Gradient Shape-Persistent π-Conjugated Dendrimers for Light-Harvesting: Synthesis, Photophysical Properties, and Energy Funneling

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• 作者：Jin-Liang Wang ; Jing Yan ; Zheng-Ming Tang ; Qi Xiao ; Yuguo Ma ; Jian Pei
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：July 30, 2008
• 年：2008
• 卷：130
• 期：30
• 页码：9952-9962
• 全文大小：582K
• 年卷期：v.130,no.30(July 30, 2008)
• ISSN：1520-5126

文摘

A new class of π-conjugated dendrimers G0, G1, and G2 was developed through a double-stage divergent/convergent growth approach, in which 5,5,10,10,15,15-hexahexyltruxene was employed as the node and oligo(thienylethynylene)s (OTEs) with different lengths as the branching moieties. The dendrimers were fully characterized by ¹H and ¹³C NMR, elemental analysis, gel permeation chromatography, and MALDI-TOF MS. Also, by using atomic force microscopy, it was observed that dendrimer G2 laid nearly flat on the mica surface as a single molecule. Dynamic light scattering results showed that the molecule retained its relatively flat shape in solution. To our best knowledge, dendrimer G2, with a radius approaching 10 nm and a molecular weight of 27 072 Da, was the largest among reported second generation dendrimers. The energy gradient in G2 was constructed by linking OTEs of increasing effective conjugation lengths from the dendritic rim to the core. The intramolecular energy transfer process was studied using steady-state UV−vis absorption and photoluminescent spectroscopies, as well as time-resolved fluorescence spectroscopy. Our structurally extended dendrimers showed an excellent energy funneling ability (their energy transfer efficiencies were all over 95%). All results demonstrate that these dendrimers are promising candidates as light-harvesting materials for optoelectronic devices.