Enantiopure J-Aggregate of Quaterrylene Bisimides for Strong Chiroptical NIR-Response

Data to report https://doi.org/10.1021/jacs.3c03367:
Chiral polycyclic aromatic hydrocarbons can be tailored for next-generation photonic materials by carefully designing their molecular as well as supramolecular architectures. Hence, excitonic coupling can boost the chiroptical response in extended aggregates but is still challenging to achieve by pure self-assembly. Whereas most reports on these potential materials cover the UV and visible spectral range, systems in the near infrared are underdeveloped. We report a new quaterrylene bisimide derivative with a conformationally stable twisted π-backbone enabled by the sterical congestion of a fourfold bay-arylation. Rendering the π-subplanes accessible by small imide substituents allows for a slip-stacked chiral arrangement by kinetic self-assembly in low polarity solvents. The well dispersed solid-state aggregate reveals a sharp optical signature of strong J-type excitonic coupling in both, absorption (897 nm) as well as emission (912 nm) far in the NIR region and reaches absorption dissymmetry factors up to 1.1×10−2. The structural elucidation was achieved by AFM and single-crystal X-ray analysis which we combined to derive a structural model of a fourfold stranded enantiopure superhelix. We could deduce the role of phenyl substituents not only granting stable axial chirality but also guiding the chromophore into a chiral supramolecular arrangement needed for strong excitonic chirality.

待报道的数据：https://doi.org/10.1021/jacs.3c03367
手性多环芳烃可通过精准调控其分子与超分子结构，适配下一代光子材料的应用需求。激子耦合（excitonic coupling）可增强扩展聚集体中的手性光学响应，但仅通过纯粹自组装实现该效应仍颇具挑战。尽管目前针对这类潜在光子材料的研究多集中于紫外及可见光谱区，但近红外（Near Infrared, NIR）波段的相关体系仍有待开发。本研究报道了一种新型四联苝双酰亚胺衍生物，其通过四重湾区芳基化带来的空间位阻效应，获得了构象稳定的扭曲π骨架。通过引入小型酰亚胺取代基以暴露π亚平面，该衍生物可在低极性溶剂中通过动力学自组装形成滑移堆叠的手性排列结构。该分散均匀的固态聚集体在近红外波段的吸收（897 nm）与发射（912 nm）光谱中，均展现出强J型激子耦合的清晰光学特征，其吸收不对称因子最高可达1.1×10⁻²。研究通过原子力显微镜（Atomic Force Microscopy, AFM）与单晶X射线衍射分析完成了结构解析，并结合二者构建了四重链状对映纯超螺旋的结构模型。我们可推导出苯基取代基的双重作用：不仅赋予分子稳定的轴向手性，还能引导生色团形成强激子手性所需的手性超分子排列结构。