CAS: Synthesis, Assembly and Photophysical Behaviors of Nonconventional Purine-Containing Conjugated Copolymers

在化学系的大分子、超分子和纳米化学（MSN）项目的支持下，迈克尔·S。作者声明：Brian K.位于诺克斯维尔的田纳西大学的Long博士正在开发含嘌呤的导电共聚物。 嘌呤是含有两个稠合在一起的环的芳香族化合物。 它们是自然界中最广泛存在的含氮杂环，是DNA和RNA中常见的结构单元。 其他嘌呤来源包括肉类、酵母、燕麦片和咖啡因。 在这个项目中，小分子化学将首先基于常规偶联反应进行，以了解含嘌呤单体的位点反应性。 所获得的知识将用于将这些单体与含硫杂环偶联，以制备定义明确的低聚物和完全共轭的共聚物。 将检查共聚物的导电和发光能力，使其成为光电器件或成像和传感应用的潜在候选者。 还将进行一系列物理和结构表征，以生成量化连接性和区域化学如何影响溶液和固态自组装以及它们如何影响物理性质的关系。 由此产生的基础化学知识的机构有可能刺激创新的设计和合成共轭聚合物的非传统的建筑单元的基础上嘌呤。 教育和培训将通过研究生的共同指导以及研究生指导计划的制定和实施来促进。 此外，来自研究中代表性不足的群体的学生将通过既定的NSF支持的校园计划参与。 通过为田纳西州科学奥林匹克竞赛提供服务，与青少年学生和广大公众接触，将促进和培养青少年学生对科学的兴趣。这项工作将研究分子设计对明确定义的低聚物和完全共轭的含嘌呤聚合物的构象、组织和性质的作用。 在第一个目标中，小分子偶联研究将被用来调查的噻吩嘌呤噻吩（TPT）三联体上的碳-碳键形成的网站的反应性偏差。这些研究有望为含嘌呤共聚物的构建提供重要见解，并以这种方式为创建明确定义的含嘌呤寡聚物和共聚物的努力提供信息。 第二个目标将集中在三聚体的合成和表征，其具有跨越嘌呤支架的确定的连接模式（2，6-、6，8-和2，8-连接），但具有区域化学的系统变化。 最后，在最后一个目标中，线性共轭和交叉共轭的嘌呤-噻吩共聚物将通过使用AB聚合或AA+BB共聚的TPT三元组的直接（杂）芳基化聚合来合成。 该研究计划的成果预计将为使用分子设计来调节共轭聚合物的纳米级组装和性质提供信息和刺激，这些聚合物由于其作为有机半导体的功能而在各种情况下都具有适用性。除了推进分子工程方法来理解新型功能聚合物的行为和性质外，这项工作还可能提供基础知识，扩大生物衍生和丰富的嘌呤在有机电子领域的潜力。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

With the support of the Macromolecular, Supramolecular and Nanochemistry (MSN) program in the Division of Chemistry, Michael S. Kilbey and Brian K. Long of the University of Tennessee, Knoxville are developing conductive purine-containing copolymers. Purines are aromatic compounds that contain two rings fused together. They are the most widely occurring nitrogen-containing heterocycles in nature and are common building blocks found in DNA and RNA. Other purine sources include meats, yeast, oatmeal and caffeine. In this project, small molecule chemistry will first be performed based on conventional coupling reactions in order to understand site reactivity of purine-containing monomers. The knowledge gained will then be used to couple these monomers with sulfur-containing heterocycles to prepare well-defined oligomers and fully conjugated copolymers. The copolymers will be examined for their ability to conduct electricity and emit light, making them potential candidates for optoelectronic devices or for imaging and sensing applications. A suite of photophysical and structural characterizations will also be performed to generate relationships that quantify how connectivity and regiochemistry affect self-assembly in solution and in the solid state, as well as how they influence photophysical properties. The resulting body of fundamental chemistry knowledge has the potential to spur innovations in the design and synthesis of conjugated polymers from nonconventional building blocks based on purines. Education and training will be promoted through co-advising of graduate students and the development and implementation of graduate student mentoring program. Additionally, students from underrepresented groups in research will be involved through established NSF-supported on-campus programs. Engagement with young learners and the greater public through service to the Tennessee Science Olympiad will promote and nurture interests of young learners in science.This work will investigate the role of molecular design on the conformation, organization and properties of well-defined oligomers and fully conjugated purine-containing polymers. In the first objective, small molecule coupling studies will be used to investigate reactivity bias of the sites used for carbon-carbon bond formation on the thiophene-purine-thiophene (TPT) triads. These studies are expected to provide critical insights into how purine-containing copolymers are constructed and, in this way, inform efforts to create well-defined purine-containing oligomers and copolymers. The second objective will focus on the synthesis and characterization of trimers with defined patterns of connectivity across the purine scaffold (2,6-, 6,8-, and 2,8-connectivity), but featuring systematic variation in regiochemistry. Finally, in the last objective, linearly conjugated and cross-conjugated purine-thiophene copolymers will be synthesized via direct (hetero)arylation polymerization of TPT triads using either AB polymerizations or AA+BB copolymerizations. Outcomes from this research program are anticipated to inform and stimulate efforts to use molecular design to modulate nanoscale assembly and properties of conjugated polymers, which find applicability in various contexts due to their functionality as organic semiconductors. In addition to advancing a molecular engineering approach to understand behaviors and properties of novel, functional polymers, this work has the potential to provide fundamental knowledge that expands the potential of bio-derived and abundant purines in organic electronics.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.