Biphasic Self-Assembly Pathways and Size-Dependent Photophysical Properties of Perylene Bisimide Dye Aggregates
Biphasic Self-Assembly Pathways and Size-Dependent Photophysical Properties of Perylene Bisimide Dye Aggregates
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DOI：
10.1021/ja409597x
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发表时间：
2013-12-18
影响因子：
15
通讯作者：
Lochbrunner, Stefan
中科院分区：
文献类型：
--
作者：
Fennel, Franziska;Wolter, Steffen;Lochbrunner, Stefan
二酰亚胺染料PBI-1在甲基环己烷中的浓度依赖吸收和温度依赖的荧光行为表明其具有两相聚集行为。在中等浓度和温度下，低荧光产率的二聚体占主导地位，这不能延伸到更长的聚集体。它们分别是在高浓度和低温下通过第二种不利于能量的二聚体物种形成的，二聚体充当了原子核。相应的聚集模型准确地再现了浓度依赖关系，并允许提取不同物种的平衡常数和光谱。光物理性质的不同表明，优先的二聚体为H型激子耦合，扩展的聚集体为J型特征，这可能与基于密度泛函计算的结构模型有关。能量学可以通过考虑氢键和pi-pi堆积相互作用来理解。
The concentration-dependent absorption and temperature-dependent fluorescence of the perylene bisimide dye PBI 1 in methylcyclohexane point to a biphasic aggregation behavior. At intermediate concentrations and temperatures, respectively, a dimer with low fluorescence yield dominates, which cannot be extended to longer aggregates. Those are formed at high concentrations and low temperatures, respectively, via a second, energetically unfavorable dimer species that acts as a nucleus. A corresponding aggregation model reproduces accurately the concentration dependence and allows extracting the equilibrium constants and spectra of the distinct species. The differences in the photophysical properties indicate H-type excitonic coupling for the favored dimer and J-type characteristics for the extended aggregates which could be related to structural models based on DFT calculations. The energetics can be understood by considering hydrogen-bonding and pi-pi-stacking interactions.