Ultrafast Photoinduced Symmetry-Breaking Charge Separation and Electron Sharing in Perylenediimide Molecular Triangles

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• 作者：Yilei Wu ; Ryan M. Young ; Marco Frasconi ; Severin T. Schneebeli ; Peter Spenst ; Daniel M. Gardner ; Kristen E. Brown ; Frank W眉rthner ; J. Fraser Stoddart ; Michael R. Wasielewski
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：October 21, 2015
• 年：2015
• 卷：137
• 期：41
• 页码：13236-13239
• 全文大小：354K
• ISSN：1520-5126

文摘

We report on a visible-light-absorbing chiral molecular triangle composed of three covalently linked 1,6,7,12-tetra(phenoxy)perylene-3,4:9,10-bis(dicarboximide) (PDI) units. The rigid triangular architecture reduces the electronic coupling between the PDIs, so ultrafast symmetry-breaking charge separation is kinetically favored over intramolecular excimer formation, as revealed by femtosecond transient absorption spectroscopy. Photoexcitation of the PDI triangle dissolved in CH₂Cl₂ gives PDI^{+鈥?/sup>鈥揚DI鈥撯€?/sup> in 蟿_CS = 12.0 卤 0.2 ps. Fast subsequent intramolecular electron/hole hopping can equilibrate the six possible energetically degenerate ion-pair states, as suggested by electron paramagnetic resonance/electron鈥搉uclear double resonance spectroscopy, which shows that one-electron reduction of the PDI triangle results in complete electron sharing among the three PDIs. Charge recombination of PDI+鈥?/sup>鈥揚DI鈥撯€?/sup> to the ground state occurs in 蟿_CR = 1.12 卤 0.01 ns with no evidence of triplet excited state formation.}