Oligonaphthofurans: Fan-Shaped and Three-Dimensional 蟺-Compounds

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• 作者：Kentaro Nakanishi ; Daisuke Fukatsu ; Kazuto Takaishi ; Taiki Tsuji ; Keita Uenaka ; Kouji Kuramochi ; Takeo Kawabata ; Kazunori Tsubaki
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：May 14, 2014
• 年：2014
• 卷：136
• 期：19
• 页码：7101-7109
• 全文大小：739K
• 年卷期：v.136,no.19(May 14, 2014)
• ISSN：1520-5126

文摘

Using a bottom-up method, we prepared a series of oligonaphthofurans composed of alternating naphthalene rings and furan rings. The largest compound (compound 25) contained 8 naphthalene units and 7 furan units. DFT calculations revealed that these compounds were fan-shaped molecules and each naphthalene ring was oriented in an alternate mountain-valley fold conformation because of steric repulsion by the hydrogens at the peri-positions. We investigated the optical properties that derived from their fan-shaped and mountain-valley sequences. As the number of aromatic rings of the oligonaphthofurans increased, the peaks of the longest wavelength absorptions in the UV鈥搗is spectra (HOMO鈥揕UMO energy gap) of these compounds steadily red-shifted, although the shapes of spectra were not sustained because of the decreasing molar absorption coefficients (蔚鈥檚) of their 位_max. We compared our results with those reported for other types of oligoaromatic compounds such as acenes 1, ethene-bridged p-phenylenes 2, rylenes 3, oligofurans 4, and oligonaphthalenes 5. The slopes of the plots between the transition energies (HOMO鈥揕UMO energy gap) of the oligoaromatic compounds and the reciprocal of the number of aromatic rings indicated that the efficiency of 蟺 conjugation of the oligonaphthofurans was comparable with that of linear and rigid acenes and rylenes. The higher-order compounds 22 and 25 aggregated even under high dilution conditions (10^鈥? M).