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Organic Chemistry Seminar

Wednesday, May 22, 2019
4:00pm to 5:00pm
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Noyes 153 (J. Holmes Sturdivant Lecture Hall)
Efficient and Versatile Annulation to Build Diverse (Macro)Molecular Ladders as Microporous Membranes and Antiaromatic Molecules
Yan Xia, Assistant Professor of Chemistry, Chemistry Department, Stanford University,

In the pursuit of unusual ladder-shaped (macro)molecular structures with unique properties, we developed Catalytic Arene-Norbornene AnnuLation (CANAL) to synthesize rigid ladder polymers from readily available norbornenes and aryl bromides. Efficient CANAL polymerization produced ladder polymers with molecular weights up to 1 MDa, various functionalities, and contorted conformations, despite the formed strained ring in each repeat unit. These ladder polymers exhibited high surface areas, high microporosity (pore width < 1 nm), and surprisingly high thermal stability up to 400 °C without detectable Tg. Membranes were fabricated as promising materials for gas separations and understanding gas transport in glassy polymers. Switching the substrates from norbornenes to oxanorbornenes, CANAL also allowed us to synthesize unusual π-systems containing antiaromatic cyclobutadienoids from readily accessible building blocks. These extended conjugated ladder molecules exhibit tunable degrees of antiaromaticity, which results in unusual bonding structures, molecular orbitals, optoelectronic properties, and chemical reactivities.

For more information, please contact Annette Luymes by phone at x6016 or by email at aluymes@caltech.edu.