Localized Emitting State and Energy Transfer Properties of Quadrupolar Chromophores and (Multi)Branched Derivatives

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• 作者：Linyin Yan ; Xudong Chen ; Qingguo He ; Yingying Wang ; Xuefei Wang ; Qianjin Guo ; Fenglian Bai ; Andong Xia ; Damir Aumiler ; Silvije Vdovi膰 ; ShengHien Lin
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：August 30, 2012
• 年：2012
• 卷：116
• 期：34
• 页码：8693-8705
• 全文大小：524K
• 年卷期：v.116,no.34(August 30, 2012)
• ISSN：1520-5215

文摘

In order to better understand the nature of intramolecular charge and energy transfer in multibranched molecules, we have synthesized and studied the photophysical properties of a monomer quadrupolar chromophore with donor鈥揳cceptor鈥揹onor (D鈥揂鈥揇) electronic push鈥損ull structure, together with its V-shaped dimer and star-shaped trimers. The comparison of steady-state absorption spectra and fluorescence excitation anisotropy spectra of these chromophores show evidence of weak interaction (such as charge and energy transfer) among the branches. Moreover, similar fluorescence and solvation behavior of monomer and branched chromophores (dimer and trimer) implies that the interaction among the branches is not strong enough to make a significant distinction between these molecules, due to the weak interaction and intrinsic structural disorder in branched molecules. Furthermore, the interaction between the branches can be enhanced by inserting 蟺 bridge spacers (鈭扖鈺怌鈥?or 鈭扖鈮鈭? between the core donor and the acceptor. This improvement leads to a remarkable enhancement of two-photon cross-sections, indicating that the interbranch interaction results in the amplification of transition dipole moments between ground states and excited states. The interpretations of the observed photophysical properties are further supported by theoretical investigation, which reveal that the changes of the transition dipole moments of the branched quadrupolar chromophores play a critical role in observed the two-photon absorption (2PA) cross-section for an intramolecular charge transfer (ICT) state interaction in the multibranched quadrupolar chromophores.