LIGHT-MEDIATED REACTIONS UNDER
CONFINEMENT
Confined-space effects in reactions were first observed with supramolecular hosts in a lock-and-key-type setting akin to enzymes. Other small organic molecules and porous supramolecular materials (e.g., cucurbit[n]urils, metal-organic frameworks (MOFs), and metal-organic cages (MOCs)) have been developed for confinement-aided applications owing to an ability to control a periodic arrangement of transition metals and ligands with Ångstrom-level precision.
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We endeavor to synthesize well-defined frameworks capable of covalent- or noncovalent-based self-assembly to mediate covalent bond formation with the precision often seen in organic solid-state chemistry.
ACS Catal. 2020, 10, 13251.
STEREOELECTRONICALLY-GOVERNED RING-
OPENING METATHESIS POLYMERIZATION
To date, methods to engineer conjugated polymers with precise positioning of donor and acceptor units are typically based on step-growth methodology that leads to ill-defined polymers. The majority of approaches to control polymer sequence rely on exploiting reactivity differences, enthalpic/entropic driving forces, or preorganization to imbue sequence control within polymers.
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Recently, our group synthesized [2.2]cyclophanes with built in A-B sequences that underwent ROMP to achieve sequence-defined donor-acceptor conjugated polymers. The overall sequence control was attributed to a stereoelectronic bias designed within the monomer that favored the ring-opening event to occur the same way for each monomer unit incorporated.
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The group is currently looking to extend this methodology to achieve other polymers by way of steric and electronic control.
Angew. Chem. Int. Ed., 2019, 58, 9527; Synlett, 2020, 31, 1435.
FUNCTIONAL POLYMERS THOUGH
PRESSURE-INDUCED PERICYCLIC REACTIONS
In line with our NSF Center for Chemical Innovation, we are interested in working to increase the scope and understanding of the high-pressure chemistry in the formation of one-dimensional rigid sp -hybridized carbon-based polymers from aromatic precursors. Single aromatic units have been utilized to synthesize 1D nanothread polymers using benzene, pyridine, and hexafluorobenzene from high pressure cycloaddition reactions.
We are interested in applying both electronically-activating and -deactivating units and other external variables (such as supramolecular chemistry) within our monomer design, as well as targeting unique molecules with lessened aromaticity. Overall efforts are geared toward interrogating their collective impact on reaction conditions, mechanism of formation, and product control.
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