Temperature-dependent conformations of exciton-coupled Cy3 dimers in double-stranded DNA
Understanding the properties of electronically interacting molecular chromophores, which involve internally coupled electronic-vibrational motions, is important to the spectroscopy of many biologically relevant systems. Here we apply linear absorption, circular dichroism, and two-dimensional fluores...
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Veröffentlicht in: | The Journal of chemical physics 2018-02, Vol.148 (8), p.085101-085101 |
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Sprache: | eng |
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Zusammenfassung: | Understanding the properties of electronically interacting molecular chromophores, which
involve internally coupled electronic-vibrational motions, is important to the
spectroscopy of many biologically relevant systems. Here we apply linear absorption,
circular dichroism, and two-dimensional fluorescence spectroscopy to study the polarized
collective excitations of excitonically coupled cyanine dimers (Cy3)2 that are
rigidly positioned within the opposing sugar-phosphate backbones of the double-stranded
region of a double-stranded (ds)–single-stranded (ss) DNA fork construct. We show that the
exciton-coupling strength of the (Cy3)2-DNA construct can be systematically
varied with temperature below the ds–ss DNA denaturation transition. We interpret
spectroscopic measurements in terms of the Holstein vibronic dimer model, from which we
obtain information about the local conformation of the (Cy3)2 dimer, as well as
the degree of static disorder experienced by the Cy3 monomer and the (Cy3)2
dimer probe locally within their respective DNA duplex environments. The properties of the
(Cy3)2-DNA construct we determine suggest that it may be employed as a useful
model system to test fundamental concepts of protein-DNA interactions and the role of
electronic-vibrational coherence in electronic energy migration within exciton-coupled
bio-molecular arrays. |
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ISSN: | 0021-9606 1089-7690 |
DOI: | 10.1063/1.5020084 |