Excited State Interactions in Calix[4]arene-Perylene Bisimide Dye Conjugates: Global and Target Analysis of Supramolecular Building Blocks

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• 作者：Catharina Hippius ; Ivo H. M. van Stokkum ; E. Zangrando ; Ren&eacute ; M. Williams ; Frank Wü ; rthner
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：September 20, 2007
• 年：2007
• 卷：111
• 期：37
• 页码：13988 - 13996
• 全文大小：303K
• 年卷期：v.111,no.37(September 20, 2007)
• ISSN：1932-7455

文摘

The photophysical properties of two supramolecular building blocks oc and oc2 consisting of a perylenebisimide chromophore substituted with either one or two calix[4]arene units in the N-imide position as wellas those of the reference compound oref without calix[4]arene substituents were investigated. A completepicture of the processes taking place after photoexcitation in toluene, CH₂Cl₂, and benzonitrile was obtainedby means of UV/vis absorption, steady state and time-resolved emission, and femtosecond transient absorptionspectroscopy. It has been found that the fluorescence emission of compounds oc (_fl = 0.03 in CH₂Cl₂) andoc2 (_fl < 0.01 in CH₂Cl₂) is almost completely quenched compared with the highly emissive referencecompound oref (_fl = 0.99 in CH₂Cl₂) because of fast electron-transfer processes from the calix[4]arenemoieties to the perylene bisimide chromophore. This predominantly takes place with rate constants of k_CS =3 × 10¹⁰ s^-1 (_CS = 32 ps) for compound oc and k_CS = 9 × 10¹⁰ s^-1 (_CS = 11 ps) for compound oc2 (inCH₂Cl₂) leading to a short-lived charge-separated state consisting of the reduced perylene bisimide unit andthe oxidized calix[4]arene moiety.