3-Trifluoroacetamidobenzoyltrifluoroacetone and its europium complexes

Full text of DOI:10.1134/S0012500811070111

ISSN 0012ꢀ5008, Doklady Chemistry, 2011, Vol. 439, Part 1, pp. 209–212. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.V. Semenov, N.V. Zolotareva, G.A. Domrachev, 2011, published in Doklady Akademii Nauk, 2011, Vol. 439, No. 3, pp. 351–354.
CHEMISTRY
3ꢀTrifluoroacetamidobenzoyltrifluoroacetone
and Its Europium Complexes
V. V. Semenov, N. V. Zolotareva, and Corresponding Member of the RAS G. A. Domrachev
Received February 24, 2011
DOI: 10.1134/S0012500811070111
Europium and terbium complexes with functional forms quickly and in high yield in the reaction of
ligands are used as luminescent labels in timeꢀresolved II in the absence of sodium hydride.
fluorescence immunoassay [1–3]. Covalent bonding
I with
Compound IV exists in acetoneꢀd6 and chloroꢀ
formꢀd3 solutions as a mixture of enol and ketone
forms in the 15 : 1 ratio. The presence of enol IVa is
confirmed by the signal at 6.91 ppm (C–H), while the
existence of diketone IVb follows from the singlet sigꢀ
to the protein molecule of the coordination comꢀ
pound that has a primary amino group at the periphery
is carried out with the use of bifunctional glutaraldeꢀ
hyde H(O)C(CH ) C(O)H [4]. Our attempt to obtain
2
3
a ligand with primary amino group by the reaction
of 3ꢀaminoacetophenone ( ) with excess of methyl
nal of two protons of the CH group at 4.81 ppm. The
mass spectrum of compound IV shows maximum
2
I
trifluoroacetate (II) and sodium hydride led to forꢀ
intensity peaks for fragment ions with
40.4, 258.3, and 307.1. The peak of the molecular ion
with 327.0 is of low intensity. The presence of the
peaks with 69.6, 258.3, and 307.1 indicates that
the fragmentation of the molecule of ꢀdiketone IV
The intermediate product in this reaction is 3ꢀtrifꢀ begins with abstraction of HF ( 20) and the CF
m/z 69.6, 216.2,
mation of 3ꢀtrifluoroacetamidobenzoyltrifluoroaceꢀ
2
tone (IVa
trifluoroacetone 3ꢀNH –C H –C(O)–CH –C(O)CF
3
, IVb) instead of expected 3ꢀaminobenzoylꢀ
m/z
2
6
4
2
m/z
(
Scheme 1).
β
m/z
3
luoroacetamidoacetophenone (III). Compound III radical (
m/z
69.3).
O
CF COOCH (II), NaH
3
3
CH3
CH3
C H OC H , 25–35°C
F3C
N
H
2
5
2
5
H N
2
O
O
I
III
O
H
O
H
H
CF3
CF3
F3C
N
+ F C
N
3
H
O
O
H
O
O
H
IVa
IVb
Scheme 1.
It is known that the protection of the primary group CF C(O)NHR is considered to be the most
3
amino group is accomplished by its transformation
into amide one [5]. The trifluoroacetamide protective
convenient because its deprotection (by the treatment
of amide with an alcoholic solution of alkali or potasꢀ
sium carbonate) is carried out under milder conditions
as compared with a nonfluorinated analogue
Razuvaev Institute of Organometallic Chemistry,
Russian Academy of Sciences, ul. Tropinina 49,
Nizhni Novgorod, 603950 Russia
CH C(O)NHR.
3
209

210
SEMENOV et al.
1
CF COOCH3
ing to H NMR, IR, HPLC, and GCꢀMS) of the tarꢀ
get compound in only 25% yield. The treatment of a
solution of compound IV in diethyl ether with sodium
hydroxide resulted in competitive cleavage of the
3
[CF C(O)] O
RNH2
RNHC(O)CF3
3
2
NaOH, CH OH, H O
3
2
RNH2.
Our attempt to prepare 3ꢀaminobenzoyltrifluoroꢀ
acetone (V) in this manner led to formation (accordꢀ
β
ꢀdiketone to compounds I and III (Scheme 2).
H
CF3
NaOH, EtOEt, H O
2
H N
IV
I
+
III
+
2
O
O
2
4% 51%
V, 25%
H
Scheme 2.
1
The H NMR spectrum of the reaction mixture carbonyl group by intramolecular hydrogen bond
shows the appearance of two singlet signals from the plays a role of a metal cation.
protons of the methyl groups in compounds I (2.47 ppm)
and III (2.59 ppm), and the IR spectrum exhibits two
The preparation of europium(III) tris(3ꢀamiꢀ
nobenzoyltrifluoroacetonate) trihydrate VII containꢀ
ing amino group was carried out by the elimimation of
the protective group under conditions similar to those
bands of the N–H stretching vibrations in the primary
–1
amino group at 3370 and 3466 cm .
Europium(III) tris(3ꢀtrifluoroacetamidobenzoylꢀ used for the reaction of ligand IV with NaOH. Comꢀ
trifluoroacetonate) trihydrate EuL · 3H O
VI) was plex VI proved to be moderately stable toward the
(
3
2
alkaline reagent. The appearance of the amino group
in the reaction product is clearly detected by IR specꢀ
troscopy. Figure 2 shows a spectral region within
4000–3000 cm for initial compound VI and the
product of its reaction with NaOH (VII). The disapꢀ
obtained from compound IV, NaOH, and europium
chloride in an aqueous alcohol medium (L is the anion
of
3ꢀtrifluoroacetamidobenzoyltrifluoroacetone).
–1
This compound is a fine orange powder.
Figure 1 shows the electronic absorption spectra of
ligand IV and complex VI. The spectra of these comꢀ
pounds are alike and composed of two absorption
bands with maxima at 242 and 324 nm. The large simꢀ
ilarity is due to the existence of both the ligand and the
complex as chelates. In the enol form of the ligand
pearance of
ν
(NH) absorption band of the amide
–1
group at 3300 cm and the emergence of two bands at
–1
3364 and 3455 cm of the primary amino group are
observed.
Compounds VI and VII exhibit strong red–orange
photoluminescence (PL) in dilute acetonitrile soluꢀ
(
IVa), the proton bound to the oxygen atom of the
–3
–6
tions (c = 10 –10 M) (Fig. 3). Emission spectra are
identical on the whole, whereas photoluminescence
excitation (PLE) spectra are different. When detected
at wavelength of Eu cation emission at 615 nm, the
A
2
42
2.0
1.5
1.0
0.5
0
3+
3
24
PLE spectra show single bands at 370 nm for comꢀ
1
1
2
242
324
2
250
300
350
400
, nm
4000
3800
3600
3400
3200
3000
, cm
λ
−
1
ν
Fig. 1. Electronic absorption spectra of acetonitrile soluꢀ
tions of ligand IV
(
–
4
(
c
= 1.8
).
×
10 M) (1) and complex VI
Fig. 2. IR spectra of compounds VI
(
1) and VII
(2) in the
–
6
c
= 6.8 10 M) (2
×
region of N–H stretching vibrations.
DOKLADY CHEMISTRY Vol. 439
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3
ꢀTRIFLUOROACETAMIDOBENZOYLTRIFLUOROACETONE
211
15
pound VI and at 405 nm for compound VII. The PL
spectra in both cases contain the strongest band of the
6
1000
5
7
3+
D0
→
F2 transition in Eu cation with
λ
615 nm.
max
800
600
400
200
0
370
Thus, our study revealed that the reaction of
ꢀaminoacetophenone with methyl trifluoroacetate
proceeds in two stages and leads to formation of
ꢀtrifluoroacetamidobenzoyltrifluoroacetone instead
of expected 3ꢀaminobenzoyltrifluoroacetone. The
reason consists in the ease of the reaction of
CF COOCH with the amino group of starting 3ꢀamiꢀ
noacetophenone and the initial formation of 3ꢀtrifluꢀ
oroacetamidoacetophenone. Luminescent europium
1
2
3
3
4
05
3
3
β
ꢀdiketonate containing primary amino group at the
periphery was obtained by the treatment of the amide
derivative with an alkali solution.
300
400
500
600
, nm
λ
Fig. 3. Fluorescence excitation spectra (
λ
= 615 nm)
reg
and fluorescence spectra of complexes (
1
)
VI
(
λ
=
ex
EXPERIMENTAL
340 nm,
c
= 6.8
×
10–6 M) and (
2)
VII
(
λ
= 440 nm, c =
ex
IR spectra were recorded as thin films between KBr
plates or as Nujol mulls on an FSM 1201 Fourierꢀ
transform IR spectrophotometer. H NMR spectra
10–3 M) in an acetonitrile solution.
3
×
1
1H NMR ((CD
)
CO
,
δ
, ppm,
J
, Hz): 2.60 (s, 3H,
= 8.03),
⎯7.89 (d, 1H, arom.), 8.00–8.02 (d, 1H, arom.),
were recorded on a Bruker Avance DPXꢀ200 specꢀ
3
2
trometer (operating at 200 MHz) at 25°С with TMS as CH C(O)–), 7.57–7.61 (t, 1H, arom.,
J
3
an internal reference. Fluorescence and fluorescence 7.7
excitation spectra were measured with a PerkinElmer 8.33 (s, 1H, arom.), 10.44 (s, 1H, NH).
LSꢀ55 spectrofluorimeter in acetonitrile solutions.
For C H F NO anal. calcd. (wt %): C, 51.95;
H, 3.49. Found (wt %): C, 51.06; H, 3.07.
10
8
3
2
Electronic absorption spectra were recorded on a
PerkinElmer Lambda 25 spectrophotometer.
3ꢀTrifluoroacetamidobenzoyltrifluoroacetone (IV).
GCꢀMS analysis was performed with a Polaris Q/
Trace GC Ultra chromatograph–mass spectrometer
using a TRꢀ5MS capillary column 60 m long and
A threeꢀnecked flask equipped with s stirrer, a dropꢀ
ping funnel, and a reflux condenser was heated to
1
00 C in an argon flow, the flask was charged with a
°
0.25 mm in diameter. The flow rate of the carrier gas
solution of 3.0 g (0.075 mol) of NaH in 100 mL of
anhydrous diethyl ether, and 19.2 g (0.15 mol) of
methyl trifluoroacetate was added dropwise with stirꢀ
ring. Then, a solution of 5.0 g (0.037 mol) of 3ꢀamiꢀ
noacetophenone in 20 mL of anhydrous diethyl ether
was added, stirred for 3 h, and a 10% solution of
H SO was added to neutral reaction. The ether layer
(
helium of M 60 grade) was 1.2 mL/min, the column
temperature was programmed from 40 to 200°C at a
rate of 10 K/min. Mass spectra were detected at an
ionizing voltage of 70 eV in the range of 40–400 dalꢀ
tons. NIST 2005 library was used for the identification
of detected substances.
2
4
The analysis of products for the reaction of comꢀ
pound IV with NaOH was accomplished with a
Knauer liquid chromatograph equipped with an UV
was separated from the aqueous solution and dried
with Na SO , and the diketone was recrystallized from
2
4
the diethyl ether–hexane mixture. The compound was
finally purified by vacuum sublimation to give 9.4 g
78%) of diketone IV.
detector using a
C18 sorbent (5
the eluent.
6
μ
×
100 mm column with a Separon Si
m) and 60% aqueous acetonitrile as
(
–1
IR (
amide I), 1614, 1550 (C=O), 1590 (amide II), 1489,
458, 1282, 1221, 1188, 1150, 1120 (CF ), 788.
ν
, cm ): 3300 (NH), 3087 (C=C–H), 1716
Sodium hydride was used as a 60% suspension in a
mineral oil (Acros). Methyl trifluoroacetate (PIM
Invest) and 3ꢀaminoacetophenone (Acros) were used
without preliminary purification.
(
1
3
1H NMR ((CD ) CO
, , ppm, J, Hz): 4.81 (s, 2H,
δ
3
2
3
ꢀTrifluoroacetamidoacetophenone (III) was CH2 in diketone), 6.91 (s, 1H, CH in enol), 7.64–7.68
obtained by the reaction of equimolar amounts of (t, 1H, arom.,
= 8.03), 8.02–8.04 (d, 1H, arom.),
J
compounds
I
and II in ether. Yield, 87%.
8.08–8.1 (d, 1H, arom.), 8.44 (s, 1H, arom.), 10.49 (s,
NH).
–1
IR (ν, cm ): 3300 (NH), 1716 (amide I), 1614,
1
1
550 (C=O), 1590 (amide II), 1489, 1458, 1282, 1221,
188, 1150, 1120 (CF3), 788.
For C H F NO anal. calcd. (wt %): C, 44.03;
H, 2.16. Found (wt %): C, 43.20; H, 2.15.
12
7
6
3
DOKLADY CHEMISTRY Vol. 439
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212
SEMENOV et al.
–
1
Europium(III) tris(3ꢀtrifluoroacetamidobenzoyltriꢀ
fluoroacetonate) trihydrate (VI). Compound IV
0.98 g, 3 mmol) was dissolved in 15 mL of 95% ethaꢀ
nol. Then, 3 mL of 1 N NaOH and 5 mL of 0.2 M
aqueous solution of europium chloride (1 mmol) was
added with vigorous stirring. To this mixture, 100 mL
IR (ν, cm ): 3364, 3455 (NH ), 3060 (C=C–H),
2
1
1
719, 1682 (C=O), 1614, 1580, 1529, 1492, 1316,
292, 1259, 1191, 1137 (CF ), 798.
(
3
For C H EuF N O anal. calcd. (wt %): C, 40.13;
30
27
9
3
9
H, 3.03. Found (wt %): C, 41.06; H, 2.83.
Analyses were performed in the Analytical Center,
Razuvaev Institute of Organometallic Chemistry, Rusꢀ
sian Academy of Sciences.
of water was added, and the mix was heated to 60 C
°
and cooled. The resulting orange precipitate of comꢀ
pound VI was purified by recrystallization from a
dichloromethane–hexane mixture. Yield, 0.5 g (43%).
ACKNOWLEDGMENTS
–1
IR (
ν
, cm ): 3300 (NH), 3087 (C=C–H), 1716
This work was supported by the Russian Foundaꢀ
tion for Basic Research (project nos. 08–03–00771
and 10–03–90006ꢀBel), the Ministry of Education
(
1
amide I), 1614 (C=O), 1590 (amide II), 1560, 1533,
489, 1465, 1299, 1225, 1188, 1150, 1120 (CF ), 788.
3
1
H NMR ((CD ) CO,
δ, ppm,
J
, Hz): 6.57 (s, 1H, and Science (State contract no. 16.740.11.0015), and
3
2
the Presidium of the Russian Academy of Sciences
program “Directed Synthesis of Substances with Preꢀ
scribed Properties and Design of Functional Materials
Based Thereof”).
CH), 6.92–7.00 (t, 1H, arom.,
J
= 8.03), 7.15–7.18
(
(
d, 1H, arom.), 7.26–7.30 (d, 1H, arom.), 10.02 (s,
1
H, arom.).
For C H EuF N O anal. calcd. (wt %):
36
24
18
3
12
C, 36.46; H, 2.04. Found (wt %): C, 37.40; H, 2.15.
REFERENCES
Europium(III) tris(3ꢀaminobenzoyltrifluoroacetoꢀ
nate) trihydrate (VII). To a magnetically stirred soluꢀ
tion of 0.5 g (0.42 mmol) of compound VI in 20 mL of
ethanol, 2 mL of 1 N NaOH was added dropwise. The
1
. Zolin, V.F. and Koreneva, L.G., Redkozemel’nyi zond v
khimii i biologii (Rare Earth Probe in Chemistry and
Biology), Moscow: Nauka, 1980.
2. Eliseeva, S.V. and Bunzil, J.ꢀC.G., Chem. Soc. Rev.
010, vol. 39, no. 2, pp. 189–227.
,
2
mixture was stirred for 7 h at 25 C. Excess alkali was
°
3
4
5
. Escribano, P., JulianꢀLopez, B., PlanellesꢀArago, J.,
neutralized with acid. The solvent and water were
removed in vacuum. The solid residue was dissolved in
dichloromethane and washed two times with water.
The organic layer was separated from the aqueous
solution and dried with Na SO . The solvent was
et al., J. Mater. Chem., 2008, vol. 8, no. 1, pp. 23–40.
. Bunzli, J.ꢀC.G., Chem. Rev., 2010, vol. 110, no. 5,
pp. 2729–2755.
.
Protective Groups in Organic Chemistry, McOmie, J.,
Ed., New York: Plenum, 1973. Translated under the
title Zashchitnye gruppy v organicheskoi khimii, Mosꢀ
cow: Mir, 1976.
2
4
removed in vacuum to give 0.25 g (70%) of comꢀ
pound VII as a yellow powder.
DOKLADY CHEMISTRY Vol. 439
Part 1
2011