This award in the Macromolecular, Supramolecular & Nanochemistry Program to Professor Jeffrey R. Long of the University of California, Berkeley, involves the synthesis and detailed characterization of a number of complexes as single-molecule magnets. The project consists of the following studies: (a) synthesis and characterization of new cyano-bridged coordination clusters and chain compounds featuring high-anisotropy rhenium-based building units, with emphasis on establishing what factors contribute to high magnetic anisotropy barriers; (b) incorporation of iron(II) complexes known to exhibit spin crossover behavior into such compounds, possibly leading to the first examples of photoswitchable single-molecule and single-chain magnets; (c) synthesis of high-symmetry, multinuclear imidazolate-bridged clusters in which vanadium(II/III) or iron(II/III) mixed valence leads to an energetically well-isolated high-spin ground state via a double exchange mechanism; (d) synthesis of lanthanide and actinide complexes with rigorous axial symmetry, which could provide a means of generating a large relaxation barrier; (e) manipulation of the ligand field, and consequently the zero-field splitting parameters, of selected trigonal pyramidal iron(II) complexes.
In sum, Dr. Long and his group will develop general strategies for the synthesis of new single-molecule magnets that are expected to reveal new types of magnetic behavior of potential interest for high-density information storage and spin-based molecular electronics.
The broader impacts of this research include a legacy of synthetic techniques, the creation of new materials of potential technological importance, and the education and training of postdoctoral, graduate, and undergraduate students in the synthesis and characterization of inorganic materials. As a related educational activity, Dr. Long will continue to lead an effort to create a materials chemistry major within the Department of Chemistry at UC Berkeley.
The research involved development of general strategies for the synthesis of new molecules that behave as magnets that can operate at increased temperatures. Such molecules are of current interest for their potential applications in high-density information storage and fast and energy-efficient computing, as well as for the investigation of new physical phenomena. The relative predictability of the structures and magnetic properties of metal-cyanide coordination clusters made them particularly amenable to the design of species exhibiting a large magnetic moment. Our effort was extended to the formation of one-dimensional chain magnets, wherein the strength of magnetic coupling could be used for increasing the magnet operation temperature, and to molecules in which the magnetic moment could be switched on and off using light. Significant additional attention was given to the development of magnets based upon molecules containing a single transition metal, lanthanide, or actinide element. The intellectual merit of this work lies in the contribution to our understanding of how to control the formation of new inorganic structures, and how to utilize that control in manipulating electronic and magnetic properties. Its broader impacts include a legacy of synthetic techniques, the creation of new materials of potential technological importance, and the education and training of postdoctoral, graduate, and undergraduate students in the synthesis and characterization of inorganic materials. As a related educational activity, the PI continued to lead an effort to create a materials chemistry major within the Department of Chemistry at the University of California, Berkeley.