connecting the two arene rings by methylene is photoreduced, the other haloarene 5 or 6 connecting by ethylene is photocyclized. In cyclohexane or acetonitrile with a small amount of triethylamine, photoreduced reactions of 5 or 6 mainly occur. In acetonitrile with sodium hydroxide, toluene, or xylene, photocyclization of 5, 6 occur exclusively. The triplet state is mainly involved in the photocyclization of 5 or 6, because of the inhibition of oxygen.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.341-341
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• 2017

Abiotic stress adversely affects crop growth worldwide. Drought of the major abiotic stresses have the most significant impact on all of the crop. The main objective of this study was to assess the effects of drought stress on photochemical performance and vitality of maize (Zea mays L.). The photochemical characteristics were analyzed in the context of period of drought stress during the maize growth. Drought experiment was carried out for four weeks, thereafter, the drought treated maize was re-watered. The polyphasic OJIP fluorescence transient was used to evaluate the behavior of photosystem II (PSII) and photosystem I (PSI) during the entire experiment period. In drought stress, the performance Index (PI) level was reached earlier when compared to the controls. For the screening of drought stress tolerance the drought factor index (DFI) of each variety was calculated as follow DFI= log(A) + 2log(B). All the fourteen cultivars show DFI ranged from -0.69 to 0.30, meaning less useful in selection of drought tolerant cultivars. PI and electron transport flux values of fourteen cultivars were to indicate reduction of photosynthetic performance during the early vegetative stage under drought stress. In conclusion, DFI and energy flux parameters can be used as photochemical and physiological index.

• Journal of Photoscience
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• 제8권1호
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• pp.9-12
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• 2001

The photoisomerization behavior of benzylideneacetophenones, known as chalcones, was studied. We synthesized the chalcone derivatives that have ether groups at 4 and 4＇ positions. Due to the electron donating ability of the ether oxygen, the bond order of the single bond between two phenyl ring of the chalcone strengthened, which eventually increased the rotational barrier of the single bond. The rotational barrier of the single bond is about 20-22 kcal/mole. Thermal recovery of this process took about 1 min. The UV-visible spectra of these chromophores exhibit two characteristic absorption peaks at 276 nm and 340 nm. The relative intensity of the peaks varies depending on the alkyl chain length of the substituent. Photo-irradiation with the 365 nm light monotonously decreases the 340 nm peak. However, the photo-irradiation with 254 nm light induce two competing processes and produced rather complicated absorption profile.

• Environmental Engineering Research
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• 제21권2호
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• pp.188-195
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• 2016

$17{\alpha}$-Ethynylestradiol (EE2) has gotten growing concerns due to its widely detected in the environment and high estrogenic potency. However, the knowledge on the photochemical behaviors of EE2 in natural waters is still limited. Herein, the photodegradation and estrogenic potency variation of EE2 induced by nitrate were studied using a sunlight simulator consisted by a 300 W medium pressure mercury lamp and 290 nm cut-off filters. It was found that EE2 could be photodegraded at a rate of $0.0193h^{-1}$ in pure aqueous solutions, and the photodegradation of EE2 could be significantly promoted by nitrate. The photodegradation removal rate of EE2 was increased from 9% in Milli-Q water to 85% in 2.0 mM nitrate solutions. Reactive species scavenging experiments demonstrated that the photogenerated $HO{\bullet}$ contributed about 55% to EE2 degradation. Fe(III), Cl- and dissolved humic acid (DHA) could inhibit the photodegradation of EE2 by competing the incident light and photogenerated $HO{\bullet}$, while $HCO_3{^-}$ had no influence on EE2 photodegradation. EE2 was determined to be phototransformed into organic chemicals without estrogenic potency by GC-MS and MCF-7 cell proliferation toxicity tests. These findings could extend our knowledge on the photochemical behaviors of steroid estrogens and provide information for ecological risk assessment.

• 대한화학회지
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• 제47권3호
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• pp.213-219
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• 2003

일산화탄소가 포화된 수용액에 광촉매로서 산화아연을 용액 1 ml 당 0.4 mg의 양을 첨가한 다음, $25{\pm}0.1^{\circ}C$에서 253.7 nm의 자외선을 조사시켜 일산화탄소의 광화학적 변환반응을 연구하였다. 그 결과 일산화탄소가 포화된 수용액은 253.7 nm의 자외선에 의해 카르복실화반응과 카르보닐화반응이 진행되어 포름산, 옥살산, 글리옥실산, 포름알데하이드 및 글리옥살이 주로 생성되었다. 이들 화합물들의 생성은 용액의 pH값에 영향을 받았는데, 산성용액에서는 포름알데하이드와 글리옥살의 생성이 증가하였으나, 염기성용액에서는 오히려 감소하였다. 하지만 유기산의 경우에는 산성용액에서는 큰 변화가 없었으나, 포름산의 경우에는 11.5 이상의 pH에서 급격히 증가하였다. 반응의 결과 생성된 각 생성물들에 대한 초기양자수득율을 계산하였으며, 이들 결과로부터 산화아연이 포함된 일산화탄소 수용액의 광화학 반응에 대한 가능한 반응메카니즘을 제시하였다.