Structure and photophysical properties of a dimeric Zn(II) complex based on 8-hydroxyquinoline group containing 2,6-dichlorobenzene unit

Article abstract of DOI:10.1016/j.tet.2012.06.103

A novel 2-substituted-8-hydroxyquinoline ligand (E)-2-[2-(2,6- dichlorophenyl)ethenyl]-8-hydroxyquinoline (HL) was synthesized and characterized by ESI-MS, NMR spectroscopy, and elemental analysis. Using solvothermal method, a dimeric complex (ZnL₂)₂ (1) was fabricated by self-assembly of Zn(II) ions with ligand HL. X-ray structural analysis shows that 1 exhibits a binuclear core, which is bridged by two 8-hydroxyquinoline rings. The supramolecular structure of 1 features a lamellar solid constructed by aromatic stacking interactions, Cl?Cl interactions and nonclassical C-H?Cl hydrogen bonds derived from 2,6-dichlorophenyl group of the ligand HL. The aggregation behavior of zinc salts and HL in solutions was investigated with a variety of techniques, including ¹H NMR, UV-vis, and photoluminescence (PL). In addition, we also studied the photophysical properties of compound 1 by UV-vis and PL. The experimental results show that the complex 1 emits yellow luminescence in the solid state.

Full text of DOI:10.1016/j.tet.2012.06.103

Tetrahedron 68 (2012) 8018e8023
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Structure and photophysical properties of a dimeric Zn(II) complex based
on 8-hydroxyquinoline group containing 2,6-dichlorobenzene unit
,
b
,
b
b
c,
Guo-Zan Yuan a , Yan-Ping Huo , Xiao-Li Nie , Xiao-Ming Fang , Shi-Zheng Zhu
*
*
*
a School of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan 243002, China
b School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
c Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel 2-substituted-8-hydroxyquinoline ligand (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline
(HL) was synthesized and characterized by ESI-MS, NMR spectroscopy, and elemental analysis. Using sol-
vothermalmethod, a dimericcomplex (ZnL2)2 (1) was fabricatedbyself-assemblyofZn(II)ionswithligandHL.
X-ray structural analysis shows that 1 exhibits a binuclear core, which is bridged by two 8-hydroxyquinoline
rings. The supramolecular structure of 1 features a lamellar solid constructed by aromatic stacking in-
teractions, Cl/Cl interactions and nonclassical CeH/Cl hydrogen bonds derived from 2,6-dichlorophenyl
group of the ligand HL. The aggregation behavior of zinc salts and HL in solutions was investigated with
a variety of techniques, including 1H NMR, UVevis, and photoluminescence (PL). In addition, we also studied
the photophysical properties of compound 1 by UVevis and PL. The experimental results show that the
complex 1 emits yellow luminescence in the solid state.
Received 29 March 2012
Received in revised form 17 June 2012
Accepted 26 June 2012
Available online 4 July 2012
Keywords:
8-Hydroxyquinoline
Dimeric complex
Crystal structure
Photophysical property
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
candidates to enhance the electron-transporting properties for
OLEDs.16,17 In the luminescent complexes reported thus far, the
Initially the 8-hydroxyquinoline ligand has been mainly applied
for analytical purposes and separation techniques. Due to the ex-
traordinary coordinating abilities, this ligand is an excellent reagent
for spectrophotometric analysis and it can be used for the extrac-
tion of metal ions as well as metal ion sensing.1e4 More recently,
tris(8-hydroxyquinoline) (Alq3) has attracted significant attention
due to their excellent solid-state properties including good electron
mobility and high luminescence.5e12 Although Alq3 is often re-
ferred to as the ‘archetypal’ electroluminescent material, its struc-
tural diversity limits our ability to understand structureeproperty
relationships in detail as organic light-emitting devices (OLEDs).
Alq3 has two geometric isomers,13 the meridianal (mer-Alq3) and
facial (fac-Alq3) forms having C1 and C3 symmetry, respectively.
Geometric isomerization and several polymorphic phases identi-
fied,14,15 suggesting that thin films deposited under different con-
ditions may have structural variations that contribute to device
property variations. So it is important to obtain the single crystal
because X-ray diffraction on single crystals is the best method for
providing their molecular structure and packing.
zinc(II) ion is often four-coordinated by two monoanionic bidentate
ligands, such as salicylideneaminate,18 dipyrrin,19 quinolinolate,17
and benzothiazolate,20 although the latter two ligands induce
recoordination in the vapor phase to give rise to luminescent
multinuclear five- or six-coordinated complexes.17,20,21 However,
multinuclear five or six-coordinated zinc(II) complexes with ex-
cellent luminescent properties have been little known until now.
Recently, Sapochak shows that the symmetry of the tetramer
[(Znq2)4] leads to a molecular and electronic structure with sig-
nificantly different electroluminescence (EL) properties.17 So they
propose that improvements of EL performance might be achieved
by control of the oligomerization of 8-hydroxyquinoline chelates of
Zn(II) and/or by improving the PL efficiency by judicious sub-
stitution of the ligand. On the other hand, in order to retain the
excellent photoelectron properties of 8-hydroxyquinoline itself and
achieve yellow-light emission, a feasible approach is to modify the
2-, 5- or 7-position of the 8-hydroxyquinoline rings with different
functional groups.22e27 Inspired by these results, we have focused
on the synthesis of multinuclear zinc(II) complexes based on novel
substituted-8-hydroxyquinoline,28 which led to successful fabri-
cation of a trimeric zinc(II) complex emitting yellow luminescence
in solution and solid state.
Recent reports have suggested that the zinc analog of Alq3,
bis(8-hydroxyquinoline)zinc(II) (Znq2) complexes may be potential
We report here the assembly of a novel lamellar solid based on
novel dimeric zinc(II) complex by combination of coordination,
* Corresponding authors. Tel.: þ86 21 54925185; fax: þ86 21 64166128; e-mail
addresses: guozan@ahut.edu.cn (G.-Z. Yuan), tigerhuo1974@yahoo.com.cn (Y.-P. Huo),
zhusz@mail.sioc.ac.cn (S.-Z. Zhu).
p/p
stacking interactions, Cl/Cl interactions, and hydrogen
bonds. The aggregation behavior of zinc salts and HL in solutions
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.06.103

G.-Z. Yuan et al. / Tetrahedron 68 (2012) 8018e8023
8019
was investigated by a variety of techniques, including 1H NMR,
UVevis, and PL. We also studied the fluorescence property in so-
lution and solid state. The results showed that complex 1 exhibits
a red shift compared with free ligand HL and emits yellow
luminescence.
shift comparing to that of HL, which can be attributed to the in-
creasing conjugated degree of the complex 1.
In order to further investigate the interaction mode of ligand HL
with Zn2þ ion, the coordination reaction of HL with Zn2þ ion was
monitored through a UVevis and fluorescence spectroscopic ti-
tration. The absorption bands of HL in MeOH dramatically changed
upon addition of Zn2þ ions. As depicted in Fig. 2, the band of HL
showed significant bathochromic shift from 283 to 300 nm. The
peak at 329 nm was found to become weak and disappeared in the
end in the presence of increasing amounts of Zn2þ ion. A new band
at 415 nm is attributed to the charge transfer from metal to ligand
band. No differences were observed in the absorption spectra after
the 1:2 ratio of Zn2þ/HL, so this experiment clearly indicates the
formation of (ZnL2)n. Results from the spectrophotometric titra-
tions were corroborated by titrations followed by emission spectra.
As shown in Fig. 3, Addition of Zn2þ produced a new emission band
centered at 610 nm with increasing intensity, while emission band
of ligand at 508 nm decreased simultaneously. This experiment
clearly showed that the coordination reached the end point at 1:2
2. Results and discussion
2.1. Synthesis considerations and spectroscopic
characterization
As outlined in Scheme 1, bidentate ligand HL was synthesized by
seacetylation of (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-aceto-
xyquinoline, which was obtained by the condensation of 8-
hydroxyquinaldine with 2,6-dichlorobenzaldehyde in acetic anhy-
dride. Heating Zn(OAc)2$6H2O and HL in a mixture of DMF, MeOH,
and water afforded red, rod-like crystals. It was formulated as
(ZnL2)2 (1) on the basis of X-ray crystallography, elemental analysis,
and IR spectroscopy.
CHO
Cl
pyridine/H2O
Cl
Cl
Ac2O
82%
N
N
CH3
96%
OCOCH3
OH
Cl
Cl
Cl
Cl
Zn(OAc)2 2H2O
70%
N
N
(Zn)2
OH
4
O
Cl
HL
1
Scheme 1. Synthesis of ligand HL and complex 1.
2.2. Coordination studies in solution
The coordination behavior of Zn(OAc)2$6H2O and HL in solu-
tions was first investigated by 1H NMR spectroscopy. In the 1H NMR
spectrum of HL the proton signals at 9.71, 8.34, 8.00, 7.85, 7.59,
7.45e7.31, 7.11 ppm can be easily assigned to each the corre-
sponding hydrogen, respectively, which indicates the presence of
the hydroxyquinoline and vinylene. The proton signal at 9.71 ppm
corresponds to HeO proton of the quinoline. One doublet at
7.87 ppm with a coupling constant¼16.4 Hz, indicates the presence
of trans configuration in the vinylene units. Upon mixing 2:1 molar
ratio of HL and zinc salt in DMSO-d6, the resonance at 9.71 ppm
corresponding to HeO proton of the quinoline gradually dis-
appeared after 1 h. With the passage of time, the resonances in the
pyridyl ring of quinoline shifted downfield while the resonances in
the phenoxide ring shifted upfield with respect to that of the free
ligand. These results indicate the occurrence of the coordination
between the ligand HL and Zn(OAc)2 (Fig. 1).
The UVevis absorption spectra of HL and complex 1 in methanol
solution are shown in Fig. 2. The absorption spectrum of HL con-
tains four bands at 205, 240, 283, and 329 nm, whereas the ab-
sorption spectrum of 1 contains three bands at 209, 300, and
415 nm. In the absorption spectrum of the ligand HL, the absorption
Fig. 1. 1H NMR spectra showing the coordination processes of complex 1 (The initial
concentration of HL in DMSO-d6 is 0.06 M.).
band at 283 nm originates from intraligand
pe
p
*
transition of
ratio of Zn2þ/L. Fluorescence photograph was obtained under ir-
radiation of UV light (365 nm). Obvious color change from blue to
yellow could be seen by naked eyes. The fluorescence intensity of
complex 1 is less than HL. This decrease in intensity may be at-
quinoline moiety. While a less intense and broader band lies at
lower energy (329 nm). As previously reported,2 this band is as-
sociated with a transition in which substantial charge density is
transferred from the oxygen atom to the quinoline moiety of the
chromophore. The absorption bands of the complex 1 exhibit a red
tributed to the
pep stacking of 1 in DMF solvent, which causes an
intersystem crossing to a nonradiative triplet state.

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G.-Z. Yuan et al. / Tetrahedron 68 (2012) 8018e8023
two ligands L. The structure of 1 is built around a dimeric Zn(II)
structure. The zinc atoms (Zn1 and Zn1A) found in the dimeric unit
is pentacoordinate, resulting in distorted trigonal bipyramidal ge-
ometry. Two of the ligands are involved in bridging through the
phenolato oxygens, while the remaining two other ligands are
bound to Zn(1) atom only. In detail, the Zn1 atom adopts a trigonal
bipyramidal geometry with the equatorial plane occupied by the
N2O donors of three ligands around the Zn1 and the apical position
by two phenol oxygen atoms (Fig. 4). The bond lengths and angels
ꢀ
around Zn(II) are 2.132(3ꢀ) and 2.222(3) A for ZneN, 1.959(3)e
ꢀ
ꢀ
ꢀ
ꢀ
2.206(3) A for ZneO, 74.95 e169.89 for OeZneO, 78.58 e135.08
for OeZneN, and 105.07ꢀ for NeZneN, respectively.
Fig. 2. (a) The UVevis absorption spectra of HL (10
m
M) and complex 1 (10
M in methanol) with Zn(OAc)2
(in H2O). Each spectrum was acquired 8 min after Zn2þ addition.
mM) in
methanol solution; (b) UVevis titrations of HL (10
m
Fig. 4. (a) Perspective views of the coordination geometries of Zn(II) atoms in 1 (some
equivalent atoms have been generated to complete the Zn coordination, H atoms
omitted for clarity). (b) The binuclear zinc molecule of 1 and its CeH/O intra-
molecular hydrogen bonding (red dashed lines) are included.
There are significant hydrogen bonds in 1. Weak nonclassical
CeH/O intramolecular hydrogen bonds between the phenolato
oxygen and the CeH group of dichlorophenyl ring or ethenyl
(C/O¼3.170e3.282 A; CeH/O¼134.0e151.0ꢀ) as well as in-
ꢀ
termolecular nonclassical CeH/Cl hydrogen bonds involving the
aromatic CeH groups and Cle atoms of adjacent 2,6-dꢀichlorophenyl
ꢀ
units of ligands HL (C/Cl¼3.571 A; CeH/Cl¼143.0 ) play a vital
role in the consolidation of the solid structure (Fig. 5b). Moreover, it
is notable that each cluster of 1 involves abundant intermolecular
p
/
p
stacking interactions. As shown in Fig. 5a, almost all aromatic
Fig. 3. Fluorescence emission changes of HL (20 mM) in ethanol solutions upon addi-
rings of 1 possess significant face-to-face stacking interactions
p
/p
tion of Zn2þ (0e2 equiv). Each spectrum was acquired 5 min after Zn2þ addition,
lex¼384 nm. Fluorescence photograph was obtained under irradiation of UV light
(365 nm).
between the ligands to form 1D chain along b-axis. The chains
further extend to a 3D network as a result of intermolecular
CeH/Cl hydrogen bonds. It is of interest to note that there are
2.3. Stucture description
two types of Cl/Cl interactions in 1 (intramolecular cis Cl/Cl
q2¼129.66ꢀ; intermolecular
ꢀ
geometry, 3.4908(14) A with q1
trans Cl/Cl geometry, 3.6075(14) A with q1
also play an important role in the assembly of the complex 1 in the
¼
¼
q2¼117.27ꢀ), which
ꢀ
Single-crystal structure analysis reveals that 1 crystallizes in the
monoclinic space group P2/n with Z¼4. The asymmetric unit con-
tains one half of a formula unit, that is, one unique Zn(II) atom and
solid state.

G.-Z. Yuan et al. / Tetrahedron 68 (2012) 8018e8023
8021
Fig. 5. (a)
p/p Stacking interactions between the ligands HL to form 1D chain along b-axis. (b) The supramolecular structure of 1 mediated by CeH/Cl hydrogen bonding (red
dashed lines).
2.4. Photophysical properties
However, the corresponding complex 1 exhibits a blue-shift in
the solid state compared with free ligand HL. The results may be
attributed to the following two reasons: (1) the coordination of
metal ions enhances the mobility of the electron transition in
backbone due to back-coupling p-bond between the metal and the
ligand, and decreases the electron transition energy of intraligand
charge transfer; (2) the ligand is coordinated with metal ions to
The synthesized product of 1 was characterized by X-ray pow-
der diffraction (XRD). As shown in Fig. 6a, the XRD patterns are very
consistent with the results simulated from single-crystal data, il-
luminating the high purity of the as synthesized sample. Lumi-
nescent properties of compounds HL and 1 were investigated in the
solid state at room temperature. The fluorescent spectra of HL and 1
display maximum emission wavelengths at 465 and 571 nm upon
excitation at 350 nm, respectively. The results indicate that the
complex 1 has yellow emission, which predominantly originates
from metal-to-ligand charge transfer (MLCT) transition in the solid
state.
form additional five-membered rings, which increases the
pep
*
conjugation length and the conformational coplanarity, accord-
ingly reduces the energy gap between the
p
and
p molecular
*
orbitals of the ligand.29 Additionally, complex 1 shows an obvious
blue-shift compared with its solution state. The blue-shift phe-
nomenon may result from the decrease of the excited-state
Fig. 6. (a) XRD patterns of complex 1 (red: calculated, blue: as-synthesized sample). (b) Emission spectra of the ligand HL and Zn complex 1 in the solid state (Ex: 350 nm).

8022
G.-Z. Yuan et al. / Tetrahedron 68 (2012) 8018e8023
energy when the solvent molecules get close to photoactive metal
centers.30
4. Experimental section
In order to further study the photophysical properties of HL and
1, the fluorescence lifetimes of HL and 1 were determined in the
4.1. Chemicals and instruments
solid state. As shown in Fig. 7, the
s
values are 62, 67
m
s, re-
All of the chemicals are commercial available, and used without
further purification. Elemental analyses were performed with an
EA1110 CHNS-0 CE elemental analyzer. The IR (KBr pellet) spectrum
was recorded (400e4000 cmꢁ1 region) on a Nicolet Magna 750 FT-
IR spectrometer. Powder X-ray diffraction (PXRD) data were col-
spectively. In addition, the fluorescence quantum yields (FPL) of
ligand HL and complex 1 were calculated by comparing the in-
tegrated photoluminescence intensities and the absorbency values
of HL (or 1) with the reference quinine sulfate. Quinine sulfate
(literature 4ST¼0.55) was dissolved in 0.5 M H2SO4 (refractive index
lected on a DMAX2500 diffractometer using Cu Ka radiation. The
(h
) of 1.33). The samples (HL or 1) were dissolved in DMF (
h
¼1.43).
calculated PXRD patterns were produced using the SHELXTL-XPOW
program and single-crystal reflection data. All fluorescence mea-
surements were carried out on an LS 50B Luminescence Spec-
trometer (Perkin Elmer, Inc., USA). All UVevis absorption spectra
were recorded on a Lambda 20 UV/Vis Spectrometer (Perkin Elmer,
Inc., USA). 1H and 13C NMR experiments were carried out on
a MERCURYplus 400 spectrometer operating at resonance fre-
quencies of 100.63 MHz. Electrospray ionization mass spectra (ES-
MS) were recorded on a Finnigan LCQ mass spectrometer using
dichloromethane/methanol as mobile phase.
The absorbency was controlled <0.05 for the samples and quinine
sulfate. The quantum yield was calculated using the below equa-
tion: 4S
yield, A is the absorbency, F is the integrated photoluminescence
intensity, is the refractive index of the solvent, S is sample, ST is
¼
4ST(0.55)(AST/AS)(FS/FST)(h2S hS2T). Where
/ 4 is the quantum
h
the standard of quinine sulfate (4ST¼0.55). Based on the equation,
the quantum yields are calculated as 0.025 and 0.013 for HL and
complex 1 in DMF, respectively. This difference in quantum yield is
in accordance with the decrease in fluorescence intensity and due
to the same reason as discussed above. The quantum yields of HL
and 1 less than 0.1 are due to the heavy atom effect of Cl
substitution.31
4.2. Synthesis of ligand HL and complex 1
4.2.1. Synthesis of (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-acetoxy-
quinoline To a solution of 8-hydroxyquinaldine (1.36 g, 8.5 mmol)
in acetic anhydride (10 mL) was added 2,6-dichlorobenzaldehyde
(1.48 g, 8.5 mmol). The mixture was heated under reflux for 10 h.
After the mixture was cooled, it was subsequently poured into ice
water (200 mL) and stirred overnight. The yellow solid obtained
was filtered and washed with water. The solid residue was
recrystallized from CH2Cl2 to afford (E)-2-[2-(2,6-dichlorophenyl)
ethenyl]-8-acetoxyquinoline (2.49 g, 82%): 1H NMR (CDCl3,
10000
1000
HL
1
100
400 MHz)
d
: 8.17 (d, J¼8.4 Hz, 1H), 7.91 (d, J¼16.4 Hz, 1H), 7.70 (dd,
J¼1.6, 8.0 Hz, 1H), 7.61 (d, J¼8.4 Hz, 1H), 7.51e7.43 (m, 3H), 7.38 (d,
J¼8.0 Hz, 2H), 2.54 (s, 3H); ESI-MS m/z: 358.0 ([MþH]þ). Elemental
analysis: found C: 63.52, H: 3.88, N: 3.72; calculated for
(C19H13Cl2NO2) C: 63.71, H: 3.66, N: 3.91 (%).
10
1
4.2.2. Synthesis of (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydro-
xyquinoline (HL) A solution of (E)-2-[2-(2,6-dichlorophenyl)
ethenyl]-8-acetoxyquinoline (2.0 g, 5.6 mmol) in pyridine (30 mL)
was refluxed for 30 min, then water (15 mL) was added. The re-
action mixture was refluxed for 12 h. After the mixture was
cooled, water (200 mL) was added to the mixture. The yellow solid
obtained was filtered and washed with water, and dried in vacuo
to give compound of HL (1.69 g, 96%). 1H NMR (DMSO-d6,
0
50
100
Times
150
200
250
(
µs)
Fig. 7. Fluorescence decay curves of HL (Ex, 350 nm; Em, 470 nm) and 1 (Ex, 380 nm;
Em, 594 nm).
400 MHz)
d
: 9.71 (s, 1H), 8.34 (d, J¼8.8 Hz, 1H), 8.00 (d, J¼16.4 Hz,
3. Conclusion
1H), 7.85 (d, J¼8.4 Hz, 1H), 7.59 (d, J¼8.0 Hz, 2H), 7.45e7.31 (m,
4H), 7.11 (dd, J¼1.6, 7.2 Hz, 1H); 13C NMR (DMSO-d6, 400 MHz)
d:
In the present work, a unique dimeric complex (ZnL2)2 (1)
was fabricated by self-assembly of Zn(II) ions with a novel 2-
substituted-8-hydroxyquinoline ligand (HL). The supramolecular
structure of 1 features a lamellar solid constructed by aro-
matic stacking interactions, Cl/Cl interactions and nonclassical
CeH/Cl hydrogen bonds derived from 2,6-dichlorophenyl group
of the ligand HL. The aggregation behavior of zinc salts and HL
in solutions was investigated with a variety of techniques, in-
cluding 1H NMR, UVevis, and PL. The luminescence properties of
compound 1 show that it emits yellow luminescence at 561 nm
152.8, 152.2, 138.0, 136.2, 134.8, 133.6, 128.7, 128.7, 128.0, 127.7,
120.4, 117.7, 110.3. ESI-MS m/z: 316.0 ([MþH]þ).Elemental analysis:
found C: 64.60, H: 3.53, N: 4.39; calculated for (C17H11Cl2NO) C:
64.58, H: 3.51, N: 4.43 (%).
4.2.3. Synthesis of (ZnL2)2 (1) A mixture of Zn(AcO)2$2H2O (7.4 mg,
0.02 mmol), HL (3.2 mg, 0.01 mmol), H2O (0.2 mL), DMF (0.2 mL),
and MeOH (2 mL) in a capped vial was heated at 80 ꢀC for 1 day.
Yellow block-like crystals of 1 were filtered, washed with MeOH
and Et2O, and dried at room temperature. Yield: 2.5 mg (72%). IR
(
lem, max) in solid state. With a precise knowledge of their
(KBr, n
/cmꢁ1): 3440.9, 3046.4, 1581.8, 1555.3, 1502.6, 1433.1, 1373.8,
single-crystal structures, the present research holds great prom-
ise in the development of novel multinuclear zinc(II) materials,
and may contribute to the understanding of structureeproperty
relationships.
1337.7,1285.9, 1176.2,1102.6, 961.6, 826.4, 774.4, 739.6, 610.0, 556.7,
515.0, 464.1, 423.4, 411.7. Elemental analysis: found C: 58.22, H:
2.83, N: 3.95; calculated for (C68H40Cl8N4O4Zn2) C: 58.70, H: 2.90,
N: 4.03 (%).

G.-Z. Yuan et al. / Tetrahedron 68 (2012) 8018e8023
8023
4.3. X-ray crystallography
Acknowledgements
Single-crystal XRD data for the compound was collected using
a Bruker Smart 1000 CCD diffractometer with Mo K radiation
This work was supported by the National Natural Science
Foundation of China (20802010, 21032006 and 21172047) and 211
project of Guangdong Province.
a
ꢀ
(l¼0.71073 A) at room temperature. The empirical absorption
correction was applied by using the SADABS program.32 The
structure was solved by using direct methods and refined by full-
matrix least-squares using F2.33 All other atoms were refined an-
isotropically in all compound 1. Crystal data and details of the data
collection are given in Table 1, whereas the selected bond dis-
tances and angles are presented in Table 2. The CCDC number is
873149.
Supplementary data
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2012.06.103.
These data include MOL files and InChIKeys of the most important
compounds described in this article.
Table 1
References and notes
Crystal data and structure refinement for 1
Identification code
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
1
C
1. Phillips, J. P. Chem. Rev. 1956, 56, 271.
68H40Cl8N4O4Zn2
2. Ballardini, R.; Varani, G.; Indelli, M. T.; Scandola, F. Inorg. Chem. 1986, 25, 3858.
3. Palacios, M. A.; Wang, Z.; Montes, V. A.; Zyryanov, G. V.; Hausch, B. J.; Jursikova,
K.; Jr, A.P. Chem. Commun. 2007, 3708.
4. Hollingshead, R. G. W. Oxine and Its Derivatives; Butterworths: London, 1954.
5. Tang, C. W.; VanSlyke, S. A. Appl. Phys. Lett. 1987, 51, 913.
6. Rai, V. K.; Srivastava, R.; Kamalasanan, M. N. Synth. Met. 2009, 159, 234.
7. Matsumoto, N.; Miyazaki, T.; Nishiyama, M.; Adachi, C. J. Phys. Chem. C 2009,
113, 6261.
8. Liu, Z. W.; Bian, Z. Q.; Hao, F.; Nie, D. B.; Ding, F.; Chen, Z. Q.; Huang, C. H. Org.
Electron. 2009, 10, 247.
9. Tao, Y. T.; Wang, Q.; Shang, Y.; Yang, C. L.; Ao, L.; Qin, J. G.; Ma, D. G.; Shuai, Z. G.
Chem. Commun. 2009, 77.
10. Chang, C. H.; Lu, Y. J.; Liu, C. C.; Yeh, Y. H.; Wu, C. C. J. Display Technol. 2007, 3,
1391.38
293(2) K
0.71073
Monoclinic
P2/n (13)
ꢀ
ꢀ
Unit cell dimensions
a¼14.648 (6) A
ꢀ
b¼9.509 (4) A
ꢀ
c¼20.341(8) A
3
ꢀ
Volume (A ), Z
2822.9(19), 2
Density (calculated) (mg/m3)
Absorption coefficient (mmꢁ1
F(000)
1.637
1.287
1408
1.65e26.01
)
193.
q
Range for data collection (ꢀ)
11. Liedtke, A.; O’Neill, M.; Wertmoller, A.; Kitney, S. P.; Kelly, S. M. Chem. Mater.
2008, 20, 3579.
Limiting indices
ꢁ18ꢂhꢂ12, ꢁ10ꢂkꢂ11, ꢁ24ꢂlꢂ25
Reflections collected
Independent reflections
Completeness to theta
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I>2
R indices (all data)
Largest diff. peak and hole (e A
12,534
12. Gather, M. C.; Alle, R.; Becker, H.; Meerholz, K. Adv. Mater. 2007, 19, 4460.
€
€
5524 [R(int)¼0.0612]
26.01/99.3%
13. Colle, M.; Gmeiner, J.; Milius, W.; Hillebrecht, H.; Bru tting, W. Adv. Funct. Mater.
2003, 13, 108.
Full-matrix least-squares on F2
5524/0/388
14. Brinkmann, M.; Gadret, G.; Muccini, M.; Taliani, C.; Masciocchi, N.; Sironi, A. J.
Am. Chem. Soc. 2000, 122, 5147.
15. Braun, M.; Gmeiner, J.; Tzolov, M.; Coelle, M.; Meyer, F. D.; Milius, W.; Helle-
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9625.
16. Huang, Q. L.; Li, J. F.; Marks, T. J. J. Appl. Phys. 2007, 101, 093101.
17. Sapochak, L. S.; Benincasa, F. E.; Schofield, R. S.; Baker, J. L.; Riccio, K. K. C.;
Fogarty, D.; Kohlmann, H.; Ferris, K. F.; Burrows, P. E. J. Am. Chem. Soc. 2002, 124,
6119.
0.997
s
(I)]
R1¼0.0492, wR2¼0.092
R1¼0.0816, wR2¼0.1027
0.645 and ꢁ0.387
ꢀꢁ3
)
18. Wang, P.; Hong, Z.; Xie, Z.; Tong, S.; Wong, O.; Lee, C.-S.; Wong, N.; Hung, L.; Lee,
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Table 2
Selected bond lengths [A] and angles [ ] for 1
ꢀ
ꢀ
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Zn(1)eO(2)
Zn(1)eO(1
Zn(1)eO(1)#1
1.959(2)
2.023(2)
2.090(2)
Zn(1)eN(2)
Zn(1)eN(1)
O(1)eZn(1)#1
2.132(3)
2.222(3)
2.090(2)
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O(2)eZn(1)eO(1)
O(2)eZn(1)eO(1)#1
O(1)eZn(1)eO(1)#1
O(2)eZn(1)eN(2)
O(1)eZn(1)eN(2)
O(1)#1eZn(1)eN(2)
O(2)eZn(1)eN(1)
O(1)eZn(1)eN(1)
O(1)#1eZn(1)eN(1)
169.89(10)
98.66(10)
74.95(11)
82.66(11)
107.15(11)
117.06(10)
101.55(10)
78.58(10)
135.08(10)
N(2)eZn(1)eN(1)
C(7)eN(1)eC(6)
105.07(11)
119.2(3)
132.0(2)
108.7(2)
119.4(3)
133.6(2)
106.0(2)
116.6(2)
132.3(2)
C(7)eN(1)eZn(1)
C(6)eN(1)eZn(1)
C(24)eN(2)eC(23)
C(24)eN(2)eZn(1)
C(23)eN(2)eZn(1)
C(1)eO(1)eZn(1)
C(1)eO(1)eZn(1)#1
32. Sheldrick, G. M. SADABS, Program for Empirical Absorption Correction of Area
€
€
Detector Data; University of Gottingen: Gottingen, Germany, 1996.
Symmetry transformations used to generate equivalent atoms: #1 -xþ3/
2, y, -zþ3/2.
33. Sheldrick, G. M. SHELXTL97, Program for Crystal Structure Refinement; University
€
€
of Gottingen: Gottingen, Germany, 1997.