Project 3: Entanglement in Mesospin Systems
3.1. Synthesis and Structural Characterization of Molecular Magnetic Systems
A main experimental thrust area is the synthesis and investigation of molecular magnets. We have prepared and studied the magnetic properties of both monodisperse organic molecules with spin values up to 10 and polydisperse organic polymers with spin values up to 5000. The first organic polymer magnet was reported recently by Rajca et al. “Magnetic Ordering in an Organic Polymer,” Science 294, 1503 (2001). The Figure below illustrates the kinds of exchange-coupled oligomers of various sizes and geometries that we are able to produce.
Examples of previously synthesized exchange-coupled organic and organometallic oligomers: (a) organic oligomer pentadecaradical, which may be viewed as a linear trimer of exchange coupled S = 7/2, 1/2,and 7/2 complexes; (b) organometallic oligomer diradical-MnII-diradical, which may be viewed as a pentamer of antiferromagnetically coupled S = 1/2, 1/2, 5/2, 1/2, and 1/2 complexes; (c) organometallic oligomer (diradical-MnII)n, which may be viewed as a linear chain of antiferromagnetically coupled S = 1/2, 1/2, and 5/2 complexes. Inset: aryl groups (Ar) for structure (a) and metal ions with ligands (Met) for structures (b) and (c).
The structures shown above are excellent model systems, exhibiting a variety of exchange interactions of importance for the understanding and exploitation of entanglement. The typical approach to synthesis of such molecule-based structures involves multi-step organic synthesis from molecular precursors, with purification and standard organic characterization, such as NMR, IR, and mass spectrometry, after each synthetic step. For crystalline materials, such as the organometallic oligomers, single crystal X-ray crystallography is also used to determine both the molecular and the solid state structure.