Functional nanotubes from self-assembling bis-urea macrocycles

在化学系大分子、超分子和纳米化学计划的支持下，南卡罗来纳大学的Linda Shimizu教授将制作被称为双尿素大环的甜甜圈形状的构建块的精确纳米级组装，这些构建块堆叠在一起形成稻草状结构或纳米管。将测试不同的策略来控制3到150个大环单体的纳米管结构的形成。对这种尺寸的组件的精确控制有可能为了解发生在这些长度尺度上的化学、光驱动和电子转移过程提供新的机会。所获得的先进知识可能在光化学、分子电子学、光氧化和光动力学治疗中具有重要意义。教育活动包括让研究生、本科生和高中生参与跨学科研究，为他们回答21世纪劳动力中遇到的具有挑战性的科学问题做好准备。该计划还将继续向当地K-12学校开展外联计划，以突出科学职业，并通过让学生参与化学演示来展示科学方法。清水教授的团队将专注于尿素大环的自我限制增长，以提供一系列长度分散程度较低的纳米组件。具体地说，将采用不同的策略，包括通过在大环外部附着大基团来阻止它们的生长，使用链阻止单体来阻止纳米管的生长，以及添加模板来稳定特定尺寸的堆栈，以精确地指导3到150个大环单体的纳米管结构的形成。他们的目标是创造一系列长度在1到50纳米之间的“分子尺子”，以弥合单分子和超分子聚合物之间的差距。新型纳米分子‘尺子’将被用于探索纳米组装长度、形貌和动力学对光致电子转移和活性氧物种形成的影响。此外，先前在晶体中的实验结果将被汇编为初始数据集，以使用机器学习来推导物理模型。其目标是确定在辐射有组织的三苯胺大环和相关系统时导致自由基阳离子/阴离子形成的关键参数。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 Linda Shimizu of the University of South Carolina will make precise nanoscale assemblies of donut shaped building blocks known as bis-urea macrocycles, which stack to make straw like structures or nanotubes. Different strategies will be tested to control the formation of nanotubular structures of between 3 and 150 macrocyclic monomers. Precise control of assemblies in this size has the potential to open new opportunities to understand chemical, light driven and electron transfer processes that occur over these length scales. The advanced knowledge acquired may have important implications in photochemistry, molecular electronics, photooxidations, and photodynamic therapy. The educational activities include engaging graduate students, undergraduates, and high school students in interdisciplinary research to prepare them to answer challenging scientific questions encountered in the twenty-first century workforce. The program will also continue an outreach program to local K-12 schools to highlight careers in science and to showcase the scientific method by engaging students in chemistry demonstrations.Professor Linda Shimizu’s team will focus on self-limiting growth of urea macrocycles to afford a series of nano assemblies with low length dispersity. Specifically, different strategies, include frustrating their growth by attaching large groups on the exterior of the macrocycles, using chain stopping monomers to halt the growth of the nanotubes, and adding templates to stabilize stacks of specific size, will be employed to precisely guide the formation of nanotubular structures of between three and 150 macrocyclic monomers. The goal is to create a series of ‘molecular rulers’ between 1 to 50 nanometers in length to bridge the gap between single molecules and supramolecular polymers. The new nanometer molecular ‘rulers’ will be applied to probe how nano assembly length, morphology, and dynamics impact photoinduced electron transfer and the formation of reactive oxygen species. In addition, prior experimental results in crystals will be compiled as an initial data set to derive physical models using machine learning. The goal is to identify key parameters that lead to radical cation/anion formation upon irradiation of organized triphenylamine macrocycles and related systems.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.