EUNSUNG LEE group
RESEARCH
Main group radical chemistry
- Organic contrast agent and qubit studies
N-heterocyclic carbenes (NHCs) have been studied in various fields, including catalyst and main group element chemistry. NHCs facilitate the generation and utilization of unstable species, including main group and organic radicals. The design and syntheses of air-persistent organic radicals (APORs) are challenging because of the abundance of reactive molecules in the air, including water, carbon dioxide, and dioxygen. NHCs are effective at stabilizing radical centers because of their bulky substituents and low-lying empty orbitals. Stable organic radicals in air by introducing NHCs have been reported and are being studied.
APORs show potential for use in various applications, such as in the development of magnetic resonance imaging contrasting agents and flexible devices. Organic radical contrasting agents have emerged as alternatives to gadolinium-based contrasting agents for MRI due to the risk of nephrogenic systemic fibrosis (NSF). The development of organic radical-based MRI contrast agents is expected to provide a safer alternative in situations where no suitable alternative is available.
In addition, radical ion pairs, consisting of a radical cation and a radical anion, have recently attracted much attention in the fields of catalysis and quantum information. However, few examples of their structures and properties have been reported due to their extreme instability and high reactivity in air. We are studying the possibility that radical pairs can be applied to the qubit, the smallest unit of quantum information processing.
Organometallics
- Development of Ligands and Catalysts
To develop new transition metal catalyst for synthesis of cyclic polymers
One of the examples is Grubbs catalyst which catalyzes metathesis reaction between two C-C double bonds. Using olefin metathesis, cyclic polymers can be accessed by ring-expansion metathesis polymerization (REMP) from cyclic monomers. Our goal is to develop a new REMP catalyst for cyclic polymers with well-controlled molecular weight and narrow polydisperity. In addition, we have done several research on the activation of small molecules such as nitrogen(N2), using low-valent metal complexes. We will also explore many spectroscopic techniques including UV‐vis, FTIR, EPR and multi‐nuclear NMR, Xray crystallography, and quantum‐chemical calculations (DFT) to understand chemical transformations that we are developing.
Organometallic compounds are widely used in many chemical reactions as homogeneous catalysts which bear their own ligands. By modifying ligand systems, characteristics and reactivities of organometallic catalysts can be dramatically changed. In our group, we focus on the synthesis of new ligand for organometallic compounds which can improve catalytic reactivities of the compounds.
Energy material synthesis through MOF/COF synthesis
Metal-Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) are innovative materials with distinct features that find widespread applications.
Generally, Metal-Organic Frameworks (MOFs) are utilized in various applications such as molecular adsorption, storage, separation, and catalytic reactions. Particularly, we have studied research using MOFs to achieve unprecedented selectivity in reactions like the C-H bond oxidation of hydrocarbons and the direct anti-Markovnikov addition of water to alkenes. This involves synthesizing MOFs with embedded organometallic catalysts and studying the impact of modifying both the MOF and catalyst components on the selectivity of organic reactions occurring within such materials.
On the other hand, COFs, as organic semiconductor materials, exhibit significant potential as photocatalysts due to their ordered crystalline structure, long-range organization, and tunable building blocks like triazine, and olefin linkages. Their high porosity, chemical stability, and thermal stability make COFs effective as heterogeneous organic photocatalysts. Similar to synthesizing MOFs, for COFs as well, we plan to design and synthesize more efficient COF-based photocatalysts by modifying various organic linkers. Our ultimate goal is to synthesize energy materials by synthesizing these MOF and COF substances.
