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Impact of the supramolecular organisation of pyrene – quinoline conjugates on their interaction with ds – DNA

Two novel pyrene – quinoline conjugates differing in the linker flexibility between aryls were prepared. In comparison with referent pyrene derivative, both conjugates showed intramolecular pyrene – quinoline stacking in an aqueous medium, much more efficient for rigid conjugate. Consequently, only rigid conjugate showed excimer fluorescence with exceptionally strong bathochromic shift (+ 55 nm) of emission maximum in respect to referent pyrene analogue and flexible conjugate. Apart from the fluorescence spectroscopy, the study includes UV/Vis spectrophotometry and circular dichroism spectroscopy, as well as the thermal melting experiments Combined studies, revealed that All studied compounds showed similar, 10 µmol dm-3 affinity toward ds – DNA, characterized in general by fluorescence quenching. The flexible conjugate showed at large excess of DNA over dye formation of pyrene – quinoline excimer, while rigid conjugate retained excimer emission throughout all DNA concentrations. Lack of significant thermal stabilization of ds – DNA by studied compounds and minor changes in CD spectrum of DNA supported non – specific agglomeration of both conjugates and referent pyrene analogue within hydrophobic DNA grooves as the dominant binding mode.

pyrene ; supramolecular organisation ; intramolecular stacking ; spectroscopy

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