The first mesogenic derivative of boron difluoride β-diketonate

Article abstract of DOI:10.1134/S1070363206050124

Boron difluoride β-diketonate exhibiting liquid crystalline as well as photoluminescence properties was prepared for the first time. It is the promising material for creating supramolecular organized luminescent media. Pleiades Publishing, Inc., 2006.

Full text of DOI:10.1134/S1070363206050124

ISSN 1070-3632, Russian Journal of General Chemistry, 2006, Vol. 76, No. 5, pp. 730 732.
Original Russian Text O.A. Turanova, A.N. Turanov, D.V. Lapaev, O.I. Gnezdilov, S.V. Lobkov, Yu.G. Galyametdinov, 2006, published in Zhurnal
Obshchei Khimii, 2006, Vol. 76, No. 5, pp. 767 769.
Pleiades Publishing, Inc., 2006.
The First Mesogenic Derivative
of Boron Difluoride -Diketonate
O. A. Turanovaa, A. N. Turanova, D. V. Lapaeva,
O. I. Gnezdilova, S. V. Lobkova, and Yu. G. Galyametdinovb
aZavoiskii Kazan Physicotechnical Institute,
Kazan Scientific Center of Russian Academy of Sciences, Sibirskii trakt 10/7, Kazan, Tatarstan, 429029 Russia
fax (8432)765075
e-mail: turanova@mail.knc.ru
bKazan State Technological University, Kazan, Tatarstan, Russia
Received August 18, 2005
Abstract Boron difluoride -diketonate exhibiting liquid crystalline as well as photoluminescence pro-
perties was prepared for the first time. It is the promising material for creating supramolecular organized
luminescent media.
DOI: 10. 1134/S1070363206050124
An interest to investigation of photophysical and
photochemical properties of the boron difluoride
-diketonate derivatives permanently increases be-
cause they exhibit high luminescence in the visible
range of spectrum [1 5]. Because of their lumine-
scence property these compounds can be used in
luminescent analysis as the components of the light-
emitting materials [6, 7]. Obtaining the compounds
capable of luminesce in the yelloworange and the red
range is particularly important [8, 9].
On the basis of the substances combining both
liquid crystal and luminescence properties it may be
possible to create defectless optic nanomaterials with
monoaxially oriented molecules of a mesogen, exibit-
ing highly efficient luminescence. We have reported
previously on the preparation of the liquid crystalline
complexes of lanthanoids forming ordered supramo-
lecularly organized media and exhibiting lineary
polarized luminescence [16, 17]. On an example of a
series of compounds it was shown that inclusion of
electron-donating groups to the aromatic -substituent
of the chelate ring and elongation of the conjugation
chain leads to increase in the intensity of lumine-
scence [1, 8]. Presence of aromatic groups and
fluorine atoms in the molecule of luminophore also
improves the brightness of radiation [18, 19].
Boron difluoride -diketonates were obtained
rather long ago (in 1924) and the methods of their
synthesis are considerably well known and systemati-
zed [10, 11]. Some compounds were the objects of
X-ray studies [2, 3], and their luminescent properties
were investigated. It was shown that their lumine-
scence intensity depends on the geometry and elec-
tronic structure of the complexes [12]. It was noted
that the mechanisms of luminescence in solution
differs from that in the crystalline state [13].
In the present work we describe syntheses of non-
mezogenic and liquid crystalline boron difluoride
-diketonates and compare their luminescent proper-
ties. Nonmezogenic dibenzoylmethane I (mp 79 C)
and 1-(4-dodecyloxyphenyl)-3-(4-tetradecyloxyphe-
nyl)-propan-1,3-dione IIa (mp 89 C) were chosen as
the ligands.
With the purpose of broadening the class of com-
pounds exhibiting intense luminescence we prepared
the first derivative of boron difluoride diketonate,
boron difluoride 1-(4-dodecyloxyphenyl)-3-(4-tetra-
-Diketone with the long alkyl substituents was
obtained by the multistage synthesis reported in [20].
decyloxyphenyl)-propan-1,3-dionate,
possessing
liquid crystal properties. Presence of mezogenic pro-
perties is a new fact for the compounds of this class,
permitting to approach to the solution of the problem
of obtaining of supramolecular organized media
necessary for creating the materials for the photonic
devices [14, 15].
For the investigation of the relationship between
the structure and the physicochemical properties the
complex of boron difluoride with dibenzoylmethane
was prepared [scheme (1)]. Composition and structure
of the obtained compounds were established by means
730

THE FIRST MESOGENIC DERIVATIVE OF BORON DIFLUORIDE -DIKETONATE
731
1
of the elemental analysis, IR and H NMR spectro-
scopy, and by the consistence of the physicochemical
constants of compounds Ia and Ib with the previously
reported data. The products obtained are stable in air
and in solutions. Their chemical stability (remaining
unchanged of the quasiaromatic ring in the reactions
of electrophilic and nucleophilic substitution) was
described in the preliminary report [11].
1.00
0.75
0.50
0.25
0
R
R
500
600
700 , nm
Normalized photoluminescent spectra of the poly-
crystalline samples Ib (dotted line) and IIb (continuous
line) at room temperature.
BF3 Et2O
HF
C O
C O
F
F
C=O
C=O
H2C
(1)
HC
B
course of several cycles of heating and cooling and
also at the prolonged keeping of the sample in the
mesophase state its mesogenic structure and its para-
meters remained unchanged.
R
R
Ia, IIa
Ib, IIb
UV spectra (in chloroform) of the obtained com-
pounds contain absorption bands in the range 265
R = R = H (I); R = C12H25O, R = C14H29O (II).
400 nm related to
* transitions in the chelate ring.
IR spectra of chelate complexes show a shift of the
bands of stretching vibrations of C=C and C=O
The figure shows normalized photoluminescence spec-
tra of the samples Ib and IIb in the polycrystalline
state at room temperature. The maximum point of
photoluminesce band of the liquid crystalline complex
IIb (530 nm) corresponds to the maximum point of
the band of the unsubstituted complex IIb. Its spec-
trum was published previously [2].
1
bonds (1592 and 1538 cm respectively) as compared
1
to the ligand (1582 cm 1 for C=C bond and 1600 cm
for C=O bond). Though it is known that the C=O
bond in the ligand is weakened due to the resonance
of the structures [21] [scheme (2)], the complex
formation with boron difluoride leads to even more
significant weakening of this bond arising from the
withdraw of electronic density from the chelate ring
by the fluorine atoms, and to decrease of the vibration
frequency.
Hence, boron difluoride -diketonate posessing the
liquid crystalline as well as the photoluminescent
properties was prepared for the first time. The inten-
sity of radiation of the liquid crystalline sample has
the same order as that of the crystalline one.
+
...
OH O
...
OH O
(2)
EXPERIMENTAL
C R
CH
R C
C R
CH
R C
The textures and the phase transfer temperatures
were obtained on a Boetius polarizational microscope
equipped with the temperature block controlled by a
personal computer. The accuracy of the temperature
measurements is 0.1 C. The IR spectra were regis-
tered on a Specord IR-75 spectrometer in vaseline oil.
1
In the H NMR spectrum the downfield shift of the
signal of CH proton by 0.39 ppm and 0.40 ppm for
compounds Ib and IIb respectively as compared to
the ligands is observed, what is also explained by the
effect of electronegative fluorine atoms on the elect-
ron density of the quasiaromatic cycle of the complex
[22].
1
The H NMR spectra were taken on a Bruker Avance
400 spectrometer in CDCl3 against TMS. The UV
spectra were measured in chloroform at the concentra-
The liquid crystalline properties of compound IIb
were investigated by means of the optic polythermal
polarization microscopy. With the complex of substitu-
ted boron fluoride -diketonate we have demonstrated
formation of thermotropic smectic A phase Cr92SA129I
(where Cr is the crystalline phase, SA is the smectic A
mesophase and I is the isotropic phase) which was
identified by the characteristic fan-like texture. In the
4
1
tions 1.5 3 10 mol l on a Specord UV-Vis spec-
trophotometer. Photoluminiscence spectra of the
samples under investigation were obtained on a poly-
functional automatized optical spectrometer construc-
ted on a base of KSVU-23 instrument. Pulse nitrogen
laser LGI-21 (wavelength 337 nm, pulse duration
10 ns, pulse frequency 50 Hz) was used as a source
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 5 2006

732
TURANOVA et al.
for excitation. A FEU-100 photomultiplier was used
as a photodetector. Photoluminescence spectra were
registered3 mcs after the exciting impulse. The
measurenents were carried out at room temperature.
5. Isfan, E. and Barabas, A., Rev. Roum. Chim., 1973,
vol. 18, no. 4, p. 5057.
6. Vasil’ev, N.N., Gorelenko, A.Ya., Kalosha, I.I.,
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Tulach, V.Ya., and Shkadarevich, A.P., Zh. Prikl.
Spektr., 1985, vol. 52, no. 1, p. 51.
The complex of boron difluoride with dibenzoyl-
methane was obtained as follows. Equivalent amount
of the boron trifluoride etherate was added dropwise
to the stirred hot solution of the ligand in toluene. The
reaction mixture was boiled for 5 10 min and then
cooled to room temperature. The precipitate obtained
was filtered off. Reaction products were yellow
powders well soluble in most organic solvents.
7. Miyata, S. and Nalwa, H.S., Organic Electrolumines-
cent Materials and Devices, Amsterdam: Gordon and
Brech, 1997.
8. Krasovitskii, B.M. and Bolotin, B.M., Organicheskie
lyuminofory (Organic Luminophores), Leningrad:
Khimiya, 1976.
Boron difluoride 1-(4-dodecyloxyphenyl)-3-(4-
tetradecyloxyphenyl)-propan-1,3-dionate (IIb).
1-(4-Dodecyloxyphenyl)-3-(4-tetradecyloxyphenyl)-
propan-1,3-dione, 0.09 g, was added with stirring to
5 ml of absolute toluene, and 0.02 ml of boron di-
fluoride etherate was added dropwise with stirring.
Resulting mixture was boiled for 10 min and stirred
for 3 h. Obtained precipitate was filtered off, crystal-
lized from ethanol and dried in a vacuum over P2O5.
9. Gukhman, E.V. and Reutov, V.A., Zh. Obshch. Khim.,
1999, vol. 69, no. 10, p. 1678.
10. Reutov, V.A. and Gukhman, E.V., Zh. Obshch. Khim.,
1999, vol. 69, no. 10, p. 1672.
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and Ryabchikova, T.S., Zh. Obshch. Khim., 1963,
vol. 33, no. 9, p. 3110.
12. Mirochnik, A.G., Bukvetskii, B.G., Gukhman, E.V.,
Zhihareva, P.A., and Karasev, V.E., Russ. J. Gen.
Chem., 2002, vol. 72, no. 5, p. 737.
Yield 0.19 g (95%). IR spectrum (vaseline oil),
,
1
cm : 1590, 1492 (C=N, phenyl); 1542, 1465, 1437,
938 (C=O); 1394, 1348, 1024 (CH3); 1172, 784, 765
[(CH2)n]; 1254 (C=C); 1218, 1103, 429, 416 (C6H4);
13. Karasev, V.E. and Korotkikh, O.A., Zh. Neorg.
Khim., 1986, vol. 31, no. 4, p. 869.
1
14. Edrington, A.C., Urbas, A.M., DeRege, P., Chen, C.X.,
Swager, T.M., Hadjichristidis, N., Xenidou, M.,
Fetters, L.J., Joannopopulos, J.D., Fink, Y., and
Thomas, E.L., Adv. Mater., 2001, vol. 13, no. 6,
p. 421.
728 [(CH2)n O]. IR spectrum (KBr), , cm : 1592
(C=C); 1538, 1430, 940 (C=O); 1376, 1022 (CH3);
1472, 1222, 1106, 720 (C6H4); 1578, 1172, 772
[(CH2)n]; 722 [(CH2)n O]. 1H NMR spectrum
(CD2Cl2), , ppm (J, Hz): 0.91 t (6H, Me, J 6.8);
1.32 m (40H, CH2); 1.81 m (4H, OCH2CH2); 4.02 t
(4H, OCH2, J 6.6); 6.93, 8.03 both d (4H, Ph, J 8.8);
7.25 s [1H, C(O)CH].
15. Abbate, G. and Oton, J.M., Adv. Mater., 2000,
vol. 12, no. 6, p. 459.
16. Galyametdinov, Yu.G., Turanova, O.A., Ven, Van,
Knyazev, A.A., and Haaze, V., Dokl. Akad. Nauk,
2002, vol. 384, no. 2, p. 206.
ACKNOWLEDGMENTS
17. Knyazev, A.A., Lobkov, V.S., and Galyametdi-
nov, Yu.G., Izv. Akad. Nauk, Ser. Khim., 2004, no. 4,
p. 904.
This work was carried out with the financial sup-
port of Russian Foundation for Basic Research (grant
no. 04-03-32923).
18. Takada, N., Tsutsui, T., and Saito, S., Japan. J. Appl.
Phys., 1994, vol. 33, p. 863.
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