CAREER: Stable Carbenes as Surface Anchoring Groups

Jeremiah A.马萨诸塞州理工学院的约翰逊获得了大分子、超分子和纳米化学项目的一项奖励，该项目对几种纳米尺寸的颗粒（纳米颗粒）的表面进行化学修饰，以使它们更适用于不同的功能。广泛的现代技术，例如，电子设备、诊断系统、传感器、药物输送剂等，依赖于纳米颗粒表面的可控的、坚固的涂层，该涂层具有将以特定方式与其他分子反应的分子层;这被称为表面功能化。令人惊讶的是，用于表面功能化的化学方法数量相对较少，对于大多数应用仅涉及少数反应，并且这些方法中的每一种都具有局限性。因此，生产和使用单层功能性单分子膜的新方法可能会对广泛的技术产生巨大影响。该项目的研究重点是开发特定的卡宾家族（活性碳化合物），作为对纳米颗粒进行单层表面改性的新方法。这种卡宾化学提供了强表面键合和合成多功能性的潜在理想组合，有可能成为不同现代纳米颗粒技术的理想平台。该研究包括NHC层形成的基础研究，以及该技术在电子和药物输送方面的应用。这项职业建议研究正在与一个外展计划相结合，该计划的重点是在小学和高中发展纳米科学日和科学博览会。该提案旨在开发可寻址的N-杂环卡宾（ANHC）作为用于制造新型金属-有机界面的通用配体。这一目标正在通过三个研究方向来实现：（1）合成具有不同空间体积和反应性的ANHC库，并在各种基底上成膜的背景下进行研究;（2）从ANHC表面引发的表面聚合的范围正在扩大到包括各种半导体聚合物和其他聚合物纳米结构;（3）利用扫描隧道显微镜断裂结（STMBJ）技术研究了bis-NHC和金属有机ANHC丝的电子性质。所提出的ANHC的合成多样性，在各种基底上形成ANHC单层并随后使这些单层官能化的能力，以及形成导电ANHC-金属界面的潜力，使得所提出的研究成为各种表面改性应用的平台技术。此外，这项研究的结果正在与一个全面的教育计划，包括课程开发在麻省理工学院和校外研究生，本科，高中和小学教育相结合。

Professor Jeremiah A. Johnson at the Massachusetts Institute of Technology is supported by an award from the Macromolecular, Supramolecular and Nanochemistry Program to chemically modify the surfaces of several-nanometer-sized particles (nanoparticles) in order to make them more useful for different functions. A broad range of modern technologies, e.g., electronics, diagnostic systems, sensors, drug delivery agents, etc., rely on controlled, robust coating of the nanoparticle surface with layers of molecules that will react in particular ways with other molecules; this is called surface functionalization. It is quite surprising that chemical methods for surface functionalization are relatively few in number, involving only a handful of reactions for most applications, and each of these methods has limitations. As a result, new approaches to produce and use single layers of functional monolayers could drastically impact a wide range of technologies. The research in this project focuses on the development of particular carbene families (reactive carbon compounds) as a new way of making single-layer surface modifications of nanoparticles. This carbene chemistry offers a potentially ideal combination of strong surface bonding and synthetic versatility with the potential to be the ideal platform for different modern nanoparticle technologies. The research encompasses fundamental studies of NHC-layer formation, as well as applications of this technology to electronics and drug delivery. This CAREER proposal research is being integrated with an outreach program focused on the development of a Nanoscience Day and science fair at an elementary and high school. This proposal seeks to develop addressable N-heterocyclic carbenes (ANHCs) as versatile ligands for the fabrication of novel metal-organic interfaces. This goal is being pursued through three research thrusts: (1) a library of ANHCs with varied steric bulk and reactivity is being synthesized and studied in the context of film formation on various substrates; (2) the scope of surface-initiated polymerization from ANHC surfaces is being expanded to include a variety of semiconducting polymers and other polymeric nanostructures; (3) the electronic properties of bis-NHCs and metal-organic ANHC wires is being studied using the scanning tunneling microscopy break junction (STMBJ) technique. The synthetic diversity of the proposed ANHCs, the ability to form ANHC monolayers on a wide array of substrates and subsequently functionalize those monolayers, and the potential to form conductive ANHC-metal interfaces makes the proposed research a platform technology for a variety of surface modification applications. Furthermore, the results of this research are being integrated with a comprehensive education plan that includes course development within MIT and extramural graduate, undergraduate, high school, and elementary education.