ORGN 385 |
| Babu Rao Renikuntla and Bruce A. Armitage. Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue Box118, Pittsburgh, PA 15213 |
| Cationic cyanine dyes spontaneously assemble into helical aggregates using DNA as a template. The aggregates are stabilized primarily by face-to-face stacking between two dyes to form noncovalent dimers. In addition, alignment of these dimers within the minor groove of double-helical DNA provides end-to-end interactions that are manifested in the optical spectroscopy of these aggregates. Mixing different dyes together leads to formation of a mixture of homo- and heterodimers. Variation of the dye heterocycles and polymethine bridge lengths failed to yield pure heteroaggregates, though. This was most likely due to the substantial differences in the conjugated systems of various cyanine dyes. In order to improve the heteroaggregation, we synthesized two thiadicarbocyanine dyes which differ in terms of substituents on the benzothiazole ring systems. In one dye, two electron-donating amino groups are attached, while the second dye features electron-withdrawing fluorine atoms. UV-vis and circular dichroism spectroscopic experiments were used to show that mixing of the two dyes together with DNA leads to exclusive formation of heteroaggregates due to electron donor-acceptor (EDA) interactions. This effect is independent of the length of the DNA template. This research represents a step forward in the controlled growth of multichromophore assemblies. |
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Physical Organic, Combinatorial, Materials, Molecular Recognition
8:00 PM-10:00 PM, Tuesday, March 30, 2004 Anaheim Convention Center -- Hall A, Poster
Division of Organic Chemistry |