Synthesis, crystal structures, and fluorescent properties of zinc(II) complexes with benzazino-2-carboxalidin-2-aminophenols

Article abstract of DOI:10.1515/chem-2015-0005

Complexes ZnL2 with novel fluorinated benzazines as tridentate ligands (HL = 6,7-difluoroquinoxalinand 6,7-difluoroquinolincarboxalidin-2-aminophenol) have been prepared. The photophisical properties of the ligands and the complexes has been studied.

Full text of DOI:10.1515/chem-2015-0005

Open Chem., 2015; 13: 61–67ꢀ
Research Article
Open Access
Emiliya Nosova*, Tatyana Stupina, Artem Chupakhin, Galina Lipunova,
Marina Valova, Pavel Slepukhin, Valery Charushin
Synthesis, crystal structures, and fluorescent
properties of zinc(II) complexes
with benzazino-2-carboxalidin-2-aminophenols
Abstract: Complexes ZnL2 with novel fluorinated benza- solubility in organic solvents, and as a result, expands
zines as tridentate ligands (HL = 6,7-difluoroquinoxalin- possibilities for application in equipment; in particular,
and
6,7-difluoroquinolincarboxalidin-2-aminophenol) it improves the quality of films based on such materials
have been prepared. The photophisical properties of the possessing unique physical and chemical properties
ligands and the complexes has been studied.
[10]. Recently we have managed to obtain new fluorine-
containing N,N,O-ligands such as (2-phenylquinazolin-
Keywords: Benzazine-2-carbaldehyde, о-Aminophenol, 4-yl)hydrazones of 2-hydroxybenzaldehydes and have
Schiff base, Zink (II) complex, Fluorescence
studied their photophysical properties [11]. Quinoxalino-2-
carboxalidin-2-aminophenols—which represent attractive
tridentate ligands for Mn(II), Fe(III), Ni(II), Cu(II) and Co(II)
complexes—have been investigated [12], but data on Zn(II)
complexesareextremelylimitedthough. Forinstance, work
[13] reports about the octahedral structure of quinoxalino-
2-carboxalidin-2-amino-5-methylphenol zinc complex, and
the geometry of the Zn(II) complex is supposedly similar
DOI: 10.1515/chem-2015-0005
received October 24, 2013; accepted May 4, 2014.
1 Introduction
Benzazines containing the azomethine fragment to the structure of the Ni(II) complex, but X-ray data in this
in position 2 could be considered as aza-analogs of publication are absent. 6,7-Difluoro-analogs of such Schiff
2-styrylbenzazines, which garner attention because of bases are not described. Even 6,7-difluoroquinoxalin-2-
their application in materials for electronic devices [1-4]. carbaldehyde, the major intermediate for their synthesis, is
On the other hand, the presence of an azometine group not mentioned in the literature. In the present paper, new
allows for the production of metalochelates, which Zn(II) complexes 5a-d (Scheme 1) have been synthesized
have photoluminescent properties and applications and their fluorescent properties investigated.
for electroluminescent materials [5-8]. Recently special
attention has been paid to N,N,O-ligands, as they are
capable to form individual lanthanide complexes with
2 Experimental procedure
intense luminescence [9].
The presence of a fluorine atom in a ligand leads
to an increase of thermal and chemical stability, and 2.1 Materials and measurements
2-Methylquinoxaline, quinaldine, selenium(IV) oxide and
*Corresponding author: Emiliya Nosova: Department of Organic
Chemistry, Chemical Technology Institute, Urals Federal University
named after the First President of Russia Boris N. Yestsin,
Ekaterinburg 620002, Russia, E-mail: emily74@rambler.ru
Tatyana Stupina, Artem Chupakhin, Galina Lipunova: Department
of Organic Chemistry, Chemical Technology Institute, Urals Federal
University named after the First President of Russia Boris N. Yestsin,
Ekaterinburg 620002, Russia
Zn(OAc)2•2H2O were purchased from Aldrich Chemical
Company Inc. and used as received. All other reagents
were of analytical grade.
2.2 Physical techniques
Galina Lipunova, Marina Valova, Pavel Slepukhin, Valery Charushin:
I. Postovsky Institute of Organic Synthesis, Ural Division of the
Russian Academy of Sciences, Ekaterinburg 620219, Russia
All melting points were determined using a Stuart SMP3
1
Melting Point Apparatus in open capillary tubes. Н NMR
© 2015 Emiliya Nosova et al., licensee De Gruyter Open.
Unauthenticated
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License.
Download Date | 1/3/16 11:17 PM

62ꢀ
ꢀ Emiliya Nosova et al.
spectra were recorded on a Bruker DRX 400 instrument Yield 0.3 g (45%), mp 132-134°C. 1Н NMR (DMSO-d6): δ 8.16
(400.13 МHz). Chemical shifs are given in ppm (δ) (1Н, dd, Н-5, 3J 10.6, 4J 8.2 Hz), 8.24 (1Н, dd, Н-8, 3J 10.5, 4J
from the internal TMS standard. Mass spectra were 8.3 Hz), 9.33 (1Н, s, Н-3), 10.18 (1Н, s, СHO). MS (ES+): m/z
obtained from a MicrOTOF-Q II mass spectral instrument 195 [M+H]+ (100 %). Anal. calc. for C9H4F2N2О: C, 55.68; H,
(Bruker Daltonics, positive or negative APCI ion source, 2.08; N, 14.43. Found: C, 55.72; H, 2.14; N, 14.38%.
electrospray ionization). Acetonitrile (99% purity) and
2-methyltetrahydrofurane (99%, stab. with ca 150-400
ppm BHT) (Alfa Aesar, UK) were used at UV-spectroscopy 2.4 Preparation of ligands 4
grade. Absorption spectra were scanned on a UV-2401
PC absorption spectrophotometer (Shimadzu, Japan) [2-(6,7-Difluoroquinoxalin-2-ylmethylen)amino]
using a 1 cm quartz cell, concentration: 0.0001 mmol mL-1 phenol (4d). To a solution of о-aminophenol (0.3 g,
(acetonitrile). Emission spectra were recorded on a Cary 2.75 mmol) in ethanol (15 mL) warmed to 60-70°C, a
Eclipse spectrofluorimeter (Varian, USA). The fluorescence solution of aldehyde 3d (0.5 g, 2.58 mmol) in ethanol
of the acetonitrile solution at T = 293 K was measured in (3 mL) was added dropwise. The mixture was heated to
a 1-cm cuvette. Low-temperature measurements were 80°C for 30 min, and then cooled to room temperature;
carried out in a liquid nitrogen cryostat OptistatDN (Oxford the resulting orange-brown solid was filtered off. Yield
Instrument) in 2-methyltetrahydrofurane solution at 0.32 g (43%), mp 225-227°C. 1Н NMR (DMSO-d6): δ 6.86 (1Н,
T = 293 K and T = 77 K.
m, Н-4’), 6.92 (1Н, m, Н-6’), 7.16 (1Н, m, Н-5’), 7.38 (1Н, m,
All reactions were monitored by thin layer Н-3’), 8.03 (2H, m, H-5, H-8), 8.95 (1Н, s, CH=N), 9.26 (1Н,
chromatography (TLC) on 0.2 mm silica gel F-254 (Merck) c, Н-3), 9.97 (1Н, c, ОН). MS (ES+): m/z 286 [M+H]+ (100%).
plates using light (254 and 365 nm) for detection. Elemental Anal. calc. for C15H9F2N3О: C, 63.16; H, 3.18; N, 14.73. Found:
analyses were performed at the Microanalytical Laboratory C, 63.20; H, 3.15; N, 17.75%.
of the Postovsky Institute of Organic Synthesis.
Ligands 4а-с were prepared by the same method;
preparation of compound 4а was reported [15].
2.3 Preparation of 6,7-difluoroquinoxalin-2- [2-(Quinolin-2-ylmethylen)amino]phenol (4а): yield
1
78%, mp 113-115°C. Н NMR (DMSO-d6): δ 6.84 (1Н, m,
carbaldehyde (3d)
Н-4’), 6.91 (1Н, m, Н-6’), 7.11 (1Н, m, Н-5’), 7.32 (1Н, m, Н-3’),
2-Methyl-6,7-difluoroquinoxalin 1d was synthesized using 7.61 (1Н, m, Н-7), 7.76 (1Н, m, Н-6), 7.95 (1H, m, H-5), 8.07
method [14].
(1H, m, H-8), 8.36 (1Н, d, Н-3, J 8.6 Hz), 8.57 (1Н, d, Н-4,
J 8.6 Hz), 8.88 (1Н, s, CH=N), 8.99 (1Н, s, ОН). MS (ES+):
[2-(6,7-Difluoroquinoxalin-2-yl)vinyl]dimethylamine m/z 249 [M+H]+ (100%). Anal. calc. for C16H12N2О: C, 77.40;
(2). To a solution of quinoxaline 1d (0.87 g, 4.83 mmol) H, 4.87; N, 11.28. Found: C, 77.45; H, 4.93; N, 11.24%.
in DMF (4 mL), N,N-dimethylformamide dimethyl acetal
(1.3 mL, 9.66 mmol) was added. The mixture was refluxed [2-(6,7-Difluoroquinolin-2-ylmethylen)amino]phenol
1
for 12 h, with solid forming afer the mixture was washed (4b): yield 74%, mp 173-175°C. Н NMR (DMSO-d6): δ 6.84
1
with ethanol. Yield 0.91 g (80%), mp 120-122°C. Н NMR (1Н, m, Н-4’), 6.91 (1Н, m, Н-6’), 7.12 (1Н, m, Н-5’), 7.31
(DMSO-d6): δ 3.05 (6Н, s, NMe2), 5.28 (1Н, m, СН=), 7.47 (1Н, m, Н-3’), 7.94 (1H, m, H-5), 7.96 (1H, m, H-8), 8.41 (1Н,
(1Н, m, СН=), 7.66 (1Н, m, Н-8), 7.83 (1Н, m, Н-5), 8.55 (1Н, d, Н-3, J 8.6 Hz), 8.60 (1Н, d, Н-4, J 8.6 Hz), 8.86 (1Н, s,
m, Н-3). Anal. calc. for C12H11F2N3: C, 61.27; H, 4.71; N, 17.86. CH=N), 9.06 (1Н, s, ОН). MS (ES+): m/z 285 [M+H]+ (100%).
Found: C, 61.40; H, 4.62; N, 17.55%.
Anal. calc. for C16H10F2N2О: C, 67.60; H, 3.55; N, 9.85. Found:
C, 67.63; H, 3.60; N, 9.79%.
6,7-Difluoroquinoxalin-2-carbaldehyde (3d). Two
grams of NaIO4 was dissolved in a phosphate buffer (рН=7, [2-(Quinoxalin-2-ylmethylen)amino]phenol (4с): yield
1
15 mL) and a solution of compound 2 (0.8 g, 3.4 mmol) in 69%, mp 236-238°C. Н NMR (DMSO-d6): δ 6.87 (1Н, m,
THF (15 mL) was added while stirring. The mixture was Н-4’), 6.93 (1Н, m, Н-6’), 7.16 (1Н, m, Н-5’), 7.39 (1Н, m,
stirred for 5 h at room temperature. Afer removing the Н-3’), 7.86 (2Н, m, Н-6, Н-7), 8.12 (2H, m, H-5, H-8), 8.96
solvent, colorless residue was washed by ethyl acetate. (1Н, s, CH=N), 9.24 (1Н, s, Н-3), 9.95 (1Н, s, ОН). MS (ES+):
Ethyl acetate solution was dried over Na2SO4, and afer m/z 250 [M+H]+ (100%). Anal. calc. for C15H11F2N3О: C,
removingthesolvent,light-brownsolidof3dwasobtained. 72.28; H, 4.45; N, 16.86. Found: C, 72.34; H, 4.50; N, 16.82%.
Unauthenticated
Download Date | 1/3/16 11:17 PM

Synthesis, crystal structures, and fluorescent properties of zinc(II) complexes ...ꢀ
ꢀ63
2.5 Preparation of Zn(II)complexes 5
Table 1: Crystallographic data of 5a.
C38H36N6O4Zn
(C32H22N4О2Zn•2C3H7NO)
295(2)
0.25×0.20×0.15
Monoclinic
С2/c
21.429(3)
10.2256(3)
17.0330(2)
117.49
3310.7(4)
4
0.793
1.417
14041
3386
1810
0.0609
0.0469
0.1108
Zn(II) Complex of [2-(6,7-difluoroquinoxalin-2-
ylmethylen)amino]phenol (5d). A methanol solution
(7 mL) of Zn(CH3COO)2•2H2O (0.035 g, 0.19 mmol) was
added to a methanol solution (18 ml) of ligand 4d
(0.1 g, 0.35 mmol) while stirring. The mixture was stirred for
48 h at room temperature, the solvent was evaporated,
and the violet residue was washed by acetonitrile (5 mL)
and diethyl ether (10 mL). Yield 0.05 g (45 %), mp > 300°C.
1Н NMR (DMSO-d6): δ 6.44 (1Н, m, Н-4’), 6.69 (1Н, m, Н-6’),
7.12 (1Н, m, Н-5’), 7.60 (1Н, m, Н-3’), 8.08 (1H, m, H-5), 8.37
(1H, m, H-8), 9.17 (1Н, s, Н-3), 9.36 (1Н, s, CH=N). Anal.
calc. for C30H16F4N6О2Zn: C, 56.88; H, 3.16; N, 13.26. Found:
C, 56.90; H, 3.21; N, 13.25%.
Empirical formula
Temperature/K
Crystal size
Crystal system
Space group
a/Å
b/Å
c/Å
β/°
V/Å3
Z
μ/mm–1
Dc/g cm–3
Reflections collected
Unique reflections
Observed reflections [I ≥ 2σ(I)]
Rint
R1 [I ≥ 2σ(I)]
Rw [I ≥ 2σ(I)]
Complexes 5а-с were prepared by the same method.
Zn(II) Complex of [2-(quinolin-2-ylmethylen)amino]
phenol (5а): yield 81%, mp > 300°C. 1Н NMR (DMSO-d6): δ
6.31 (1Н, m, Н-6’), 6.36 (1Н, m, Н-4’), 6.98 (1Н, m, Н-5’), 7.42
(2Н, m, Н-6, Н-7), 7.58 (1H, m, H-5), 7.78 (1Н, m, Н-3’), 7.89
(1H, m, H-8), 8.09 (1Н, d, Н-3, J 8.5 Hz), 8.56 (1Н, d, Н-4,
J 8.5 Hz), 9.31 (1Н, s, CH=N). Anal. calc. for C32H22N4О2Zn:
C, 68.64; H, 3.96; N, 10.01. Found: C, 68.58; H, 3.92; N,
10.08%.
GООF
1.004
Δρmin/Δρmax ē/см–3
θ range for data collection
0.522/-0.185
2.700 to 26.390
Red crystals suitable for X-ray diffraction were 2.6 X-ray crystallography
obtained by slow cooling of hot saturated solution of 5а in
dry dimethylformamide.
Zn(II) Complex of
X-Ray analysis, including data collection, cell refinement
and data reduction, was carried out with an Oxford
[2-(6,7-difluoroquinolin-2- DiffractionXcaliburSCCDdiffractometerusingCrysAlisPro
ylmethylen)amino]phenol (5b): yield 73%, mp > 300 sofware package on standard procedure (graphite
1
°C. Н NMR (DMSO-d6): δ 6.36-6.43 (3Н, m, 2Н-6’, Н-4’), monochromatized radiation with λ(MoKα)= 0.71073 Å,
6.02 (1Н, m, Н-4’), 7.02-7.11 (2Н, m, 2Н-5’), 7.26-7.31 (1Н, m, ω-scanning with a step 1o); the empirical absorption
Н-3’), 7.56 (1Н, d, Н-3, J 9.6 Hz), 7.79 (1Н, d, Н-3, J 8.6 Hz), correction [16] was applied. The structure was solved by
7.97 (2H, m, 2H-5), 8.05-8.18 (2H, m, 2H-8), 8.39-8.44 (1Н, direct method and refined against F2 by full-matrix least-
m, Н-3’), 8.61 (1Н, d, Н-4, J 9.6 Hz), 8.64 (1Н, d, Н-4, J 8.6 squares using the SHELXTL package [17]. All non-hydrogen
Hz), 9.02 (1Н, s, CH=N), 9.39 (1Н, s, CH=N). Anal. calc. for atoms were refined anisotropically; hydrogen atoms were
C32H18F4N4О2Zn: C, 60.83; H, 2.87; N, 8.87. Found: C 60.79; placed in idealized positions and were constrained to ride
H 2.83; N 8.93%.
on their parent atoms. The crystallographic data for the
complex 5a are summarized in Table 1. Selected bond
Zn(II) Complex of [2-(quinoxalin-2-ylmethylen)amino] lengths and angles are summarized in Table 2.
1
phenol (5с): yield 77%, mp > 300°C. Н NMR (DMSO-d6):
δ 6.40 (1Н, m, Н-6’), 6.45 (1Н, m, Н-4’), 7.05 (1Н, m, Н-5’),
7.50 (1Н, m, Н-3’), 7.56 (1H, m, H-8), 7.69 (1H, m, H-7), 7.82
(1H, m, H-5), 8.01 (1H, m, H-6), 9.44 (1Н, s, Н-3), 9.48 (1Н,
s, CH=N). Anal. calc. for C30H20N6О2Zn: C, 64.13; H, 3.59; N,
14.96. Found: C 64.09; H 3.55; N 15.01%.
Unauthenticated
Download Date | 1/3/16 11:17 PM

64ꢀ
ꢀ Emiliya Nosova et al.
SeO ,
dioxane
2
OMe
NMe2
Y
X
NaIO4
H
Y
Y
X
F
F
N
OMe
Y
N
CH3
N
CH=CH-NMe2
N
O
1a-d
3a-d
2
NH2
OH
Y
X
Y
Y
X
Zn(OAc)2
Y
N
N
N
O
N
Zn
4a-d
O
N
HO
1, 3, 4, 5: X = CH, Y = H(a), F(b); X = N, Y = H(c), F(d)
N
Y
Y
5a-d
X
Scheme 1: Synthesis of the Schiff bases 4a-d and their Zn(II) complexes 5a-d.
Table 2: Selected bond lengths (Å) and angles (0) for 5a.
Bond
Length (Å)
2.074(2)
2.087(2)
2.346(2)
1.290(4)
1.317(4)
1.368(4)
1.277(4)
1.396(4)
1.424(4)
1.456(4)
0.9300
Angle
(0)
Zn(1)-O(1)
Zn(1)-N(2)
Zn(1)-N(1)
O(1)-C(11)
N(1)-C(2)
N(1)-C(10)
N(2)-C(1)
N(2)-C(12)
C(12)-C(11)
C(2)-C(1)
C(1)-H(1A)
C(3)-C(2)
C(10)-C(9)
C(10)-C(5)
C(11)-C(16)
O(1)-Zn(1)-N(2)
O(1)-Zn(1)-N(1)
N(2)-Zn(1)-N(1)
C(11)-O(1)-Zn(1)
C(2)-N(1)-C(10)
C(2)-N(1)-Zn(1)
C(10)-N(1)-Zn(1)
C(1)-N(2)-C(12)
C(1)-N(2)-Zn(1)
C(12)-N(2)-Zn(1)
C(13)-C(12)-N(2)
N(2)-C(1)-C(2)
C(16)-C(11)-C(12)
O(1)-C(11)-C(16)
O(1)-C(11)-C(12)
N(1)-C(2)-C(1)
N(1)-C(2)-C(3)
N(2)-C(12)-C(11)
N(1)-C(10)-C(9)
N(1)-C(10)-C(5)
79.26(9)
151.25(9)
73.68(9)
112.72(18)
118.3(2)
110.14(19)
130.76(19)
127.3(3)
119.9(2)
112.62(18)
125.1(3)
118.5(3)
116.0(3)
122.4(3)
121.5(3)
117.1(3)
1.413(4)
1.397(4)
1.430(4)
1.411(4)
123.1(3)
113.2(3)
119.9(3)
121.4(3)
Unauthenticated
Download Date | 1/3/16 11:17 PM

Synthesis, crystal structures, and fluorescent properties of zinc(II) complexes ...ꢀ
ꢀ65
is based on the interaction of 2-methylbenzazine with
N,N-dimethylformamide dimethyl acetal and oxidation
of the intermediate obtained with sodium periodate.
The structures of aldehyde 3d and intermediate 2 were
1
confirmed by the H NMR data. о-Hydroxyazomethynes
4a-d have been synthesized by interaction of aldehydes
3a-d with о-aminophenol in boiling ethanol during
30 min. The subsequent reaction of 4a-d with zinc acetate
in methanol led to formation of the Zn(II) complexes 5a-d
(Scheme 1).
There are no signals of OH-groups in 1H NMR spectra
of 5a-d. The downfield shif of H-8 proton signals for
difluoroderivatives 5b,d and the upfield shif of such
protons for non-fluorinated derivatives 5a,c are observed
in comparison with signals of the corresponding ligands
4. Shif of CH=N proton signal of complexes 5a-d in the
weak field was noted, as was shif of H-6’ protons signals
for 5a-d and H-3’ protons signals for 5a,b,d in the strong
field, in comparison with signals of 4.
Figure 1: The structure of 5a showing the atom-numbering scheme
(crystallographic independent non-hydrogen atoms are numbered).
Table 3: Photophysical data for UV and FL spectra Schiff bases 4 and
Zn(II) complexes 5 in 2-methyltetrahydrofurane at 77 K.
3.2 Crystal structure
X-ray crystal structure determination was performed
to confirm the structure of the complex 5а (Fig. 1, the
numbering of atoms accepted in structural experiment is
shown). In x-ray data, the compound grown up from DMF
is crystallized as solvate 5а:DMF 1:2.
The complex is crystallized in the centrosymmetric
space group. The molecule of the complex is placed
in a private position on a rotation axis, while the Zn
atom coordinates around itself two tridentate ligands.
The ligand molecule closes two five-membered helate
cycles. Coordination around the central atom is a
distorted octahedron, thus bond lengths Zn(1)-O(1)
Compound
4a
X
Y
λa , nm
λf , nm (I, a. u)*
CH
H
248, 368
−
5a
4b
5b
4c
5c
4d
5d
CH
CH
CH
N
H
F
360, 556
368
651 (334)
−
F
362, 550
378
616 (478)
−
H
H
F
N
375, 589
375
715(160)
570 (40)
657 (650)
N
N
F
366, 553
*Excitement was carried out to areas of a long-wave band of and Zn(1)-N(2) are comparable (2.074(2) and 2.087(2) Å
absorption
respectively), bond length Zn(1)-N(1) is much greater
(2.346(2) Å), which indicates a mutual pushing away of
a proton at C(9) from the atoms of the second ligand,
3 Results and discussion
and a general removal of the quinoline fragment from its
plane. Fragments of the ligands are planar; the maximal
3.1 Synthesis and NMR spectra
deviations of non-hydrogen atoms from least-squared
plane is 0.077 Å. The planes of the ligands are situated
2-Formylbenzazines 3a-c are successfully formed at almost perpendicularly (with a deviation less 10). This
oxidation of 2-methylderivatives 1a-c with selenium stereometry of the complex is typical and, in particular,
dioxide in boiling dioxane [18-20]. This way did not is comparable with a stereometry of Ni-complex of
allow individual aldehyde 3d to be obtained, owing to quinoxaline derivative from paper [13]. However, in the
a condensation process between formed aldehyde with Ni-complex [13], the deviations of the atoms of ligands
residue of 2-methylderivative 1d. For this reason we chose from least-squared plane are more significant (appox.
themethoddescribedfor2-methyl-3-phenyl-3H-quinazolin- 0.16 Å), and the ligand is probably characterized better
4-ones [21], for the synthesis of aldehyde 3d. This method by conformational flexibility.
Unauthenticated
Download Date | 1/3/16 11:17 PM

66ꢀ
ꢀ Emiliya Nosova et al.
0.06
60
50
40
30
20
10
0
Fluorescence of complex 5a in 2-methyltetrahydrofurane
solution at room temperature is also low, nevertheless at
77 К it increases considerably (Fig. 3). Complexes 5b-d
demonstrate the same increase in fluorescent intensity.
Photophysical data for UV and FL spectra at 77 K are
shown in Table 3.
2 x 25
1
0.05
0.04
0.03
0.02
0.01
0.00
Schiff bases bearing quinoxaline fragments (4c,d)
show long-wave shif of absorption bands compared with
analogs bearing quinoline fragments (4a,b). The
5
complexes
5 show considerable long-wave shif of
absorption maximum compared with the corresponding
400
500
600
700
800
900
ligands 4.
Wavelength (nm)
The
5
complexes
exhibit
intense
red
Figure 2: UV-vis spectra 5a in CH3CN (1) fluorescence emission photoluminescence with maxima at 616-715 nm.
(λex=530) in CH3CN (intensity of fluorescence is increased on 25).
Emission spectra of difluoroderivatives 5b, 5d are
characterized by blue shifs in comparison with non-
fluorinated analogs 5а, 5с (Table 3). It should be noted
0.15
0.10
0.05
0.00
400
350
300
250
200
150
100
50
that in such conditions, ligand 4d demonstrates a weak
orange luminescence (Table 3).
3
4
1
4 Conclusion
New Schiff bases as types of N,N,O-ligands were
prepared, and their complex formations with zinc cations
were studied. The complexes were characterized by
1
elemental analysis, Н NMR spectra, and single crystal
2
X-ray determination. Influence of structural factors on
photophysical properties of ligands and complexes
was shown; the fluorescent properties of the complexes
0
800
400
500
600
700
Wavelength (nm)
Figure 3: UV-vis spectra 5a in 2-Me THF (1); fluorescence emission indicate that they may have interesting applications.
(λex=530) in 2-Me THF at 297 K (2); fluorescence excitation (λobs=650);
(3) and fluorescence emission (λex=530); (4) in 2-Me THF at 77 K.
Acknowledgement: This work was supported by the
Russian Foundation for Basic Research (grant 14-03-
00340), the Grants Council of the President of the Russian
3.3 Fluorescent character of the ligands and Federation (grant NSh-3656.2014.3) and Ural Division of
Russian Academy of Sciences (project 12-P-3-1020).
the complexes
The Schiff bases 4a-d and the Zn(II) complexes Supplementary material: CCDC-996034 contain the
5a-d display low photoluminescence in acetonitrile supplementary crystallographic data for this paper. These
solution at room temperature. Complex formations are data can be obtained free of charge at http://www.ccdc.
accompanied by chelatation of o-hydroxyazomethine, cam.ac.uk/const/retrieving.html or from the Cambridge
increasing the rigidity of the ligand and preventing photo- Crystallographic Data Center (CCDC), 12 Union Road,
induced transfer of an electron, which leads to stronger Cambridge CB2 1EZ, UK; Fax:+44(0)1223-336,033 or E-mail:
emission [22-24]. The 5 complexes possess low red deposit@ccdc.cam.ac.uk.
photoluminescence (for example, compound 5a, Fig. 2).
Unauthenticated
Download Date | 1/3/16 11:17 PM

Synthesis, crystal structures, and fluorescent properties of zinc(II) complexes ...ꢀ
ꢀ67
References
[1] Lipunova G.N., Nosova E.V., Trashakhova Т.V., Charushin V.N., [13] Sebastian M., Arun V., Robinson P.P., Varghese A.A., Abraham R.,
Rus. Chem. Rev., 2011, 80, 1115
Suresh E., Yusuff K.K.M., Polyhedron, 2010, 3014
[14] Nosova E.V., Trashakhova T.V., Ustyugov V.S., Mochul’skaya N.N.,
Valova M.S., Lipunova G.N., Charushin V.N., Rus. Chem. Bull.,
2011, 60, 942
[2] Wang S.L., Lin J.M., Chem. Phys. Lett., 2007, 444, 71
[3] Barberis V.P., Mikroyannidis J.A., Synth. Met., 2006, 156, 865
[4] Cazaux L., Faher M., Picard C., Tisnes P., Can. J. Chem., 1993,
71, 2007
[15] Seyhan M., Chem. Ber., 1952, 85, 436
[5] Sano T., Nishio Y., Hamada Y., Takahashi H., Usuki T., [16] Clark R.C., Reid J.S., Acta Cryst. A, 1995, 51, 887
Shibata K., J. Mater. Chem., 2000, 10, 157
[17] Sheldrick G.M., Acta Cryst. A, 2008, 64, 112
[6] Pivovarov А.P., Kaplunov M.G., Yakuschenko I.К., Belov М.Yu., [18] Tang A., Lien E.J., Lai M.M.C., J. Med. Chem., 1985, 28, 1103
Nikolaeva G.V., Efimov О.N., Rus. Chem. Bull., 2002, 51, 67
[7] Kaplunov M.G., Yakuschenko I.К., Krasnikova S.S.,
[19] Milton J., Wren S., Wang S., Folkes A., Chuckowree I., Hancox T.,
Miller W., Sohal S., WO Pat, 2004, 65389
Shamaev S.N., Pivovarov А.P., Efimov О.N., Rus. Chem. Bull., [20] Jarikote D.V., Li W., Jiang T., Eriksson L.A., Paul V., Murphy P.V.,
2004, 53, 2148
Bioorg. Med. Chem., 2011, 19, 826
[8] Kaplunov M.G., Yakuschenko I.К., Krasnikova S.S., Pivovarov А.P., [21] Chenard B.L., Welch W.M., Blake J.F., Batler T.W., Reinhold A.,
Balashova I.О., High Energy Chemistry, 2008, 42, 563
[9] Shavaleev N.M., Scopelliti R., Gumy F., Bunzil J.C.G., Inorg.
Chem., 2008, 47, 9055
[10] Shi Y.W., Shi M.M., Huang J.C., Chen H.Z., Wang M., Lin M.D.,
Ma Y.G., Xu H., Yang B., Chem. Commun., 2006, 1941
Ewing F.E., Menniti F.S., Pagnozzi M.J., J. Med. Chem., 2001, 44,
1710
[22] Metelitsa A.V., Burlov A.S., Borogkina I.G., Bren V.A.,
Garnovskii A.D., Minkin V.I., Bezuglyi S.O., Russian Journal of
Coordination Chemistry, 2006, 32, 858
[11] Trashakhova Т.V., Nosova E.V., Slepukhin P.A., Valova М.S., [23] Chattopadhyay T., Mukherjee M., Banu K.S., Banerjee A.,
Lipunova G.N., Charushin V.N., Rus. Chem. Bull., 2011, 60, 2347 Suresh E., Zangtando E., Das D., J. Coord. Chem., 2009, 62, 967
[12] Mayadevi S., Yusuff K.K.M., Synth. React. Inorg. Met.-Org. [24] Basak S., Sen S., Banerjee S., Mitra S., Rosair G.,
Chem., 1997, 27, 319 Rodriquez M.T.G., Polyhedron, 2007, 26, 5104
Unauthenticated
Download Date | 1/3/16 11:17 PM