Templating Photodimerization of Coumarins within a Water-Soluble Nano Reaction Vessel
作者:S. Karthikeyan、V. Ramamurthy
DOI:10.1021/jo0606498
日期:2006.8.1
An octahedral Pd nanocage serves as a reaction vessel to control photodimerization of coumarins in water. The coumarin derivatives explored in this study react within the Pd nanocage to selectively yield a syn head−head dimer, whereas in water, they yield either a mixture of dimers or a different isomer. The selective dimerization is interpreted to mean that the monomers are preorganized by the cage
八面体钯纳米笼用作控制容器中香豆素光二聚化的反应容器。在这项研究中探索的香豆素衍生物在Pd纳米笼中发生反应,选择性地产生了一个syn head - head二聚体,而在水中,它们要么生成二聚体的混合物,要么生成不同的异构体。选择性二聚化被解释为意味着单体通过弱的分子间作用力被笼子预组织。与先前用于控制光二聚化反应的几何结构的其他宿主相比,在纳米笼中获得的选择性更为通用和可预测。
Manipulating Photochemical Reactivity of Coumarins within Cucurbituril Nanocavities
作者:Nilotpal Barooah、Barry C. Pemberton、J. Sivaguru
DOI:10.1021/ol801256r
日期:2008.8.7
Coumarin derivatives that are either cationic (7-ammonium) or neutral (7-hydroxy, 7-methoxy, 6-methyl) form a 1:2 host-guest complex with cucurbit[8]uril (CB[8]). Direct irradiation of these coumarin@CB[8] complexes in water gives head-to-tail (HT) adduct as the major product. The nature of the functional group (polar or nonpolar) at the 6 or 7 position on the coumarin dictates the type of HT adduct
phenomena of the crystal were observed. As a result of sublimation from granular crystals of 7-methoxycoumarin, several kinds of shaped crystals, including thin rod-shaped crystals, hollow cone-shaped crystals, and crystalline capsules were formed. Photoinduced bending due to the dimerization reaction was observed in the thin rod-shaped crystals. The hollow crystals showed photosalient phenomena upon UV
Among the various substituted coumarins investigated only 7-acetoxycoumarin is observed to photodimerize topochemically in the crystalline state and this observation may be of importance in the context of "crystal engineering".
Stereospecific photodimerization of coumarins in crystalline inclusion complexes. Molecular and crystal structure of 1:2 complex of (S,S)-(-)-1,6-bis(o-chlorophenyl)-1,6-diphenyl-hexa-2,4-diyne-1,6-diol and coumarin