Charge transfer through DNA/DNA duplexes and DNA/RNA hybrids: Complex theoretical and experimental studies

•Study of charge transfer processes in short DNA/DNA and RNA/DNA duplexes with virtually equivalent sequences.•Temperature dependent steady state and time-resolved fluorescence spectroscopy, Density Functional Theory.•More effective charge transfer in RNA/DNA hybrids-delocalized HOMO and holes, specific base stacking and conformational flexibility.•RNA/DNA and DNA/DNA charge transfer properties-connected with temperature affected structural changes.•Charge transfer/fluorescence spectroscopy probe of even tiny changes of molecular structures and settings.

Oligonucleotides conduct electric charge via various mechanisms and their characterization and understanding is a very important and complicated task. In this work, experimental (temperature dependent steady state fluorescence spectroscopy, time-resolved fluorescence spectroscopy) and theoretical (Density Functional Theory) approaches were combined to study charge transfer processes in short DNA/DNA and RNA/DNA duplexes with virtually equivalent sequences. The experimental results were consistent with the theoretical model - the delocalized nature of HOMO orbitals and holes, base stacking, electronic coupling and conformational flexibility formed the conditions for more effective short distance charge transfer processes in RNA/DNA hybrids. RNA/DNA and DNA/DNA charge transfer properties were strongly connected with temperature affected structural changes of molecular systems - charge transfer could be used as a probe of even tiny changes of molecular structures and settings.

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