Two types of
dimeric complexes [Ln
2(hfa)
6(
2-O(CH
2)
2NHMe
2)
2] an
d [Ln(th
d)
2(
2,
2-O(CH
2)
2NMe
2)]
2 (Ln= Y
III, Eu
III, G
dIII, Tb
III, Tm
III, Lu
III; hfa
- = hexafluoroacetylacetonato, th
d- =
dipivaloylmethanato) areobtaine
d by reacting [Ln(hfa)
3(H
2O)
2] an
d [Ln(th
d)
3], respectively, with
N,
N-
dimethylaminoethanol in toluenean
d are fully characterize
d. X-ray single crystal analysis performe
d for the Tb
III compoun
ds confirms their
dimeric structure. The coor
dination mo
de of
N,
N-
dimethylaminoethanol
depen
ds on the nature of the
ddle">-
diketonate. In [Tb
2(hfa)
6(
2-O(CH
2)
2NHMe
2)
2], eight-coor
dinate Tb
III ions a
dopt
distorte
d square antiprismaticcoor
dination environments an
d are O-bri
dge
d by two zwitterionic
N,
N-
dimethylaminoethanol ligan
ds with aTb1···Tb2 separation of 3.684(1) Å. In [Tb(th
d)
2(
2,
2-O(CH
2)
2NMe
2)]
2, the
N,
N-
dimethylaminoethanol actsas chelating-bri
dging O,N-
donor anion an
d the Tb
III ions are seven-coor
dinate; the Tb1···Tb1A separationamounts to 3.735(2) Å within centrosymmetric
dimers. The
dimeric complexes are thermally stable up to180
deg.gif">C, as shown by thermogravimetric analysis, an
d their volatility is sufficient for quantitative sublimation un
der re
duce
d pressure. The Eu
III an
d Tb
III dimers
display metal-centere
d luminescence, particularly[Eu
2(hfa)
6(O(CH
2)
2NHMe
2)
2] (quantum yiel
d = 58%) an
d [Tb(th
d)
2(O(CH
2)
2NMe
2)]
2 (32%). Consi
deration of energy migration paths within the
dimers, base
d on the stu
dy of both pure an
d Eu
III- or Tb
III-
dope
d(0.01-0.1 mol %) Lu
III analogues, lea
ds to the conclusion that both the
ddle">-
diketone an
d N,
N-
dimethylaminoethanol ligan
ds contribute significantly to the sensitization process of the Eu
III luminescence. The ancillaryligan
d increases consi
derably the luminescence of [Eu
2(hfa)
6(O(CH
2)
2NHMe
2)
2], compare
d to [Ln(hfa)
3(H
2O)
2],through the formation of intra-ligan
d states while it is
detrimental to Tb
III luminescence in both
ddle">-
diketonates.Thin films of the most luminescent compoun
d [Eu
2(hfa)
6(O(CH
2)
2NHMe
2)
2] obtaine
d by vacuum sublimation
display photophysical properties analogous to those of the soli
d-state sample, thus opening perspectives forapplications in electroluminescent
devices.