8
76
GOLOVACH et al.
Table 2. Luminescence intensity of solutions of the Tb(III) complexes with ligands L1 and L2 in the absence and presence
= 1 × 10–4 mol/L (ethanol), c
= 1 × 10 mol/L (acetonitrile), c
–4
= 1 × 10 mol/L
–4
of Cu(II) ions (c
Tb, Cu
L1, L2
hydrazine hydrate
(
ethanol))
∆
E = E – E ,
kcal/mol
c
l
No.
Solution composition
Ilum, rel. units
Intensity ratio
1
2
3
4
5
TbL1
4 (I0)
460 (I)
196 (I1)
47 (I2)
17 (I3)
I/I = 115
–183.1
–215.2
–103.2
–
0
TbCuL1
TbL2
I /I = 4.2
1
2
I /I = 11.5
TbL2 + CuCl (1 : 1)
1
3
2
TbL2 + CuCl + hydrazine hydrate (1 : 1 : 1)
–
2
The Ilum values are reduced to the common recording conditions.
oxygen atoms, sensitize the Tb(III) luminescence. As
distinct from this pattern, the Cu(I) ions reduced by
hydrazine hydrate quench the TbL2 luminescence
more strongly than Cu(II), presumably because of the
more efficient excitation energy transfer to Cu(I) than
to Cu(II).
REFERENCES
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For the TbL1, TbCuL1, and TbL2 complexes, the
complex strain energy was evaluated. In all cases,
ΔE < 0. The TbCuL1 complex is the most favorable
one. It is impossible to model a TbL2 complex with
copper since the closed ligand can form a complex
only with Tb(III).
3
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and that quantum-chemical methods should be used
to evaluate the strain energy, our results are consistent
with the experimental data.
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TbCuL1 complex consists of fixing the macroheterocy-
cles, which results in the higher stability of the Tb com-
plex; at the same time, and this is more important, the
Cu(I) ions is located at a definite distance (R ~ 3.6 Å)
from the Tb(III) ion optimal for its sensitization. The
copper(I) ion located in the outer sphere of this com-
plex has no such an effect; rather, it results in lumines-
cence quenching.
239 (2002).
10. S. B. Meshkova, Z. M. Topilova, V. P. Gorodnyuk,
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Translated by G. Kirakosyan
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY
Vol. 61
No. 7
2016