Displacement assay detection by a dimeric lanthanide luminescent ternary Tb(III)-cyclen complex: high selectivity for phosphate and nitrate anions.
The luminescent dimeric ternary lanthanide–cyclen complexes (2-(Ln.1)2; Ln = Tb/Eu) were designed and both their self-assembly formation and their ability to detect anions via displacement assays were investigated using spectrophotometric titrations in MeOH solution. The formation of 2-(Tb.1)2 and 2-(Eu.1)2 was investigated in solution, and determination of the binding constants and stoichiometry showed that the former was formed almost exclusively over the 1:1 complex 2-(Tb.1) after the addition of two equivalents of 2; while for 2-(Eu.1)2 a mixture of both stoichiometries existed even after the addition of four equivalents of 2. Of these two systems, 2-(Tb.1)2 was studied in details as a probe for anions, where significant changes where observed in the photophysical properties of the complex; with the characteristic Tb(III)-centred emission being fully switched off upon the sensing of phosphates and nitrate, giving rise to the formation of a H2PO4(-):Tb.1 complex in a 1:2 stoichiometry upon sensing of H2PO4(-) by 2-(Tb.1)2, while NO3(-) gave 1:1 complex formation and two equivalents of NO3(-)·Tb.1.
School of Chemistry and Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland. gunnlaut@tcd.ie.
David F
DF
Caffrey
Thorfinnur
T
Gunnlaugsson
D000838:Anions / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D000080027:Cyclams; D019281:Dimerization; D006571:Heterocyclic Compounds / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry; D009566:Nitrates / Q000032:analysis*; D010710:Phosphates / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D013725:Terbium / Q000737:chemistry*
D000838:Anions; D056831:Coordination Complexes; D000080027:Cyclams; D006571:Heterocyclic Compounds; D028581:Lanthanoid Series Elements; D009566:Nitrates; D010710:Phosphates; D013725:Terbium; C038072:cyclen