Synthesis of Mesomorphic Derivatives of Methyl 2,4-Dihydroxybenzoate and Spectral and Luminescence Properties of Their Lanthanide Complexes

Article abstract of DOI:10.1134/S1070363218120174

The derivatives of methyl 2,4-dihydroxybenzoate containing fragments of different organic acids in position 4 have been synthesized. Their mesomorphic properties have been investigated. Lanthanide complexes of the prepared compounds have been obtained. Th

Full text of DOI:10.1134/S1070363218120174

ISSN 1070-3632, Russian Journal of General Chemistry, 2018, Vol. 88, No. 12, pp. 2564–2571. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © N.S. Novikova, E.D. Kilimenchuk, R.V. Kondrat’eva, O.I. Teslyuk, I.I. Zheltvai, 2018, published in Zhurnal Obshchei Khimii, 2018,
Vol. 88, No. 12, pp. 2049–2056.
Synthesis of Mesomorphic Derivatives
of Methyl 2,4-Dihydroxybenzoate and Spectral
and Luminescence Properties of Their Lanthanide Complexes
N. S. Novikovaa*, E. D. Kilimenchuka, R. V. Kondrat’evaa,
O. I. Teslyuka, and I. I. Zheltvaia
a Bagatskii Physico-Chemical Institute, National Academy of Sciences of Ukraine,
Lustdorfskaya doroga 86, Odessa, 650080 Ukraine
*e-mail: nadyas.n73@gmail.com
Received May 17, 2018
Revised May 17, 2018
Accepted May 24, 2018
Abstract—The derivatives of methyl 2,4-dihydroxybenzoate containing fragments of different organic acids in
position 4 have been synthesized. Their mesomorphic properties have been investigated. Lanthanide complexes
of the prepared compounds have been obtained. Their spectral properties have been studied.
Keywords: methyl 2,4-dihydroxybenzoate derivatives, mesomorphism, lanthanide complexes, luminescence
DOI: 10.1134/S1070363218120174
Previously we have obtained a series of derivatives
of 2-hydroxybenzoic acid with different structure and
studied the conditions of complex formation Tb(III)
ion [1]. It has been shown that the intensity of their
luminescence increases in following series: esters of 2-
acyloxybenzoic acid < esters of 2-methoxybenzoic
acid < esters of 2-hydroxybenzoic acid. Further, we
have prepared the derivatives of 2,4-dihydroxybenzoic
acid and its aldehyde acylated at position 4 as well as
their luminescing complexes with Eu(III) (for
aldehydes) and Tb(III) (for acids), but the intensity of
luminescence of these complexes has been moderate
[3]. Most of the prepared ligands has exhibited
mesomorphic properties. The studies devoted to the
preparation of liquid-crystalline lanthanide complexes
based on mesogenic and non-mesogenic ligands are
known [3–5].
teristic of derivatives of methyl 2,4-dihydroxybenzoate.
The preparation and investigation of some of such
compounds is reported herein.
Synthesis of methyl 2,4-dihydroxybenzoate deriva-
tives is represented at Scheme 1. The starting methyl
2,4-dihydroxybenzoate 2 was prepared via refluxing
2,4-dihydroxybenzoic acid 1 in methanol in the
presence of catalytic amount of sulfuric acid as
described in [6]. Then, [4-(2-hydroxymethoxycarbo-
nyl)phenyl]4-alkoxybenzoates 8a, 8b and [4-(2-hydroxy-
methoxycarbonyl)phenyl]4-(4-alkoxybenzoyloxy)ben-
zoates 8c, 8d were prepared via the interaction of ester
2 with 4-alkoxybenzoic acids 4a, 4b and 4-(4-alkoxy-
benzoyloxy)benzoic acids 7 (synthesized as described
in [7, 8]) via the carbodiimide mechanism. The
reaction was carried out at molar ratio of methyl 2,4-
dihydroxybezoate : acid = 2 : 1.
Basing on the earlier reports, we can conclude that
the combination of ester and hydroxyl fragments in the
coordination site of lanthanide complexes is optimal to
achieve strong photoluminescence, owing to the
formation of stable six-membered chelate cycle. More-
over, the ligand molecule should contain other func-
tional groups to modulate other important properties of
the lanthanide complexes (thermal stability and solu-
bility in organic solvents). Such structure is charac-
The structures of the final compounds 8a–8d were
confirmed by means of 1Н NMR spectroscopy.
The investigation of the prepared derivatives of 2,4-
dihydroxybenzoic acid using polarization microscopy
revealed the formation of liquid-crystalline phases.
The types of mesophase and temperatures of phase
transitions are given in the Table 1. According to the
obtained data, [4-(2-hydroxymethoxycarbonyl)phenyl]-
2564

SYNTHESIS OF MESOMORPHIC DERIVATIVES
2565
Scheme 1.
C15H31COOH
3
COOH
COOH
OH
H2n+1CnO
4a, b
SOCl2
HO
1
COCl
H2n+1CnO
CH3OH
H+
5a, b
COOCH3
OH
COH
HO
HO
COH
COO
H2n+1CnO
2
Py
6a, b
Jonas reagent
COO
COOH
H2n+1CnO
7a, b
DCC, DMAP
COOCH3
OH
ROOC
8a_f
COO
n = 7 (c), 16 (d);
H2n+1CnO
n = 7 (a), 16 (b) ;
,
,
R = H2n+1CnO
Ph (e), C15H31 (f).
4-alkoxybenzoates 8a, 8b formed monotropic nematic
and smectic phases at in a narrow temperature range, at
relatively low temperature. In the case of compound
8b with longer terminal group, polymorphism was
observed. Incorporation of an additional aromatic cycle
(compounds 8c, 8d) resulted in significant increase and
broadening of the temperature range of the mesophase
existence. Moreover, both mesophases became
enantiotropic; polymorphism was observed for the
compound containing terminal heptyloxy group.
decanoate 8f containing long alkyl group at position 4
were prepared for comparative investigation of the
mesomorphic properties. The synthesis of compound
8e via carbodiimide mechanism failed: only the side
product (N-acylurea) was isolated. Therefore, synthetic
approach involving acyl chlorides was used instead.
Benzoyl chloride 5 was obtained using the reaction
with thionyl chloride [9]. The acylation of methyl 2,4-
dihydroxybenzoate was carried out in anhydrous ether
medium at cooling with ice and using Py to bind the
evolving НСl (Scheme 1). The structure of [4-(2-
hydroxymethoxycarbonyl)phenyl]benzoate 8e was
[4-(2-Hydroxymethoxycarbonyl)phenyl]benzoate 8e
containing a non-substituted benzoic acid moiety at posi-
tion 4 and [4-(2-hydroxymethoxycarbonyl)phenyl]hexa-
1
confirmed by means of Н NMR spectroscopy. In
detail, the proton of the hydroxy group was registered
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 12 2018

2566
NOVIKOVA et al.
Table 1. Types of mesomorphism and temperatures of phase
transitions for derivatives of methyl 2,4-dihydroxybenzoate
8a–8f
Table 2. Spectral and luminescence parameters of derivatives
of methyl 2,4-dihydroxybenzoate 8a–8f
Comp.
no.
ε,
λabs,
nm
λex,
nm
E(T1),
Comp. no.
n
Temperatures of phase transitions, °Сa
L cm–1 mol–1
cm–1
8а
8b
8c
8d
8e
8f
7
Cr 67 I 59.3 N 42.3 Cr
16
7
Cr 76.4 I 65.4 N 60.3 Sm 56.0 Cr
Cr 117 Sm 126 N >200 I
Cr 98.07 SmA 156.I N 171.2 I
Cr 90.0 I
8а 41700
8b 23200
265.6
340
21100
21186
266.1
273
345
16
Ph
8c
8e
8f
44000
265.0
340
365
340
20700
20790
20705
C15H31 Cr 43.0 I
34700, 9500
17100, 6700
241.2, 300
242.6, 300.8
а
(Cr) solid crystal, (N) nematic phase, (SmA and Sm) smectic
phases, (Ι) isotropic liquid.
as singlet at 10.94 ppm, protons of the aromatic cycle
in the ortho-position to carbonyl group were registered
as doublet at 8.20 ppm, protons at meta- and para-
positions of the ring resonated as multiplet signals at
7.72–7.6 and 7.58–7.44 ppm ranges, respectively.
According to the data given in the Table 2, ligands
8b and 8c absorbed short-wave light with λmax = 265–
266 nm and showed high energies of the triplet states
Е(Т1)= 20700–21186 cm–1 and Е(Т1)= 23480–23980 cm–1,
indicating the possibility of intramolecular excitation
transfer to Ln(III) ion. The values of molar
absorptivity (23200 and 44000 L cm–1 mol–1 for
compounds 8b and 8c, respectively) indicated strong
absorption of UV radiation by those compounds.
Compounds 8e and 8f did not possess meso-
morphism. The significance decrease in the melting
point was observed for the derivative of hexadecenoic
acid 8f.
It was shown that the derivatives of methyl 2,4-
dihydroxybenzoate presented in Table 2 formed
complexes with Tb(III) ion exhibiting strong lumine-
scence. The band corresponding to electric dipole
The possibility of the formation as well as spectral
and luminescence properties of Tb(III) complexes with
derivatives of methyl 2,4-dihydroxybenzoate have
been studied (Table 2). The data on compound 8d were
extracted from [10]. The preparation of lanthanide
complexes with 2,4-dimethoxybenzoic acid and
observation of strong emission bands of Tb(III) have
been reported [11], but the authors did not provide the
luminescence spectra.
5
transition D4→7F5, hypersensitive to the influence of
the ligand field, was the strongest in the luminescence
spectrum of Tb(III) complex, revealing the transitions
from 5D4 excited state to sublevels of the ground state:
7
7
7F6 (λ = 490 nm), F5 (λ = 544 nm), F4 (λ = 584 and
592 nm), and 7F3 (λ = 620 nm) (Fig. 1). The energy of
triplet excited states of the ligands was higher than that
of the D4 excited state of Tb(III) ion (20500 cm–1). As
5
a result, efficient excitation energy transfer to resonance
state of Tb(III) occurred.
The investigation of the solution pH influence on
luminescence of Tb(III) complexes with the studied
ligands showed that the complexes were formed in
weakly acidic and neutral media (pH = 6.6–7.0, Table 3).
In acidic solutions, the degree of the complexes
formation was low; in alkali solutions, the complexes
were decomposed into the lanthanide hydroxides. The
highest value of Ilum was achieved in the case of
complexing in aqueous solutions. Molecules of DMSO
and DMF could substitute the ligands from inner
coordination sphere of Tb(III) ion because of the
λ, nm
Fig. 1. Excitation and luminescence spectra of Tb(III)
complexes with ligands 8a (1) (λex = 340 nm), 8e (2), 8f (3)
(λex = 340 nm), 8b (4) (λex = 345 nm), and 8c (5) (λex = 340 nm).
c
Tb = 1×10–4 M, cL = 5×10–4 M.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 12 2018

SYNTHESIS OF MESOMORPHIC DERIVATIVES
2567
Table 3. Conditions of complexing and spectral and
luminescence parameters of solutions of Tb(III) complexes
presence of donor oxygen and nitrogen atoms,
respectively. As a result, in those cases Ilum value was
decreased.
with derivatives of methyl 2,4-dihydroxybenzoate (cLn
=
1×10–4 M, cL = 5×10–4 M)
Components ratio in complexes determined using
the limited logarithm was Ln : L1 = 1 : 2. The
dependence of Ilum value of the complexes on the con-
centrations of terbium and ligands was studied. The optimal
Tb concentration was found to be of 1×10–4 mol/L, and
that of the ligands was of 5×10–4 mol/L. The highest
Ilum values were observed immediately after the
components mixing and remained stable for 72 h.
The influence of additional ligands (L2) on the Ilum
value of complexes was investigated in view of the
formation of coordination-unsaturated compounds.
Insignificant increase in the Tb(III) luminescence in
the complexes with compound 8b was observed in the
presence of organic bases: trioctylphosphine oxide,
triphenylphosphine oxide, and α,α'-dipyridyl (by 1.2,
1.3, and 1.6 times, respectively). The same effect was
observed for the complexes with ligand 8e in the
presence of triphenylphosphine oxide and α,α'-
dipyridyl (by 1.2 and 1.3 times, respectively, Table 4).
I
lum, rel. units
Complex
рН
544 nm 582 nm 622 nm
Tb(8а)2
Tb(8b)2
Tb(8c)2
Tb(8e)2
Tb(8f)2
6.6
6.9
7.1
6.8
7.0
1526
521
173
72
143
41
723
105
209
148
63
1407
972
139
135
pattern was observed in the case of the formation of
hetero-ligand complexes Tb(8b)2 with α,α'-dipyridyl
(Fig. 2). The luminescence excitation spectra of Tb(III)
complex with ligand 8a contained a broad band in the
250–300 nm range. In the case of the formation of
Tb(III) hetero-ligand complexes with ligand 8a and
α,α'-dipyridyl, the band in the 250–300 nm range was
not observed, only the band in the 300–380 nm range
with maximum at 340 nm was present (Fig. 3). Using
the limited logarithm method, it was shown that inner
coordination sphere of the complexes contained one
molecule of the organic base, and the components ratio
in the hetero-ligand complexes was Tb(III) : L1 : L2 =
1 : 2 : 1.
The formation of hetero-ligand complexes was
confirmed by spectrophotometry and luminescence
spectroscopy: the shift and splitting of the band
corresponding to the Ln(III) transition hypersensitive
to the introduction of the second ligand were observed.
For example, the change in the excitation spectrum
Table 4. Influence of additional ligands (L2) on luminescence intensity of Tb(III) complexes with derivatives of methyl ester
of 2,4-dihydroxybenzoic acida
I, rel. units
I/I0
Complex
I0, rel. units
Tb(8a)2
Tb(8b)2
Tb(8c)2
Tb(8e)2
Tb(8f)2
1600
502
714
590
721
631
644
1012
645
1745
781
0.4
1.2
1.0
0.4
0.6
0.6
1.1
1.6
0.9
1.3
0.7
1.3
1.3
1.2
0.8
723
925
715
1407
972
1609
799
1830
680
I0 and I are intensities of luminescence in the absence and in the presence of L2; сTb = 1×10–4 M, c(L1) = 5×10–4 M, с(L2) = 4×10–4 M, λlum
=
a
544 nm.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 12 2018

2568
NOVIKOVA et al.
λ, nm
λ, nm
Fig. 3. Excitation and luminescence spectra of Tb(III)
complexes with ligand 8a (1) and hetero-ligand complexes
in the presence of triphenylphosphine oxide (2) and α,α'-
dipyridyl (3). сTb = 1×10–4 M, с(L1) = 5×10–4 M, с(L2) =
4×10–4 M.
Fig. 2. Excitation and luminescence spectra of Tb(III)
complexes with ligand 8b (1) and hetero-ligand complexes
in the presence of triphenylphosphine oxide (2) and α,α'-
dipyridyl (3). сTb = 1×10–4 M, с(L1) = 5×10–4 M, с(L2) =
4×10–4 M.
[4-(2-Hydroxymethoxycarbonyl)phenyl]benzoate
8e was the only of the studied compounds which
formed luminescing complex with Eu(III). Probably, in
that case excitation transfer from triplet state of the
Tb(III) complex with [4-(2-hydroxymethoxycarbo-
nyl)phenyl]4-hexadecyloxybenzoate 8b soluble in
CHCl3, CCl4, and chlorobenzene and exhibiting strong
luminescence with λmax = 545 nm was obtained and
isolated for the preliminary assessment of its practical
application. Excitation and luminescence spectra of
that complex are given at Fig. 5. The investigation of
structure of the prepared complex will be reported
separately.
5
ligand (20790 cm–1) to the D1 level (19000 cm–1) of
europium ion took place, followed by non-radiative
5
transition to the first excited state D0 (17 cm–1), from
which irradiation occurred. Wide energy gap between
the metal and ligand levels enhanced the non-radiative
energy losses, and the complex exhibited weak
luminescence. The strongest band of the luminescence
spectra of the europium complex corresponded to the
5D0→7F2 transition, with maximum at 612 nm. For the
rest of methyl 2,4-dihydroxybenzoate derivatives, energy
of the triplet states was significantly higher than that of
excited state of Eu(III) ion, and the major part of energy
was lost without emission.
In summary, the derivatives of methyl 2,4-dihyd-
roxybenzoate containing fragment of mesogenic 4-n-alkoxy-
benzoic or 4-(4-alkoxybenzoyloxy)benzoic acids in
position 4 were found to be optimal for the preparation
of lanthanide complexes. The presence of long terminal
hydrocarbon substituents hindering crystallization allowed
the preparation of the low-defective films and achieve
maximal radiation efficiency. The luminescence
intensity of the prepared coordination compounds with
Tb(III) ions in solution as well as in solid state
exceeded that of known carboxylate complexes. That
fact, along with good solubility in organic solvents,
makes those compounds promising for their applica-
tion as emission elements.
It was shown using the limited logarithm method
that the composition of Eu(III) complexes with com-
pound 8e formed at low concentrations of the ligand
(about equal to the lanthanide content) corres-ponded
to Eu : 8e = 1 : 1. The components ratio was changed
to Eu : 8e = 1 : 2 at higher ligand concentration.
The study of the effect of additional ligands on
luminescence of the formed hetero-ligand complexes
showed that the most prominent increase in the Ilum
value of Eu(III) in complex with ligand 8e was
observed in the presence of triphenylphosphine oxide
and 1,10-phenantroline as organic bases (by 55 and
35 times, respectively, Fig. 4).
EXPERIMENTAL
1Н NMR spectra of solutions in CDCl3 or DMSO-d6
were recorded using a Bruker AVANCE DRX 500
spectrometer (operating frequency 500 MHz, internal
reference – TMS). Excitation and luminescence
spectra of the ligands and complexes were registered
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 12 2018

SYNTHESIS OF MESOMORPHIC DERIVATIVES
2569
λ, nm
Fig. 4. Excitation and luminescence spectra of Eu(III)
complexes with ligand 8e (1) and hetero-ligand complexes
in the presence of triphenylphosphine oxide (2) and α,α'-
dipyridyl (3). cEu = 1×10–4 M, с(L1) = 5×10–4 M, с(L2) =
4×10–4 M.
λ, nm
Fig. 5. Excitation and luminescence spectra of Tb(III)
complexes with ligand 8b.
using a Fluorolog FL 3-22 spectrofluorometer (HORIBA
Jobin-Yvon Inc., France). Temperatures of phase
transitions were studied via polarization microscopy
using a POLAM R-312 microscope and a DSC Q2000
differential scanning calorimeter (USA) (heating rate
1 deg/min). Energies of the triplet states of organic
ligands were calculated from the phosphorescence
spectra of their complexes with gadolinium and
yttrium at 77 K. рН values of the solutions were
measured using a ОР-211/1 pH-meter (Radelkis,
Hungary) (glass electrode calibrated using standard
buffer solutions).
4-(4-Hexadecyloxybenzoyloxy)benzaldehyde (6b).
The preparation procedure and constants are given in
[8].
4-(4-Heptyloxybenzoyloxy)benzoic acid (7a) was
prepared using a method similar to the one described
1
in [8]. Yield 4.0 g (72.3%), white solid substance. Н
NMR spectrum (DMSO-d6), δ, ppm (J, Hz): 0.90 t
(3Н, СН3, 3J = 6.9), 1.26–1.49 m (8Н, СН2), 1.73–1.81
m (2Н, СН2СН2О), 4.11 t (2Н, СН2О, 3J = 6.5), 7.14 d
3
3
(1Н, Ar, J = 8.8), 7.42 d (2Н, ArСООН, J = 8.6),
8.05–8.14 m (2Н, Ar, 2Н, ArСООН). Found, %: С
71.02; Н 6.64. C23H28O5. Calculated, %: С 70.77; Н
6.80.
Methyl-2,4-dihydroxybenzoate (2) was prepared
as described in [6]. Yield 50%, mp 116°С (mp 117–
118°С [6]).
4-(4-Hexadecyloxybenzoyloxy)benzoic acid (7b).
The preparation procedure and constants are given in
[8].
4-n-Heptyloxybenzoyl chloride (5a) was prepared
as described in [9]. Yield 93.2%, colorless liquid, bp
208°С (4 mmHg).
[4-(2-Hydroxymethoxycarbonyl)phenyl]-4-heptyl-
oxybenzoate (8a). 0.59 g (0.48 mmol) of 4-dimethyl-
aminopyridine (DMAP) was added to a solution of 1.3 g
(6 mmol) of ester 2 and 1.4 g (6 mmol) of 4-(4-heptyl-
oxybenzoyloxy)benzoic acid in 20 mL of anhydrous
chloroform under stirring. After 10 min, 1.24 g
(6 mmol) of N,N'-dicyclohexylcarbodiimide (DCC)
was added. The reaction mixture was stirred for 10 h at
room temperature. The precipitate was filtered off and
washed with methylene chloride (15 mL); the residue
of dicyclohexylurea precipitate was filtered off, and
the solvent was removed under reduced pressure. The
final product was recrystallized from an ethanol–
4-Hexadecyloxybenzoyl chloride (5b) was prepared
using the same method. Yield 95.2%, mp 50°С.
4-(4-Heptyloxybenzoyloxy)benzaldehyde (6a) was
prepared as described in [7]. Yield 66.7%, white
crystals, mp 56°С. 1Н NMR spectrum (CDCl3), δ, ppm
(J, Hz): 0.89 t (3Н, СН3, 3J = 7.2), 1.20–1.55 m (8Н,
СН2), 1.76–1.90 m (2Н, СН2СН2О), 4.05 t (2Н, СН2О,
3
3J = 6.5), 6.98 d (2Н, Ar, J = 8.7), 7.40 d (2Н,
ArСОН, 3J = 8.4), 7.97 d (2Н, ArСОН, 3J = 8.4), 8.14
3
d (2Н, Ar, J = 9.0), 10.02 s (1Н, СОН). Found, %: С
74.29; Н 7.04. C21H24O4. Calculated, %: С 74.09; Н 7.10.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 12 2018

2570
NOVIKOVA et al.
benzene mixture (5 : 1), then from 95 mL of hexane
and 35 mL of benzene. The final product was purified
using by column chromatography (Al2O3, L = 40/250
eluent—chloroform). Yield 1.2 g (46%), white solid
substance. 1Н NMR spectrum (CDCl3), δ, ppm (J, Hz):
added to a solution of 2.22 g (0.01 mmol) of com-
pound 2 in 15 mL of anhydrous diethyl ether. A
solution of 1 mL (0.0086 mol) of benzoyl chloride in
5 mL of anhydrous benzene was slowly added to the
cooled (0°С) reaction mixture. The mixture was kept
overnight, stirred at room temperature for 10 h, and
then poured onto crushed ice. The precipitate was
filtered off. The filtrate was extracted with benzene
(3 × 35 mL) and dried over MgSO4. After the removal
of benzene, the precipitate was twice recrystallized
from ethanol with activated carbon. Yield 0.75 g
(32%), white solid substance. 1Н NMR spectrum
(CDCl3), δ, ppm (J, Hz): 3.97 s (3Н, СООСН3), 6.81–
3
0.91 t (3Н, СН3, J = 6.9), 1.20–1.51 m (7Н, СН2),
1.75–1.90 m (2Н, СН2СН2О), 3.97 s (3Н, СООСН3),
3
4.05 t (2Н, СН2О, J = 6.6), 6.77–6.79 d. d (1Н, Н5,
4
4
3J = 8.8, J = 2.2), 6.87 d (1Н, Н3, J = 2.2), 6.97 d
(2Н, Н10,12, J = 8.8), 7.90 d (1Н, Н6, J = 8.6), 8.12 d
3
3
(2Н, Н9,13, J = 8.6), 10.91 s (1H, OH). Found, %: С
3
68.56; Н 6.61. C22H26O6. Calculated, %: С 68.38; Н 6.78.
[4-(2-Hydroxymethoxycarbonyl)phenyl]-4-hexa-
decyloxybenzoate (8b) was prepared similarly. Yield
81.2%, white solid substance. 1Н NMR spectrum
3
4
6.79 d. d (1Н, ArOH, J = 8.8, J = 1.0), 6.89 d (1Н,
4
ArOH, J = 1.0), 7.42–7.59 m (2Н, Ar), 7.60–7.72 m
(1Н, Ar), 7.91 d (1Н, ArOH, 3J = 8.5), 8.19 d (2Н, Ar,
3J = 7.1), 10.94 s (1H, OH). Found, %: С 66.30; Н
4.20. C15H12O5. Calculated, %: С 66.18; Н 4.44.
3
(CDCl3), δ, ppm (J, Hz): 0.90 t (3Н, СН3, J = 6.9),
1.21–1.52
m
(26Н, СН2), 1.78–1.90
m
(2Н,
СН2СН2О), 3.98 s (3Н, СООСН3), 4.06 t (2Н, СН2О,
3
4
3J = 6.6), 6.79–6.81 d. d (1Н, Н5, J = 8.8, J = 2.2),
[4-(2-Hydroxymethoxycarbonyl)phenyl]hexa-
decanoate (8f). 40.3 mg (0.33 mmol) of DMAP was
added to a solution of 0.74 g (3.3 mmol) of ester 2 and
0.845 g (3.3 mmol) of anhydrous n-decanoic acid in
25 mL of anhydrous chloroform under stirring. After
10 min, 0.681 g (3.3 mmol) of DCC was added. The
obtained reaction mixture was stirred for 23 h at room
temperature. Then the precipitate was filtered off.
After removal of solvent, the precipitate was
recrystallized from ethanol. Yield 3.5 g (26.3%), white
6.89 d (1Н, Н3, J = 2.2), 6.98 d (2Н, Н10,12, J = 8.8),
4
3
7.91 d (1Н, Н6, J = 8.6), 8.13 d (2Н, Н9,13, J = 8.6),
10.92 s (1H, OH). Found, %: С 72.80; Н 8.43.
C31H26O6. Calculated, %: С 72.63; Н 8.65.
3
3
[4-(2-Hydroxymethoxycarbonyl)phenyl]-4-(4-
heptyloxybenzoyloxy)benzoate (8c) was prepared
similarly. Yield 63.5%, white solid substance. 1Н NMR
spectrum (CDCl3), δ, ppm (J, Hz): 0.92 t (3Н, СН3,
3J = 6.5), 1.22–1.64 m (10Н, СН2), 1.75–1.96 m (2Н,
СН2СН2О), 3.99 s (3Н, СООСН3), 4.07 t (2Н, СН2О,
1
crystalline substance, mp 43°С. Н NMR spectrum
(CDCl3), δ, ppm (J, Hz): 10.88 s (1H, OH), 7.85 d (1Н,
Ar, 3J = 8.8), 6.8–6.65 m (2Н, Ar), 3.95 s (3Н, ОСН3),
2.75–2.40 m [2Н, СН2С(О)], 1.90–1.60 m [2Н,
СН2СН2С(О)], 1.6–1.1 m (24Н, СН2), 0.88 t (3Н,
3
4
3J = 6.5), 6.79–6.82 d. d (1Н, Н5, J = 10.6, J = 2.2),
6.90 d (1Н, Н3, J = 2.2), 7.00 d (2Н, Н17,19, J = 8.8),
4
3
7.39 d (2Н, Н10,12, J = 8.6), 7.93 d (1Н, Н6, J = 8.6),
3
3
8.17 d (2Н, Н16,20, J = 8.6), 8.27 d (2Н, Н9,13, J =
8.6), 10.95 s (1H, OH). Found, %: С 68.91; Н 5.87.
C29H30O8. Calculated, %: С 68.76; Н 5.97.
3
3
3
СН3, J = 6.9). Found, %: С 70.89; Н 9.40. C24H37O5.
Calculated, %: С 71.08; Н 9.19.
Procedure of preparation of complexes. 0.1 M
stock solutions of Tb(III) or Eu(III) chlorides for the
investigation of complex formation were prepared via
following procedure. High-pure terbium (99.988%)
and europium oxides (99.99%) were dissolved in
hydrochloric acid (1 : 1), and the excess of acid was
evaporated off. The solid residue was dissolved in
methanol and diluted in a measuring flask to the
required volume. The concentration of lanthanide ions
was determined using complexometric titration. Initial
solutions of reagents with concentration 0.1 mol/L
were prepared via dissolution of the weighed portions
in ethanol. The calculated volume of 0.01 M solution
of TbCl3 or EuCl3 was put in a test tube, and 0.01 M
ligand solution was added to the components ratio
[4-(2-Hydroxymethoxycarbonyl)phenyl]-4-(4-
hexadecylozybenzoyloxy)benzoate (8d) was prepared
1
similarly. Yield 52%, white solid substance. Н NMR
spectrum (CDCl3), δ, ppm (J, Hz): 0.88 t (3Н, СН3,
3J = 6.9), 1.21–1.53 m (26Н, СН2), 1.77–1.89 m (2Н,
СН2СН2О), 3.97 s (3Н, СООСН3), 4.05 t (2Н, СН2О,
3
4
3J = 6.6), 6.79–6.82 d. d (1Н, Н5, J = 8.8, J = 2.2),
6.89 d (1Н, Н3, J = 2.2), 6.98 d (2Н, Н17,19, J = 8.8),
4
3
7.38 d (2Н, Н10,12, J = 8.8), 7.92 d (1Н, Н6, J = 8.8),
3
3
8.16 d (2Н, Н16,20, J = 8.8), 8.26 d (2Н, Н9,13, J =
8.8), 10.93 s (1H, OH). Found, %: С 72.25; Н 7.53.
C38H48O8. Calculated, %: С 72.13; Н 7.65.
3
3
[4-(2-Hydroxymethoxycarbonyl)phenyl]benzoate
(8e). 0.68 g (0.0086 mol) of anhydrous pyridine was
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 12 2018

SYNTHESIS OF MESOMORPHIC DERIVATIVES
2571
2014, vol. 87, no. 6, p. 787. doi 10.1134/
S1070427214060202
2. Derkach, L.G., Teslyuk, O.I., Novikova, N.S., Doga, P.G.,
Yarkova, M.Yu., and Meshkova, S.B., Russ. J. Gen.
Chem., 2014, vol. 84, no. 7, p. 1293. doi 10.1134/
S107036321407007X
Ln : L = 1 : 5. Solvents were added to the final volume
(5 or 10 mL). Then the mixture was kept during
30 min for the complex formation. For the preparation
of hetero-ligand complexes, 0.4–0.5 mL (10–2 M) of
ethanolic solution of trioctylphosphine oxide or 0.3–
0.4 mL of aqueous solution of 1,10-phenantroline was
added to the complex solution. The рН value was
adjusted by the addition of 40% aqueous solution of
urotropine.
3. Duncan, Graham-Rowe, Energy News, 2009, p. 9.
4. Galyametdinov, Yu.G., Turanova, O.A., Ven Van,
Knyazev, A.A., and Haase, W., Doklady Chem, vol. 384,
nos. 1–3, p. 144. doi 10.1023/A:1015557629627
Tb(III) complex with [4-(2-hydroxymethoxycar-
bonyl)phenyl]4-hexadecylbenzoate. 0.1 mmol of
aqueous solution of Tb(ClO4)3 and several drops of
NH4OH were added to a solution of 154 mg
(0.3 mmol) of compound 8b in 20 mL of ethanol
obtained at heating to ~35°С. The formed white
precipitate was filtered off, washed with cold ethanol,
and dried. Yield 115 mg (66%).
5. Suárez, S., Mamula, O., Imbert, D., Piguet, C., and
Bünzli, J.-C.G., Chem. Commun., 2003, p. 1226. doi
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CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 12 2018