title: New insights into structure and luminescence of Eu(III) and Sm(III) complexes of the 3,4,3-LI(1,2-HOPO) ligand.
abstract: We report the preparation and new insight into photophysical properties of luminescent hydroxypyridonate complexes [M(III)L](-) (M = Eu or Sm) of the versatile 3,4,3-LI(1,2-HOPO) ligand (L). We report the crystal structure of this ligand with Eu(III) as well as insights into the coordination behavior and geometry in solution by using magnetic circular dichroism. In addition TD-DFT calculations were used to examine the excited states of the two different chromophores present in the 3,4,3-LI(1,2-HOPO) ligand. We find that the Eu(III) and Sm(III) complexes of this ligand undergo a transformation after in situ preparation to yield complexes with higher quantum yield (QY) over time. It is proposed that the lower QY in the in situ complexes is not only due to water quenching but could also be due to a lower degree of f-orbital overlap (in a kinetic isomer) as indicated by magnetic circular dichroism measurements.
authors.affiliation: Chemical Science Division, Lawrence Berkeley National Laboratory, and Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: Lena J
authors.initials: LJ
authors.lastname: Daumann
authors.forename: David S
authors.initials: DS
authors.lastname: Tatum
authors.forename: Benjamin E R
authors.initials: BE
authors.lastname: Snyder
authors.forename: Chengbao
authors.initials: C
authors.lastname: Ni
authors.forename: Ga-lai
authors.initials: GL
authors.lastname: Law
authors.forename: Edward I
authors.initials: EI
authors.lastname: Solomon
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Raymond
mesh_terms: D005063:Europium / Q000737:chemistry*; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D008024:Ligands; D008163:Luminescent Measurements; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D011728:Pyridones / Q000737:chemistry*; D012493:Samarium / Q000737:chemistry*
chemical_list: C000594124:1,5,10,14-tetra(1-hydroxy-2-pyridon-6-oyl)-1,5,10,14-tetraazatetradecane; D006573:Heterocyclic Compounds, 1-Ring; D008024:Ligands; D009942:Organometallic Compounds; D011728:Pyridones; D012493:Samarium; D005063:Europium