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Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs
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Leveraging Divergent Ligand-to-Metal Charge-Transfer Excited State Pathways for Catalyst Control over Alkoxyl Radical
Zilu Tang1, Yetong Lin1, Arshad Mehmood2,3
1Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.
Journal of the American Chemical Society
|February 4, 2026
Summary
Titanium catalysts enable new organic synthesis pathways by tuning ligand-to-metal charge-transfer (LMCT) excited states. This allows for controlled radical generation and tandem reactions, significantly enhancing reaction rates.
Area of Science:
- Organic Synthesis
- Photochemistry
- Organometallic Chemistry
Background:
- Ligand-to-metal charge-transfer (LMCT) excitation is a key method for generating heteroatom radicals in organic synthesis.
- Exploiting alternative LMCT excited-state processes beyond metal-ligand bond homolysis remains largely unexplored.
- Titanium alkoxides offer potential for novel LMCT excited-state reactivity.
Purpose of the Study:
- To develop a general strategy for tuning reaction pathways from LMCT excited states of titanium alkoxides.
- To enable tandem β-scission/Giese addition reactions using these novel pathways.
- To investigate catalyst-controlled radical generation and subsequent reactions.
Main Methods:
- Utilized electronically tuned titanium catalysts to control LMCT excited-state processes.
- Investigated tandem β-scission/Giese addition reactions with various alcohols.
- Employed intramolecular competition studies and computational modeling.
Main Results:
- Demonstrated a general strategy for tuning reaction courses from titanium alkoxide LMCT excited states.
- Achieved tandem β-scission/Giese addition reactions for both scission-amenable and recalcitrant alcohols.
- Observed up to a 103-fold rate enhancement for catalyst-controlled scission compared to free alkoxyl radicals.
Conclusions:
- Developed a versatile reactivity paradigm based on titanium alkoxide LMCT excited states.
- Highlighted the significant rate enhancement achievable through excited-state β-scission.
- Computational studies support the mechanism involving a scission-promoting LMCT excited state.
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