ORGN 233 |
Highly stable self-association of guanidiniocarbonyl pyrrole carboxylate zwitterions in aqueous solvents: From dimers to supramolecular oligomers
| Carsten Schmuck, Institut für Organische Chemie, Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg, 97074, Germany |
| We recently found that 2-(guanidiniocarbonyl)-1H-pyrroles bind carboxylates by ion pairing in combination with multiple hydrogen bonds even in highly polar solvents. Based on this novel recognition motif, new supramolecular structures can be designed. Self-complementary guanidiniocarbonyl pyrrole/carboxylate zwitterions form intramolecular loops, dimers or oligomers depending on the molecular structure of the zwitterion and the experimental conditions. For example, a rigid zwitterion forms highly stable 1:1 dimers even in water held together solely by electrostatic interactions: an extensive network of hydrogen bonds in combination with two mutual interacting ion pairs. Such binding motifs might be useful for the design of new materials such as supramolecular polymers. We present here the syntheses of such zwitterions and the evaluation of their self-assembly properties (e.g. by nmr, uv, esi-ms, x-ray and theoretical calculations, respectively). 
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