物理化学学报 >> 1997, Vol. 13 >> Issue (11): 984-991.doi: 10.3866/PKU.WHXB19971106

研究论文 上一篇    下一篇

卟啉-酞菁分子内能量传递和电子转移的溶剂效应

李希友,田宏健,许慧君   

  1. 中国科学院感光化学研究所,北京 100101
  • 收稿日期:1997-01-16 修回日期:1997-04-14 发布日期:1997-11-15
  • 通讯作者: 许慧君

The Solvents Effects on Intramolecular Energy and Electron Transfer of Porphyrin-phthalo cyanime Heterodimers

Li Xi-You,Tian Hong-Jian,Xu Hui-Jun   

  1. Institute of Photographic Chemistry,Chinese Academy of Sciences,Beijing 100101
  • Received:1997-01-16 Revised:1997-04-14 Published:1997-11-15
  • Contact: Xu Hui-Jun

摘要:

用稳态荧光光谱研究了以氧原子和哌嗪作为连接基的卟啉酞菁二元分子在不同溶剂中的分子内能量传递和电子转移过程. 结果表明, 分子内的能量传递和电子转移是两个相互竞争的过程,在非极性溶剂中,激发单重态的能量传递是主要过程,而在极性溶剂中则以电子转移为主. 运用Rehm-Weller公式计算了两种二元化合物在不同溶剂中的电子转移反应的自由能变化△G ET 0,表明溶剂的极性对电子转移反应的自由能变化△GET0影响很大. 极性越大, 体系中的电子转移反应的△G ET 0越负,电子转移反应越易进行. 由于电子转移过程较能量传递过程进行得快,所以表现为体系中能量传递效率降低而电子转移效率增大. 两种二元化合物的能量传递效率(φEnT)和电子转移效率(φET)随溶剂的极性的变化具有相同的变化趋势.

关键词: 溶剂效应, 二元化合物, 能量传递, 电子转移

Abstract:

Intramolecular energy transfer and electron transfer of porphyrin-phthalocyanine heterodimers, linked by oxygen atom or piperazine in different solvents were investigated by fluorescence spectroscopy. The energy transfer and electron transfer efficiency were calculated. It has been found that energy transfer occurred in competition with electron transfer process depending on the polarity of the solvents. In polar solvents, electron transfer prevails while the energy transfer is favored in nonpolar solvents. The driving force(△GET0)of the electron transfer reaction in different solvents was estimated using Rehm-Weller equation. The results indicated that the conformations of the heterodimers as well as the ability of the solvent to stablize the charge-seperated state affect the photophysical process greatly. Good correlations of φEnT and φET with solvent polarity f have been obtained.

Key words: Solvent effect, Dyad, Energy transfer, Electron transfer