Ultrafast IR spectroscopy of polymeric cytosine nucleic acids reveal the long-lived species is due to a localised stateElectronic supplementary information (ESI) available: Biexponential kinetic fits for systems studied. See DOI: 10.1039/c2cp23774a

• Main Authors: Keane, Páraic M, Wojdyla, Michal, Doorley, Gerard W, Kelly, John M, Clark, Ian P, Parker, Anthony W, Greetham, Gregory M, Towrie, Michael, Magno, Luís M, Quinn, Susan J
• Format: Journal Article
• Language: English
• Published: 11.04.2012
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c2cp23774a

The decay pathways of UV-excited cytosine polymers are investigated using picosecond time-resolved infrared spectroscopy. Similar yields of a non-emissive 1 nπ* state are found in the single-stranded dC 30 polymer as in the dCMP monomer, but with a longer lifetime in the polymer (80 ps vs. 39 ps). A longer lifetime is also found in the d(CpC) dinucleotide. No evidence of excimer states is observed, suggesting that localised 1 nπ* excited states are the most significant intermediates present on the picosecond timescale. A dark 1 nπ* state is observed in UV-excited cytosine polymers and its lifetime is lengthened relative to the monomer.