A Supramolecular Chemistry Approach to Precisely Controlled Multi-Porphyrin Arrays in Water

化学学部的大分子、超分子和纳米化学项目支持杜兰大学化学系Jayawickramarajah教授的项目。Jayawickramarajah博士正在开发一种合成方法，在水中制造精确控制的多卟啉阵列。本研究的目标是设计一个二维循环结构系统，形成三维圆柱体，可以改善光吸收和电子转移方向。该项目使用了一种称为自组装的过程，其中合成颜色分子（卟啉）通过混合精心选择的组件自发地形成所需的3D结构。此外，该项目利用水（一种丰富且无毒的液体）作为反应介质。除了增加我们对分子组装和光收集的基本理解外，该项目还包括一个扩展组件，重点是提高K-12学生对化学和科学的兴趣。由多层二维循环发色团阵列组成的定义三维圆柱体的结构对于光子应用具有吸引力，因为这种三维结构可以提供增强的光吸收和激发能量转移（EET）的方向性。卟啉环可以被密集地包裹在功能性固体衬底上。研究小组合成了这些组件，然后研究了这些圆柱体在水中的组装。该策略利用一系列超分子组装模式，包括阳离子诱导的鸟苷或异鸟苷寡核苷酸杂交，形成圆柱形四联体和五联体。重要的是，研究人员建议将独特的发色团定位在沿圆柱体的特定位置，以实现定向EET。捕光卟啉可以避免有害的自堆积，从而表现出优越的光物理特性。通过与Rubtsov和Schmehl研究小组合作进行的稳态和时间分辨荧光测量来分析这些特性。拓展计划包括Jayawickramarajah教授开创的服务学习课程，重点是杜兰大学的本科生在新奥尔良市中心的公立学校开展以化学为中心的服务学习活动。

The Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division supports the project by Professor Jayawickramarajah, of the Department of Chemistry at Tulane University. Dr. Jayawickramarajah is developing an synthetic approach to make precisely controlled mutli-porphyrin arrays in water. The goal of this research is to design a system of 2-dimensional cyclic structures to form 3-dimensional cylinders that can improve light absorption and direction for electron transfer. The project uses a process called self-assembly, where the synthetic color molecules (porphyrins) spontaneously form the desired 3D architectures by mixing of carefully chosen components. Further, the project utilizes water (an abundant and non-toxic liquid) as the medium for the reaction. In addition to increasing our fundamental understanding of molecular assembly and light-collection, this project also includes an outreach component that focuses on enhancing the interest of K-12 students in chemistry and science. The construction of defined 3D cylinders composed of multiple rungs of 2D cyclic chromophore arrays is attractive for photonic applications since such 3D architectures may provide enhanced light absorption, and directionality for excitation energy transfer (EET). The porphyrin rings can be packed densely onto functional solid substrates. The research team synthesizes the components and then studies the assembly of the cylinders in water. The strategy harnesses an array of supramolecular assembly modes, including cation-induced guanosine or isoguanosine oligonucleotide hybridization to form cylindrical quadruplexes and pentaplexes. Importantly, the researchers propose to position unique chromophores at specific sites along the cylinders to achieve directional EET. The light-harvesting porphyrins are precluded from undergoing detrimental self-stacking and thus exhibit superior photophysical properties. These properties are analyzed via steady-state and time-resolved fluorescence measurements that are conducted in collaboration with the Rubtsov and Schmehl research groups. The outreach plan includes a service-learning course pioneered by Professor Jayawickramarajah and focuses on undergraduates from Tulane conducting chemistry-centered service learning activities at inner-city New Orleans public schools.