Heteroleptic homo
dinuclear complexes [Sm(fod)
3
(μ-bpp)Sm(fod)
3
] and [Eu(fod)
3
(μ-bpp)Eu(fod)
3
] and their
diamagnetic analogue [Lu(fod)
3
(μ-bpp)Lu(fod)
3
] (fod is the anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione
(Hfod) and bpp is 2,3-bis(2-pyridyl)pyrazine) are synthesized and
thoroughly characterized. The lanthanum gave a 1:1 adduct of La(fod)
3
and bpp with the molecular formula of [La(fod)
3
bpp]. The
1
H NMR and
1
H-
1
H COSY
spectra of the complexes were used to assign the proton resonances.
In the case of paramagnetic Sm
3+
and Eu
3+
complexes,
the methine (of the fod moiety) and the bpp resonances are shifted
in the opposite direction and the paramagnetic shifts are dipolar
in nature, which decrease with increasing distance of the proton from
the metal ion. The single-crystal X-ray analyses reveal that the complexes
(Sm
3+
and Eu
3+
) are dinuclear and crystallize
in the triclinic
P
1 space group. Each metal in a
given complex is eight coordinate by coordinating with six oxygen
atoms of three fod moieties and two nitrogen atoms of the bpp. Of
the two metal centers, in a given complex, one has a distorted square
antiprism arrangement and the other acquires a distorted dodecahedron
geometry. The Sparkle RM1 and PM7 optimized structures of the complexes
are also presented and compared with the crystal structure. Theoretically
observed bond distances are in excellent agreement with the experimental
values, and the RMS deviations for the optimized structures are 2.878,
2.217, 2.564, and 2.675 Å. The photophysical properties of Sm
3+
and Eu
3+
complexes are investigated in different
solvents, solid, and PMMA-doped thin hybrid films. The spectroscopic
parameters (the Judd–Ofelt intensity parameters, radiative
parameters, and intrinsic quantum yield) of each Eu
3+
sites
are calculated using the overlap polyhedra method. The theoretically
obtained parameters are close to the experimental results. The lifetime
of the excited state is 38.74 μs for Sm
3+
and 713.62
μs for the Eu
3+
complex in the solid state.
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