Synthesis of perylene–porphyrin building blocks and rod-like oligomers for light-harvesting applications
作者:Robert S. Loewe、Kin-ya Tomizaki、W. Justin Youngblood、Zhishan Bo、Jonathan S. Lindsey
DOI:10.1039/b205680a
日期:——
We present the synthesis of four peryleneâporphyrin building blocks for use in Glaser, Sonogashira, or Suzuki polymerizations. The building blocks bear synthetic handles (4-ethynylphenyl, 4-iodophenyl, bromo) at the trans
(5,15)
meso-positions of a zinc porphyrin and contain two or four perylene-monoimide dyes attached at the 3,5-positions of the non-linking meso-aryl rings of the porphyrin. Each perylene-monoimide bears three 4-tert-butylphenoxy substituents (at the 1-, 6-, and 9-positions) and two isopropyl groups (on the N-aryl unit) for increased solubility. In each case the intervening linker is a diarylethyne unit that bridges the N-imide position of the perylene and the meso-position of the porphyrin. The peryleneâporphyrin building blocks were prepared by (1) reaction of a diperylene-dipyrromethane with an aldehyde yielding a trans-A2B2-porphyrin, (2) reaction of a diperylene-aldehyde with a dipyrromethane yielding a trans-A2B2-porphyrin, and (3) reaction of a diperylene-dipyrromethane with a dipyrromethane-dicarbinol yielding a trans-AB2C-porphyrin or ABCD-porphyrin. The building blocks were subjected to Glaser, Sonogashira, or Suzuki coupling conditions in an effort to prepare oligomers containing porphyrins joined via 4,4â²-diphenylbutadiyne (dpb), 4,4â²-diphenylethyne (dpe), or 1,4-phenylene linkers (p), respectively. Each porphyrin in the backbone bears two or four pendant perylene-monoimide dyes. The Glaser and Sonogashira reactions afforded a distribution of oligomers, whereas the Suzuki reaction was unsuccessful. The oligomers were soluble in solvents such as toluene, THF, or CHCl3 enabling routine handling. The use of perylenes results in (1) increased light-harvesting efficiency particularly in the green spectral region where porphyrins are relatively transparent and (2) greater solubility than is achieved with the use of porphyrins alone. The soluble peryleneâporphyrin oligomers are attractive for use as light-harvesting materials in molecular-based solar cells.
我们展示了四种用于Glaser、Sonogashira或Suzuki聚合的苝–卟啉构件的合成。这些构件在锌卟啉的反式(5,15)美索位点上带有合成手柄(4-乙炔基苯基、4-碘苯基、溴)并在卟啉的非连接美索芳香环的3,5位上附有两个或四个苝单酰亚胺染料。每个苝单酰亚胺上都有三个4-叔丁基苯氧基取代基(位于1、6和9位)和两个异丙基(在N-芳基单元上),以提高溶解度。在每种情况下,介导链是一个二芳基乙炔单元,连接苝的N-酰亚胺位和卟啉的美索位。苝–卟啉构件的制备方法包括:(1)将二苝-二吡咯烷与醛反应生成反式A2B2-卟啉;(2)将二苝-醛与二吡咯烷反应生成反式A2B2-卟啉;(3)将二苝-二吡咯烷与二吡咯烷-二醇反应生成反式AB2C-卟啉或ABCD-卟啉。这些构件在Glaser、Sonogashira或Suzuki偶联条件下进行处理,以便制备包含通过4,4'-二苯基丁炔(dpb)、4,4'-二苯乙炔(dpe)或1,4-苯基链接(p)连接的卟啉的低聚物。骨架中的每个卟啉附有两个或四个悬挂的苝单酰亚胺染料。Glaser和Sonogashira反应产生了低聚物的分布,而Suzuki反应则未成功。所制备的低聚物在如甲苯、THF或CHCl3等溶剂中可溶,便于常规操作。使用苝可以导致(1)在卟啉相对透明的绿色光谱区域内,光捕获效率的提高;(2)相比仅使用卟啉,获得更高的溶解度。这些可溶的苝–卟啉低聚物在基于分子的太阳能电池中作为光捕获材料具有吸引力。