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

在化学系大分子、超分子和纳米化学计划的支持下，德克萨斯大学奥斯汀分校的Zachariah A.Page博士正在开发用于合成可回收聚合物的光选择性含硼染料催化剂。首先将通过系统的研究来优化这些染料的结构和反应活性，以了解它们的电子和化学性质。然后，成功的候选者将被用来利用光来制备动态的聚(氨基甲酸酯)网络。聚氨基甲酸酯是一类重要的塑料，广泛用于制造涂料、胶粘剂和密封剂。将单个建筑单元连接成长聚合物链的光也将被用来通过简单地改变波长和强度来一次一个地断开它们的连接。因此，这种光切换将导致可回收利用。与这项研究相关的研究有可能提供与光控制聚合有关的基本化学知识，以及如何使用它来有效地制备可回收的聚合物材料。因此，拟议工作中强调的化学也解决了目前和正在进行的塑料废物积累的全球问题。这项研究将为本科生和研究生培养聚合物化学提供新的机会。将启动多样性研讨会，并开发一门关于有机化学本科生同伴指导的新课程。此外，这项工作还将积极支持公众教育和外展。佩奇博士将创建一个关于光作为科学工具的跨学科聚合物教学模块，以吸引来自STEM领域少数民族人口比例不成比例的机构的初中生和高中生。还将开展涉及校际学生与北卡罗来纳州立大学互动的外联活动。本研究将致力于发展含苯并硫化物的波长选择性二吡咯亚甲基(BODIPY)光笼，作为可控阴离子光氧化还原聚合的催化剂。基本策略使用温和的反应条件和可见光到近红外(近红外)光来可逆地裂解BODIPY衍生物，并产生能够引发聚合的强亲核试剂(硫酸盐阴离子)。具体地说，具有(二)硫代尿烷和亚胺/肼/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，这些材料在很大程度上仍未使用光驱动方法进行检查。重点将放在通过BODIPY染料的结构修饰来优化反应性和动力学，以了解它们的电子性质和对不同波长和强度的光的响应。提出的结构-反应性研究可以提供与光氧化还原引发聚合合成可回收聚合物相关的基础化学知识。拟议的通过不同光强度和波长控制聚合的能力有可能实现聚合物材料的精确2D图案化和3D打印，对组织工程、机器人、光学涂层和图像传感具有长期的潜在科学影响。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, 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.