Nitric oxide-induced fluorescence enhancement by displacement of dansylated ligands from cobalt

Mi Hee Lim, Chaoyuan Kuang, Stephen J. Lippard

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


The cobalt complexes [Co(Ds-AMP)2] (1) and [Co(Ds-AQ) 2] (2), where Ds-AMP and Ds-AQ are the conjugate bases of dansyl aminomethylpyridine (Ds-HAMP) and dansyl aminoquinoline (Ds-HAQ), respectively, were synthesized in two steps as fluorescence-based nitric oxide (NO) sensors and characterized by X-ray crystallography. The fluorescence of the two complexes was significantly quenched in CH3CN or CH3OH compared to that of the free Ds-HAMP or Ds-HAQ ligands. Addition of NO to a CH3CN solution of 1 or 2 enhanced the integrated fluorescence emission by factors of 2.1(+0.3) or 3.6(+0.4) within 35 or 20 min, respectively. Introduction of NO to methanolic solutions of the complexes similarly increased the fluorescence by 1.4(±0.1) for 1 or 6.5(±1.4) for 2 within 1 h. These studies demonstrate that 1 and 2 can monitor the presence of NO with turn-on emission and that their fluorescence responses are more rapid than those of previously reported cobalt systems in coordinating solvents such as CH 4CN and CH3OH. 1H NMR and IR spectroscopic data revealed the formation of a {Co(NO)2}10 cobalt-dinitrosyl adduct, with concomitant dissociation of one ligand from the cobalt center, as the metal-containing product of the NO reactions, a result indicating NO-induced ligand release to be the cause of the fluorescence increase.

Original languageEnglish (US)
Pages (from-to)1571-1576
Number of pages6
Issue number10
StatePublished - Oct 2006
Externally publishedYes


  • Cobalt
  • Dyes
  • Fluorescence
  • Nitric Oxide
  • Sensors

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Organic Chemistry


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