Control and quantification of interchromophoric coupling in single-molecule defined shape-persistent oligomers

我们建议合成定义明确的分子模型系统，通过光谱学读出π共轭低聚物之间的电子耦合激发态，并结合量子化学计算来表征这种耦合。这种激发态耦合对于基于共轭聚合物的器件的光电性质起着特别重要的作用，但在这种无序材料中难以控制和量化。新型分子介观材料系统将被利用作为模型系统，以开发设计规则，并正确地解释光致发光（PL）的可观测值，例如PL寿命，PL量子产率和发射波长，在几个形态参数方面，例如参与π共轭分子单元的距离，数量和长度。独立于光谱学，低聚物之间的距离将通过STM和NMR实验来确定。分子间光谱性质的分子内化将通过新颖的材料系统来实现，所述材料系统利用对以下各项的控制：（i）通过附接至精心设计的分子夹的分子内π-缀合的低聚物-低聚物距离;（ii）π-缀合的低聚物长度;以及（iii）参与的π-缀合的低聚物的数量。由于这些π共轭低聚物之间距离的微小变化将导致不同的光谱特性，因此将采用单分子光谱来解开这些模型系统中的任何结构异质性。这些结果将被专门用于利用PL作为一个微小的结构报告，即interchromophoric距离变化的子-nigström长度尺度，在一个模型系统。这种耦合不能充分地描述在传统的术语中的H-聚集或激基缔合物的形成。因此，它是强制性的比较实验结果与量子化学计算，以获得一个基本的理解π共轭低聚物的分子间耦合机制。

We propose to synthesize well-defined molecular model systems to read out electronically coupled excited states between pi-conjugated oligomers by spectroscopy and to characterize this coupling in combination with quantum chemical calculations. This kind of excited state coupling plays a particularly important role regarding the optoelectronic properties of conjugated polymer based devices, but is difficult to control and to quantify in such disordered materials. Novel molecular mesoscopic material systems will be exploited as model systems to develop design rules and to correctly interpret observables of the photoluminescence (PL), e.g. the PL lifetime, PL quantum yield and wavelength of emission, in terms of several morphological parameters, e.g. distance, number and length of participating pi-conjugated molecular units. Independent from optical spectroscopy, the distance between the oligomers will be determined by means of STM and NMR experiments. Intramolecularization of intermolecular spectroscopic properties will be achieved by novel material systems which exploit a control of (i) the intramolecular pi-conjugated oligomer-oligomer distance by attachment to carefully designed molecular clamps; (ii) the pi-conjugated oligomer length; and (iii) the number of participating pi-conjugated oligomers. Since tiny variations in distance between these pi-conjugated oligomers will result in different spectroscopic properties, single-molecule spectroscopy will be employed to unravel any structural heterogeneity within these model systems. The results will be used specifically to exploit the PL as a reporter on tiny structural, i.e. interchromophoric distance variations on sub-Ångström length scales, within a model system. This coupling cannot be described sufficiently in the conventional terms of either H-aggregation or excimer formation. Therefore it is mandatory to compare the experimental results with quantum chemical calculations in order to obtain a fundamental understanding of the intermolecular coupling mechanism of the pi-conjugated oligomers.