Hydrothermal synthesis, structures, luminescence and magnetic properties of Zn(II) and Cu(II) complexes with new hydrazone ligand

Article abstract of DOI:10.1016/j.molstruc.2011.11.008

Two new complexes [Zn(HL)₂(py)₂] (1) and [Cu(HL)]₂ (2) have been synthesised from a bidentate Schiff base ligand HL (benzylidene acetophenone benzoyl hydrazone). The crystal structures of complex 1 and complex 2 were deter

Full text of DOI:10.1016/j.molstruc.2011.11.008

Journal of Molecular Structure 1018 (2012) 78–83
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Hydrothermal synthesis, structures, luminescence and magnetic properties
of Zn(II) and Cu(II) complexes with new hydrazone ligand
⇑
Chang-zheng Zheng, Liang Wang , Juan Liu
School of Environmental and Chemical Engineering, Xi’an Polytechnic University, Xi’an 710048, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 July 2011
Received in revised form 2 October 2011
Accepted 7 November 2011
Available online 29 November 2011
Two new complexes [Zn(HL)2(py)2] (1) and [Cu(HL)]2 (2) have been synthesised from a bidentate Schiff
base ligand HL (benzylidene acetophenone benzoyl hydrazone). The crystal structures of complex 1 and
complex 2 were determined by single-crystal X-ray diffraction. The data indicate that: the complex 1
crystallizes in the monoclinic space group P2(1)/n, with a (nm) = 1.35816(8), b (nm) = 2.39486(13),
c (nm) = 1.41368(8),
clinic space group Pꢀ1, with
(°) = 71.5020(10), b (°) = 78.5850(10),
site of metal ion is occupied by secondary ligand of pyridine. The mononuclear units in 1 and 2 are packed
and interactions respectively. The results of analytical, IR and TG analysis
a
(°) = 90, b (°) = 96.0840(10),
(nm) = 1.02483(8),
(°) = 74.3110(10), Z = 1. Moreover, the unsaturated coordination
c
(°) = 90, Z = 4. The complex 2 crystallizes in the tri-
a
b
(nm) = 1.35797(11), (nm) = 1.38271(11),
c
Keywords:
a
c
Hydrothermal synthesis
Hydrazone ligand
Complexes
Crystal structure
Luminescence
through weak CAHꢁ ꢁ ꢁ
p
p–p
studies are presented in this paper. Both the ligand and complex 1 show fluorescence in DMF solutions
at room temperature. The complex 2 variable-temperature (300–1.8 K) magnetic test show that there is
ferromagnetic intramolecular interaction and weak antiferromagnetic intermolecular interaction.
Ó 2011 Elsevier B.V. All rights reserved.
Magnetic properties
1. Introduction
been attracting much attention because of their chemical and
industrial versatility, and strong tendency to chelate to transition
Metal–organic coordination compounds have raised an upsurge
of interest in the fields of crystal engineering and functional mate-
rials, due to their intriguing structural features as well as desired
properties [1–4]. The rational design and synthesis of novel coordi-
nation complexes based on transition or non-transition metals and
multifunctional bridging ligands is of great research interest, due
to their interesting topologies and potential applications as func-
tional materials. Schiff bases are very interesting compounds be-
cause of their model character and practical applications [5,6]
and also these are very important classes of organic compounds
from both practical and theoretical points of view. Methods of syn-
thesis and numerous applications in organic chemistry of com-
pounds have been summarized [7]. In recent years, transition
metal complexes of asymmetrical Schiff base ligands have at-
tracted enormous attentions due to their diversity of molecular
structures [8–12] and important properties, such as catalysis,
porosity, chirality, luminescence, non-linear optics, ferroelectrics,
magnetism [13–21]. Hydrazone is not only an important com-
pound of Schiff bases but also a major polydentate ligands. Due
to their variable bonding when forming complexes with metal
ions, the coordination chemistry of hydrazones has been inten-
sively investigated. In terms of chemical field hydrazones have
metals [22,23], lanthanide metals [24] and main group metals
[25,26].
To the best of our knowledge, the chemical properties of com-
plexes can be tuned to force metal ions to adopt unusual coordina-
tion geometry. The present work is a part of our study on the metal
complexes of benzoyl hydrazone. Herein we report the synthesis,
structure, fluorescence and magnetic properties of the compounds,
C54H44N6O2Zn and C88H68N8O4Cu2. The procedure of synthesis (HL)
is shown in Scheme 1.
2. Experimental
2.1. Materials and measurements
All starting materials and solvents used in this work were of ana-
lytical grade and used as purchased from Sinopharm Chemical
Reagent Co. Ltd. without further purification. Elemental analyses
(C, H, N) were performed using a Vario EL elemental analyzer. FT-
IR spectrum was measured as KBr pellets on a Nicolet Nexus FT-IR
spectrometer in the 4000–400 cmꢀ1 region. Thermogravimetric
analyses (TGA) were carried out on a Perkin–Elmer Pyris-1, Thermo-
gravimetric analyzer operating at a heating rate of 10 K minꢀ1 in a
flow of dry oxygen-free nitrogen at 20 mL minꢀ1. Fluorescence mea-
surements were performed on a Model RF-5 spectrofluorimeter. The
temperature dependence magnetic susceptibilities were measured
⇑
Corresponding author. Tel.: +86 29 82330169.
E-mail address: wllily315668256@yahoo.com.cn (L. Wang).
0022-2860/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2011.11.008

C.-z. Zheng et al. / Journal of Molecular Structure 1018 (2012) 78–83
79
Scheme 1. Synthetic route of the ligand.
on polycrystalline samples with a Quantum Design SQUID MPMS-XL
susceptometer operating at a magnetic field 0.1 T over a tempera-
ture range 1.8–300 K. The crystal structures were determined by
single-crystal X-ray diffraction. SHELXS97, SHELXL97 software were
then used for structure solution and refinement correspondingly.
obtained. Anal. Calcd. (%) for C54H44N6O2Zn: C, 74.22; H, 5.13; N,
9.67. Found (%): C, 74.18; H, 5.07; N, 9.61. Selected IR (KBr pellet,
cmꢀ1):
m
(C@C) 1545;
m(CAN) 1209; m(NAH) 3244; m(CAO) 1276.
2.4. Preparation of the complex [Cu(HL)]2 (2)
2.2. Preparation of the ligand
A
mixture of HL (0.0326 g, 0.10 mmol), Cu(NO3)2ꢁ3H2O
(0.0242 g, 0.10 mmol) and H2O (5.00 mL), several drops of metha-
nol solution were placed in a Parr Teflon-lined stainless steel vessel
(25 mL), and then the vessel was sealed and heated at 413 K for 3 d.
After the mixture was slowly cooled to room temperature, several
blue crystals were obtained. Anal. Calcd. (%) for C88H68N8O4Cu2: C,
74.02; H, 4.83; N, 7.81. Found (%): C, 73.98; H, 4.80; N, 7.85. Se-
Acetophenone (3.00 g, 0.025 mol), benzaldehyde (2.66 g,
0.025 mol) and sodium hydroxide (12.5 mL, concentration: 10%)
were mixed in 7.50 mL ethanol at room temperature and the
mixture was refluxed for 7 h stirringly. Then the crystals were
precipitated and collected by filtration. Finally the product was
recrystallizedfrom ethanoland driedunder reduced pressure to give
compound of benzylidene acetophenone. Yield: 76%. The schematic
diagram showing the synthesis of it is shown in Scheme 1. Anal.
Calcd. (%) for C15H12O: C, 86.42; H, 5.76; N, 0. Found (%): C, 86.50;
lected IR (KBr pellet, cmꢀ1):
3241; (CAO) 1268.
m(C@C) 1551; m(CAN) 1213; m(NAH)
m
2.5. X-ray crystal structure determinations
H, 5.81; N, 0. Selected IR (KBr pellet, cmꢀ1):
(C@O) 1741; (C@C) 1650.
Ethyl benzoate (3.76 g, 0.025 mol) was dissolved in anhydrous
m(C@C)ar 1598, 1503;
m
m
Diffraction intensities for two complexes were collected on a
Bruker SMART 1000 CCD area-detector with Mo Ka radiation
(k = 0.71073 Å) using an
and 2). Diffraction intensity data were collected in the h range of
1.73–25.05 for complex 1 and 1.62–25.05 for complex 2. The col-
lected data were reduced using the SAINT program [27], and
empirical absorption corrections were performed using the SAD-
ABS program [28]. Two structures were solved by direct methods
and refined using full-matrix least square techniques on F2 with
ethnol (20 mL) at room temperature and heated at 363 K. Hydra-
zine hydrate (1.50 g, 0.030 mol) was added into the mixture. After
being refluxing for 7–8 h, the mixture was cooled to room temper-
ature. Then the crystals were precipitated and collected by filtra-
tion. Finally, the product was recrystallized from ethanol and
dried under reduced pressure to give compound of benzoyl hydra-
zine. Yield: 72% (synthetic route is described as Scheme 1). Anal.
Calcd. (%) for C7H8N2O: C, 61.71; H, 5.84; N, 20.51. Found (%): C,
x scan mode at 298 2 K (complexes 1
61.75; H, 5.92; N, 20.58. Selected IR (KBr pellet, cmꢀ1):
1592, 1522; (C@O) 1735; (NAH) 3253; (CAN) 1205.
m(C@C)
m
m
m
Table 1
Crystal data and structure refinement for complexes 1–2.
Benzoyl hydrazine (3.13 g, 0.023 mol) was dissolved in anhy-
drous ethnol (30 mL) at room temperature and heated at 373 K.
Benzylidene acetophenone (4.79 g, 0.023 mol) was added into the
mixture. After being refluxing for 7–8 h, the mixture was cooled
to room temperature. Then the crystals were precipitated and col-
lected by filtration. Finally, the product was recrystallized from
ethanol and dried under reduced pressure to give compound ben-
zylidene acetophenone benzoyl hydrazone (HL). Yield: 65% (syn-
thetic route is described as Scheme 1). Anal. Calcd. (%) for
1
2
Formula
Fw
T (K)
Cryst. syst.
Space group
a (Å)
C
54H44N6O2Zn
C88H68N8O4Cu2
1428.66
874.32
298(2)
298(2)
Monoclinic
P2(1)/n
13.5816(8)
23.9486(13)
14.1368(8)
90
96.0840(10)
90
4572.2(4)
4
Triclinic
Pꢀ1
10.2483(8)
13.5797(11)
13.8271(11)
71.5020(10)
78.5850(10)
74.3110(10)
1743.6(2)
1
b (Å)
c (Å)
C
22H18N2O: C, 80.86; H, 5.52; N, 8.52. Found (%): C, 80.98; H,
5.56; N, 8.59. Selected IR (KBr pellet, cmꢀ1):
(C@C) 1602;
(C@O) 1682; (C@N) 1628; (CAN) 1215.
a
(°)
b (°)
m
c
(°)
m
m
m
V (Å3)
Z
q
calcd. (mg mꢀ3
)
1.270
1.361
2.3. Preparation of the complex [Zn(HL)2(py)2] (1)
F(000)
1824
742
h rang.(°)
l
k (Å)
R (int)
R1, wR2[I > 2
R1, wR2 (all data)
Peak and hole (eÅꢀ3
1.73–25.05
0.585
0.71073
0.0304
0.0480, 0.1391
0.0755, 0.1632
0.725, ꢀ0.564
1.62–25.05
0.671
0.71073
A
mixture of HL (0.0326 g, 0.10 mmol), Zn(NO3)2ꢁ6H2O
(mmꢀ1
)
(0.0297 g, 0.10 mmol), pyridine (0.0079 g, 0.10 mmol) and H2O
(5.00 mL), several drops of methanol were placed in a Parr
Teflon-lined stainless steel vessel (25 mL), and then the vessel
was sealed and heated at 413 K for 3 d. After the mixture was
slowly cooled to room temperature, several colorless crystals were
0.0200
r(I)]
0.0407, 0.0899
0.0579, 0.0968
0.220, ꢀ0.273
)

80
C.-z. Zheng et al. / Journal of Molecular Structure 1018 (2012) 78–83
Table 2
Selected bond distances (Å) and bond angles (°) for complexes 1–2.
Distances
Å
Angle
°
Angle
°
1
Zn(1)AO(1)
Zn(1)AO(2)
Zn(1)AN(5)
Zn(1)AN(2)
Zn(1)AN(4)
Zn(1)AN(6)
2.065(2)
2.075(2)
2.166(3)
2.173(3)
2.220(3)
2.231(3)
O(1)AZn(1)AO(2)
O(1)AZn(1)AN(5)
O(2)AZn(1)AN(5)
O(1)AZn(1)AN(2)
O(2)AZn(1)AN(2)
N(5)AZn(1)AN(2)
175.24(9)
86.89(10)
88.44(10)
75.46(10)
109.23(10)
162.26(12)
O(2)AZn(1)AN(4)
N(5)AZn(1)AN(4)
N(2)AZn(1)AN(4)
O(1)AZn(1)AN(6)
O(2)AZn(1)AN(6)
N(2)AZn(1)AN(6)
74.56(10)
89.54(11)
93.64(10)
87.95(11)
91.58(10)
86.03(11)
2
Cu(1)AO(1)
Cu(1)AO(2)
Cu(1)AN(4)
Cu(1)AN(2)
1.8902(15)
1.9278(15)
2.025(2)
O(1)ACu(1)AO(2)
O(1)ACu(1)AN(4)
O(2)ACu(1)AN(4)
O(1)ACu(1)AN(2)
177.79(7)
97.61(7)
80.36(7)
80.58(7)
O(2)ACu(1)AN(2)
N(4)ACu(1)AN(2)
C(7)AO(1)ACu(1)
N(1)AN(2)ACu(1)
101.16(7)
165.30(8)
112.37(14)
110.53(13)
2.0373(19)
Table 3
CAHꢁ ꢁ ꢁ
p parameters donor/acceptor scheme (Å, °) for 1.
DAHꢁ ꢁ ꢁA
DAH
Hꢁ ꢁ ꢁA
Dꢁ ꢁ ꢁA
DAHꢁ ꢁ ꢁA
C47AH47ꢁ ꢁ ꢁCg1
C46AH46ꢁ ꢁ ꢁCg2
0.931
0.931
2.197
2.687
3.076
3.495
128.284
151.747
the program SHELXL-97 [29]. All non-hydrogen atomic positions
were located in difference Fourier maps and refined anisotropi-
cally. Some of hydrogen atoms were placed in their geometrically
generated positions and other hydrogen atoms were located from
the different Fourier map and refined isotropically. Crystallo-
graphic data are given in Table 1. Selected bond distances and an-
Fig. 2. Coordinated circumstance of Zn(II).
gles are given in Table 2. CAHꢁ ꢁ ꢁ
p parameters donor/acceptor
scheme (Å, °) for 1 are given in Table 3.
distances are 2.065(2) Å and 2.075(2) Å, respectively, which are
shorter than reported [30]. C(7)AN(1) (1.318(4) Å), C(29)AN(3)
(1.313(4) Å) and C(30)AN(4) (1.304(4) Å) are longer than the
C@N double bond (1.30 Å), but shorter than the CAN single bond
(1.443 Å). Different angles around the zinc atom and their sum of
360.02° indicate a nearly coplanar geometry of the metal environ-
ment. The N(4)AZn(1)AN(6) angle is 165.23°, which indicates that
N(4) and N(6) are closely located at the vertical line of the plane.
The bonds of [C(7)AO(1) (1.278(4) Å), C(29)AO(2) (1.287(4) Å),
C(7)AN(1) (1.318(4) Å), C(29)AN(3) (1.313(4) Å)] are compared
with [CAO (1.43 Å), C@O (1.20 Å), CAN (1.47 Å), C@N (1.27 Å)] sug-
gesting an enol coordination model for ligands. Bond lengths of
C(6)AC(7) (1.494(5) Å) and C(8)AC(15) (1.453(5) Å) confirm the
sp2 hybridization of carbon atom [31]. The mononuclear units in
3. Results and discussion
3.1. Structure descriptions of the complex 1
As shown in Fig. 1, there is one independent molecule in the
asymmetric unit. Complex 1 is mononuclear six-coordinated zinc.
The coordination environment of Zn is comprised of two pyridine
ligands and two hydrazone ligands (two O atoms, four N atoms).
The zinc(II) center in 1 adopts a similar to distorted octahedron
configuration (Fig. 2). O1, N2, O2 and N5 constitute a pyramid’s
bottom. N4 and N6 occupy the top position, which complete the
coordination environment of Zn center. The bond lengths of
Zn(1)AN(2), Zn(1)AN(4), Zn(1)AN(5) and Zn(1)AN(6) are
2.173(3) Å, 2.220(3) Å, 2.166(3) Å and 2.231(3) Å, respectively,
these data indicate the bonds are very close to the complex with
identical coordination [30]. The Zn(1)AO(1), Zn(1)AO(2) bond
1 are packed alongside with each other through weak CAHꢁ ꢁ ꢁ
p
interactions. Along with this shortest interaction (H47 to the cen-
troid of ring C1AC6: 2.197 Å) propagating crystallographic c-axis,
another relatively weak CAHꢁ ꢁ ꢁ
p interaction (H46 to the centroid
of ring C9AC14: 2.687 Å) runs in the direction of c-axis with the
formation of a 2D sheet structure (Fig. 3). For 1, Cg1 phenyl ring
C1AC6 at x, y, z; Cg2 phenyl ring C9AC14 at ꢀ0.5 + x, 0.5 ꢀ y,
ꢀ0.5 + z.
3.2. Structure descriptions of the complex 2
The structure of compound 2 is shown in Fig. 4, accompanied by
an atomic numbering scheme for the asymmetric unit. Complex 2
is dinuclear five-coordinated copper. The coordination environ-
ment of Cu is comprised of two hydrazone ligands (three O atoms,
two N atoms). The copper(II) center in 2 adopts a structure which is
similar to double-pyramid configuration (Fig. 5). O1, N2, O2 and N4
constitute a pyramid’s bottom. O2A occupies the top position,
which complete the coordination environment of Cu center
Fig. 1. Molecular structure of the title complex 1.

C.-z. Zheng et al. / Journal of Molecular Structure 1018 (2012) 78–83
81
Fig. 3. A view of 2D sheet structure in 1 formed through CAHꢁ ꢁ ꢁ
p interactions.
Fig. 6. A view of 2D sheet structure in 2 formed through p–p interactions.
Fig. 4. Molecular structure of the title complex 2.
[33]. C(7)AN(1)(1.309(3) Å) and C(8)AN(2) (1.317(3) Å) are longer
than the C@N double bond (1.30 Å) but shorter than the CAN sin-
gle bond (1.443 Å). Different angles around the copper atom and
their sum of 359.71° indicate a nearly coplanar geometry of the
metal environment. The bonds of [C(7)AO(1) (1.292(3) Å),
C(29)AO(2) (1.308(3) Å), C(7)AN(1) (1.309(3) Å), C(29)AN(3)
(1.301(3) Å)] are compared with [CAO (1.43 Å), C@O (1.20 Å),
CAN (1.47 Å), C@N (1.27 Å)] suggesting an enol coordination mod-
el for ligands. Bond lengths of C(6)AC(7) (1.476(3) Å) and
C(8)AC(15) (1.443(3) Å) confirm the sp2 hybridization of carbon
atom [31]. The dinuclear units in 2 are packed alongside with each
other through weak
p–p interactions. There are p–p interactions
between the aromatic rings of the neighboring chain with a cen-
troid–centroid distance between neighboring aromatic rings of
3.3624(4) Å, generating an extended two-dimensional architecture
(Fig. 6). For 2, Cg1 phenyl ring C17AC22 at 1 ꢀ x, 1 ꢀ y, ꢀz; Cg2
phenyl ring C39AC44 at 1 ꢀ x, 1 ꢀ y, 1 ꢀ z.
Fig. 5. Coordinated circumstance of Cu(II).
(symmetry code: [1 ꢀ x, 1 ꢀ y, 1 ꢀ z]). The bond lengths of
Cu(1)AN(2) and Cu(1)AN(4) are 2.037(19) Å and 2.025(2) Å. These
are very close to the complex with identical coordination [32]. The
Cu(1)AO(1), Cu(1)AO(2) bond distances are 1.890(15) Å and
1.928(15) Å, respectively, which are shorter than the reported
3.3. Thermogravimetric analysis
Thermogravimetric analysis (TGA) was carried out to examine
the thermal stability of the two compounds. The crushed single-
crystal sample was heated up to 1000 °C in N2 at a heating rate

82
C.-z. Zheng et al. / Journal of Molecular Structure 1018 (2012) 78–83
Fig. 7. TG curves of compounds 1 and 2.
Fig. 8. Emission spectra: fluorescence in DMF solutions at 298 K of ligand and
complex 1.
of 10 °C minꢀ1. The typical TG curves of the two compounds are
shown in Fig. 7, respectively.
The TG curves for 1 show that it is stable up to 158.39 °C with-
out any weight loss, which means the compound could retain
structural integrity to 158.39 °C. From 158.39 to 191.68 °C, the to-
tal loss of 16.95% is consistent with the pyrolysis of pyridyl frag-
ments. From 296.79 to 334.10 °C, the total loss of 70.48% is
consistent with the pyrolysis of coordinated benzoyl hydrazine
fragments and benzene-methyl phenylethyl fragments. The final
residue was probably ZnO (remaining weight: found: 9.26%, calcd.
12.57%).
The TG curves for 2 show that it is stable up to 291.05 °C with-
out any weight loss, which means the compound could retain
structural integrity to 291.05 °C. From 291.05 to 363.05 °C, the to-
tal loss of 84.39% is consistent with the pyrolysis of benzene-
methyl phenylethyl fragments and hydrazine groups fragments.
The final residue was probably CuO (remaining weight: found:
11.19%, calcd. 15.61%).
with a Quantum Design (SQUID) magnetometer MPMS-XL-5 in a
field of 1000 Oe (Fig. 9) on a powdered fresh sample from the same
uniform batch. Moreover, we use a dinuclear copper model with
H ¼ ꢀ2JS1S2 (S1 = S2 = 1/2) given by the equation as follows:
^
^ ^
ꢀ
ꢁ
2Ng2b2
5 þ expðꢀ4J=KTÞ
vM
¼
KðT ꢀ hÞ 5 þ 3 expðꢀ4J=KTÞ þ expðꢀ6J=KTÞ
to simulate the experimental results of vMT vs. T and vM vs. T plots
[37]. vM is the dinuclear copper complexes molecular moore sus-
ceptibility; h is the Curie–Weiss parameters; N is the Avogadro’s
constant; g is the Landé factor; K is the Boltzmann constant; b is
the Bohr magneton; T is the temperature; J is the dinuclear copper
units of magnetic interaction parameters.
As can be seen from Fig. 9, the complex 2 with
temperature and increase gradually, in 12 K, M value began near a
sharp increase. As can be seen from the plots of experimental data,
the experimental
MT value at 300 K is 1.17 emu K molꢀ1. These
values are the expected ones for two magnetically quasi-isolated
spin doublets. Upon cooling down, the MT value continuously in-
creases, reaching a maximum value of 1.27 emu K molꢀ1 at 50 K.
This behavior of the MT curve shows that there exist ferromag-
netic interactions in complex 2. As the temperature further
reduced, MT value has decreased, indicating weakinter
vM value of lower
v
3.4. Luminescence behaviors
v
The photoluminescence behavior of the free Schiff base ligand
(HL) and its corresponding zinc(II) compounds were studied in
the solid state at room temperature. The emission spectra of HL
and compound 1 are depicted in Fig. 8. Upon photoexcitation at
402 nm, the free HL exhibits a broad fluorescent emission centered
at 409 nm and 436 nm. Upon photoexcitation at 452 nm, the corre-
sponding compound 1 show more intense photoluminescence
with the main emission at 463 nm. The emission band for com-
pound 1 is different to that found for the free ligand in terms of
v
v
v
a
position and band shape. Therefore, the luminescence behaviors
1
[34–36] in 1 may be attributed to the intraligand
(p–
p⁄) transi-
tion, and greater intensity may presumably be due to the increase
in conformational rigidity of the ligand upon coordination. Mean-
while, compared with the emission spectrum of HL, a apparently
red shift of 54 nm in 1 has been observed, which is considered to
mainly arise from the coordination effect of Zn(II) with the ligand.
Furthermore, the incorporation of Zn(II) effectively increases the
conformational rigidity of HL and reduces the loss of energy via
vibration motions. Thus, the enhanced fluorescence intensities of
the two compounds are detected.
3.5. Magnetic properties
Variable temperature magnetic susceptibility vM measure-
ments (in the range of 1.8–300 K) for complex 2 were carried out
Fig. 9. Temperature dependence of vM and
vMT vs. T for complex 2.

C.-z. Zheng et al. / Journal of Molecular Structure 1018 (2012) 78–83
83
molecular antiferromagnetic coupling effect. A best fit leads to the
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sion, magnetic results show that there is a ferromagnetic intramo-
lecular interaction and weak antiferromagnetic intermolecular
interaction in the complex 2.
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Its transition metal complexes ([Zn(HL)2(py)2], [Cu(HL)]2) are
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1
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Crystallographic data (excluding structure factors) for the struc-
ture(s) reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publi-
cation numbers: CCDC_827557 (1), CCDC_827558 (2). These data
can be obtained free of charge from the Cambridge Crystallo-
graphic Data Centre (CCDC), CCDC, 12, Union Road, Cambridge
CB2 1EZ, UK; fax: +44 1223 336 033; E-mail: deposit@ccdc.
cam.ac.uk.
Acknowledgment
We thank the Natural Science Foundation of Shaanxi Province,
People’s Republic of China (2009JM2012) for financial support.