Molecular push-pull nanographene-derivatives as vis/NIR fluorescent dyes

本研究项目的目的是制备和表征基于二氨基二氰基醌(DADQ)基序的新型荧光染料，以推导出这些DADQ衍生物在不同微环境和纳米结构下的光学、光谱和光物理性质的结构-性质关系。这意味着以下步骤：首先，合成了具有DADQ基元的纳米级推拉染料。在这里，咪唑给体和二氰亚甲基受体分别作为推式和拉式取代基。Pi-体系是在我们最近发现的六苯并冠烯(HBC)基序和五烯基序的基础上扩展而来的。这里的目的是将这些DADQ衍生物的吸收和发射带相对于基本DADQ基序移动到更长的波长。然后，在发色基序的外围进行极性和离子基团的官能化，以控制局部极性和聚集行为。此外，不同取代基如烷基、含氟烷基或醚基的溶解度也不同。随后，研究了所制备的DADQ衍生物在不同极性和/或正构性和粘度的微环境中的光学和光物理性质，以确定具有特别有趣的荧光性质(中到高的量子产率；最好是长波长荧光)和高光稳定性的DADQ结构。为此，我们在不同的溶剂和溶剂混合物中进行了稳态和时间分辨荧光研究，以确定与有效荧光相关的分子环境/环境参数，如极性和粘度。对于选定的DADQ，还研究了荧光的温度依赖关系，以获得机理结论。此外，还研究了所制备的DADQ衍生物在固体或晶体中的光学光谱性质，以及所选择的DADQ在不同微环境中的聚集行为和它们的光稳定性。基于这些结果，有趣的DADQ染料被选入不同材料组成的水分散纳米结构中，从而具有不同的极性，例如不同尺寸的聚合物和二氧化硅颗粒(非多孔；介孔)。此外，还研究了DADQ染料在胶束结构中的包埋情况。通过比较DADQ衍生物在粒子或胶束体系中的光学和光物理性质，以及在溶液和固体中的性质，可以得出结构-性质关系，特别是DADQ荧光以及它们作为一种新的染料类别的潜在应用。

The aim of this research project is to prepare and characterize new fluorescent dyes based on the diaminodicyanoquinone (DADQ) motif in order to derive structure-property relationships for the optical spectroscopic and photophysical properties of these DADQ derivatives in different microenvironments and nanostructures. This implies the following steps: First, nanographene-like push-pull dyes with DADQ motif are synthesized. Here, imidazole donor and dicyanomethylene acceptors are incorporated as push- and pull- substituents, respectively. The pi-systems are extended based on the hexabenzocoronene (HBC) motif and the pentaphene motif, which we discovered recently. The aim is to here to shift the absorption and emission bands of these DADQ derivatives to longer wavelength relative to the basic DADQ motif. Then, functionalization with polar and ionic groups is performed at the periphery of the chromophoric motif to control the local polarity and aggregation behavior. In addition, the solubility is varied by substituents such as alkyl, F-containing alkyl or ether groups. Subsequently, the optical and photophysical properties of the prepared DADQ derivatives are studied in microenvironments of different polarity and/or proticity and viscosity to identify DADQ structures with particularly interesting fluorescence properties (moderate to high quantum yields; preferably long-wavelength fluorescence) and high photostability. For this purpose, steady state and time-resolved fluorescence studies are performed in different solvents and solvent mixtures to determine the molecular environments/environmental parameters relevant for efficient fluorescence, such as polarity and viscosity. For selected DADQs, the temperature dependence of fluorescence is also investigated for mechanistic conclusions. Furthermore, the optical spectroscopic properties of the prepared DADQ derivatives in the solid state or crystal are investigated as well as the aggregation behavior of selected DADQs in different microenvironments and their photostability. Based on these results, interesting DADQ dyes are selected for the incorporation into water-dispersible nanostructures of different material compositions and thus varied polarity such as polymer and silica particles (non-porous; mesoporous) of different sizes. In addition, the encapsulation of DADQ dyes in micellar structures is investigated. By comparing the optical and photophysical properties of the DADQ derivatives in particles or micellar systems with those in solution and in the solid state, structure-property relationships can be derived, especially for the DADQ fluorescence as well as their potential for future use as a novel dye class.