CAREER: Design Strategies for High-Performance Bismuth- and Lanthanide-Based Single-Molecule Magnets

Michigan State University, East Lansing MI

Investigators

Abstract

With support from the Chemical Structure, Dynamics & Mechanisms-B Program of the Chemistry Division, Selvan Demir of the Department of Chemistry at Michigan State University is employing organometallic chemistry to develop new classes of molecular compounds with interesting magnetic properties, known as single-molecule magnets (SMMs). The exciting potential applications of SMMs span from high-density information storage, quantum computing, to spin-based electronic devices, but hinge on increasing the spin-reversal barrier, magnetic blocking temperature, and coercive field - all metrics that describe the molecule’s ability to retain information after removing an applied external magnetic field. This project will develop new rational design strategies to engender new types of SMMs comprising bismuth and the paramagnetic lanthanides. The combination of the electronic features of bismuth and lanthanide sites could usher in a new generation of SMMs with unparalleled performance characteristics. The project tightly integrates academic research and education in several ways to provide the highest level of education to the public and students at all stages. This includes a creative approach “Science Meets Art” that utilizes the power of visualization to facilitate entry into the elaborate spin-based science subject where exhibitions in a gallery and museums are planned. The development of an experimental quantum information science course accompanied with a magnetism kit is also encompassed alongside lectures at local schools. Single molecule magnets (SMMs) exhibit a barrier to spin reversal and in the absence of quantum tunneling, magnetic hysteresis similar to bulk magnets. Therefore, one of the most important but also challenging goals is to increase simultaneously spin ground state and magnetic anisotropy, critical goals in the pursuit of strongly coupled multinuclear SMMs. Strong coupling is required as it suppresses fast relaxation pathways such as quantum tunneling which is needed for high-temperature SMMs. In addition, new chemical space must be explored to advance the field. Accordingly, this project aims to develop new rational design strategies to engender (i) the first bismuth-centered SMMs, (ii) new lanthanide SMMs containing bismuth radicals, (iii) new redox-active heterocyclic ligands composed of bismuth and nitrogen donors, (iv) the first multinuclear SMMs consisting of bismuth-nitrogen heterocyclic bridges, and (v) the first multinuclear SMMs containing bismuth-nitrogen heterocyclic radicals. From a fundamental point of view, the thorough study of magnetic coupling pathways through diamagnetic and paramagnetic bridges has the potential to advance knowledge of relaxation dynamics occurring in SMMs, and in so doing, pave the way for future SMM design. 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.