Chiroptical Properties of Oligomeric Squaraine Dyes

手性发色团被广泛应用于手性分子传感器、光化学反应催化剂和圆极化发光有机发光器件中。强旋光效应的产生，即高旋光强度的圆二色性和强烈的圆极化发光，是手性发色团开发和应用的热点。分子低聚和聚合方胺染料在生物医学和光电子器件方面也具有广泛的应用潜力。它们在红至近红外光谱区表现出强烈的吸收带，荧光量子产率高。因此，我们打算利用这些有利的光学性质，并将其扩展为热学性质。手性寡聚方胺染料的合成及其在光电器件中应用的手性特性的表征是本项目的主要目标。因此，我们将把手性中心直接纳入吲哚胺方卡因染料的pi体系中，而不是像以前已知的手性方卡因那样，通过简单地附加手性侧链。通过这种方式，我们希望显著提高热学性能。这些性质将通过二聚体和螺旋折叠体的合成进一步增强，因为对于低聚物，我们期望通过激子手性效应耦合单体方烷的光学跃迁。

Chiral chromophores are widely used as chiroptical molecular sensors, as catalyst in photochemical reactions and as emitters in OLEDs with circular polarized luminescence (CPL). The generation of strong chiroptical effects, that is, a high rotatory strength of circular dichroism and an intense circular polarized luminescence, are in focus of the development and application of chiral chromophores. Molecular oligomeric and polymeric squaraine dyes also possess a broad potential for applications in biomedicine and optoelectronic devices. They show intense absorption bands in the red to near-infrared spectral region with high fluorescence quantum yields. Thus, we intend to use these advantageous optical properties and to extend them with chiroptical properties. The synthesis of chiral oligomeric squaraine dyes and the characterisation of their chiroptical properties for future applications in optoelectronic devices thus is the prime goal of this project. Hereby, we shall incorporate the chiral centre directly into the pi-system of the indolenine squaraine dyes, and not, as has be done in previously known chiral squaraines, by simply attaching chiral side chains. In that way, we hope to increase the chiroptical properties significantly. These properties shall further be enhanced by the synthesis of dimers and helical foldamers, because for oligomers we expect a coupling of optical transitions of monomeric squaraines by the exciton chirality effect.