Chiroptical Properties of Oligomeric Squaraine Dyes

手性发色团被广泛用作手性分子传感器、光化学反应催化剂和圆偏振发光有机发光器件的发光体。强手性效应的产生，即高旋转强度的圆二向色性和强烈的圆偏振发光，是手性生色团开发和应用的重点。分子齐聚和聚合方酸染料在生物医学和光电子器件中也具有广泛的应用潜力。它们在红色到近红外光谱区显示出强烈的吸收带，具有很高的荧光量子产率。因此，我们打算利用这些有利的光学特性，并将其扩展为手写学特性。因此，手性低聚方酸染料的合成及其手性性质的表征是本项目的主要目标。因此，我们将把手性中心直接结合到吲哚方酸染料的pi-体系中，而不是像以前在手性方酸中所做的那样，通过简单地连接手性侧链来实现。通过这种方式，我们希望显著提高手部的性能。这些性质将通过合成二聚体和螺旋折叠体来进一步增强，因为对于低聚物，我们期望通过激子手性效应耦合单体方块的光学跃迁。

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.