Azido- and amino-substituted dipicolinates for the sensitization of the luminescent lanthanides EuIII and TbIII
作者:Katherine R. Johnson、Ana de Bettencourt-Dias
DOI:10.1016/j.ica.2020.120003
日期:2021.1
Dipicolinate-based ligands substituted with azido- or amino- functional groups were synthesized and characterized. Crystal structures of E-N3, C-N3, C-NH2, and E-NH2 were obtained, and the ability of these compounds to sensitize Ln(III) luminescence (Ln(III) = Eu-III and Tb-III)was explored. Luminescence efficiencies of Eu-III and Tb-III were determined and are phi(Eu) = 0.11%, 0.15%, and 13.8% for [Ln(CN3)(3)](3+), [Ln(E-N3)(3)](3+), [Ln(C-NH2)(3)](3+), respectively, and phi(Tb) = 0.30%, 0.27%, and 28.9% for [Ln(C-N3)(3)](3+), [Ln(E-N3)(3)](3+) , [Ln(E-NH2)(3)](3+). The highest luminescence efficiencies are phi(Eu) = 14.4% for [Eu(E-NH2)(3)](3+) and phi(Tb) = 29.7% for [Tb(C-NH2)(3)](3+). Similar S-1 and T-3 excited state energies were observed for all ligands and did not explain the observed discrepancies in luminescence efficiency of their Tb-III and Eu-III complexes. Further analysis revealed that the azido-derivatives were not photostable, which likely contributed to the low luminescence efficiency.