Erratum: Bright oligothiophene N-succinimidyl esters for efficient fluorescent labeling of proteins and oligonucleotides (Bioconjugate Chemistry (January/February 2006) 17:1 (58-67))

BRIGHTOLIGOTHIOPHENEN-SUCCINIMIDYLES-TERS FOR EFFICIENT FLUORESCENT LABELING OFPROTEINS AND OLIGONUCLEOTIDESIn our work (1), we have discovered an inconsistency in thedefinition of the molecular geometry of compound5used inthe theoretical calculations. We used a molecular structure withaCdC double bond on thesuccinimidylgroup, while thesuccinimidyl group instead has single CsC bonds. The structureemployed in calculations is known asmaleimideinstead.We repeated the theoretical calculations using the correctmolecular structure. We found small changes in the electronicstructure and optical properties. Molecular orbitals localized onthe succinimidyl group are shifted in energy, so that now the LUMO is no longer localized on the succinimidyl group but rather on the bithiophene. New HOMO and LUMO orbitals are reported in Figure 1. The optically active state (computed atthe CC2 level) is found at 4.01 eV, almost the same energy asin previous calculations, since the side group has a negligibleeffect on it, but now it is the lowest excited state and it ischaracterized by a HOMOfLUMO transition. Finally, we emphasize that the main conclusions drawn from theoretical calculations, based on considerations of optically active states and analysis of model compoundAT2, still hold unaffected.