What can bulky ligands do for you? Designing Low-coordinate Single Molecule Magnets and Blue OLEDs Using Sterically Encumbering Ligands
Current state of the art hard disk storage uses magnetic nanoparticles that are approximately 10-100 nm to store the 1’s and 0’s of digital data. Shrinking the size of these particles further will result in hard drives with higher information storage density. As nanoparticles become smaller than ~10 nm, they leave the realm of nanoparticles and enter the realm of single molecules. Thus, the final frontier in the development of magnets for information storage lies in the development of permanent magnets that consist of only one molecule – single molecule magnets (SMMs). However, the current state of the art SMMs are only effective at cryogenic temperatures, limiting their practical use in consumer devices. Our group addresses these limitations through the development of sterically bulky carbazole and indoline ligands. These ligands feature flanking diarylmethyl groups that limit coordination to the metal and enforce an axial coordination geometry to enhance the SMM properties of these compounds. These complexes feature a weak interaction between the peripheral aryl rings and the metal center. By changing the electronics of the aryl rings, the M···C ipso interaction can be tuned, allowing us to elucidate the effect that these peripheral interactions have on the magnetic properties of the compound. These sterically bulky carbazole ligands also feature impressive luminescent properties. Upon deprotonation, these ligands display efficient blue fluorescence, with photoluminescent yields of up to 80%. These high quantum yields result from the steric bulk of the flanking groups on these ligands limiting non-radiative decay pathways. Thus, these ligands are excellent candidates for Blue OLEDs to be used in next generation digital displays.