Light-Harvesting and Ultrafast Energy Migration in Porphyrin-Based Metal鈥揙rganic Frameworks
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- 作者：Ho-Jin Son ; Shengye Jin ; Sameer Patwardhan ; Sander J. Wezenberg ; Nak Cheon Jeong ; Monica So ; Christopher E. Wilmer ; Amy A. Sarjeant ; George C. Schatz ; Randall Q. Snurr ; Omar K. Farha ; Gary P. Wiederrecht ; Joseph T. Hupp
- 刊名：The Journal of the American Chemical Society
- 出版年：2013
- 出版时间：January 16, 2013
- 年：2013
- 卷：135
- 期：2
- 页码：862-869
- 全文大小：490K
- 年卷期：v.135,no.2(January 16, 2013)
- ISSN：1520-5126
文摘
Given that energy (exciton) migration in natural photosynthesis primarily occurs in highly ordered porphyrin-like pigments (chlorophylls), equally highly ordered porphyrin-based metal鈥搊rganic frameworks (MOFs) might be expected to exhibit similar behavior, thereby facilitating antenna-like light-harvesting and positioning such materials for use in solar energy conversion schemes. Herein, we report the first example of directional, long-distance energy migration within a MOF. Two MOFs, namely F-MOF and DA-MOF that are composed of two Zn(II) porphyrin struts [5,15-dipyridyl-10,20-bis(pentafluorophenyl)porphinato]zinc(II) and [5,15-bis[4-(pyridyl)ethynyl]-10,20-diphenylporphinato]zinc(II), respectively, were investigated. From fluorescence quenching experiments and theoretical calculations, we find that the photogenerated exciton migrates over a net distance of up to 45 porphyrin struts within its lifetime in DA-MOF (but only 3 in F-MOF), with a high anisotropy along a specific direction. The remarkably efficient exciton migration in DA-MOF is attributed to enhanced 蟺-conjugation through the addition of two acetylene moieties in the porphyrin molecule, which leads to greater Q-band absorption intensity and much faster exciton-hopping (energy transfer between adjacent porphyrin struts). The long distance and directional energy migration in DA-MOF suggests promising applications of this compound or related compounds in solar energy conversion schemes as an efficient light-harvesting and energy-transport component.