Ladder Oligomers and Polymers: Self-Assemblies and Opto-Electric Properties.

在化学系大分子、超分子和纳米化学项目的支持下，芝加哥大学的余鲁平教授正在开发用于构建共轭梯形聚合物的新型发光构建块。共轭聚合物是一类独特的非金属聚合物，其半导体性质类似于化学元素硅。它们被广泛应用于太阳能电池、LED屏幕和其他利用电能转化为光的应用。另一方面，梯形聚合物是一种具有梯形连接性的双链聚合物。它们是通过四个化学键将主聚合链上的重复单元相互连接起来制备的，而不是传统塑料中通常看到的两个键。在这项研究中，发光积木的结构特征将首先使用合成和计算技术相结合的方法进行优化。然后将构建梯形聚合物，并使用各种分析技术系统地研究其物理性质。重点将放在开发能够更有效地实现电和光相互转换的材料上。这项工作有可能扩大有机半导体分子、合成和聚合物方面的知识。在这项工作中制备的材料预计也将影响更高效的数字显示器和光学互连的发展。参与这项工作的学生将接受合成聚合物化学、光物理表征技术和器件制造方面的广泛培训。外展活动将集中在邻里学校项目上，这是芝加哥大学历史最悠久的社区项目之一。在这个项目中，学生将扮演导师、助教、学前专家和技术协调员的角色，在芝加哥南部有50个地点，每年有4000名当地学生。重点将放在鼓励和激励来自代表性不足群体的学生在STEM领域接受教育和从事职业的活动。这项研究将致力于合理开发梯形齐聚物和聚合物的新合成方法，重点是电荷转移和发光的优化。首先将合成单体，并使用密度泛函计算指导其设计。合成化学将涉及两种不同的方法。第一个两步法将重点放在环化反应，其中使用Heck偶联反应来获得梯形结构。第二个一步法将包括“梯化”，以同时形成稠环结构，并将通过利用弗里德兰德缩合反应来完成。这些单体和低聚物的聚合将产生具有明确结构和优化性能的共轭聚合物。还将使用各种分析技术对制备的聚合物进行详细表征，并将提供必要的信息，用于结构-性质关联和阴影进入这些发光聚合物的聚集状态。作为这项工作的结果，将合成的可折叠半阶梯共轭聚合物可能通过促进快速电荷传输同时避免紧密的分子间H-聚集来解决OLET(有机发光晶体管)所面临的巨大挑战。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professor Luping Yu of the University of Chicago is developing novel luminescent building blocks for the construction of conjugated ladder polymers. Conjugated polymers are a unique class of non-metallic polymers with semiconducting properties resembling that of the chemical element silicon. They are extensively used in solar cells, LED screens and other applications that utilize the conversion of electricity to light. Ladder polymers, on the other hand, are a type of double stranded polymers with the connectivity of a ladder. They are prepared by interconnecting repeating units along the main polymer chain by four chemical bonds, instead of the two bonds typically seen in conventional plastics. In this research, structural features of luminescent building blocks will first be optimized using a combination of synthetic and computational techniques. Ladder polymers will then be constructed, and their physical properties systematically studied using a variety of analytical techniques. A strong emphasis will be placed on development of materials that can more efficiently interconvert electricity and light. This work has the potential to lead to expansion of knowledge in organic semiconducting molecules, syntheses and polymers. Materials prepared in this work are also expected to impact development of more efficient digital displays and optical interconnectors. Students involved in this work will receive a broad training in synthetic polymer chemistry, photophysical characterization techniques and device fabrications. The outreach activities will focus on The Neighborhood School Program, which is one of the University of Chicago’s longest-standing community programs. In this program, students will play roles as tutors, teaching assistants, pre-school specialists, and technology coordinators with 50 sites on Chicago’s south side and with 4,000 local students each year. Strong emphasis will be placed on activities that encourage and motivate students from underrepresented groups to pursue education and careers in STEM fields. This research will focus on rational development of novel synthetic approaches towards ladder oligomers and polymers, with a strong focus on optimization of charge transfer and light emission. Monomers will first be synthesized, and their design guided using DFT calculations . Synthetic chemistry will involve two different approaches. The first two-step approach will focus on cyclization in which the Heck coupling reaction is used to obtain the ladder structures. The second single-step approach will consist of “ladderization” to simultaneously form the fused ring structures and will be accomplished by utilizing Friedlander condensation reaction. Polymerization of these monomers and oligomers will yield conjugated polymers with well-defined structures and optimized properties. Detailed characterization of the prepared polymers will also be performed using a variety of analytical techniques and will provide the necessary information for the structure-property correlation and shade light into the aggregation state of these luminescent polymers. The foldable semi-ladder conjugated polymers that will be synthesized as a result of this work can potentially address the big challenge confronted in the OLET (organic light-emitting transistors), by facilitating the fast charge transport while avoiding tight intermolecular H-aggregation that quenches luminescence.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.