Boron Dipyrromethene Photocages for Mild and Selective Light-Driven Polymer Chemistry

在化学学部大分子、超分子和纳米化学项目的支持下，德克萨斯大学奥斯汀分校的Zachariah A. Page博士正在开发含硼的光选择性染料，作为合成可回收聚合物的催化剂。为了了解染料的电子和化学性质，我们将首先通过系统的研究来优化染料的结构和反应性。成功的候选材料将用于光制备动态聚氨酯网络。聚氨酯是一类重要的塑料，广泛用于制造涂料、粘合剂和密封剂。将单个建筑单元连接成长聚合物链的光，也可以通过简单地改变其波长和强度来逐个断开它们。因此，这种光开关将导致可回收性。与本研究相关的研究有可能提供与光控聚合相关的基础化学知识，以及如何利用光控聚合有效地制备可回收的聚合物材料。因此，在拟议的工作中强调的化学也解决了当前和正在进行的塑料废物积累的全球问题。本研究将为高分子化学的本科生和研究生的培养提供新的机会。将举办多元化研讨会，并开设有机化学本科生同侪辅导新课程。此外，这项工作还将积极支持公众教育和宣传。佩奇博士将创建一个跨学科的聚合物教学模块，将光作为科学工具，吸引来自STEM领域少数民族比例不成比例的机构的初高中学生。还将建立涉及与北卡罗莱纳州立大学校际学生互动的外展活动。本课题将重点研究以苄基硫化物为催化剂的波长选择性二吡咯烷硼（BODIPY）光笼的开发，用于可控阴离子光氧化还原聚合。潜在的策略是使用温和的反应条件和可见光到近红外（近红外）光来可逆地切割BODIPY衍生物，并产生可以引发聚合的强亲核试剂（硫代阴离子）。具体来说，具有（二）硫脲和亚胺/腙/肟功能的可回收动态聚合物网络的制备将被强调为软材料，在很大程度上仍未使用光驱动方法进行研究。重点将放在通过结构修饰bodipy基染料的反应性和动力学优化上，以了解它们的电子性质和对不同波长和强度光的响应。提出的结构-反应性研究可以提供与利用光氧化还原引发聚合合成可回收聚合物相关的基本化学知识。通过不同的光强度和波长来控制聚合的能力有可能实现聚合物材料的精确2d图案和3d打印，对组织工程、机器人、光学涂层和图像传感具有长期潜在的科学影响。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Dr. Zachariah A. Page of the University of Texas at Austin is developing light-selective boron containing dyes as catalysts for the synthesis of recyclable polymers. The structure and reactivity of these dyes will first be optimized through systematic studies in order to understand their electronic and chemical properties. Successful candidates will then be used to prepare dynamic poly(urethane) networks using light. Poly(urethanes) are an important class of plastics which is extensively used to make coatings, adhesives and sealants. The light that will connect individual building units into long polymer chains will also be used to disconnect them one at a time by simple changing its wavelength and intensity. Hence, this light-toggling will lead to recyclability. Studies associated with this research have the potential to provide fundamental chemistry knowledge associated with light controlled polymerization and how it can be used to efficiently prepare recyclable polymeric materials. As such, chemistry emphasized in the proposed work also addresses the current and ongoing global issue of plastic waste accumulation. This research will provide new opportunities for undergraduate and graduate student training in polymer chemistry. Diversity seminars will be initiated, as well as development of a new course in undergraduate peer mentoring for organic chemistry. Moreover, the work will also positively support public education and outreach. Dr. Page will create an interdisciplinary polymer teaching module on light as a tool in science to engage middle and high school students from institutions with disproportionate populations of minorities in STEM fields. Outreach activities involving intercollegiate student interactions with North Carolina State University will also be established. This research will focus on development of wavelength-selective boron dipyrromethene (BODIPY) photocages bearing benzyl sulfides as catalysts for controlled anionic photoredox polymerization. The underlying strategy uses mild reaction conditions and visible-to-NIR (near infrared) light to reversibly cleave BODIPY derivatives and generate strong nucleophiles (thiolate anions) that can initiate polymerization. Specifically, the preparation of recyclable dynamic polymer networks bearing (di)thiourethane and imine/hydrazone/oxime functionality will be emphasized as soft materials that remain largely unexamined using light-driven approaches. Strong emphasis will be placed on the optimization of reactivities and kinetics through structural modification of BODIPY-based dyes in order to understand their electronic properties and responses to light with different wavelengths and intensities. Proposed structure-reactivity studies could provide fundamental chemistry knowledge associated with the synthesis of recyclable polymers using photoredox initiated polymerization. The proposed ability to control the polymerization by different light intensities and wavelengths has the potential to permit the precise 2D-patterning and 3D-printing of polymeric materials, with long-term potential scientific impact upon tissue engineering, robotics, optical coatings and image sensing.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.