The effect of the 4-amino functionality on the photophysical and DNA binding properties of alkyl-pyridinium derived 1,8-naphthalimides

Banerjee, Swagata, Kitchen, Jonathan A., Gunnlaugsson, Thorfinnur and Kelly, John M. (2013) The effect of the 4-amino functionality on the photophysical and DNA binding properties of alkyl-pyridinium derived 1,8-naphthalimides. Organic & Biomolecular Chemistry, 11 (34), 5642-5655. (doi:10.1039/C3OB40370J). (PMID:23873271)

Abstract

The synthesis and characterisation of two cationic pyridinium based 4-amino-1,8-naphthalimide derivatives ( and ) are described and compared to those of compound . The photophysical properties of and are shown to vary greatly with the solvent polarity and H-bonding ability. The dimethylamino substitution in results in a weak quantum yield of fluorescence emission due to faster non-radiative deactivation of the excited singlet state than that seen for . As with , the fluorescence of was found to be enhanced in its 1:1 complex with 5'-adenosine-monophosphate (5'-AMP) while it was partially quenched in its complex with 5'-guanosine-monophosphate (5'-GMP). In contrast, the fluorescence of was enhanced ('switched on') in the presence of both adenine and guanine rich sequences. Linear and circular dichroism studies showed that each of , and binds to double-stranded DNA by intercalation. However, and do not show the preference for AT-rich DNA observed for . Comparative fluorescence studies with double stranded DNA show that the emission of was 16 times enhanced in its DNA bound form, suggesting potential use of this structure as a spectroscopic probe for studying nucleic acid structure.

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Contributors

Author: Jonathan A. Kitchen

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