CAREER: Soft Light-Harvesting Systems Based on inter-Conjugated Polyelectrolyte Complexes

天然的光合生物使用高度专业化的超级结构，容纳许多分子成分。 这些组件协同工作，有效地将阳光转化为电池的化学燃料。 这些成分的排列方式使得当太阳光被色素（含颜色的化合物）吸收时，能量可以在能量损失之前迅速从一个成分转移到下一个成分。 大自然使用捕光细胞器以显着的效率完成能量转移。人工模仿这种复杂的结构可能会导致轻质材料的形成，其光合功能可以精确控制。然而，制造人工光合系统仍然是一个重大挑战。 在NSF化学部大分子、超分子和纳米化学项目的支持下，加州大学圣克鲁斯分校（UCSC）的Ayzner教授和他的学生正在构建基于软分子材料（如聚合物）的人工集光细胞器。这些聚合物可以自组装成更大的结构，可以通过空间快速传输激发态，从而模仿光合细胞器的基本方面。该项目为研究生提供培训机会。 Ayzner教授正在使用能量收集的主题作为工具，教授先进的化学解决问题的技能，以转移学生，从而帮助他们在化学科学的持续成功做好准备。完成人工捕光细胞器的形成首先需要为组装和连接具有更大结构支架的高效电子能量转移（EET）中继奠定基础。为此，Ayzner教授正在将共轭聚电解质（CPE）合成和组装成供体/受体复合物，其结构和热力学可以通过电子和离子自由度之间的耦合来控制。本项目通过系统地调节CPE的平均链长和化学结构来阐明CPE的主链如何影响复合物内的EET效率。然后，在CPE间的复合物的共存相中的相分离行为和EET的特征在于阐明过量的离子对光捕获的影响。然后，复合物与自组装的囊泡型隔室连接，以形成柔软的捕光超结构的基础。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Natural photosynthetic organisms use highly specialized super-structures that house many molecular components. These components work in concert to efficiently convert sunlight to chemical fuel for the cell. The components are arranged so that when sunlight is absorbed by the pigments (color-containing compounds), the energy can move quickly from one component to the next before the energy is lost. Nature accomplishes energy transfer with remarkable efficiency using light-harvesting organelles. Mimicking such a complex structure artificially could lead to formation of light-weight materials, whose photosynthetic function could be exquisitely controlled. However, making artificial photosynthetic systems remains a major challenge. With support from the Macromolecular, Supramolecular and Nanochemistry Program of the NSF Division of Chemistry, Professor Ayzner at the University of California, Santa Cruz (UCSC) and his students are building artificial light-harvesting organelles based on soft molecular materials, such as polymers. These polymers can self-assemble into larger structures that can rapidly transport excited states through space, thus mimicking the fundamental aspects of photosynthetic organelles. The project is providing training opportunities for graduate students. Professor Ayzner is using the topic of energy harvesting as the vehicle to teach advanced chemical problem-solving skills to transfer students, thereby helping to prepare them for sustained success in the chemical sciences. Accomplishing the formation of an artificial light-harvesting organelle first requires laying a foundation for assembling and interfacing an efficient electronic energy transfer (EET) relay with a larger structural scaffold. To this end, Professor Ayzner is synthesizing and assembling conjugated polyelectrolytes (CPE) into donor/acceptor complexes, whose structure and thermodynamics can be controlled via the coupling between electronic and ionic degrees of freedom. This project elucidates how the backbone of a CPE influences the EET efficiency within the complex by systematically tuning the mean polyelectrolyte length and chemical structure. The phase separation behavior and EET in co-existing phases of inter-CPE complexes is then characterized to elucidate the influence of excess ions on light-harvesting. Complexes are then interfaced with self-assembled vesicle-type compartments to form the foundation of a soft light-harvesting super-structure. Characterization of resulting assemblies involves combining time-resolved electronic spectroscopy, photon scattering, microscopy and rheological measurements.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.