In this project, funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Prof. Talat S. Rahman of University of Central Florida and Prof. Ludwig Bartels of the University of California, Riverside, and their students will use a combination of scanning tunneling microscopy and first principles electronic structure calculations to image and understand the formation of metal coordination networks on a number of metallic surfaces. They will explore in detail electronic properties of these supported metal coordination centers to address properties such as (i) charge transfer (between molecule & substrate, metal-center & molecule, and metal-center & substrate), and (ii) shape and energetics of molecular orbitals and their relation to conventional metal organic chemistry. Tuning of the effective oxidation state of metal-centers and of ligand HOMO-LUMO gaps by suitable choice of the substrate electronic properties will provide descriptors for variation of the local chemical and geometrical environment. Furthermore, general rules that define the coordination geometry around metal-centers on surfaces will be sought and conditions for stability of coordination centers with specific geometry (e.g., triagonal vs. square) will be tested. Attention will also be paid to understanding the magnetic characteristics of metal coordination centers: metal-center/molecule/substrate combinations which conspire to produce stable magnetic networks will be pursued.
This project will provide state of the art modeling and/or laboratory experiences for graduate and undergraduate students and junior scientists who will be learning the techniques of chemical synthesis, formation of metal coordination networks on various metallic surfaces, imaging, and complementary ab initio electronic structure calculations. The project consists of a systematic exploration of coordination chemistry at metal surfaces which will provide the framework for establishing the rules that distinguish it from conventional ligand field and crystal field theory, which govern solution-phase metal organic chemistry. Examination of vibrational and magnetic characteristics of the systems and the special role of dispersion forces will add further value to the proposed work. Through leadership by a theorist, this project is certain to create systematic understanding, deeper insights and faster validation of findings and their generalizations to other systems. The proposed work is expected to have impact on industrial methodologies and society at large by providing access to metal coordination networks in a deterministic fashion. Control of such structures will allow continuous surface patterning from the atomic to the macroscopic scale, which should prove important for a large range of microelectronic, optoelectronic and magnetic applications. The work will also provide opportunities for educational and outreach activities with proven broad national, international and societal impact.
