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Luminescence Resonance Energy Transfer in Heterodinuclear Ln III Complexes for Sensing Biologically Relevant Anions
Author(s) -
Andolina Christopher M.,
Morrow Janet R.
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201000779
Subject(s) - chemistry , lanthanide , luminescence , europium , ligand (biochemistry) , resonance (particle physics) , tris , phosphate , crystallography , inorganic chemistry , ion , organic chemistry , physics , optoelectronics , biochemistry , receptor , particle physics
Dinuclear lanthanide(III) complexes of the macrocycles 1,4‐bis[1‐4,7,10‐ tris(carbamoylmethyl)‐1,4,7,10‐tetraazacyclododecane]‐ m ‐xylene ( 1 ) and 1,3‐bis[1‐4,7,10‐tris(carbamoylmethyl)‐1,4,7,10‐tetraazacyclododecane]‐ p ‐xylene ( 2 ) with Ln III = Eu III , Tb III were prepared. Studies using direct excitation ( 7 F 0 → 5 D 0 ) europium(III) luminescence spectroscopy show that several anions including phosphate, methylphosphate, double‐stranded DNA, a DNA hairpin loop, and fluoride bind to both Eu III centers in Eu 2 ( 1 ) in solutions at pH 7.0, 0.100 M NaNO 3 . Recovered luminescence lifetime data is consistent with replacement of water ligands by these anions. There are distinct changes in the relative intensities of Eu III emission peaks for complexes of Eu 2 ( 1 ) and Eu 2 ( 2 ) with phosphate, fluoride, carbonate, and phosphate ester ligands. This suggests that the Eu III dinuclear complexes show promise as ratiometric sensors for these anions. In contrast, the emission peak ratios for the Tb 2 ( 1 ) and Tb 2 ( 2 ) complex show a lower response upon binding of each anionic ligand. Luminescence resonance energy transfer (LRET) studies with mixed Eu III /Nd III complexes show that the phosphate complexes of Ln 2 ( 1 ) or Ln 2 ( 2 ) both have Ln III –Ln III internuclear distances of 7.7 ± 0.9 Å and the methylphosphate complexes of Ln 2 ( 1 ) and Ln 2 ( 2 ) have internuclear distances of 7.8 ± 0.6 and 8.0 ± 0.7 Å, respectively. LRET experiments also show the two lanthanide ion centers in Ln 2 ( 2 ) are 8.4 ± 0.5 Å apart when bound to GC rich duplex DNA. None of the other anions (carbonate, fluoride, DNA hairpins) form complexes that show measurable energy transfer between the lanthanide ions, which is consistent with intranuclear distances >8 Å.