物理化学学报 >> 2009, Vol. 25 >> Issue (12): 2493-2500.doi: 10.3866/PKU.WHXB20091217

研究论文 上一篇    下一篇

四苯基卟啉锌J-聚集体的光谱与晶体结构分析

李晔, 韩伟伟, 廖明霞   

  1. 北京科技大学应用科学学院化学系, 北京 100083
  • 收稿日期:2009-07-20 修回日期:2009-09-19 发布日期:2009-11-27
  • 通讯作者: 李晔 E-mail:liye@sas.ustb.edu.cn

Spectroscopic and Crystal Structural Analyses of Zinc (II) Tetraphenylporphyrin J-aggregates

LI Ye, HAN Wei-Wei, LIAO Ming-Xia   

  1. Department of Chemistry, School of Applied Science, University of Science and Technology Beijing, Beijing 100083, P. R. China
  • Received:2009-07-20 Revised:2009-09-19 Published:2009-11-27
  • Contact: LI Ye E-mail:liye@sas.ustb.edu.cn

摘要:

四苯基卟啉锌在完全无水的乙氰中发生自聚现象, 聚集体的形成可以通过稳态光谱来证实. 吸收光谱和荧光发射光谱的红移表明四苯基卟啉锌的聚集体是卟啉之间以头对头的方式排列, 即J-聚集体. 进一步研究表明聚集体的形成还依赖于溶剂. 光谱和激发态寿命的测定结果表明聚集体的辐射跃迁速率比单体快两倍, 这表明形成的J-聚集体存在超辐射. 四苯基卟啉锌的晶体呈现出杆状的结构. 通过X射线的结构分析, 提出了一个四苯基卟啉锌J-聚集体的结构模型. 四苯基卟啉锌中的一个苯基和相邻的四苯基卟啉锌中的吡咯垂直并通过C—H…π键相互作用. 最后讨论了乙氰配位后对四苯基卟啉锌中Zn—N键的影响.

关键词: 光谱, 四苯基卟啉锌, J-聚集体, 晶体结构

Abstract:

The self-assembly behavior of non-aqueous zinc (II) tetraphenylporphyrin (ZnTPP) was studied in dry acetonitrile. A red shift in the absorption and fluorescence spectra implies that a part of ZnTPP molecules self-associate into J-aggregates in a head-to-head arrangement. The formation of ZnTPP J-aggregates is dependent on the solvents. The spectroscopic and excited state lifetime measurements indicate that the radioactive decay rate of the aggregates is two times faster than that of the monomer, which is indicative of superradiance from the aggregates. Optical microscopy of a ZnTPP microcrystal shows a rod-like molecular arrangement during crystal growth. An X-ray structural analysis and an illustration of crystal packing in ZnTPP(CH3CN) also show that one of the peripheral phenyl groups of a ZnTPP molecule interacts perpendicularly with the pyrrole ring of an adjacent porphyrin molecule. These π-π interactions are actually an edge-to-face C—H…π interaction. We, therefore, propose a structural model for the ZnTPP J-aggregates. The effects of the Zn—N coordination bond distance in a single crystal are discussed based on different packing arrangements.

Key words: Spectroscopy, Zinc (II) tetraphenylporphyrin, J-aggregates, Crystal structure

MSC2000: 

  • O641