• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Modified windmill porphyrin arrays: Coupled light-harvesting and charge separation, conformational relaxation in the S-1 state, and S-2-S-2 energy transfer [Review]
【24h】

Modified windmill porphyrin arrays: Coupled light-harvesting and charge separation, conformational relaxation in the S-1 state, and S-2-S-2 energy transfer [Review]

机译：改进的风车卟啉阵列：耦合的光收集和电荷分离，S-1状态下的构象弛豫和S-2-S-2能量转移[综述]

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The architecture of windmill hexameric zinc(II) -porphyrin array 1 is attractive as a light-harvesting functional unit in view of its three-dimensionally extended geometry that is favorable for a large cross-section of incident light as well as for a suitable energy gradient from the peripheral porphyrins to the meso-meso-linked diporphyrin core. Three core-modified windmill porphyrin arrays 2-4 were prepared for the purpose of enhancing the intramolecular energy-transfer rate and coupling these arrays with a charge-separation functional unit. Bisphenylethynylation at the meso and meso positions of the diporphyrin core indeed resulted in a remarkable enhancement in the intramolecular S-1-S-1 energy transfer in 2 with tau =2 similar to 3ps, as revealed by femtosecond time-resolved transient absorption spectroscopy. The fluorescence lifetime of the S-2 state of the peripheral porphyrin energy donor determined by the fluorescence up-conversion method was 68 fs, and thus considerably shorter than that of the reference monomer (150 fs), suggesting the presence of the intramolecular energy-transfer channel in the S-2 state manifold. Such a rapid energy transfer can be understood in terms of large Coulombic interactions associated with the strong Soret transitions of the donor and acceptor. Picosecond time-resolved fluorescence spectra and transient absorption spectra revealed conformational relaxation of the S-1 state of the diporphyrin core with tau =25ps. Upon photoexcitation of models 3 and 4, which bear a naphthalenetetracarboxylic diimide or a meso-nitrated free-base porphyrin attached to the modified diporphyrin core as an electron acceptor, a series of photochemical processes proceeded, such as the collection of the excitation energy at the diporphyrin core, the electron transfer from the S-1 state of the diporphyrin to the electron acceptor, and the electron transfer from the peripheral porphyrins to the diporphyrin cation radical, which are coupled to provide a fully charge-separated state such as that in the natural photosynthetic reaction center. The overall quantum yield for the full charge separation is better in 4 than in 3 owing to the slower charge recombination associated with smaller reorganization energy of the porphyrin acceptor. [References: 111]
机译：风车六聚体锌（II）-卟啉阵列1的结构吸引人，因为其三维扩展的几何形状有利于大截面的入射光以及合适的能量从周围的卟啉到介孔连接的二卟啉核心的梯度。为了提高分子内能量传递速率并将这些阵列与电荷分离功能单元偶联，制备了三个核心修饰的风车卟啉阵列2-4。飞秒时间分辨瞬态吸收光谱法显示，在二卟啉核心的内消旋和内消旋位置上的双苯基乙炔化确实导致分子内S-1-S-1能量转移显着增强，tau = 2类似于3ps。通过荧光上转换方法确定的外围卟啉能量供体的S-2状态的荧光寿命为68 fs，因此比参考单体的荧光寿命（150 fs）短，表明存在分子内能量- S-2状态歧管中的​​传输通道。可以通过与供体和受体的强索雷特跃迁相关的大库仑相互作用来理解这种快速的能量转移。皮秒时间分辨的荧光光谱和瞬态吸收光谱显示，tau = 25ps时双卟啉核心的S-1状态呈构象松弛。在模型3和模型4的光激发下，模型3和4带有萘四甲酸二亚胺或内消旋的游离碱卟啉，并附接到作为电子受体的改性二卟啉核上，随后进行了一系列光化学过程，例如在二卟啉核，电子从二卟啉的S-1状态转移到电子受体以及电子从周围的卟啉转移到二卟啉阳离子自由基，它们耦合在一起以提供完全的电荷分离状态，例如在天然光合作用反应中心。由于与卟啉受体的重组能较小有关的较慢的电荷重组，完全电荷分离的总量子产率在4中比3中更好。 [参考：111]

著录项

相似文献

  • 外文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号