STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES
Lanthanide complexes with calix[4]arenes lower rim substituted with two azacrown ether fragments are reported. The size of the substituent cavity varied from 4 to 6 heteroatoms. The complexes were analyzed by means of IR, NMR, ESI mass spectroscopy. It is assumed that the coordination of Ln(III) ion...
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| author | Smola, Serhii Rusakova, Natalia Alekseeva, Olena Basok, Stepan Kirichenko, Tatiana Korovin, Oleksandr Malinka, Olena Semenishyn, Nikolay |
| author_facet | Smola, Serhii Rusakova, Natalia Alekseeva, Olena Basok, Stepan Kirichenko, Tatiana Korovin, Oleksandr Malinka, Olena Semenishyn, Nikolay |
| author_institution_txt_mv | [
{
"author": "Serhii Smola",
"institution": "A.V. Bogatsky Physico-chemical Institute National Academy of Sciences of Ukraine"
},
{
"author": "Natalia Rusakova",
"institution": "A.V. Bogatsky Physico-chemical Institute National Academy of Sciences of Ukraine"
},
{
"author": "Olena Alekseeva",
"institution": "A.V. Bogatsky Physico-chemical Institute National Academy of Sciences of Ukraine"
},
{
"author": "Stepan Basok",
"institution": "A.V. Bogatsky Physico-chemical Institute National Academy of Sciences of Ukraine"
},
{
"author": "Tatiana Kirichenko",
"institution": "A.V. Bogatsky Physico-chemical Institute National Academy of Sciences of Ukraine"
},
{
"author": "Oleksandr Korovin",
"institution": "A.V. Bogatsky Physico-chemical Institute National Academy of Sciences of Ukraine"
},
{
"author": "Olena Malinka",
"institution": "Odessa National Academy of Food Technology"
},
{
"author": "Nikolay Semenishyn",
"institution": "A.V. Bogatsky Physico-chemical Institute National Academy of Sciences of Ukraine"
}
] |
| author_sort | Smola, Serhii |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:47Z |
| description | Lanthanide complexes with calix[4]arenes lower rim substituted with two azacrown ether fragments are reported. The size of the substituent cavity varied from 4 to 6 heteroatoms. The complexes were analyzed by means of IR, NMR, ESI mass spectroscopy. It is assumed that the coordination of Ln(III) ions occurs through the donor atoms of the lower rim; the counter anion and solvent molecule are also coordinated. Lanthanide-centered characteristic luminescence was observed in Eu(III), Tb(III) and Yb(III) complexes. The most efficient 4f-luminescence is observed for terbium-containing complexes with benzo-crown-derived ligands. The pathways of the sensitization of 4f-luminescence are discussed. |
| doi_str_mv | 10.33609/2708-129X.87.10.2021.103-115 |
| first_indexed | 2025-09-24T17:43:41Z |
| format | Article |
| fulltext |
103
УДК: 546.650:547.639.5:535.37 doi: 10.33609/2708-129X.87.10.2021.103-115
STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES
OF LANTHANIDE-CONTAINING COMPLEXES
WITH AZACROWN CALIXARENES
Smola S.S.1, Rusakova N.V.1, Alekseeva O.A.1, Basok S.S.1, Kirichenko T.I.1, Korovin O.Yu.1,
Malinka O.V.2, Semenyshyn N.N.1
1A.V. Bogatsky Physico-chemical Institute, National Academy of Sciences of Ukraine, 86, Lustdorf-
skaya doroga, 65080 Odessa, Ukraine
2Odessa National Academy of Food Technology, 112, Kanatna Street, 65039 Odessa, Ukraine
email: sssmola@gmail.com
Lanthanide complexes with calix[4]arenes lower rim substituted with two azacrown ether
fragments are reported. The size of the substituent cavity varied from 4 to 6 heteroatoms. The
complexes were analyzed by means of IR, NMR, ESI mass spectroscopy. It is assumed that the
coordination of Ln(III) ions occurs through the donor atoms of the lower rim; the counter
anion and solvent molecule are also coordinated. Lanthanide-centered characteristic lumi-
nescence was observed in Eu(III), Tb(III) and Yb(III) complexes. The most efficient 4f-lumi-
nescence is observed for terbium-containing complexes with benzo-crown-derived ligands.
The pathways of the sensitization of 4f-luminescence are discussed.
Keywords: lanthanide complexes, calix[4]arenes, azacrown ethers, luminescence.
INTRODUCTION. Calix[4]arenes can
be considered as universal building blocks,
as their molecules have a characteristic fea-
ture – the presence of two «rims», which can
be modified by functional groups of different
nature, and a hydrophobic cavity as an addi-
tional binding site. The functionalization of
the calix[4]arene macrocycle with polydentate
substituents purposefully influences the com-
plexing properties, including the possibilities
of the preparation of mono- or heteronuclear
complexes of various compositions. Particu-
lar interest is shown in the design of calix[4]
arenes lower rim substituted with crown ether
fragments. Such combination increases the co-
ordination ability of calixarenes, reduces their
conformational mobility and can be used for
ion and molecular recognition [1–3].
As a rule, lanthanide-calix[4]arene com-
plexes are formed through coordinating groups
at the lower rim which is easily achieved by the
functionalization of phenolic OH groups. The
first structures of mono- and binuclear euro-
pium-containing compounds with p-tert-bu-
tyl-calix[4]arene and its derivatives both in
solid state and in solutions were reported by
J.M. Harrowfield and coworkers in the 1985–
1990s [4–6]. In subsequent works, with the
STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING
COMPLEXES WITH AZACROWN CALIXARENES
104 ISSN 2708-129X. Укр. хім. журн., 2021
INORGANIC CHEMISTRY
development of synthetic procedures, both the
range of functionalized ligands and the number
of lanthanide ions were increased. The general
method of synthesis consists in the interaction
of lanthanide salts (most often chlorides, nit
rates, or picrates) and calix[4]arenes in an an-
hydrous solvent or in a mixture of solvents in
the presence of triethylamine. The latter, as in
the case of other metals, promotes the disso-
ciation of phenolic groups, thereby facilitating
the formation of complexes.
4f-Luminescence in lanthanide complexes
with a number of calix[4]arenes is caused by
intramolecular energy transfer from the or-
ganic part of the molecule to the metal ion. It
can be assumed that it manifests itself in such
compounds as crown-calix[4]arenes, while
the lanthanide ion can be coordinated by both
calix[4]arene and crown ether fragments. The
number of studies on the spectral luminescent
properties of complexes of such compounds
with lanthanide ions is rather low. In the pre
sent work, we report our study of the spectral
luminescent properties of lanthanide complex-
es with calix[4]arene derivatives substituted
with two azacrown ether fragments. The size of
the substituent cavity varied from 4 to 6 hete
roatoms.
EXPERIMENT AND DISCUSSION OF
THE RESULTS. Calix[4]arenes L1H2 – L7H2
[7, 8] (Table 1) and the corresponding lantha-
nide-containing complexes were synthesized
according to the methods described in [9, 10]
in the presence of equimolar quantities of tri
ethylamine. Complexes were isolated in solid
state and identified by means of elemental analy-
sis, mass spectrometry, IR, 1H NMR spectrosco-
py. The geometry optimization of the structures
of complexes was performed by the methods of
molecular mechanics (HyperChem, MM+).
The absorption spectra in the UV and visi-
ble regions were recorded on a spectrophoto
meter Ulab S261UV in 10 mm quartz cuvettes,
and in the IR region (4000–400 cm-1) on a
Shimadzu FT-IR8400S spectrophotometer (in
KBr pellets).
Fluorescence excitation and emission spec-
tra, as well as phosphorescence and 4f-lumi-
nescence were recorded on a Fluorolog FL 3-22
spectrofluorimeter (Horiba Jobin Yvon, Xe-
450 W ozone-free lamp) equipped with a pho-
tomultiplier R928P (Hamamatsu, Japan) for
the visible spectral region and a liquid nitrogen
cooled InGaAs detector (DSS-IGA020L, Elec-
tro-Optical Systems, Inc.) for the NIR.
The values of the singlet (ES) and triplet
levels (ET) of the derivatives of calix[4]arenes
and lutetium-containing complexes were de-
termined by a known procedure [11] at 77K
using phosphorescence spectra obtained with
different time delays after the excitation pulse
ceased. The values of the relative quantum
yield of 4f-luminescence (φ) of lanthanide
ions (measurement error ± 20%) in complexes
were calculated as in [11, 12]. The number of
coordinated solvent molecules in complexes
was estimated using the Horrocks and Sudnick
method [13, 14].
The studied compounds can be divided
into two groups. The first consists of calix[4]
arene macrocycles linked to azacrown ether by
an amide bond (L1H2 - L4H2) and the second
consists of their reduced analogs (L5H2 - L7H2).
The complexes with the ratio Ln:LnH2 = 1:1, in
which f-cations are coordinated by the donor
OH-groups of calix[4]arene, were obtained by
the equimolar interaction of the starting mate-
rials. Excess of lanthanide salt provides sand-
wich structures with the 2:1 ratio.
Smola S.S., Rusakova N.V., Alekseeva O.A., Basok S.S., Kirichenko T.I., Korovin O.Yu., Malinka O.V., Semenyshyn N.N.
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UCJ № 10 / Vol. 87
Table 1
Calix[4]arenes modified with azacrown ethers, used in this work.
OH O 2
R
Ligand Nomenclature name R
L1H2
5,11,17,23-tetra-tert-butyl-25,27-bis[(1,4,7-trioxa-10-azacyclododec-
10-yl)carbonylmethoxy]-26,28-dihydroxycalix[4]arene
O
O
O
N
O
L2H2
5,11,17,23-tetra-tert-butyl-25,27-bis[(1,4,7,10-tetraoxa-13-
azacyclopentadec-13-yl)carbonylmethoxy]-26,28-
dihydroxycalix[4]arene
O
O O
O
N
O
L3H2
5,11,17,23-tetra-tert-butyl-25,27-bis[(6,7,9,10,12,13,15,16-
octahydro-5,8,14,17-tetraoxa-11-azabenzocyclopentadecen-11-yl)
carbonylmethoxy]-26,28-dihydroxycalix[4]arene
O
O O
O
N
O
L4H2
5,11,17,23-tetra-tert-butyl-25,27-bis[(1,4,7,10,13-pentaoxa-16-
azacyclooctadec-16-yl)carbonylmethoxy]-26,28-
dihydroxycalix[4]arene
O
O
N
O
OO
O
L5H2
5,11,17,23-tetra-tert-butyl-25,27-bis[(1,4,7-trioxa-10-azacyclododec-
10-yl)ethoxy]-26,28-dihydroxycalix[4]arene
O
O
N
O
L6H2
5,11,17,23-tetra-tert-butyl-25,27-bis[(1,4,7,10-tetraoxa-13-
azacyclopentadec-13-yl)ethoxy]-26,28-dihydroxycalix[4]arene
O O
O
N
O
L7H2
5,11,17,23-tetra-tert-butyl-25,27-bis[(1,4,7,10,13-pentaoxa-16-
azacyclooctadec-16-yl)ethoxy]-26,28-dihydroxycalix[4]arene
O
N
O
OO
O
STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING
COMPLEXES WITH AZACROWN CALIXARENES
106 ISSN 2708-129X. Укр. хім. журн., 2021
INORGANIC CHEMISTRY
The obtained compounds were analyzed by
physico-chemical methods. The ESI mass spect
ra of all complexes contain peaks of molecular
ions corresponding to mononuclear blocks.
As an example, Fig. 1 shows a mass spectrum
of a lutetium-containing complex with L2H2,
which contains the peak of a molecular ion
(m/z = 1414), which indicates the presence of
a chloride anion and one solvent molecule in
the complex. The peaks with a lower m/z val-
ue correspond to fragments without acetonitrile
molecule, chlorine atom, and one or two aza-
crown ether fragments (peaks with m / z = 1375,
1340, 1123, and 906, respectively).
Fig. 1. ESI-mass spectrum of [LuL2Cl(СН3CN)].
The coordination of lanthanide ions by the
donor groups of calix[4]arene is confirmed by
IR spectroscopy data. The vibration band of
the OH groups of the starting calix[4]arenes
(ν(O-H) = 3150–3250 cm-1) is absent in the
spectra of all complexes. In the spectra of
complexes with L1-4H2, the vibration bands of
carbonyl groups with maxima in the range of
1640–1690 cm-1 undergo a low-frequency shift
of 20–30 cm-1, which indicates their participa-
tion in the coordination of the metal ion. The
vibration band of the ether bonds of the lower
rim of calix[4]arene (ν(C-O) = 1030–1040 cm-1)
is shifted to the low-frequency region by 50–
60 cm-1 in comparison with the spectra of the
initial compounds. At the same time, the vi-
bration bands of the ether groups of azacrown
substituents (ν(Ccrown-O) = 1125–1135 cm-1) do
not change. The formation of complexes is also
evidenced by the appearance of a low-frequen-
cy band at 450–460 cm-1, which refers to the
vibrations of lanthanide-oxygen bonds. The
position and intensity of the remaining bands
in the spectra of complexes do not undergo
significant changes in comparison with the
spectra of the starting compounds.
Smola S.S., Rusakova N.V., Alekseeva O.A., Basok S.S., Kirichenko T.I., Korovin O.Yu., Malinka O.V., Semenyshyn N.N.
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UCJ № 10 / Vol. 87
Fig. 2.1H NMR spectrum [LuL3Cl(CH3CN)] (CDCl3, 25 °C).
A 1H NMR spectrum of the [LuL4Cl(CH3CN)]
complex as an example is shown in Fig. 2.
The signals of the protons of phenyl hydroxo
groups, which are at 7.50–7.70 ppm in the
spectra of free ligands, disappear upon comp
lexation, which indicates their substitution.
All signals corresponding to the calix[4]
arene macrocycle are shifted: the signals of aryl
protons and the protons of tert-butyl groups
are shifted downfield by 0.09–0.11 and 0.05–
0.08 ppm, respectively, and the doublets from
methylene bridges, which are in the spectra of
calixarenes at 3.28 and 4.44 ppm, shift towards
each other by 0.09–0.15 ppm, which indicates
a smaller flattening of the calix[4]arene con-
formation in the complex. The participation of
the carbonyl oxygen atoms of the amide group
in coordination is confirmed by the shift of the
δ(OCH2CO) signals of 0.08–0.13 ppm, as well
as the appearance of a triplet of N-CH2 groups
at 3.87–3.95 ppm. The position of the signals of
the remaining protons of the azacrown ether
substituent in the range 3.60–3.70 ppm does not
change. As for amine derivatives (complexes
with L5H2 – L7H2), small changes in the intensity
of the main signals of the methylene groups of
azacrown ethers in the region of 3.55–4.10 ppm
probably indicate the formation of a system of
intra- and intermolecular hydrogen bonds.
The data obtained and the MM+ calcula-
tions (Fig. 3) allowed us to conclude that in
the complexes with L1H2 – L4H2 compounds,
the coordination polyhedron of lanthanide is
formed by four oxygen atoms of the lower rim
and carbonyl groups. Considering the coordi-
nation of the counterion of lanthanide salt and
one solvent molecule (acetonitrile), the coor-
dination number of lanthanide ion in com-
plexes is 8. As for the complexes with calix[4]
arenes L5H2 – L7H2, the coordination site of the
lanthanide ion consists of four oxygen atoms
of the lower rim of calix[4]arene, the chloride
anion, and the solvent molecule, the coordina-
tion number of Ln(III) is 6.
STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING
COMPLEXES WITH AZACROWN CALIXARENES
108 ISSN 2708-129X. Укр. хім. журн., 2021
INORGANIC CHEMISTRY
Fig. 3. Calculated spatial models of Ln(III) complexes with L2H2 (left)
and L6H2 (right) (hydrogen atoms are omitted).
The absorption spectra of lanthanide com-
plexes with azacrown ether-functionalized ca-
lix[4]arenes are characterized by three bands.
The introduction of substituents leads to the
appearance of an additional band in the region
λmax = 270–275 nm (37040–36360 cm–1, logε =
1.2–1.5).Manifesting as a shoulder, it overlaps
with the band of the calix[4]arene molecule at
276–283 nm (36230–35340 cm-1), and the bands
at 284–291 nm (35210–34360 cm-1), which cor-
respond to π→π* transitions in the aromatic
fragments of calix[4]arenes. The absorption
spectra of the complexes in acetonitrile are also
characterized by three bands in the range of 281–
286 nm (35590–34970 cm-1, logε = 3.78–3.86),
290–294 nm (34480–34000 cm-1, logε = 3.74–
4.17) and 304–310 nm (32890–32260 cm-1, logε
= 3.57–3.73). The bathochromic shift of the first
two bands is 240–380 cm-1 compared to ligands,
except for the complex with benzo-crown-de-
rivative [LuL3Cl(CH3CN] - Δλ = =1260 cm-1
and 1210 cm-1, for the first and second bands,
respectively. The appearance of a band with
a maximum in the region of 304–310 nm is
characteristic of complexes of phenolic calix[4]
arenes, when the metal ion replaces protons of
OH groups. An increase in the number of gly-
col fragments in the azacrown ether substitu-
ent, as well as the presence of a carbonyl group
in the link, practically does not affect the cha
racteristics of the absorption bands of ligands
and complexes (Table 2).
One of the conditions for effective 4f-lumi-
nescence in the coordination compounds of
lanthanides is the presence of excited singlet
(S1) and triplet (T1) levels of ligands higher than
the resonance levels of metals. The energy of
excited levels was determined by studying the
molecular fluorescence and phosphorescence
spectra of solutions of the corresponding luteti-
um complexes (Table 2). The fluorescence spec-
tra of Lu(III) complexes are similar and consist
Smola S.S., Rusakova N.V., Alekseeva O.A., Basok S.S., Kirichenko T.I., Korovin O.Yu., Malinka O.V., Semenyshyn N.N.
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UCJ № 10 / Vol. 87
of a wide band in the range of 390-450 nm with
nanosecond range decay time. In comparison
with the spectra of free ligands, they are charac-
terized mainly by a bathochromic shift of the flu-
orescence bands (940–2880 cm-1) and an almost
2.5–3 fold decrease in lif time. The difference is
the complexes with 12-azacrown-4-derivatives
L1H2 and L5H2, where a hypsochromic shift was
recorded: 970 cm-1 and 1500 cm-1, respectively,
which is probably associated with a deviation
of the coplanarity of the complex. Phospho-
rescence spectra recorded at 77K with a 50 ms
time delay are presented as a wide band in the
range of 430–470 nm. The energies of triplet
states in lutetium complexes (ET) were found to
be in the range of 21650–22570 cm-1. It should
be noted that the energy difference between the
S1- and T1-levels is small: 570–1300 cm-1, which
makes possible energy transfer from the S1-le
vel of the ligand to the radiative levels of lan-
thanide ions. The possibility of energy transfer
from the S1-levels to Ln(III) ions does not ex-
clude the participation of T1-levels in the sen-
sitization of the lanthanide-centered lumines-
cence, as well as energy back transfer from the
radiative level of, for example, europium ions
(E(5D2) = 21500 cm-1), which is energetically
possible [15].
Table 2
Characteristics of absorption, fluorescence and phosphorescence spectra of lutetium
complexes with azacrown ether-functionalized calix[4]arenes (С=1×10-3 M, CH3CN).
Complex λI, λII, λIII, nm
(log ε)
λfl,
nm τ, ns ES, cm-1 λphos,
nm ET, cm-1 ΔE-T,
cm-1
[LuL1Сl-
(CH3CN)]
282
(3.83)
291
(3.82)
305
(3.72) 442 13.4 22620 454 22030 590
[LuL2Сl-
(CH3CN)]
281
(3.84)
291
(3.81)
306
(3.70) 438 13.4 22830 452 22120 710
[LuL3Сl-
(CH3CN)]
286
(4.28)
294
(4.17)
310
(3.69) 450 18.5 22220 462 21650 570
[LuL4Сl-
(CH3CN)]
284
(3.78)
291
(3.73)
304
(3.57) 441 13.3 22680 457 21880 800
[LuL5Сl-
(CH3CN)]
282
(3.79)
290
(3.74)
306
(3.68) 421 12.7 23750 443 22570 1180
[LuL6Сl-
(CH3CN)]
282
(3.86)
292
(3.81)
307
(3.73) 427 12.1 23420 446 22420 1000
[LuL7Сl-
(CH3CN)]
281
(3.82)
290
(3.77)
305
(3.62) 424 12.8 23590 449 22270 1320
STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING
COMPLEXES WITH AZACROWN CALIXARENES
110 ISSN 2708-129X. Укр. хім. журн., 2021
INORGANIC CHEMISTRY
The second, no less important condition for
observing intense luminescence is the optimal
energy gap between the triplet level of the ligand
and the resonance level of the lanthanide ion. As
already noted, for each element and each type
of ligand, there is a certain optimal energy gap.
Thus, for efficient energy transfer in europium
complexes, the difference between the energy of
the triplet level of the organic ligand and that
of the resonant 5D0 level of europium (III) ion
should be between 2500–3500 cm-1 and for terbi-
um (III) ion, 2500–4000 cm-1 [11, 15]. However,
for example, for 3-methyl-1-phenyl-4-formyl-
5-hydroxypyrazolates of Eu(III) and Tb(III)
this regularity, so called «Latva’s rule», is not
observed, and an intense luminescence of terbi-
um (III) ion is observed at an energy gap of only
200 cm-1, and the europium complex does not
exhibit luminescence at ΔE = 3450 cm-1. In this
case, the luminescence intensity is relatively low
due to the scattering of radiation energy at the
high-lying sublevels of the ground state [16, 17].
It can be seen from the data obtained that
excitation energy transfer from azacrown ca-
lix[4]arenes is possible to europium (III) ions
(5D0 and 5D1, E = 17250 cm-1 and 19000 cm-1, re-
spectively), terbium (III) (E(5D4) = 20450 cm-1),
and to the low-lying excited levels of Ln(III)
ions luminescent in the NIR region: neodymi-
um (III) (E(4F3/2) = 11500 cm-1) and ytterbium
(III) (E(2F5/2) = 10300 cm-1 ).
Nevertheless, in Nd(III) complexes the
emission signal is very low, which is proba-
bly caused by the quenching effect of C-H-
(2950 cm-1) and C-N- (2250 cm-1) vibrations
in both the ligand and solvent molecules. In
Eu(III), Tb(III), and Yb(III) complexes chara
cteristic 4f-luminescence bands are observed.
Fig. 4. 4f-Luminescence spectra of complexes [EuL2Сl(CH3CN)] (left) and [EuL6Сl(CH3CN)] (right).
The coordination environment of the lan-
thanide ion was analyzed using emission spec-
tra of Eu(III) compounds at 77K [14], whose
luminescence occurred from the 5D0 and 5D1
levels. In the spectrum of [EuL2Сl(CH3CN)],
there is a splitting into three components of
Smola S.S., Rusakova N.V., Alekseeva O.A., Basok S.S., Kirichenko T.I., Korovin O.Yu., Malinka O.V., Semenyshyn N.N.
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UCJ № 10 / Vol. 87
the bands corresponding to the transitions
5D0→7F1 and 5D0→7F2, which is characteristic
of eight-coordinated europium ion (Fig. 4).
This indicates that the type of the point sym-
metry group of the polyhedron of the Eu(III)
ion is close to C2v and the geometric structure
of square antiprism, in accordance with the
proposed structural formula. In the spectrum
of the [EuL6Сl(CH3CN)] complex two intense
bands corresponding to the transition from
the 5D0 level to the 7F2 and 7F1 levels undergo
splitting into two components, which is a con-
sequence of the distortion of the octahedral
configuration of europium to C4v type.
The excitation spectra of Tb(III) complex-
es (Fig. 5) are similar and consist of a wide
band with maxima at 363–367 nm. Upon ex-
citation at the maximum of this band, emis-
sion spectra are represented as a set of bands
of low intensity ligand-centered emission in
the 380–420 nm region as well as intense nar-
row bands of Tb-centered luminescence in
the visible region. These peaks correspond to
energy transitions: 5D4→7F6 (487 nm), 5D4→7F5
(542 nm), 5D4→7F4 (580 nm and 587 nm),
5D4→7F3 (620 nm), and 5D4→7F2 (643 nm and
650 nm). The quantum yield of terbium com-
plexes is higher than that of the corresponding
europium complexes (Table 3).
Fig. 5. Photoluminescence excitation (left) and emission (right)
spectra of [TbL1Сl(CH3CN)].
STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING
COMPLEXES WITH AZACROWN CALIXARENES
112 ISSN 2708-129X. Укр. хім. журн., 2021
INORGANIC CHEMISTRY
The highest values of the quantum yields of
4f-luminescence are observed for the complex-
es with the benzo-crown ether derivative L3H2,
as compared to the corresponding complexes
[LnL2Сl(CH3CN)] and [LnL6Сl(CH3CN)] (Ta-
ble 3). It can be assumed that the presence of a
benzene ring in the 15-azacrown-5 heterocycle
leads to a redistribution of the electron densi-
ty not only in the fragments of the substituent,
but also in the molecule of this compound as a
whole. This can be caused by an increase in the
rigidity of the entire azacrown ether unit and a
violation of the symmetry of the arrangement
of oxygen atoms in the cycle. The number of
coordinated solvent molecules in complexes
was estimated and it was found that one sol-
vent molecule is coordinated in all of the com-
plexes.
Table 3
Characteristics of the 4f-luminescence of Ln(III) complexes with azacrown ether-calix[4]
arenes (С=1×10-4 M, methanol).
Complex φ τ(МеОН), mcs τ(МеОD), mcs q(МеОН)
[EuL1Сl(CH3CN)] 0.024 425 507 0.8
[EuL2Сl(CH3CN)] 0.023 398 469 0.8
[EuL3Сl(CH3CN)] 0.032 551 774 1.1
[EuL4Сl(CH3CN)] 0.019 428 552 1.1
[EuL5Сl(CH3CN)] 0.024 482 607 0.9
[EuL6Сl(CH3CN)] 0.017 419 551 1.2
[EuL7Сl(CH3CN)] 0.020 455 550 0.8
[TbL1Сl(CH3CN)] 0.432 858 2594 0.9
[TbL2Сl(CH3CN)] 0.448 853 3009 1.2
[TbL3Сl(CH3CN)] 0.452 915 3954 1.2
[TbL4Сl(CH3CN)] 0.421 795 2284 1.1
[TbL5Сl(CH3CN)] 0.290 871 2712 0.9
[TbL6Сl(CH3CN)] 0.293 823 2816 1.3
[TbL7Сl(CH3CN)] 0.386 805 2368 1.1
As can be seen, the optimal gap condition
ΔET1→4f* is not fulfilled for all Ln(III) ions.
A particularly large difference between the
energy of the triplet levels of the ligands and
the energy of the resonant 2F5/2 level, which
reaches values greater than 10000 cm – 1, is ob-
served in the case of ytterbium (III) complex-
es, which does not allow one to expect intense
emission from the complexes. In the lumines-
cence spectrum of the ytterbium complex, one
band is observed due to the transition from the
emitting level 2F5/2 to the only ground level 2F7/2;
however, due to the distortion of the coordi-
nation polyhedron, the luminescence band
splits with the appearance of three maxima at
982 nm, 1014 nm, and 1060 nm (Fig. 6). As
in the case of Eu(III) and Tb(III) complexes,
the highest quantum yield of Yb-centered lu-
minescence was found in the complex with the
benzo-crown ether derivative L3H2 (Table 4).
Smola S.S., Rusakova N.V., Alekseeva O.A., Basok S.S., Kirichenko T.I., Korovin O.Yu., Malinka O.V., Semenyshyn N.N.
113https://ucj.org.ua
UCJ № 10 / Vol. 87
Fig. 6. Photoluminescence excitation (left) and emission (right) spectra of [YbL3Сl(CH3CN)].
Table 4
Values of the quantum yield of Yb(III) complexes with azacrown ether-calix[4]arenes.
Ligand L1H2 L2H2 L3H2 L4H2 L5H2 L6H2 L7H2
φ 0.0042 0.0037 0.0054 0.0032 0.0037 0.0048 0.0041
CONCLUSIONS. Thus, methods of synthe-
sis have been developed and the structure of
coordination compounds of lanthanides with
lower rim functionalized calix[4]arenes with
azacrown ethers has been proposed. It was
found that the values of the triplet levels of
the ligands facilitate the transfer of excitation
energy to the radiative levels of Ln(III) ions,
which luminesce both in the visible and in the
IR spectral regions. The most efficient 4f-lumi-
nescence is observed for terbium-containing
complexes with benzo-crown-derived ligands.
It was found that the presence of macrocyclic
substituents leads to a decrease in the energy of
the singlet and triplet levels of calix[4]arenes.
ACKNOWLEDGEMENTS
The work was performed within the
state budget theme «Prediction, mo-
lecular design and directed synthesis of
new coordination compounds of metals
of groups II and III of the Periodic Table
with specified optical properties», state
registration number: 0221U101322.
STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING
COMPLEXES WITH AZACROWN CALIXARENES
114 ISSN 2708-129X. Укр. хім. журн., 2021
INORGANIC CHEMISTRY
СТРУКТУРА ТА СПЕКТРАЛЬНО-ЛЮМІНЕСЦЕНТ-
НІ ВЛАСТИВОСТІ ЛАНТАНІДВМІСНИХ КОМП-
ЛЕКСІВ З АЗАКРАУН-КАЛІКСАРЕНАМИ
Смола С. С.1, Русакова Н. В.1,
Алексеєва О. О.1, Басок С. С.1,
Кіріченко Т. І.1, Коровін О. Ю.1,
Малінка О. В.2, Семенішин М. М.1
1Фізико-хімічний інститут ім. О. В. Богат-
ського НАН України, 86, Люстдорфська до-
рога, Одеса 65080, Україна
2Одеська національна академія харчових
технологій, 112, вул. Канатна, Одеса 65039,
Україна
email: sssmola@gmail.com
Отримано комплекси лантанідів із ка-
лікс[4]аренами, заміщеними по нижньому
ободу двома азакраун-естерними фраг
ментами. Розмір порожнини замісника
варіювався від 4 до 6 гетероатомів. Комп-
лекси аналізували за допомогою ІЧ, ЯМР,
ЕСІ-мас-спектроскопії. Припущено, що
координація іонів Ln(III) відбувається
за допомогою донорних атомів нижньо-
го ободу, протиіон і молекула розчинника
також є координованими. У комплексах
Eu(III), Tb(III) та Yb(III) спостерігали лан-
танід-центровану характерну люмінес-
ценцію. Найбільш ефективна 4f-люмінес-
ценція спостерігається для тербійвмісних
комплексів із лігандами, що містять бензо-
краун-похідні ліганди. Обговорюються
шляхи сенсибілізації 4f-люмінесценції.
Ключові слова: комплекси лантанідів,
калікс[4]арени, азакраунестери, люмінес-
ценція.
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Стаття надійшла 14.11.2021.
|
| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-372 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:07:11Z |
| publishDate | 2021 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/9a/11d755094a84fb8b439a887df0fcab9a.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-3722026-07-22T08:23:47Z STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES Smola, Serhii Rusakova, Natalia Alekseeva, Olena Basok, Stepan Kirichenko, Tatiana Korovin, Oleksandr Malinka, Olena Semenishyn, Nikolay lanthanide complexes, calix[4]arenes, azacrown ethers, luminescence. Lanthanide complexes with calix[4]arenes lower rim substituted with two azacrown ether fragments are reported. The size of the substituent cavity varied from 4 to 6 heteroatoms. The complexes were analyzed by means of IR, NMR, ESI mass spectroscopy. It is assumed that the coordination of Ln(III) ions occurs through the donor atoms of the lower rim; the counter anion and solvent molecule are also coordinated. Lanthanide-centered characteristic luminescence was observed in Eu(III), Tb(III) and Yb(III) complexes. The most efficient 4f-luminescence is observed for terbium-containing complexes with benzo-crown-derived ligands. The pathways of the sensitization of 4f-luminescence are discussed. V.I.Vernadsky Institute of General and Inorganic Chemistry 2021-11-26 Article Article Inorganic Chemistry Неорганическая химия Неорганічна хімія application/pdf https://ucj.org.ua/index.php/journal/article/view/372 10.33609/2708-129X.87.10.2021.103-115 Ukrainian Chemistry Journal; Vol. 87 No. 10 (2021): Ukrainian Chemistry Journal; 103-115 Украинский химический журнал; ##issue.vol## 87 ##issue.no## 10 (2021): Ukrainian Chemistry Journal; 103-115 Український хімічний журнал; Том 87 № 10 (2021): Український хімічний журнал; 103-115 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/372/193 Copyright (c) 2021 Serhii Smola, Natalia Rusakova, Olena Alekseeva, Stepan Basok, Tatiana Kirichenko, Oleksandr Korovin, Olena Malinka, Nikolay Semenishyn https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Smola, Serhii Rusakova, Natalia Alekseeva, Olena Basok, Stepan Kirichenko, Tatiana Korovin, Oleksandr Malinka, Olena Semenishyn, Nikolay STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES |
| title | STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES |
| title_full | STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES |
| title_fullStr | STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES |
| title_full_unstemmed | STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES |
| title_short | STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES |
| title_sort | structure and spectral-lumuinescent properties of lanthanide-containing complexes with azacrown calixarenes |
| topic_facet | lanthanide complexes calix[4]arenes azacrown ethers luminescence. |
| url | https://ucj.org.ua/index.php/journal/article/view/372 |
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