Electronic interactions in helical stacked arrays of the modified DNA base pyrrolocytosine

Prakash P. Neelakandan, Martin McCullagh, George C Schatz, Frederick D Lewis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


The thermal stability and ultraviolet and circular dichroism spectra of nine synthetic DNA hairpins possessing one or more PC-G base pairs (PC = pyrrolocytosine) have been investigated. One group of hairpins possess 1-5 sequential PC-G base pairs while another group possess two PC-G base pairs separated by 1-3 A-T base pairs. The first group displays a nearly linear dependence of UV and exciton-coupled circular dichroism (EC-CD) band intensity upon the number of neighboring chromophores, whereas the second group shows weak EC-CD only at the shortest distances between non-neighboring chromophores. This result stands in marked contrast to the exciton coupling seen between stilbene chromophores separated by as many as a dozen base pairs. The weak exciton coupling between non-neighboring PC chromophores, like that of the natural nucelobases, is attributed to their relatively weak electronic transition dipoles.

Original languageEnglish (US)
Pages (from-to)5199-5204
Number of pages6
JournalJournal of Physical Chemistry B
Issue number17
StatePublished - May 3 2012

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry


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