• Rapid Communication in Photoscience
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• 제4권1호
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• pp.12-15
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• 2015

Intramolecular photocycloaddition of ferulic acid derivatives proceeded in high yields to give head-to-head intramolecular photodimers as three atropisomers. The photocycloaddition was sensitized by triplet sensitizers such as benzophenone, whereas photocycloreversion was promoted by 9,10-dicyanoanthracene (DCA) as an electron-transfer photocatalyst. On the other hand, intermolecular photocycloaddition afforded a head-to-tail photodimer.

• Journal of Photoscience
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• 제10권1호
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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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• 제20권1호
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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.

• Bulletin of the Korean Chemical Society
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• 제19권5호
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• pp.501-503
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• 1998

In this work, we applied the 1D $11^B$ nutation NMR method for the analysis of the local structural environments in powdered borosilicates $(SiO_2-B_2O_3)$. Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density ma trix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D $11^B$ nutation NMR experiment. The $11^B$ NMR parameters, quadrupole coupling constants $(e^2qQ/h)$ and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.

• 한국결정학회지
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• 제5권2호
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• pp.100-107
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• 1994

분자내 (2+2) 광고리화 반응을 통하여 pyridine의 새로운 N1-pentenyl유도체가 얻어졌다. 이 물질의 구조는 단 결정 X-선 회절법에 의해 해석되었다. 이 화합물은 rhombohedral계( R3, a=27.767(5)A, c=6.390(2)A)로 결정화된다. 이 구조에서는 2개의 6각 고리와 1개의 4각 고리가 N-C 또는 C-C bonds를 공유하면서 fuse되어 있고, pyridine고리는 의자모양의 형태를 취하고 있다. 점대칭으로 연관된 한 쌍의 분자들이 uracil 부분의 N,0 원자 사이의 H를 통하여 수소결합을 생성하고 있는 것이 관찰되었다.

• Journal of Photoscience
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• 제10권1호
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• pp.121-126
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• 2003

Irradiation of an acetonitrile solution containing dimethylbis(4-vinylphenylmethyl)silane 1a in the presence of 9,10-dicyanoanthracene leads to formation of the intramolecular photocycloadduct, 2-sila-cyclobuta[2.3]cyclophane(2a). In contrast, prolonged irradiation gave insoluble polymeric material. The photocycloreversion of 2a occurs efficiently (quantum yields exceeds unity) by use of redox-type photosensitization in the presence of magnesium perchlorate. The transient absorption spectra generated by pulse radiolysis and gamma-radiolysis show that the radical cation species generated from 1a is different from that arising from 2a.

• 한국결정학회지
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• 제1권2호
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• pp.84-90
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• 1990

1,3-Diazatricyclo (5.2.1.O5.10) decade-2,4dione, C8H10N2O2의 단위세포 상수는a=6.585(7), b=9.089(4), c=12.937(10)A, β=95.72(5)˚, V=770.43, Dc=1.4391c0, 1=1.Ocm-1,7 =295 ˚K, 공간군은 P21/n이고 단사 정계이며 Z =4이 다. λ(Mo K u ) =0.7093A을 사용한 698개 의 회절 반점에 대한 최종 신뢰도 R값은 0.037이다. 본 화합물은 N1-(w-butenyl)uracil의 분자내 (2+2) 광고리화 반응 생성물이며, (5.1. 2.O5.10) tricyclic 계에 속한다. Inversion symmetry에 의해 관련된 한 쌍의 분자들은 uracil 부분의 02와H3간 의 강한 수소 결합을 하고있다