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

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• 作者：Rika Nogita ; Kumi Matohara ; Minoru Yamaji ; Takuma Oda ; Youichi Sakamoto ; Tsutomu Kumagai ; Chultack Lim ; Mikio Yasutake ; Tetsuro Shimo ; Charles W. Jefford ; and Teruo Shinmyozu
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：October 27, 2004
• 年：2004
• 卷：126
• 期：42
• 页码：13732 - 13741
• 全文大小：268K
• 年卷期：v.126,no.42(October 27, 2004)
• ISSN：1520-5126

文摘

Thephotochemical reaction of [3₃](1,3,5)cyclophane 2, which is a photoprecursor for the formationof propella[3₃]prismane 18, was studied using a sterilizing lamp (254 nm). Upon photolysis in dry and wetCH₂Cl₂ or MeOH in the presence of 2 mol/L aqueous HCl solution, the cyclophane 2 afforded novel cagecompounds comprised of new skeletons, tetracyclo[6.3.1.0.^2,70^4,11]dodeca-5,9-diene 43, hexacyclo[6.4.0.0.^2,60.^4,110.^5,100^9,12]dodecane 44, and pentacyclo[6.4.0.0.^2,60.^4,110^5,10]dodecane 45. All of these productswere confirmed by the X-ray structural analyses. A possible mechanism for the formation of thesephotoproducts via the hexaprismane derivative 18 is proposed. The photophysical properties in the excitedstate of the [3_n]cyclophanes ([3_n]CP, n = 2-6) were investigated by measuring the emission spectra anddetermining the quantum yields and lifetimes of the fluorescence. All [3_n]CPs show excimeric fluorescencewithout a monomeric one. The lifetime of the excimer fluorescence becomes gradually longer with theincreasing number of the trimethylene bridges. The [3_n]CPs also shows excimeric phosphorescence spectrawithout vibrational structures for n = 2, 4, and 5, while phosphorescence is absent for n = 3 and 6. Withan 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.