Collaborative Research: Directing molecular assemblies into covalently bonded 2D organic materials

罗格斯大学新玩法的Robert Bartynski和Sylvie Rangan教授以及罗格斯大学纽瓦克的Elena Galoppini教授得到了美国国家科学基金会化学部大分子、超分子和纳米化学（MSN）计划的支持，以开发在金属表面上创建碳基二维材料的新方法。 定制设计的分子构建块的有序阵列组装在单晶表面上，然后经受外部刺激，例如热、光或高能电子，以将相邻分子连接在一起，从而产生延伸的二维片材。 在暴露于外部刺激之前，通过明智地选择和放置化学结构单元来控制片材的拓扑结构和功能。 由此产生的片材有望显示出各种各样的新特性和现象，如新形式的磁性，导电性，电阻很小或没有电阻，以及有效的发光或吸收光。 该研究项目的成功为二维材料在纳米电子，传感器，太阳能电池，发光二极管和其他需要可加工性，可调谐性，高性能和传统材料无法获得的特性的设备中的新应用开辟了道路。 在实施该项目的过程中，参与的学生在多学科科学研究环境中接受了广泛的培训，并有机会与国家实验室的科学家进行互动。 来自代表性不足的少数群体的本科生参与了该项目，高中学生和教师得到了指导。 该项目为二维（2D）材料的表面合成生成了一个“工具箱”。 探索了与表面合成相关的不同键合机制，并开发了创建表面反应层次结构的方法，以指导分子单元之间形成分子间C-C键，从而创建新的2D有机系统。 该工具箱涉及（a）开发具有置于战略位置的官能团的特别设计的分子前体，（B）使用官能团之间的分子间和/或分子内相互作用以及对织构化金属的表面模板效应，以控制分子前体在单晶表面上的组装。 特别强调通过脱氢（消除H2）、脱卤（消除X2，X = Br、Cl、I）和脱氢（消除HF）反应形成C-C键。 所得2D结构的性质通过表面科学技术（包括扫描隧道显微镜）的综合组合来研究，并且电子性质通过基于同步加速器的电子光谱学的组合来检查，直接和反向光电发射以及ab-该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的支持知识价值和更广泛的影响审查标准。

Professors Robert Bartynski and Sylvie Rangan of Rutgers University New Brunswick and Professor Elena Galoppini of Rutgers University Newark are supported by the Macromolecular, Supramolecular and Nanochemistry (MSN) Program in the Division of Chemistry of the National Science Foundation to develop new methods for the creation of carbon-based two-dimensional materials on metal surfaces. Ordered arrays of custom designed molecular building blocks are assembled on single crystal surfaces then subjected to an external stimulus, such as heat, light, or energetic electrons, to link together neighboring molecules creating an extended two-dimensional sheet material. The topology and functionality of the sheet are controlled by judicious selection and placement of the chemical building blocks prior to exposure to the external stimulus. The resulting sheets hold the promise of displaying a wide variety of novel properties and phenomena such as new forms of magnetism, conduction of electricity with little or no resistance, and efficient emission or absorption of light. Success of this research project opens the way to new applications of two-dimensional materials in nano-electronics, sensors, solar cells, light-emitting diodes, and other devices that require processability, tunability, high performance, and properties that cannot be obtained with conventional materials. During the course of conducting the project, the students involved are broadly trained in a multidisciplinary science research environment and provided a chance to interact with scientists in national laboratories. Undergraduate students from under-represented minority groups are involved in the project and high school students and teachers are mentored. The project generates a "toolbox" for on-surface synthesis of two-dimensional (2D) materials. Different bonding mechanisms that are relevant to on-surface synthesis are explored and ways to create a hierarchy of surface reactions to direct the formation of intermolecular C-C bonds between molecular units to create new 2D organic systems are developed. The toolbox involves (a) the development of specially designed molecular precursors with functional groups placed at strategic positions, (b) the use of inter-molecular and/or intra-molecular interactions between functional groups, as well as surface templating effects on textured metals, to control the assembly of the molecular precursors on single crystal surfaces. A particular emphasis is placed on the formation of C-C bonds by dehydrogenation (elimination of H2), dehalogenation (elimination of X2, X = Br, Cl, I) and dehydrofluorination (elimination of HF) reactions. The nature of the resulting 2D structures are studied through an integrated combination of surface science techniques, including scanning tunneling microscopy, and the electronic properties are examined through a combination of synchrotron-based electron spectroscopies, direct and inverse photoemission as well as ab-initio theoretical methodsThis 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.