Blue highly fluorescent boron difluoride complexes based on phthalazine-pyridine

Article abstract of DOI:10.1039/c6nj00726k

Three new boron difluoride complexes based on phthalazine-pyridine, denoted (6), (7) and (8), have been synthesized and their photophysical and electrochemical properties have been studied. Solutions of these new BF₂-complexes exhibit an intense blue fluorescence under UV light at low concentrations. Fluorescence quantum yields (QYs) have been determined by photoluminescence (PL) spectroscopy and decay times (τ) by semi-empirical methods. QYs of (6), (7) and (8) vary from 25% to 79%. HOMO and LUMO energy levels have been estimated by cyclic voltammetry and PL spectroscopy. The HOMO and LUMO energy levels, at ～-5.3 eV and ～-2.3 eV, respectively, make these new complexes interesting candidates as blue emitters in OLED applications.

Full text of DOI:10.1039/c6nj00726k

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New Journal of Chemistry
ARTICLE
Blue highly fluorescent boron difluoride complexes based on
phthalazine-pyridine
Received 00th January 20xx,
Accepted 00th January 20xx
a
b
a
a
Thi Minh Ha Vuong, Jennifer Weimmerskirch-Aubatin, Jean-François Lohier, Nathalie Bar,
c
b
b
d
d
Sophie Boudin, Christophe Labbé, Fabrice Gourbilleau, Hien Nguyen, Tung Thanh Dang, Didier
DOI: 10.1039/x0xx00000x
a
Villemin. †
www.rsc.org/
Three new boron difluoride complexes based on phthalazine-pyridine, denoted (6), (7) and (8) have been synthesized and
2
their photophysical and electrochemical properties have been studied. Solutions of these new BF -complexes exhibit an
intense blue fluorescence under UV at low concentrations. Fluorescence Quantum Yields (QY) have been determined by
PhotoLuminescence (PL) spectroscopy and decay times (ꢀꢁ by semi-empirical methods. QY of (6), (7) and (8) vary from
2
5% to 79%. HOMO and LUMO energy levels have been estimated by cyclic voltammetry and PL spectroscopy. The HOMO
and LUMO energy levels, at ~-5.3 eV and ~ -2.3 eV respectively, make these new complexes interesting candidates for blue
emitters in OLED applications.
derivatives with subsequent chelation of the resulting Schiff
8
base. They exhibit weak fluorescent quantum yields in
Introduction
solution due to their vibrational deactivation but important
The design and synthesis of functionalised aza-BODIPY
complexes have attracted a huge interest in diverse research
ones in solid state as a result of aggregation-induced emission.
8
Most of compounds of type II have been synthesized
a, b, e
1
fields . Particularly, aza-BODIPY has been thoroughly
based on various palladium-catalysed cross-coupling reactions
9
as a key step. Their boron complexes exhibit large Stokes
investigated to apply in optoelectronic devices such as
2
fluorescent sensors, fluorescent indicators, and fluorescent
3
4
5
switches, laser dyes, organic photovoltaic cells and OLEDs.
6
7
shifts along with high quantum yields both in solution and in
9
a, b, e
solid state.
In the case of type III complexes, it is difficult
The families of boron complexes are based on N^O, C^O, and
2
N^N chelates rigidified by a boron fragment. There are many
to give a synthetic step/procedure for their synthesis because
of the different constructions in both sides of the six-
types of boron complexes with various rings, the five- and six-
membered rings are the most common ones. Among them,
the six-membered ring type I boron complexes (scheme 1)
have been synthesized by the condensation of pyridine
1
0
membered ring. Interestingly, in this type III. Kobayashi et al
reported the synthesis of pyrrolopyrrole aza-boron
difluoridepyrroles based on modified diketopyrrolopyrroles
1
0b,c,g,I
and azapyrrolopyrroles.
Their important electronic
delocalization over the π-conjugated backbone made these
boron complexes highly fluorescent in the red and near infra-
1
0a-c,i
10h
red regions.
The azaboron diquinomethene complexes
have been reported as highly fluorescent blue and green
emitters. Basing on the above-mentioned studies, in this work,
we describe the synthesis as well as the photophysical and
electrochemical properties of three new pyridine-
iminophthalazine chelates of boron (III) synthesized through a
new simple procedure.
This journal is © The Royal Society of Chemistry 20xx
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ARTICLE
New Journal of Chemistry
R
X
R
R
X
R2
R3
R2
R1
X
N
F
N
B
N
F
N
N
F
N
R1
B
R4
B
Scheme 2: Synthesis of boron difluoride complexes based on
phthalazine-pyridine: i) NH NH .H O (1.1 eq), acetic acid,
20°C, 4h, (yield 93%) ; ii) POCl (4.0 eq), 110°C, 1h (yield 83%)
; iii) 2-aminopyridine (1.1 eq), NaH (4.0 eq), dioxane, 60°C, 16h
Scheme 1: Various six-membered rings of N,N chelation (yield 47%) ; iv) 2-aminopyridine (2.1 eq), NaH (4.8 eq),
F
F
F
2
2
2
Type III
Type I
Type II
1
3
X=C-R or N
modes.
dioxane, 60°C, 16h (yield 59%) ; v) and vi) Et
3
N (0.5 mL),
O (1.5 mL), THF/toluene, reflux, overnight (yield 41%) ;
B(OH) (1.1 eq), Pd(PPh Cl (5% mmol), K CO (2.0
O 4/1, MW 110°C, 60 min (yield 75%).
BF
3
Et
2
vii) C
6
H
5
2
3
)
2
2
2
3
Results and discussion
eq), Dioxane/H
2
Synthesis
Crystal structure
The synthetic approaches for boron (III) complexes are
Structure of complex (6) drawn in Figure 1 was unambiguously
depicted in scheme 2. Two N^N bi-dentate ligands (4) and (5)
characterized by X-ray crystallography analysis. Crystal data
are given in the experimental section.
based on 2-aminopyridine and phthalazine were obtained
after three classical steps. The first step is the synthesis of 2,3-
In the molecule, the opposite atoms B1 and N5 deviate from
the mean N2 C8 N5 C14 N6 B1 ring plane (R.M.S. deviation of
fitted atoms = 0.1092) by 0.1136 (9) and 0.1731 (9) Å
respectively, which leads to a boat-shaped deformation. The
dihedral angle between pyridine ring and pyridazine ring is
N,N-dihydrophthalazine-1,4-dione (
phthalic anhydride and hydrazine in acetic acid. Continuously,
compound ( ) was reacted with phosphoryl chloride to give
,4-dichlorophthalazine
2) by condensation of
2
1
(
3).
Then,
(4) and
1-chloro-4-(2’-
1,4-di(2’-
pyridyl)aminophthalazine
pyridyl)aminophthalazine
1
4.546 (69) °.
(5) were obtained by suitable
The B-F and B-N bond lengths are inequivalent with distances
of 1.3652 (17) and 1.3913 (18) Å and 1.5387 (18) and 1.5568
equivalent addition of sodium hydride and 2-aminopyridine.
By sequential treatment of ( ) and ( ) with boron trifluoride
etherate in the presence of triethylamine in toluene, BF
complexes ( ) and ( ) were synthesized with a yield of
approximately 40 %. Substitution of chloro group of complex
) by a phenyl group to complex ( ) was achieved via a Suzuki
Palladium-catalysed cross coupling.
4
5
(
18) Å respectively.
2
-
The crystal structure of complex (
6
) showed several inter-
6
7
molecular interactions. Four hydrogen bonds between
complexes and water molecules (Figure 2 bottom) are
presents and summarised in Table 1.
(
7
8
1
1
All new compounds
1
11
9
13
were structurally characterized by H, B, F, C NMR and
HRMS spectroscopies.
Table 1: Hydrogen-bond geometry (Å, °)
D—H
⋯
A
D—H
H
⋯
A
D
⋯A
D—H⋯A
ii
i
O
Cl
O1—H7
O1—H8
O1—H8
N3—H1
⋯
⋯
⋯
⋯
N5
0.90 (2) 2.04 (2) 2.934 (2) 175.5 (19)
0.84 (2) 2.09 (2) 2.899 (2) 161 (2)
0.84 (2) 2.55 (2) 2.940 (2) 109.7 (18)
0.86 (2) 2.21 (2) 3.043 (2) 161.4 (15)
O
i
NH
N
N4
O
O
N
Cl
N
O
H
ii
O1
3
1
2
iv
iii
iii
O1
Symmetry codes: (i) 1+x, y, z; (ii) 2−x, 1-y, -z; (iii) 1-x, 1-y, -z.
Cl
NH
N
N
N
HN
N
NH
An additional strong CH...Halogen interaction [C18-H18...F2 =
2,28 Å] is also present, the distance between the atoms
involved is far less than the sum of the Van der Waals radii of
these atoms, i.e. 2.67 Å. The cohesion of organic molecules
within the crystal is finally reinforced by π–π intermolecular
interactions between phtalazine rings, the distance from plane
to plane being 3.435 Å (Figure 2 up).
N
N
4
N
5
vi
v
7
Cl
N
N
N
N
B
F
HN
N
F
N
N
vii
N
B
N
F
F
6
Ph
N
N
N
N
8
B
F
F
2
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solution of anthracene in absolute ethanol was chosen and the
complexes (6), (7) and (8) were dissolved in chloroform. The QY
14
reported by Dawson et al. for anthracene in ethanol was
considered as reference. The absorbance spectra of the complexes
(
6), (7), (8) and anthracene are displayed on Figure 3.
Figure 1: Structure of complex (6). Selected bond lengths (Å),
angles (°) and dihedral angles (°): N6-B1 1.5568(18), N2-N1
1.3759(14), N2-B1 1.5387(18), N3-H1 0.860(18), B1-F1
1.3652(17), B1-F2 1.3913(18), F1-B1-F2 110.64(12), N1-N2-B1
113.22(10), N2-B1-N6 105.79(10).
Figure 3 : Room Temperature (RT) absorbance spectra of reference
anthracene) and complexes (6), (7), (8) solutions. For each solution,
(
the most intense peak is indicated.
The absorbance spectra are composed of main peaks at 373 nm,
3
85 nm 391 nm and 405 nm wavelengths for complex (6), at 355
nm, 372 nm and 392 nm for complex (7), and at 336 nm, 350 nm,
73 nm, and 393 nm for complex (8). For each spectrum, the
3
maximum absorbance peak wavelength is indicated in Figure 3. The
optical gap energies deduced from the absorption edges are 2.98
eV, 3.09 eV and 3.07 eV for the complexes (6), (7), (8), respectively
(
Table 3). The substitution of the chloro-group of complex (7) by the
pyridylamino- or the phenyl-group in complexes (6) and (8)
increases the number of molecular orbitals and consequently
reduces the optical gap energy, as shown by the trend
Figure 2: Intermolecular interactions in crystals of (6).
∆
Eꢌꢍꢎꢏꢐꢁꢑ>ꢑ∆Eꢌꢍꢎꢏꢒꢁꢑ> ∆Eꢌꢍꢎꢏꢓꢁ.
Photophysical properties
Quantum yield determination
Figure 4 represents the PL Excitation (PLE) and PL spectra of the
The relative Quantum Yields (QY) Φ of the boron (III) complexes (6), reference (anthracene), complexes (6), (7) and (8) solutions. The
1
2
(
7), (8) were determined by the following formula:
shapes of the PLE spectra are almost identical to the shape of the
absorbance spectra in Figure 3. The maximum absorption
wavelengths for the anthracene, complexes (6), (7) and (8) are
similar to the maximum excitation ones, i.e. at 355 nm, 385 nm, 391
nm, and 392 nm respectively. The emission bands of complexes (6),
ꢉ
Φꢂ ꢅꢃ ꢇꢂ
Φꢃ ꢅꢂ ꢇꢃ
ꢈ
ꢈ
ꢂ
ꢄ
ꢆ
ꢆ
(1)
ꢉ
ꢃ
where subscripts ꢊ and ꢋ refer to the sample and the reference
respectively, ꢅ is the absorbance at the excitation wavelength, ꢇ is
the integrated PhotoLuminescence (PL) intensity and ꢈ is the
refractive index of the solvent at the excitation wavelength. To
determine the QY, two conditions must be satisfied: i) the reference
and the sample must absorb and emit light in the same wavelength
(
7), and (8) have almost the same shape, with sharper peaks for the
complex (7). The maximum PL peaks for the anthracene, complexes
6), (7) and (8) are recorded at 398 nm, 420 nm, 398 nm and
00 nm respectively. The Stokes shifts for complexes (6), (7), and (8)
(
4
-1
-1
-1
are 2165 cm , 449 cm and 510 cm , respectively.
1
3
range, ii) the excitation wavelength must be identical for the
reference and the sample. To fulfil these requirements a reference
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New Journal of Chemistry
1
ꢔꢕ
Φ
ꢔ
ꢄ
(
2)
ꢘ ꢙꢏꢚꢁꢛꢚ
ꢘ ꢚꢖꢜꢙꢏꢚꢁꢛꢚ ꢞ ꢆ ꢛ ꢆ ꢚ
ꢅ
ꢄ 2,880 ꢆ 10ꢖꢗꢈꢉ
ꢝ
ꢑꢛꢚ
where ꢔ is the radiative decay time (s), in absence of non-radiative
ꢕ
recombination mechanisms, Φ is the quantum yield, ꢔ is the
measurable decay time, ꢈ is the refractive index of the solvent at
the excitation wavelength λexc, ꢙꢏꢚꢁ is the intensity of the
fluorescence spectrum, ꢅ is the absorbance, ꢞ is the concentration
-
3
in mol.cm and ꢛ is the length of the container in cm. The
-1
frequency ꢚ is in cm . The integration on the absorbance is not
done on the whole absorption spectrum, but only from 300 nm to
the absorption edge. In order to test the validity of this formula, the
semi-empirical decay time of anthracene was estimated first. The
calculations led to the values ꢔ ꢄ 6.0ꢑns and ꢔ ꢄ 1.7ꢑns, which are
ꢕ
of the same order than the experimental value, τ
ꢄ 5ꢑns,
ꢟꢠꢍ
1
6
measured for anthracene in ethanol by Lampert et al. Similar
calculations applied to the complexes (6), (7), and (8) solutions, led
to ꢔꢏꢓꢁ ꢄ 0.9ꢑns, ꢔꢏꢐꢁ ꢄ 3.1ꢑnsꢑandꢑꢔꢏꢒꢁ ꢄ 3.1ꢑns respectively (Table
2
). The decay times, estimated for complexes (6), (7) and (8) are of
1
0h,i
the same order than the ones measured for similar molecules.
These results have to be confirmed by appropriated decay time
measurements, since the temporal detection limit of our
equipment is higher than these values of decay times.
Table 2 : Relative Quantum Yield (QY) and semi-empirical decay
times ꢏꢔꢁ calculated for anthracene and complexes (6), (7) and (8).
ꢔꢕ (ns)
6.0
ꢔ(ns)
1.7
Φ(%)
14
Anthracene
Complex (6)
Complex (7)
Complex (8)
28
25
52
79
3.6
0.9
Figure 4 : RT PLE (dash line) and PL (continue line) spectra of (a)
anthracene, (b) complex (6), (c) complex (7) and (d) complex (8).
The value of the excitation or emission wavelengths and the Stokes
shift are indicated.
6.0
3.1
4.0
3.1
Electrochemical properties
QY of complexes (6), (7) and (8) have been determined using the HOMO and LUMO energy levels have been estimated from cyclic
formula (1) and the absorption and photoemission data of voltammetry. Cyclic Voltammograms (CV) of (6), (7) and (8)
anthracene, (6), (7) and (8) complexes. In order to optimize the complexes are shown on Figure 5. The oxidation and reduction
+
excitation wavelength for all the solutions, a compromise excitation peaks of ferrocene/ferrocenium (Fc/Fc ) used as reference are
wavelength of 375 nm was chosen. This choice is carefully detailed observed at 0.16 V and 0 V respectively. The (6), (7) and (8)
in supplementary data. The estimated QY (Φ) equals to 25%, 52% complexes exhibit subtle oxidation peaks located at Eꢌꢠꢤ
=
ꢍꢟꢡꢢꢑꢣꢡꢠ
and 79% for complexes (6), (7) and (8) respectively (Table 2). We
can notice that the substitution of a phenyl group from complex (8)
by a pyridylamino- or a chloro-group to complexes (6) and (7)
decreases the fluorescence QY. Similarly to the aza-boron-
0
.90 V, 1.12 V and 0.85 V respectively and reduction peaks located
ꢥꢟꢦ
at E
= - 0.50 V, - 0.54 V and - 0.54 V respectively (Table 3).
ꢍꢟꢡꢢꢑꢣꢡꢠ
In order to confirm the attribution of the latter peaks to complexes
6), (7) and (8), CV of complex free solutions and of more
concentrated complex solutions have been recorded
corresponding CV are reported in supplementary materials). The
(
1
0h
diquinomethene complexes reported by Wang et al,
the
substitution by a more electro-withdrawing or donating group
(
1
0a-
decreases the QY. Compared to QY of other type (III) molecules,
absence of oxidation and reduction peaks of complexes for the free
complex solutions and the presence of more intense peaks for the
more concentrated complex solutions confirm the previous
attribution. The HOMO and LUMO energy levels of (6), (7) and (8)
complexes have been deduced from the potentials of the oxidation
c,h,i
complexes (6) and (7) exhibit medium QY and complex (8) is
highly luminescent.
Semi-empirical determination of the decay time
Based on absorption and photoluminescence data, luminescence
decay time of complexes (6), (7) and (8) were estimated using the
+
ꢌꢠꢤ
peak onsets versus Fc/Fc E
ꢑꢏVꢁꢑꢑand from the optical
ꢍꢟꢡꢢꢑꢌꢧꢨꢟꢎꢑꢩꢨꢑꢪꢫ
1
5
gap energies ꢑ∆Eꢌꢍꢎ, estimated from the absorption edges (Table 3).
Strickler-Berg formula:
4
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The HOMO and LUMO energy levels are close for complexes (6), (7) chromatography (TLC), silica gel-coated substrates “60 F254”
and (8) with Eꢬꢭꢮꢭ~ -5.3 eV and Eꢯꢰꢮꢭ~ -2.3 eV. We can notice from Merck were used and compounds were detected by
that the substitution of the phenyl group of complex (8) by a more illumination with UV lamp (λ = 254 or 365 nm).
electron donating or withdrawing group as the pyridylamino- or Microwave irradiation were done with a monowave 300
chloro- group in complex (6) or (7) stabilizes the HOMO level as Anthon Paar cavity at 2450MHz.
1
13
H and C NMR experiments were recorded in the listed
shown by the trend Eꢬꢭꢮꢭꢏꢒꢁ ꢱꢑEꢬꢭꢮꢭꢏꢓꢁ ꢱ Eꢬꢭꢮꢭꢏꢐꢁ.
deuterated solvents (internal standard) on Bruker
Spectrometers Avance 400. Multiplicity of NMR signal was
denoted as br (broad), m (multiplet), s (singlet), d (doublet), t
Table 3 : Electrochemical characteristics of complexes (6), (7) and
(
8)
(
triplet). Mass analyses were carried out on LCMS QTOF Micro
ꢥꢟꢦ
ꢌꢠꢤ
ꢍꢟꢡꢢꢑꢣꢡꢠ
ꢌꢠꢤ
ꢍꢟꢡꢢꢑꢌꢧꢨꢟꢎ
ꢌꢠꢤ
E
E
E
E
ꢑ
ꢍꢟꢡꢢꢑꢌꢧꢨꢟꢎꢑꢩꢨꢑꢪꢫ
∆
ꢏeVꢁ
E
ꢌꢍꢎ
E
ꢏeVꢁ
ꢬꢭꢮꢭ
E
ꢯꢰꢮꢭ
b
ꢏeVꢁ
WATERS machine.
ꢍꢟꢡꢢꢑꢣꢡꢠ
a
(
V)
(V)
ꢏVꢁ
ꢏVꢁ
(
(
(
6) -0.50 0.90
7) -0.54 1.12
0.63
0.66
0.57
0.55
0.58
0.49
2.98 -5.35 -2.37
3.09 -5.38 -2.29
3.07 -5.29 -2.22
2
,3-Dihydrophthalazine-1,4-dione (2)
A mixture of phthalic anhydride (7.40 g, 50.0 mmol), hydrazine
hydrate (2.80 mL, 55.0 mmol, 1.1 eq) was heated to 120°C in
acetic acid for 4h. Then, the reaction mixture was cooled to
8) -0.54 0.85
a
ꢌꢠꢤ
E
ꢬꢭꢮꢭꢏeVꢁ ꢄꢑꢲeꢏE
ꢑꢏVꢁꢑꢳ 4.8ꢁ
ꢍꢟꢡꢢꢑꢌꢧꢨꢟꢎꢑꢩꢨꢑꢪꢫ
b
E
ꢯꢰꢮꢭꢏeVꢁ ꢄ ꢑEꢬꢭꢮꢭꢏeVꢁ ꢳ ∆EꢏeVꢁ
room temperature and filtered to give a white solid (7.52 g, 93
1
). H-NMR (DMSO, 400 MHz) δ = 11.53 (br s, 2H), 8.06 (m,
%
2
H), 7.87 (m, 2H).
1
,4-Dichlorophthalazine (3)
,3-Dihydrophthalazine-1,4-dione (2) (7.52 g, 46.4 mmol) was
2
heated to 110°C in 18mL (4 eq) of phosphoryl chloride. After
one hour, the reaction mixture was cooled to room
temperature and added dropwise to crushed ice. The formed
precipitate was filtered, washed with H
2
O, and then dried in
1
vacuum to give a white solid (7.64 g, 83%). H-NMR (DMSO,
1
3
00 MHz) δ = 8.34 (m, 2H), 8.27 (m, 2H). C-NMR (DMSO, 100
4
MHz) δ = 155.2, 136.2, 127.1, 126.1.
1
-Chloro-4(2’-pyridyl)aminophthalazine (4)
Sodium hydride (60 % in mineral oil) (1.60 g, 40.0 mmol) was
carefully added into a mixture of 1,4-dichlorophthalazine (
Figure 5 : Cyclic voltammograms of acetonitrile solutions of (6), (7)
-3
-3
3
)
and (8) complexes (2.10 M), ferrocene (10 M) and TBAP (0.1 M).
(
1.99 g, 10 mmol) and 2-aminopyridine (1.034 g, 11.0 mmol,
1.1 eq) in 25 mL of freshly distilled dioxane. The resulting
mixture was stirred at 60°C for 16h. Then, it was quenched
carefully with water and was acidified with aqueous
hydrochloric acid 1M. After that, the mixture was washed with
Conclusions
In this article, we described an efficient synthesis of new boron
2
difluoride BF -complexes based on phthalazine-pyridine which
CHCl (50 mL x3), and the organic phase was concentrated in
3
performed high intensive emission in solution. The
photophysical properties of these novel emitters could be
finely tunable through the various substitution at the 1-postion
of the phthalazine core. Then, the resulting complexes and
their photophysical properties are currently being studied and
will be attempted to apply in OLED devices.
vacuum. The crude product was then purified by silica-gel
column chromatography (eluted with Cyclohexane/AcOEt: 3/1)
1
to give the expected product as a white solid (1.21 g, 47%). H-
NMR (DMSO, 400 MHz) δ = 10.02 (s, 1H), 8.72 (d, J = 7.8 Hz,
1
7
=
1
1
H), 8.36 (d, J = 4.4 Hz, 1H), 8.24 (d, J = 7.8 Hz, 1H), 8.19 (d, J =
.7 Hz, 2H), 8.08 (m, 2H), 7.82 (td, J = 7.7 Hz, 1.6, 1H), 7.08 (t, J
1
3
6.0 Hz, 1H). C-NMR (DMSO, 100 MHz) 153.7, 153.0, 148.4,
38.3, 134.2, 134.2, 133.8, 126.3, 125.2, 124.4, 121.4, 118.8,
15.0.
Experimental
1
,4-Di(2’-pyridyl)aminophthalazine (5)
Sodium hydride (60 % in mineral oil) (1.60g, 24.0 mmol) was
carefully added into a mixture of 1,4-dichlorophthalazine (
0.98 g, 5 mmol) and 2-aminopyridine (0.98 g, 10.5 mmol, 2.1
1
. Synthesis and NMR characterisations
All chemicals and solvents were purchased from chemical
suppliers and were used as received, unless otherwise
mentioned.
3
)
(
eq) in 25 mL of distilled dioxane. The resulting mixture was
stirred at 60°C for 16h. Then, it was quenched carefully with
water and was acidified with aqueous hydrochloric acid 1M.
After that, the solvent was removed and the residue was
Purification of products was performed by column flash
chromatography on Geduran® Si 60 silica gel (40-63 µm) from
Merck with analytically pure solvents. For analytical thin layer
This journal is © The Royal Society of Chemistry 20xx
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ARTICLE
New Journal of Chemistry
1
washed with CHCl
3
3
to eliminate the non-reacted 2- powder (0.27g, 41%). H-NMR (CDCl , 400 MHz) δ = 9.00 (d, J =
aminopyridine. The crude product was then purified by silica- 7.4 Hz, 1H, H6), 8.45 (br s, 1H, H13), 8.26 (d, J = 7.4 Hz, 1H, H3),
gel column chromatography (eluted with AcOEt/MeOH: 10/1) 8.09 (t, J = 7.4 Hz, 1H, H4), 8.05 (t, J = 7.4 Hz, 1H, H5), 8.02 (t, J
1
to give product as a white solid (0.71 g, 59%). H-NMR (CD
3
OD, = 7.0 Hz, 1H, H11), 7.58 (d, J = 8.6 Hz, H10), 7.26 (t, J = 7.0 Hz,
1
00 MHz) δ = 8.98 (dd, J = 6.1, 3.3 Hz, 2H), 8.58 (d, J = 5.7 Hz, 1H, H12). C-NMR (CDCl
3
4
3
, 100 MHz) 153.5 (C9), 150.8 (C8),
2
H), 8.37 (dd, J = 6.1, 3.3 Hz, 2H), 8.32 (t, J = 7.2 Hz, 2H), 7.98 145.9 (C1), 141.4 (C11), 138.0 (C13), 134.3 (C4), 133.4 (C5),
1
d, J = 8.7 Hz, 2H), 7.52 (dd, J = 7.2 Hz, 5.2H). C-NMR (CD
3
(
3
OD, 127.9 (C7), 127.3 (C2), 127.2 (C6), 125.6 (C3), 123.6 (C10),
1
00 MHz) 150.7, 148.8, 143.4, 140.5, 135.4, 124.4, 121.8, 116.8 (C12). F-NMR (CDCl
+
19.6, 116.1, [M+H] calcd: 315.1358, found: 315.1366.
9
1
3
, 376 MHz) -135,68 (dd, J = 50.98
11
Hz, J = 25.49 Hz, 2F), B-NMR (CDCl3, 128 MHz) 0.89 (t, J =
1
+
5.50 Hz, 1B), [M+Na] calcd: 327.0396, found: 327.0396.
2
Complex (6)
5
Complex (8)
4
3
6
7
1
1
0
3
N
B
9
11
2
1
8
1
5
N
N
12
1
6
N
14
To 1,4-(2’-pyridyl)aminophthalazine (
5
) (0.31 g, 1.0 mmol) in
F
F
1
7
toluene/THF was added 0.5 ml of Et
3
N, and then subsequently
added of BF ·OEt (1.5 mL) through syringe. The reaction
2
3
The mixture of complex (
acid (136 mg, 1.1 mmol), bistriphenylphosphine palladium (II)
dichloride (70 mg, 0.05 mmol), and K CO (276 mg, 2 mmol)
was dissolved in dioxane-H O (4:1, 5.0 mL). The resulting
mixture was subjected to microwave irradiation for 60 min at
10°C. After cooling down to room temperature, the reaction
mixture was extracted with CHCl (20 mL × 3). The organic
layers were combined, dried over anhydrous Na SO , filtered,
7) (0,32 g, 1.0 mmol), phenyl boronic
mixture was heated to reflux overnight. After cooling down to
room temperature, the reaction mixture was extracted with
AcOEt (30 mL × 3). The organic layers were combined, dried
2
3
2
2 4
over anhydrous Na SO , filtered, and evaporated to dryness
under vacuum. The crude product was purified by column
chromatography on silica gel (Cyclohexane/AcOEt: 1/1) to give
1
the final product as a yellow powder (0.15g, 41%). H-NMR
1
3
2
4
(
CDCl
H16), 8.21-8.12 (m, 2H, H13 and H19), 8.03 (br s, 1H, H3), 7.91
t, J = 7.8 Hz, 1H, H4), 7.83 (t, J = 7.8 Hz, 1H, H5), 7.78 (t, J = 8.3
Hz, 1H, H17), 7.72 (t, J = 8.7 Hz, 1H, H11), 7.32 (d, J = 8.7 Hz,
H, H10), 6.98 (t, J = 6.8 Hz, 1H, H12), 6.92 (t, J = 6.4 Hz, 1H,
3
, 400 MHz) δ = 8.89 (d, J = 7.8 Hz, 1H, H6), 8.50 (br s, 1H,
and evaporated to dryness under vacuum. The crude product
was purified by column chromatography on silica gel
(
(
Cyclohexane/AcOEt: 4/1) to give final product as a yellow
1
3
powder (0.26 g, 75%). H-NMR (CDCl , 400 MHz) δ = 8.99 (d, J =
1
1
3
6.5 Hz, 1H, H6), 8.32 (d, J = 5.2 Hz, 1H, H13), 7.92-7.82 (m, 4H,
H3, H4, H5 and H11), 7.75-7.69 (m, 1H, H15), 7.55-7.51 (m, 2H,
H18). C-NMR (CDCl
3
, 100 MHz) 153.7 (C9), 152.6 (C15), 149.3
(
(
(
(
(
C8), 147.4 (C19), 145.5 (C1), 140.3 (C11), 139.3 (C17), 137.4
H16 and H17), 7.50-7.45 (m, 1H, H10), 7.09 (t, J = 6.8 Hz, 1H,
13
H12). C-NMR (CDCl , 100 MHz) 153.7 (C9), 153.6 (C1), 150.8
3
C13), 133.8 (C4), 132.4 (C5), 127.9 (C7), 127.8 (C6), 123.3
C10), 122.6 (C2), 121.2 (C3), 117.9 (C18), 115.4 (C12), 113.7
1
9
11
(C8), 140.9 (C11), 137.8 (C13), 135.1 (C14), 133.5 (C4), 132.2
C16). F-NMR (CDCl
CDCl
63.1341, found: 363.1349.
3
, 376 MHz) -137,61 (br, 2F), B-NMR
+
(C5), 130.0 (C15), 129.4 (C17), 128.6 (C16), 127.4 (C2), 127.3
19
3
, 128 MHz) 1.03 (t, J = 25.27 Hz, 1B), [M+H] calcd:
(C7), 127.0 (C6), 126.7 (C3), 123.3 (C10), 116.1 (C12). F-NMR
3
(
3
CDCl , 376 MHz) -135,82 (dd, J = 50.38 Hz, J = 25.19 Hz, 2F).
1
1
+
B-NMR (CDCl3, 128 MHz) 1.28 (t, J = 25.34 Hz, 1B), [M+H]
calcd: 369.1097, found: 369.1099.
Complex (7)
2
. Single crystal X Ray diffraction
Single crystals of ( ) suitable for X-ray crystallographic analysis
were obtained by slow evaporation of CH Cl solution. X-ray
diffraction data collection were performed at 150 K with
graphite–monochromatized Mo K radiation ( = 0.71073 Å)
(0.51g, 2.0 on a Bruker–Nonius Kappa CCD area detector diffractometer.
N, and then Formula : C18 O ; Formula weight : 380.17 ; Crystal
(1.5 mL) through syringe. The system : monoclinic ; Space group : P2(1)/n ; Cell parameters :
reaction mixture was heated to reflux overnight. After cooling a = 10.5846(4) Å, b = 7.6098(3) Å, c = 21.9235(10) Å,
6
2
2
α
λ
To 1-chloro-4(2’-pyridyl)aminophthalazine
(4)
mmol) in CHCl
3
was added 0.5 mL of Et
OEt
3
2 6
H15BF N
subsequently added of BF
3
2
α
= γ =
3
down to room temperature, the reaction mixture was 90°,
β =100.651(2)°, V = 1735.44(12) Å ; Z = 4 ; Calculated
3
–1
extracted with AcOEt (30 mL × 3). The organic layers were density = 1.455 g/cm
2
combined, dried over anhydrous Na SO , filtered, and R[F >2σ(F )] = 0.0388 ; wR(F ) = 0.1076. Program(s) used to
2 4
;
ꢀ = 0.110 mm ; Rint = 0.0252 ;
2
2
evaporated to dryness under vacuum. The crude product was solve structure : SHELXS97. Program(s) used to refine structure
purified by column chromatography on silica gel : SHELXL–2014. Software used to prepare material for
(Cyclohexane/AcOEt: 3/1) to give final product as a yellow publication
:
SHELXTL. CCDC 1030686 contains the
6
| J. Name., 2012, 00, 1-3
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NP lee wa s eJ od uo r nn oa tl aod fj uC s ht em ma ri sg it nr sy
View Article Online
DOI: 10.1039/C6NJ00726K
Journal Name
ARTICLE
supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge
7
8
Qian, G., Wang, Z. Y., Chem. Asian J., 2010, 5, 1006.
(a) Hong, Y., Lam, J. W. Y., Tang, B. Z.,Chem.
Commun.,2009, 4332; (b) Hong, Y., Lam, J. W. Y., Tang,
B. Z.,Chem. Soc. Rev.,2011, 40, 5361; (c) Liu, X., Ren, Y.,
Crystallographic
Data
Center
via
www.ccdc.cam.ac.uk/data_request/cif
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Xia, H., Fan, H., Mu, Y., Inorg. Chim. Acta., 2010, 363
441; (d) Macedo, F. P., Gwengo, C., Lindeman, S. V.,
Smith, M. D., Gardinier, J. R.,Eur. J. Inorg. Chem.,2008,
200; (e) Perumal, K., Garg, J. A., Blacque, O., Saiganesh,
R., Kabilan, S., Balasubramanian, K. K., Venkatesan,
K.,Chem. Asian. J.,2012, , 2670; (f) Ren, Y., Liu, X. Gao,
,
1
3. Absorbance and Photoluminescence measurements
3
The absorbance spectra were measured at room temperature
on a Perkin-Elmer UV-Visible Spectrophotometer with a
resolution of 1 nm. The PL and PLE spectra were measured at
room temperature using a Horiba Jobin Yvon Fluorolog-3
spectrofluorimeter with a 450 W xenon lamp, with a resolution
of 1 nm. Absorbance and photoluminescence spectra were
7
W., Xia, H., Ye, L., Mu, Y., Eur. J. Inorg. Chem.,2007,
1808; (g) Zhao, D., Li, G., Wu, D., Qin, X., Neuhaus, P.,
Cheng, Y., Yang, S., Lu, Z., Pu, X., Long, C., You, J.,Angew.
Chem. Int. Ed, 2013, 52, 13676.
(a) Araneda, J. F., Piers, W. E., Heyne, B.; Parvez, M.,
McDonald, R.,Angew. Chem. Int. Ed,2011, 50, 12214; (b)
Esparza-Ruiz, A., Peña-Hueso, A., Nöth, H., Flores-Parra,
A., Contreras, R.,J. Organomet. Chem.,2009, 694, 3814;
9
measured on CHCl
on a reference solution of anthracene in absolute ethanol (4
mg dissolved in 250 mL of solvent). For QY and calculations,
3
solutions of complexes (6), (7) and (8) and
ꢔ
1
7
18
(
c) Frath, D., Poirel, A., Ulrich, G., De Nicola, A., Ziessel,
refractive indexes n of ethanol and chloroform and
1
reference QY of anthracene in ethanol were considered.
4
R.,Chem. Commun.,2013, 49, 4908; (d) Liddle, B. J., Silva,
R. M., Morin, T. J., Macedo, F. P., Shukla, R., Lindeman,
S. V., Gardinier, J. R.,J. Org. Chem,2007, 72, 5637; (e)
Morin, T. J., Lindeman, S. V., Gardinier, J. R.,Eur. J. Inorg.
Chem., 2009, 104; (f) Nawn, G., Oakley, S. R., Majewski,
M. B., McDonald, R.,Patrick, B. O., Hicks, R. G.,Chem.
4
. Electrochemical measurements
Electrochemical measurements were performed with
VersaStat potentiostat using a three electrodes cell with a Pt
working electrode, a Pt counter electrode and a Ag/AgNO
reference electrode (Ag in a 0.01 M AgNO and 0.1 M TBAP
TetraButyl Ammonium Perchlorate) acetonitrile solution). The
electrolytes were deoxygenated acetonitrile solutions of
a
Sci., 2013,
Aprahamian, I.,Chem. Sc.,2012,
4
, 612; (g) Yang, Y., Su, X., Carroll, C. N.,
3
3, 610.
3
1
0
(a) Fischer, G. M., Daltrozzo, E., Zumbusch, A.,Angew.
Chem. Int. Ed, 2011, 50, 1406; (b) Fischer, G. M., Ehlers,
A. P., Zumbusch, A., Daltrozzo, E.,Angew. Chem. Int.
Ed,2007, 46, 3750; (c) Fischer, G. M., Isomäki-Krondahl,
M., Göttker-Schnetmann, I., Daltrozzo, E., Zumbusch,
A.,Chem. Eur. J., 2009, 15, 4857; (d) Kubota, Y., Tsuzuki,
T., Funabiki, K., Ebihara, M., Matsui, M., Org. Lett.,2010,
12, 4010; (e) Liu, Q. D., Mudadu, M. S.,Thummel, R.,
Tao, Y., Wang, S.,Adv. Func. Mater.,2005, 15, 143; (f)
Quan, L., Chen, Y., Lu, X.-J., Fu, W-F.,Chem. Eur. J., 2012,
(
-
3
complexes (
6
), (
10 M), used as an internal reference. The cyclic
voltammograms were recorded during 3 cycles between - 1.75
7) or (8) (2.10 M), TBAP (0.1 M) and ferrocene
-3
(
V (starting potential) and 1.75 V vs Ag/AgNO
rate.
3
at a 0.2 V/s scan
18, 14599; (g) Shimizu, S., Iino, T., Araki, Y., Kobayashi,
N.,Chem. Commun.,2013, 49, 1621; (h) Wang, D., Liu, R.,
Chen, C., Wang, S., Chang, J., Wu, C., Zhu, H., Waclawik,
E. R., Dyes Pigm.,2013, 99, 240; (i) Wiktorowski, S.,
Fischer, G. M., Winterhalder, M. J., Daltrozzo, E.,
Zumbusch, A.,Phys. Chem. Chem. Phys.,2012, 14, 2921;
Acknowledgements
The authors wish to thank Karine Jarsalé for the mass
spectroscopy spectra and Rémi Legay for NMR spectra
analysis. We gratefully acknowledge financial support from the
(
j) Zhou, Y., Xiao, Y., Li, D., Fu, M., Qian, X., J. Org. Chem,
008, 73, 1571.
2
«
Ministère de la Recherche et des Nouvelles Technologies »,
CNRS (Centre National de la Recherche Scientifique), the
Région Basse-Normandie » and the European Union (FEDER
11 Medda, F., Sells, E., Chang, H-H. Dietrich, J., Chappeta,
S., Smith, B., Gokhale, V., Meuillet, E.J., Hulme, C.,
Bioorg. Med. Chem. Lett., 2013, 23, 528.
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1
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1
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funding). The authors acknowledge the financial support of the
french Agence Nationale de la Recherche (ANR), through the
program “Investissements d’Avenir”(ANR-10-LABX-09-01),
LabEx EMC and the Vietnam National Foundation for Science
and Technology Devellopement (NAFOSTED 104.01-2012.26).
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Strickler, S. J. & Berg, R. A. J. Chem. Phys, 1962 37, 814–
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Notes and references
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This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
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New Journal of Chemistry
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DOI: 10.1039/C6NJ00726K
Graphical abstract
Synthesis and characterizations of three blue fluorescent phthalazine-pyridine boron complexes with
quantum yields up to 79%.
52 %
4
00 nm
N
N
N
F
Cl
N
B
F
N
N
B
N
N
F
Ph
N
B
N
N
NHPyr
N
F
F
F
2
5 %
20 nm
79 %
4
4
00 nm