Synthesis and optical properties of p-(4,4-difluoro-4-boron-3a,4a-diaza-s-indacene-8-yl)-4’-benzoyloxy-2-hydroxybenzaldehyde

Full text of DOI:10.1134/S1070363216080351

ISSN 1070-3632, Russian Journal of General Chemistry, 2016, Vol. 86, No. 8, pp. 1973–1975. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © M.S. Gruzdev, U.V. Chervonova, А.М. Kolker, 2016, published in Zhurnal Obshchei Khimii, 2016, Vol. 86, No. 8, pp. 1399–1401.
LETTERS
TO THE EDITOR
Synthesis and Optical Properties
of p-(4,4-Difluoro-4-boron-3a,4a-diaza-s-indacene-8-yl)-
4'-benzoyloxy-2-hydroxybenzaldehyde
M. S. Gruzdev*, U. V. Chervonova, and А. М. Kolker
Krestov Institute of Solutions Chemistry, Russian Academy of Sciences, ul. Akademicheskaya 1, Ivanovo, 153045 Russia
*e-mail: gms@isc-ras.ru
Received April 21, 2016
Keywords: BODIPY, fluorescence, quantum yield, Stokes shift
DOI: 10.1134/S1070363216080351
The derivatives of 4,4-difluoro-4-boron-3а,4а-diaza-
s-indacene (BODIPY) possess practically useful
properties and have found a number of various
applications. They act as fluorescence probes in
biology [1], sensors for ions determination [2], drug
delivery systems [3], fluorescent switches [4], electro-
luminescent films [5], laser dyes [6], and sensibilizers
for photoelements [7]. Functionalization of boron-
fluoride complexes of dipyrrolylmethenes by means of
chemical modification of substituents in different
positions of the molecule allows an easy control of
photophysical properties of the chromophore [8]. The
molecule has several potential sites for the addition of
functional groups. A modified BODIPY may act as a
building block in the synthesis of the derivatives with
practically valuable physico-chemical characteristics.
-3а,4а-diaza-s-indacene-8-yl)benzoic acid 4 was used
for modification, prepared via condensation of 4-
formylbenzoic acid 1 in pyrrole medium with catalytic
amount of 0.1 mol/L HCl, oxidation of dipyrrolyl-
methane 2 with chloranil to dipyrrolylmethene 3, and
complex formation of the latter with boron trifluoride
etherate in the presence of triethylamine (Scheme 1).
Aldehyde 5 was prepared from compound 4 via
esterification with p-hydroxysalicylic aldehyde. The
reaction was performed in the presence of different
catalysts: 4-dimethylaminopyridine (DMAP), 4-dimethyl-
aminopyridine-p-toluenesulfonate, or 4-pyrrolidino-
pyridine. The yield of the product in the reactions
DMAP, 4-dimethylaminopyridine-p-toluenesulfonate,
and 4-pyrrolidinopyridine was up to 1.5, 11, and
12.6%, respectively (Scheme 2).
This work aimed to prepare a meso-substituted
BODIPY, the derivative of salicylic aldehyde, and
investigate its optical properties. (4,4-Difluoro-4-boron
Electronic absorption and emission spectra of com-
pounds 4 and 5 were registered in CH2Cl2, c = 1 mmol/L.
Scheme 1.
O
H
O
OH
O
OH
O
N
OH
NEt3
BF3 OEt
0.1 M HCl
p-chloroanil
СH2Cl
+ 1
N
H
H
O
OH
HN
N
NH
NH
N
F2B
1
3
4
2
1973

1974
GRUZDEV et al.
Scheme 2.
N
N
O
O
N
N
O
O
DCC catalyst
F2B
+
HO
F2B
O
H
СH2Cl2
OH
H
OH
4
5
OH
The absorption and fluorescence maximums were
observed at 505 (4), 506 (5) nm and at 546 (4), 545 (5)
nm, respectively; hence, the Stokes shift equaled 41 (4)
and 39 (5) nm. The quantum yield of fluorescence was
calculated with respect to fluorescein as reference, in
0.1 mol/L NaOH (ΦS = 0.85 [9]): 0.016 (4) and 0.055 (5).
product was fine-disperse dark red powder. Yield was
depended on the catalyst used (1.5–12.6%). IR
spectrum, ν, cm–1: 3122, 3099 m (CHAr), 1737 s
(C=O), 1663 s [C(O)O], 1571, 1543 s (C=C, C=N),
1
1415, 1385 s (CHO), 1112, 1076 s (B–F). H NMR
spectrum (CDCl3), δ, ppm: 6.59 d (2H, CHheterocycle, J =
4.3 Hz), 6.91 d (2H, CHheterocycle, J = 4.3 Hz), 6.95 d
(2H, CHAr, J = 2.4 Hz), 7.68 d (1H, CHAr, J = 8.5 Hz),
7.74 d (2H, CHAr, J = 8.5 Hz), 7.99 s (2H, CHheterocycle),
8.36 d (2H, CHAr, J = 7.9 Hz), 9.92 s (1H, OH), 11.29
s (1H, CHO). Mass spectrum, m/z (Irel, %): 431 (39)
[M – H]+, Found, %: C 63.51; H 3.87; N 6.53.
C23H16BF2N2O4. Calculated, %: C 63.77; H 3.72; N 6.47.
(4,4-Difluoro-4-boron-3а,4а-diaza-s-indacene-8-
yl)benzoic acid (4). A solution of 4-carboxybenzal-
dehyde (1.5 g, 0.01 mol) in pyrrole (6.93 mL, 0.01 mol)
was kept with 0.1 mol/L HCl for 12 h. Then the
reaction mass was dissolved in CH2Cl2, washed with
water (3 × 75 mL), dried over Na2SO4, and and was
chromatographed on silica gel by 1 : 1 dichloromethane–
ethyl acetate mixture as eluent. The obtained dipyrrol-
ylmethene 3 was dissolved in CH2Cl2, chloranil (5.9 g,
0.024 mol) was added, the mixture was stirred for 4 h
(TLC monitoring). After the reaction was complete,
triethylamine (6.67 mL, 0.048 mol) and, on cooling,
BF3·OEt2 (6.08 mL, 0.048 mol) were added. The
reaction mixture was stirred for 12 h, washed with
water (3 × 75 mL), and dried over Na2SO4. After triple
chromatography on silica with acetone–dichloro-
methane (1 : 1) as eluent, product 4 was obtained as
fine-disperse powder. Yield 3.05 g (82%). IR spectrum,
ν, cm–1: 3116 w (CHAr), 1691 s (C=O), 1574, 1546 s
IR spectra were recorded using a Bruker Vertex
1
80V spectrometer at 7500–350 cm–1 (KBr pellets). Н
and 13С NMR spectra were recorded using a Bruker
500 instrument in CDCl3 relative to TMS. Elemental
analysis was performed using a Flash EA 1112
analyzer. Mass spectra were registered with JMS-700
JEOL (FAB) and JMS-100GCV JEOL (EI) instru-
ments. The spectra of absorption and fluorescence
were recorded using a СМ 2203 (SOLAR) spectro-
fluorimeter in dichloromethane in a 10 mm quartz cell.
ACKNOWLEDGMENTS
1
(C=C, C=N), 1114, 1074 s (B–F). H NMR spectrum
(CDCl3), δ, ppm: 6.59 d (2H, CHheterocycle, J = 3.7 Hz),
6.91 d (2H, CHheterocycle, J = 4.3 Hz), 7.71 d (2H, CHAr,
J = 7.9 Hz), 7.99 s (2H, CHheterocycle), 8.32 d (2H, CHар,
J = 7.9 Hz). Mass spectrum, m/z (Irel, %): 312 (30)
[M – H]+, Found, %: C 61.54; H 3.91; N 8.79.
C16H12BF2N2O2. Calculated, %: C 61.38; H 3.86; N 8.94.
This work was financially supported by the
President of RF (grant No. MK-70.2014.3), Russian
Foundation for Basic Research (grant no. 14-03-
31280_mol_а), and Russian Science Foundation (grant
no. 16-13-10371) with the use of equipment of the
Center for Collective Use “Upper Volga Regional
Center for Physico-Chemical Research.”
p-(4,4-Difluoro-4-boron-3a,4a-diaza-s-indacene-
8-yl)4'-benzoyloxy-2-hydroxybenzaldehyde (5). 2,4-
dihydroxybenzaldehyde (0.66 g, 4.8 mmol), dicyclo-
hexylcarbodiimide (1.59 g, 7.8 mmol), and the catalyst
were added to a solution of compound 4 (1.49 g,
4.8 mmol) in CH2Cl2 (50 mL). The mixture was stirred
for 12 h, the formed precipitate was filtered off, the
solvent was removed, and solid residue was purified
by chromatography on on silica gel with CHCl3. The
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SYNTHESIS AND OPTICAL PROPERTIES
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