Structure-property relationship of perylene bisimide macrocycles probed by atomic force microscopy and single-molecule fluorescence spectroscopy.
Structure-property relationship of perylene bisimide macrocycles probed by atomic force microscopy and single-molecule fluorescence spectroscopy.
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DOI：
10.1021/nn400616u
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发表时间：
2013-05
期刊：
影响因子：
17.1
通讯作者：
Jieun Lee;V. Stepanenko;Jaesung Yang;Hyejin Yoo;F. Schlosser;Daniel Bellinger;B. Engels;I. Scheblykin;F. Würthner;Dongho Kim
中科院分区：
文献类型：
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作者：
Jieun Lee;V. Stepanenko;Jaesung Yang;Hyejin Yoo;F. Schlosser;Daniel Bellinger;B. Engels;I. Scheblykin;F. Würthner;Dongho Kim
利用原子力显微镜（AFM）和凝聚相单分子荧光光谱研究了一系列由3~6个苝酰亚胺（PBI）染料组成的不同环尺寸的大环化合物的性质。通过分子动力学模拟（PM6-DH2方法）和CNs在高度有序热解石墨（HOPG）表面的原子力显微镜（AFM）高度图像，证明了PBI环状阵列（CNs，N = 3，4，5和6）的结构随着环尺寸的增加而发生畸变. MD模拟表明，只有C5和C6环是高度柔性的分子，其平面化沿着伴随着显著的能量损失。因此，这两种分子在HOPG表面上都没有显示出有序的吸附层。相比之下，C3和C4是更刚性的分子，导致良好有序的六边形（C3）和矩形（C4）2D晶格。在单分子水平上，我们发现单个氯化萘的荧光性质受到结构变化的影响。随着环尺寸的增大，氯化萘的荧光寿命变短，荧光分布变宽，这是由于环的结构发生了畸变。此外，与较大的氯化萘相比，较小环尺寸的氯化萘具有更好的结构和更平坦的结构，因此具有更高的光稳定性和更高的激发能转移效率。因此，这些观察结果证明，不仅五溴二苯醚大环化合物是人工捕光系统的理想候选物，而且氯化萘的物理化学性质与氯化萘的结构刚性密切相关。
Properties of a series of acetylene-linked perylene bisimide (PBI) macrocycles with different ring size composed of three to six PBI dyes were investigated by atomic force microscopy (AFM) and single-molecule fluorescence spectroscopy in a condensed phase. It was demonstrated that the structures of PBI cyclic arrays (CNs, N = 3, 4, 5, and 6) become distorted with increasing the ring size through molecular dynamics (MD) simulations (PM6-DH2 method) and AFM height images of CNs on highly ordered pyrolytic graphite (HOPG) surface. The MD simulations showed that only C5 and C6 rings are highly flexible molecules whose planarization goes along with a significant energetic penalty. Accordingly, both molecules did not show ordered adlayers on a HOPG surface. In contrast, C3 and C4 are far more rigid molecules leading to well-ordered hexagonal (C3) and rectangular (C4) 2D lattices. At the single-molecule level, we showed that the fluorescence properties of single CNs are affected by the structural changes. The fluorescence lifetimes of CNs became shorter and their distributions became broader due to the structural distortions with increasing the ring size. Furthermore, the CNs of smaller ring size exhibit a higher photostability and an efficient excitation energy transfer (EET) due to the more well-defined and planar structures compared to the larger CNs. Consequently, these observations provide evidence that not only PBI macrocycles are promising candidates for artificial light-harvesting systems, but also the photophysical properties of CNs are strongly related to the structural rigidity of CNs.