Distribution of distances in donor-acceptor pairs of cyanine dyes upon electronic excitation energy transfer in the presence of DNA

Electronic excitation energy transfer (EEET) between molecules of carbocyanine dyes, which form noncovalent complexes with DNA, has been studied by picosecond spectroscopy. Three oxacarbocyanine dyes have been used as electronic excitation energy donors, and 3,3′-diethylthiacarbocyanine iodide has served as an acceptor dye. An analysis of the kinetic dependences permitted obtaining the data on distribution of the distances in donor-acceptor pairs upon EEET. The effect of the acceptor concentration on the parameters of distribution of its molecules in the quenching microphase has been revealed.