CAREER: Investigating Surface Ligand Doping, Organization and Valency in Semiconductor Nanocrystal Quantum Dots: A Bridge Between Nano Chemistry Research and Education

化学系的高分子、超分子和纳米化学(MSN)计划支持爱荷华州立大学哈维尔·贝拉教授的职业生涯奖研究和教育计划。贝拉教授和他的学生研究新的表面配体掺杂策略，这种策略能够控制每个纳米晶体的官能化程度或价态。作为这项工作的一部分，贝拉教授的团队将研究表面修饰导致的配体组织、表面化学和纳米晶体性质的变化。在胶体半导体中，控制每个纳米晶体的功能化程度仍然是一个悬而未决的挑战。表面修饰通常是通过与过量的端羧酸或端胺的硫醇进行配体交换来进行的。然而，这种方法不能控制表面改性的程度。为了解决这个问题，贝拉教授和他的学生们将合成表面掺杂的带有化学活性天然配体的量子点并表征其表面微结构，合成用于表面掺杂的模块化功能多齿配体并研究其与量子点的配体交换行为，以及探索将表面掺杂量子点用于稀土的光学活化和配给。这项研究将对我们微调能量和电荷转移供体和受体的数量和相对构型的能力产生积极的影响，提供对跨越无机-有机-溶剂界面的激子衰减路径的前所未有的控制。这项研究的成功将导致制造、组装和发现用于成像、生物、能源和催化的功能纳米材料的强大战略。例如，特定官能团的表面覆盖程度将影响纳米晶体的表面亲和力和渗透性，以及它在生物组织和亚细胞结构中定位、穿透和运输的能力。此外，对表面掺杂纳米晶体的高级表征将进一步加深我们对表面配体组织及其对光电性质的影响的理解。这项提议的教育目标是通过在大学范围内举办纳米系列研讨会和在爱荷华州立大学开设纳米化学课程来缩小纳米技术研究和教育方面的差距，并通过为西班牙裔和拉丁裔/a学生和家庭举办不同的招生和双语活动来扩大参与。每周一次的研讨会和一个正式的课程将促进各部门纳米技术研究人员之间的互动和交流。通过用两种语言交流科学，贝拉教授将直接面向日益增长的人口群体，提高人们对纳米科学的认识和倡导，将其作为改善社区、国民经济和环境的一种方式。

The Macromolecular, Supramolecular, and Nanochemistry (MSN) program of the Division of Chemistry supports the CAREER Award's research and education program of Prof. Javier Vela at Iowa State University. Prof. Vela and his students investigate new surface ligand doping strategies that enable to control the degree of functionalization or valency per nanocrystal. As part of this effort, Prof. Vela's group will investigate the changes in ligand organization, surface chemistry and nanocrystal properties that result from surface modification. Controlling the degree of functionalization per nanocrystal remains an unsolved challenge in colloidal semiconductors. Surface modification is routinely performed by ligand exchange with excess carboxylate- or amine-terminated thiols. However, this method fails to control the extent of surface modification. To solve this problem, Prof. Vela and his students will synthesize surface-doped quantum dots capped with chemically-active native ligands and characterize their surface microstructures, synthesize modular functional polydentate ligands for surface-doping and study their ligand exchange behavior with quantum dots, and explore the use of surface-doped quantum dots for lanthanide optical activation and rationing of rare earths. This research will positively impact our ability to fine-tune the number and relative configuration of energy- and charge-transfer donors and acceptors, providing unprecedented control over exciton decay pathways across the inorganic-organic-solvent interface.Success of this research will result in powerful strategies to fabricate, assemble and discover functional nanomaterials for imaging, biology, energy and catalysis. For example, the extent of surface coverage by a particular functional group will impact a nanocrystal's surface affinity and permeability, and its ability to localize, penetrate, and be transported across biological tissues and subcellular structures. In addition, advanced characterization of surface-doped nanocrystals will further our understanding of surface-ligand organization and of how this affects optoelectronic properties. The educational goals of this proposal are to close gaps in nanotechnology research and education by introducing a university-wide nano seminar series and a nanochemistry course at Iowa State University, and to broaden participation via diverse recruiting and bilingual activities for Hispanic and Latino/a students and families. A weekly seminar and a formal course will promote interactions and facilitate exchanges among nanotechnology researchers across departments. By communicating science in two languages, Prof. Vela will directly address a growing demographic to raise awareness and advocacy for nanoscience as a way to improve the community, the national economy, and the environment.