Functional nanotubes from self-assembling bis-urea macrocycles

在化学系大分子、超分子和纳米化学项目的支持下，南卡罗来纳州大学的琳达·清水教授将制作被称为双脲大环化合物的甜甜圈形结构单元的精确纳米级组件，这些结构单元堆叠在一起，形成稻草状结构或纳米管。 将测试不同的策略以控制3至150个大环单体的纳米管结构的形成。 精确控制这种尺寸的组件有可能为理解这些长度尺度上发生的化学，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方面具有重要意义。 教育活动包括让研究生、本科生和高中生参与跨学科研究，让他们做好准备，回答在21世纪世纪劳动力中遇到的具有挑战性的科学问题。 该计划还将继续推广计划，以当地的K-12学校，突出在科学的职业生涯，并展示科学方法，让学生参与化学演示。琳达清水教授的团队将专注于尿素大环的自限制增长，以提供一系列的纳米组装与低长度分散性。 具体而言，将采用不同的策略，包括通过在大环外部连接大基团来阻止它们的生长，使用链终止单体来停止纳米管的生长，以及添加模板以稳定特定尺寸的堆叠，以精确地引导3至150个大环单体的纳米管结构的形成。 目标是创造一系列长度在1到50纳米之间的“分子标尺”，以弥合单分子和超分子聚合物之间的差距。新的纳米分子“统治者”将被应用于探测纳米组装长度，形态和动力学如何影响光诱导电子转移和活性氧的形成。 此外，先前在晶体中的实验结果将被编译为初始数据集，以使用机器学习导出物理模型。 目标是确定导致有组织的三苯胺大环化合物和相关系统在辐照后形成自由基阳离子/阴离子的关键参数。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, 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.