Guest-Induced Modulation of the Energy Transfer Process in Porphyrin-Based Artificial Light Harvesting Dendrimers

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• 作者：Dajeong Yim ; Jooyoung Sung ; Serom Kim ; Juwon Oh ; Hongsik Yoon ; Young Mo Sung ; Dongho KimWoo-Dong Jang
• 刊名：Journal of the American Chemical Society
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：139
• 期：2
• 页码：993-1002
• 全文大小：746K
• ISSN：1520-5126

文摘

A series of dendritic multiporphyrin arrays (P_ZnTz-nP_FB; n = 2, 4, 8) comprising a triazole-bearing focal zinc porphyrin (P_Zn) with a different number of freebase porphyrin (P_FB) wings has been synthesized, and their photoinduced energy transfer process has been evaluated. UV/vis absorption, emission, and time-resolved fluorescence measurements indicated that efficient excitation energy transfer takes place from the focal P_Zn to P_FB wings in P_ZnTz-nP_FB’s. The triazole-bearing P_Zn effectively formed host–guest complexes with anionic species by means of axial coordination with the aid of multiple C–H hydrogen bonds. By addition of various anionic guests to P_ZnTz and P_ZnTz-nP_FB’s, strong bathochromic shifts of P_Zn absorption were observed, indicating the HOMO–LUMO gap (ΔE_HOMO–LUMO) of P_Zn decreased by anion binding. Time-resolved fluorescence measurements revealed that the fluorescence emission predominantly takes place from P_Zn in P_ZnTz-nP_FB’s after the addition of CN^–. This change was reversible because a treatment with a silver strip to remove CN^– fully recovered the original energy transfer process from the focal P_Zn to P_FB wings.