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Synthesis and luminescence studies of lanthanide complexes (Gd, Tb, Dy) with phenyl- and 2-pyridylthiolates supported by a bulky β-diketiminate ligand. Impact of the ligand environment on terbium() emission
Ist Teil von
New journal of chemistry, 2020-12, Vol.44 (45), p.19769-19779
Ort / Verlag
Cambridge: Royal Society of Chemistry
Erscheinungsjahr
2020
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
The range of lanthanide complexes with bulky
N
,
N
′-bis(Dipp)-substituted β-diketiminate ligand Nacnac
−
= CH(CMe(NDipp))
2
−
(Dipp = 2,6-diisopropylphenyl) has been expanded to the complexes [Ln(Nacnac)I
2
(thf)
n
] (
1
Ln
, Ln =
Gd
,
Tb
,
n
= 2;
Dy
,
n
= 1; thf = tetrahydrofuran). They were further used in salt metathesis reactions with KSPh and KS(2-Py) (2-Py = 2-pyridyl), resulting in thiolato complexes [Ln(Nacnac)(SPh)
2
(thf)] (
2
Ln
) and [Ln(Nacnac)(SPy)
2
] (
3
Ln
). As an analogue of
2
Tb
without coordinated thf molecules, binuclear complex [{Tb(Nacnac)(SPh)}
2
(μ-SPh)
2
] (
4
Tb
) was obtained by reaction of dry TbI
3
with K(Nacnac) and KSPh in Et
2
O followed by recrystallization from toluene. The diiodo complexes possess different numbers of coordinated thf molecules and different coordination polyhedra owing to the lanthanide contraction. On the contrary, all
2
Ln
and
3
Ln
have the same molecular and crystal structures for a given thiolate, owing to the coordination rigidity provided by edge coordination of a Ph cycle or by chelating binding of a S(2-Py)
−
ligand. UV-vis and photoluminescence spectra were registered for all compounds. A triplet level of the Nacnac
−
ligand of 2.22 × 10
4
cm
−1
was determined from the solid-state emission of Gd complex
1
Gd
at 77 K; the triplet level in
2
Gd
and
3
Gd
was found at 2.16 × 10
4
cm
−1
. Emission lifetimes and quantum yields were measured for all Tb compounds with the highest values for thiolato complexes
2
Tb
and
3
Tb
, while
1
Tb
showed only weak emission. The relationship of the emission properties with the molecular and crystal structures is discussed, and better antenna properties are proposed for thiolato rather than for Nacnac
−
ligands.
Structure-dependent photoluminescence was studied for lanthanide complexes with widespread Nacnac ligands, supplemented by thiolates; notable antenna properties of the latter are revealed.