ORGN 182 |
| Dynamic covalent chemistry, the production of molecular compounds through thermodynamically controlled reactions, has generated much interest of late. Perhaps the most useful facet of this type of chemistry is its ability to error check and proof-read, i.e., that the molecules can equilibrate and adapt to changing reaction conditions in situ. These principles are demonstrated in dramatic fashion through the solubilization of a dynamer made from 1 (Box) and 2,2′-oxybis(ethylamine). This material is insoluble in all conventional solvents. Gel-permeation chromatography of a dilute solution obtained by extended heating of the dynamer in dimethylformamide shows the existence of almost all conceivable polymeric species, with a molecular weight range of 3000 to 2.8 million and a polydispersity of 7. However, the addition of a drop of trifluoroacetic acid renders the imine bonds dynamic once again, and all of the material breaks down to its precursors and dissolves in CD3CN, CD3NO2, D2O, CD3COCD3 and CD3OD. Surprisingly, the material is also rendered soluble, sans acid, upon addition of a dialkylammonium ion dumbbell – shown in green and blue below – which templates the formation of a [24]crown-8-like bicyclic compound at the expense of all other chemical species. 1H NMR spectroscopy and electrospray ionization mass spectrometry confirms the existence of this interlocked compound.
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Total Synthesis, Materials, Devices and Switches, Molecular Recognition and Self-Assembly, Biologically-Related Molecules and Processes
8:00 PM-10:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Sci-Mix
Division of Organic Chemistry |
