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Nitric Oxide‐Induced Fluorescence Enhancement by Displacement of Dansylated Ligands from Cobalt
Author(s) -
Lim Mi Hee,
Kuang Chaoyuan,
Lippard Stephen J.
Publication year - 2006
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.200600042
Subject(s) - cobalt , nitric oxide , fluorescence , chemistry , cobalt oxide , biophysics , oxide , displacement (psychology) , photochemistry , biochemistry , inorganic chemistry , organic chemistry , biology , optics , psychology , psychotherapist , physics
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 CH 3 CN or CH 3 OH compared to that of the free Ds‐HAMP or Ds‐HAQ ligands. Addition of NO to a CH 3 CN 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 3 CN and CH 3 OH. 1 H 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.