Self-Assembled Multi-Component Catenanes: Structural Insights into an Adaptable Class of Molecular Receptors and -Catenanes
NORTH CAROLINA UNIV AT CHAPEL HILL OFFICE OF SPONSORED RESEARCH
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Under acidic conditions 50 equiv TFA, combinations of hydrazide A-B monomers self assemble into octameric 2 -catenanes with high selectivity for 1sub32sub2, where 1 is a D-Pro-X X Aib, Ac4c, Ac6c, L-4-Cl-PhGly derived monomer and 2 is an L-Pro-L-arylGly Pro Pro, trans-F-Pro, trans-HO-Pro, aryl naphthyl, phenyl derived monomer. Five different combinations of monomers were studied by X-ray crystallography. In each case, the unique aryl glycine unit is located in the core of the structure where the aryl ring templates a CH-pi-CH sandwich. Analysis of metrical parameters indicate that this core region is highly conserved, while the more peripheral zones are flexible. 1H NMR spectroscopy indicate that the solid state structures are largely retained in solution, though several non-C2 symmetric compounds have a net C2-symmetry that indicate accessible dynamic processes. Catenane dynamic processes were additionally probed through HD exchange, with the core being inflexible relative to the peripheral structure. Mass spectrometry was utilized to identify the constitutional isomerism in the minor asymmetric 1sub52sub3 catenanes.
- Physical Chemistry
- Atomic and Molecular Physics and Spectroscopy