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The University of Southampton

Shape-selective fluxional carbon cages Seminar

15:30 - 16:30
18 December 2019

For more information regarding this seminar, please email Prof. Steve Goldup at .

Event details

Dr. Paul McGonigel presents a seminar as part of the Functional Inorganic, Materials and Supramolecular Chemistry Research Group’s seminar series.

Dynamic covalent rearrangements of fluxional carbon cages, such as bullvalenes and barbaralanes, impart ‘shapeshifting’ molecular properties.1 This seminar will describe a barbaralanes that exhibit fluxional constitutions and fluxional sp3-C stereochemistry. Derivatives bearing two aryl groups (example below) interconvert dynamically between two constitutional isomers in solution, but resolve to single isomers upon crystallisation. Unexpectedly, the minor solution-phase isomers are resolved in two instances. Through dynamic NMR, crystallographic and DFT analyses, we show that the isomer observed in the solid state is not a direct consequence of the equilibrium distribution in solution or any specific noncovalent interactions. Rather, the dynamic preferential crystallisation is dictated by differences in molecular size and shape.2 By changing the substitution pattern of the barbaralanes, the fluxional rearrangement gives rise to rapidly interconverting mixture of enantiomers – formally inverting sp3-C stereocentres. The fluxional carbon stereocentres can be controlled by covalent modification or noncovalent bonding interactions.

1 A. N. Bismillah, B. M. Chapin, B. A. Hussein, P. R. McGonigal, Chem. Sci. in press. 2 A. N. Bismillah, J. Sturala, B. M. Chapin, D. Yufit, P. Hodgkinson, P. R. McGonigal, Chem. Sci. 2018, 9, 8631.

Speaker information

Dr. Paul R. McGonigal, Durham University. The McGonigal Group develops functional organic materials by exploiting our expertise in stabilized, highly substituted aromatic carbocations. Students in the group are exposed to a wide range of techniques in organic synthesis, advanced spectroscopy, organometallics, electrochemistry, and DFT modeling.

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