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Title

Photochemical Study of [33](1,3,5)Cyclophane and Emission Spectral Properties of [3n]Cyclophanes (n = 2-6)

Authors
Nogita, Rika
Matohara, Kumi
Yamaji, Minoru
Oda, Takuma
Sakamoto, Youichi
Kumagai, Tsutomu
Lim, Chultack
Yasutake, Mikio
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Published in Journal of the American Chemical Society. 2004, vol. 126, no. 42, p. 13732-13741
Abstract Thephotochemical reaction of [33](1,3,5)cyclophane 2, which is a photoprecursor for the formation of propella[33]prismane 18, was studied using a sterilizing lamp (254 nm). Upon photolysis in dry and wet CH2Cl2 or MeOH in the presence of 2 mol/L aqueous HCl solution, the cyclophane 2 afforded novel cage compounds comprised of new skeletons, tetracyclo[6.3.1.0.2,704,11]dodeca-5,9-diene 43, hexacyclo[6.4.0.0.2,60.4,110.5,1009,12]dodecane 44, and pentacyclo[6.4.0.0.2,60.4,1105,10]dodecane 45. All of these products were confirmed by the X-ray structural analyses. A possible mechanism for the formation of these photoproducts via the hexaprismane derivative 18 is proposed. The photophysical properties in the excited state of the [3n]cyclophanes ([3n]CP, n = 2-6) were investigated by measuring the emission spectra and determining the quantum yields and lifetimes of the fluorescence. All [3n]CPs show excimeric fluorescence without a monomeric one. The lifetime of the excimer fluorescence becomes gradually longer with the increasing number of the trimethylene bridges. The [3n]CPs also shows excimeric phosphorescence spectra without vibrational structures for n = 2, 4, and 5, while phosphorescence is absent for n = 3 and 6. With an increase in symmetry of the benzene skeleton in the [33]- and [36]CPs, the probability of the radiation (phosphorescence) process from the lowest triplet state may drastically decrease.
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NOGITA, Rika et al. Photochemical Study of [33](1,3,5)Cyclophane and Emission Spectral Properties of [3n]Cyclophanes (n = 2-6). In: Journal of the American Chemical Society, 2004, vol. 126, n° 42, p. 13732-13741. https://archive-ouverte.unige.ch/unige:6990

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Deposited on : 2010-06-18

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