Wang Gang, Wang Weina, Miao Rong, Shang Congdi, He Meixia, Peng Haonan, He Gang, Fang Yu
Key Laboratory of Applied Surface and Colloid Chemistry (Ministry of Education), School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China.
Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, P. R. China.
Phys Chem Chem Phys. 2016 Apr 28;18(17):12221-30. doi: 10.1039/c6cp01447j.
A perylene bisimide (PBI) derivative (C-PBI-Py) of pyrene (Py) and cholesteryl residue (C) possessing intra-molecular energy transfer properties and three reference compounds (C-Py, C-PBI, PBI-Py) were designed and synthesized, where C was introduced in order to enhance the solubility of the relevant compounds in organic solvents. UV-vis absorption, steady-state fluorescence, cyclic voltammetric and theoretical calculation studies revealed that: (1) the PBI unit and Py moiety of C-PBI-Py could act as two individual chromophores, (2) the excited state energy of Py could transfer to PBI within a single molecule of the compound, and (3) the PBI moiety of the compound tends to form aggregates and shows PBI excimer emission. Time-resolved and temperature-dependent emission spectroscopy studies revealed the presence of both H-type excimer and J-type excimer, and formation of them via either the Birks' scheme or the pre-formed scheme due to strong π-π stacking that was elucidated by concentration-dependent (1)H NMR spectroscopy measurement. In addition, the studies also indicated that the energy transfer occurs via an electron exchange mechanism (Dexter scheme). Results of this study will be useful in the development of new solvatochromic and other environment-sensitive fluorophores based on alteration of intra-molecular energy transfer efficiency.
设计并合成了一种具有分子内能量转移性质的芘（Py）和胆固醇残基（C）的苝二酰亚胺（PBI）衍生物（C-PBI-Py）以及三种参考化合物（C-Py、C-PBI、PBI-Py），引入C是为了提高相关化合物在有机溶剂中的溶解度。紫外-可见吸收光谱、稳态荧光光谱、循环伏安法和理论计算研究表明：（1）C-PBI-Py的PBI单元和Py部分可作为两个独立的发色团；（2）Py的激发态能量可在化合物的单个分子内转移至PBI；（3）该化合物的PBI部分倾向于形成聚集体并表现出PBI准分子发射。时间分辨和温度依赖发射光谱研究表明存在H型准分子和J型准分子，且由于浓度依赖的¹H NMR光谱测量所阐明的强π-π堆积作用，它们通过伯克斯机制或预形成机制形成。此外，研究还表明能量转移通过电子交换机制（德克斯特机制）发生。本研究结果将有助于基于分子内能量转移效率的改变开发新型溶剂致变色及其他环境敏感荧光团。
