Collaborative Research: Radical and Biradical Polycyclic Aromatic Hydrocarbons in Complex Aggregation Environments

About This Grant

With the support of the Macromolecular, Supramolecular, and Nanochemistry program in the Division of Chemistry, Professors Hans Lischka of Texas Tech University and Miklos Kertesz of Georgetown University will develop and apply high-level computational methods to elucidate new design principles for the technologically important area of novel carbon nano-aggregates, which are crucial for the development of organic semiconductors for quantum devices, spintronics and biosensors. The work will focus on the discovery of new open shell multiradical polycyclic aromatic hydrocarbons (PAHs), their accurate characterization, and their association mechanisms in complex environments relevant for the understanding of the formation of carbon nanoparticles. For this purpose, combinations of highly innovative theoretical multireference methods available in the COLUMBUS program system of the Lischka group and artificial intelligence (AI) approaches will be applied together with the comprehensive chemical expertise of the Kertesz group. These investigations will lead to important expertise for the control and tuning of spin properties of PAH aggregates leading to the prediction of magnetic, optical and transport properties of new semiconductor materials. These computational technologies will provide new scientific opportunities and will have the potential for significant societal impact. Educational aspects are emphasized at graduate and undergraduate levels with the long-term goal of contributing to the availability of a technically competent new generation of scientists trained in a wide combination of computational methodologies. Effective ways to elevate the public awareness of science will be pursued by specific discovery-based science content incorporated in courses designed for non-science major college students. A new scope of computational investigations will be developed concentrating on complex modeling aiming at the determination of ensemble structures where radicals and biradicals are embedded in an unstructured PAH environment to allow better representation of realistic models like the Yen-Mullins model for asphaltenes or carbon nanodots. The tools for the creation of these ensemble structures are based on meta dynamics and replica exchange molecular dynamics which will be combined with efficient quantum chemical methods to reproduce the main features of the open shell PAH systems. As important new areas, the magnetic properties of single-sheet PAHs adsorbed on gold surfaces will be investigated to explain scanning tunneling microscopy (STM) and non-contact atom force microscopy (nc-AFM) experiments since they provide new possibilities to create a multitude of open shell PAHs with π paramagnetism. The developed multi-reference methods provide ideal possibilities for urgently needed accurate predictions and better understanding of the open shell character of these unique compounds. This 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.