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

点击翻译按钮获取中文摘要

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.