Syntheses, crystal structures, and fluorescent studies of Cu(II) and Zn(II) complexes bearing 2-acetonaphthonebenzoylhydrazone ligand

Article abstract of DOI:10.1080/24701556.2016.1278554

Two new mononuclear metal–organic complexes with hydrazone ligand, namely bis(2-acetonaphthonebenzoylhydrazonato)copper and bis(2-acetonaphthonebenzoylhydrazonato)zinc have been prepared. The complexes have been characterized by physicochemical methods an

Full text of DOI:10.1080/24701556.2016.1278554

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Syntheses, Crystal Structures and Fluorescent Studies of Cu(II) and Zn(II) Complexes
Bearing 2-Acetonaphthonebenzoylhydrazone Ligand
Yueqin Li1,*, Zhiwei Yang1, Benteng Song2, Hongqiang Xia2, Zhuye Wang1
1School of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, P. R. China
2State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Centre for
Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science,
Wuhan 430071, P. R. China
*Corresponding author. Email: yueqinli@163.com
Two new mononuclear metal-organic complexes with hydrazone ligand, namely
bis(2-acetonaphthonebenzoylhydrazonato)copper
and
bis(2-acetonaphthonebenzoylhydrazonato)zinc have been prepared. The complexes have
been characterized by physico-chemical methods and single crystal X-ray diffraction study.
The Cu and Zn atoms in both complexes are coordinated by N and O donor atoms of ligand,
forming a distorted tetrahedral geometry. Optical properties of the metal complexes were
studied by UV–Vis absorption and photoluminescence emission spectroscopy. Geometry
optimization, the highest occupied molecular orbital (HOMO) and lowest unoccupied
molecular orbital (LUMO) energy levels as well as the energy gap of both complexes have
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been carried out by DFT calculations.
Keywords
2-acetonaphthonebenzoylhydrazone; Cu(II) complex; Zn(II) complex; photoluminescence; DFT
calculations
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INTRODUCTION
Hydrazones are a special group of compounds in the Schiff base family. They are characterized
by the presence of >C=N–N=C<. The presence of two inter-linked nitrogen atoms was separated
from imines, oximes, etc. Hydrazones are considered privileged Schiff base ligands because they
are easily prepared by a simple one-pot condensation reaction by using of carbonyl compound
and primary amines as starting materials.[1] Hydrazone Schiff bases of acyl, aroyl and
heteroacroyl compounds have an additional donor sites like C=O, which makes them more
flexible and versatile. This versatility has made hydrazones good polydentate chelating agents
that can form a variety of complexes with various transition and inner transition metals and have
attracted the attention of many researchers. The coordination behaviour of hydrazones is known
to depend on the pH of the medium, the nature of the substituents and also on the position of the
hydrazone group relative to other moieties. Moreover, deprotonation of the –NH group, which is
readily achieved in the complexes ligand in particular, results in the formation of tautomeric
anionic species (–C(O)–NH–N=C< ↔ –C(OH)=N–N=C< ↔–C(O-)=N–N=C<), having new
coordination properties.[2, 3]
Hydrazones containing complexes play an important role as pharmaceutical chemicals,
biological materials[4] and in pharmacology,[5] due to their sensitivity and selectivity to metal
ions.[6] On the other hand, some transition metal complexes based on hydrazone ligands are of a
considerable interest. Cu(II) complexes are shown as potent inhibitor of DNA synthesis and cell
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growth,[7] others are studied as therapeutic agents in the treatment of cancer,[8] and some have
potential for Alzheimer disease therapy.[9] Recently, a number of attempts have been made to
obtain Co(II), Ni(II), Cu(II) and Zn(II) complexes with o-amino acetophenone benzoyl
hydrazone, which have been well characterized by elemental analyses and spectral data.[10] Cu(II)
and Ni(II) complexes containing anthranoylhydrazone ligands and heterocyclic coligand have
been synthesized by Gup group.[2, 3] Recently, this group have investigated the DNA binding and
cleavage properties of Cu(II) complexes based on acylhydrazone ligands, and they found the
copper complexes show nuclease activity.[11, 12]
All these reported complexes were characterized using spectroscopic techniques and the
structures were proposed accordingly. Yet, none was characterized unambiguously by its crystal
structure. Herein, we were motivated to report the synthesis and characterization of Cu(II) and
Zn(II) complex based on 2-acetonaphthonebenzoylhydrazone ligand along with the crystal
structure of the obtained complexes, and to described thermogravimetric, spectroscopic and
electrochemical properties of both complexes. DFT calculations were also carried out in an
attempt to compare theoretical and experimental structures of such compounds with some
physical aspects.
EXPERIMENTAL
Materials and Measurements
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All chemicals and solvents were obtained from commercial sources as reagent grade and used
without further purification in the syntheses. Melting points were measured on a WRS-1B digital
melting point apparatus. Elemental analyses for C, H and N were performed on a Perkin Elmer
240 C elemental analyzer. The FT-IR measurements (KBr pellets) were recorded in the range of
400–4000 cm-1 on the instrument of Thermo Nicolet Nexus 670 infrared spectrometer. NMR
spectra were recorded on a Bruker Advance 300 spectrometer at resonant frequencies of 300
1
13
MHz for H and 75 MHz for C nuclei using CDCl3 as solvent and tetramethylsilane as the
reference. The UV-Vis spectra of the ligand and complexes were obtained on a Varian Cary 300
UV-Vis spectrophotometer in chloroform solution. Fluorescence emission spectra were
measured with Varian Cary Eclipse Fluorescence spectrometer at room temperature.
Synthesis of 2-Acetonaphthonebenzoylhydrazone Ligand (HL)
To a solution of 2-acetonaphthone (1.360 g, 8 mmol) in anhydrous ethanol (40 mL) was added
two drops of glacial acid. A solution of benzoylhydrazine (1.089 g, 8 mmol) in anhydrous
ethanol (20 mL) was added dropwise over a period of 10 min with stirring. The desired
benzoylhydrazone precipitated during the reaction. After refluxing the reaction mixture for 6 h,
the product was filtered and washed several times with anhydrous ethanol and recrystallized
from toluene, giving light yellow needle-like solid. Yield 2.12 g (92 %). M.p. = 196 – 197 ºC.
Anal. Calcd. for C19H16N2O (FM 288.34): C 79.14, H 5.59, N 9.72; Found: C 79.34, H 5.69, N
9.96 %. 1H NMR (ppm, 300 MHz, CDCl3): 9.02 (s, 1 H, N–H), 7.48~7.88 (m, 11 H, Ar–H), 8.17
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(s, 1 H, 1-naphthalene ring), 2.44(s, 3 H, -CH3); 13C NMR (ppm, 75 MHz, CDCl3): 164.0, 154.9,
135.5, 134.1, 133.3, 132.7, 131.4, 128.5, 128.3, 127.9, 127.7, 127.5, 126.8, 126.4, 123.6, 14.3
ppm. FTIR data (KBr, cm-1): 3348, 3060, 2966, 2926, 1666, 1583, 1521, 1489, 1379, 1269, 947,
743, 706.
Synthesis of Bis(2-acetonaphthonebenzoylhydrazonato)copper (CuL2)
A solution of copper(II) acetate monohydrate (0.080 g, 0.4 mmol) in 10 mL of acetonitrile/
tetrahydrofuran (V/V=1:1) mixed solvent was added dropwise with stirring to a solution of
2-acetonaphthonebenzoylhydrazone (0.231 g, 0.8 mmol) in 20 mL of acetonitrile/
tetrahydrofuran (V/V=1:1) mixed solvent. The reaction mixture was stirred for 4 h at room
temperature to give a dark green solution. Upon keeping the solution in air for about a week,
black block-like single crystals suitable for X-ray diffraction were deposited at the bottom of the
vessel. The isolated product was washed three times with cold methanol, and dried in a vacuum
over night. Yield 0.153 g (60 %). M.p.: 223 – 224 ºC. Anal. Calcd. for C38H30O2N4Cu (FM
638.20): C 71.51, H 4.74, N 8.78 %; Found: C 71.37, H 4.43, N 9.08 %. FTIR data (KBr, cm-1):
3052, 2926, 2847, 1598, 1493, 1442, 1370, 995, 750, 711, 591, 528.
Synthesis of Bis(2-acetonaphthonebenzoylhydrazonato)zinc (ZnL2)
A solution of zinc(II) acetate dihydrate (0.088 g, 0.4 mmol) in 10 mL of methanol was added
dropwise with stirring to a solution of 2-acetonaphthonebenzoylhydrazone (0.231 g, 0.8 mmol)
in 20 mL of methanol. The reaction mixture was stirred for 4 h at room temperature to give a
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colorless solution. Upon keeping the solution in air for about a week, colorless needle-like single
crystals suitable for X-ray diffraction were deposited at the bottom of the vessel. The isolated
product was washed three times with cold methanol, and dried in a vacuum over night. Yield
0.169 g (66 %). M.p.: 263 – 264 ºC. Anal. Calcd. for C38H30O2N4Zn (FM 640.03): C 71.31, H
1
4.72, N 8.75; Found: C 71.15, H 4.77, N 8.73 %. H NMR (ppm, 300 MHz, CDCl3): 7.14~7.81
(m, 11 H, Ar–H), 8.19 (s, 1 H, 1-naphthalene ring), 1.98 (s, 3 H, -CH3); 13C NMR (ppm, 75 MHz,
CDCl3): 171.5, 164.4, 135.5, 135.4, 133.7, 132.5, 130.6, 128.9, 128.2, 127.9, 127.5, 127.4, 126.8,
126.3, 123.4, 17.2. FTIR data (KBr, cm-1): 3059, 2930, 2850, 1590, 1510, 1441, 1366, 996, 750,
708, 601, 531.
Crystal Structure Determination
The X-ray single-crystal data for HL, CuL2 and ZnL2 were recorded on a Brucker SMART Apex
CCD detector diffractometer with graphite-monochromated MoKα radiation (λ = 0.71073 Å).
The collected data were reduced using the SAINT program,[13] and multi-scan absorption
corrections were performed using the SADABS program.[14] The structures were solved by direct
methods and refined by full-matrix least squares on F2 using SHELXL-97.[15] All non-hydrogen
atoms were refined anisotropically. Experimental details for X-ray data collection of HL and
both of complexes are presented in Table 1. Selected bond lengths and angles are given in Table
2. Crystallographic data for HL, CuL2 and ZnL2 have been deposited with the Cambridge
Crystallographic Data Centre (CCDC 1463822, 1486530 and 748315).
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RESULTS AND DISCUSSION
Synthesis of HL and the Complexes
The reaction of 2-acetonaphthone with benzoylhydrazine in anhydrous ethanol gave
2-acetonaphthonebenzoylhydrazone as a pale yellow crystalline solid. Then two metal
complexes were prepared by the reaction of copper acetate monohydrate and zinc acetate
dihydrate with 2-acetonaphthonebenzoylhydrazone in stoichiometry, respectively. Synthetic
route for complexes are shown in Scheme 1. Complexes are very stable to moisture and oxygen.
The complexes are insoluble in ethanol and methanol, whereas they are highly soluble in toluene,
dichloromethane, chloroform, and N,N-dimethylformamide.
General Characterization of the Complexes
According to the literatures,[2, 3] hydrazone ligands exist in keto or enol tautomeric form in the
solid. In FTIR spectrum of the free ligand (Figure 1), the stretching vibration of υ(N–H) occurred
at 3349 cm-1; Strong υ(C=O) absorption band was observed at 1666 cm-1 which indicated it was
in the keto form in the solid state.[16] The absorption peak at 1521 cm-1 was assigned to the
stretching vibration of C=N group. However, in the FTIR spectra of the complexes, υ(C=O),
υ(C-N) and υ(N-H) stretching vibrations disappears but two new bands are observed at 1493,
1366 cm-1 of CuL2 and 1510, 1370 cm-1 of ZnL2 due to the >C=N–N=C< and C–O stretches,
respectively, suggesting that the coordination takes place in enol tautomeric form. Furthermore,
1
HL and ZnL2 were characterized by NMR spectroscopy (Figure 2). When compared the H
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NMR spectra of ZnL2 and that of the free ligand, the chemical shift of -CH3 showed upfield
shifting from 2.44 ppm of free ligand to 1.98 ppm. Also, chemical shifts of the aromatic protons
(7.14 ~ 7.81 ppm) moved upfield comparing with those in free ligand (7.48 ~ 7.88 ppm). The
disappearance of the nitrogen-bonded proton signal (9.02 ppm) also verified the successful
reaction of the active hydrogen atom of HL with zinc acetate dihydrate. These data were in good
agreement with previously reported for the similar compounds.[17] Although a resolvable NMR
spectrum of CuL2 could not be measured owing to paramagnetism, the results of the elemental
analysis are consistent with the required by the proposed formula. The spectroscopic data and the
elemental analysis results in affair agreement with the expected structures suggest the successful
preparation of HL and the target complexes.
Structure Description of the HL and the Complexes
Molecular structures of HL and complexes were depicted in Figure 3, Figure 4 and Figure 5,
respectively. Selected bond distances (Ǻ) and bond angles (°) were given in Table 2. In HL, the
imine-N and carbonyl-O provides a fixed coordination mode with NO bidentates. The C(7)–O(1),
N(1)–N(2) , N(1)–C(3) and N(2)–C(7) bond distances of 1.2203(18), 1.3876(16), 1.2867(18) and
1.3511(19) Å, respectively, are consistent with C=O double bond, N-N single bond, C=N double
bond and N-C single bond. The conjugated system of the ligand makes its planar molecular
structure. In both complexes, the ligand coordinated to either Cu or Zn atom in enol tautomeric
form. The ligand acts as bidentate monobasic bonding through azomethine nitrogen atoms (N1,
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N2) and deprotonated enolate groups (O1, O2) forming a distorted tetrahedral geometry around
metal atoms.
Specifically, as for CuL2, it crystallizes in the space group P21/c. The bond lengths for
Cu(1)–O(1), Cu(1)–O(2), Cu(1)–N(2) and Cu(1)–N(4) are 1.907 (3), 1.897(3), 1.942(4) and
1.967(4) Å, respectively. The variation in Cu(1)–N(2) and Cu(1)–N(4) indicates the different
strength of the bond formed by each of the coordination nitrogen atoms. The single bond of
N(1)–C(7) and N(3)–C(26) are 1.294(6) and 1.303(6) Å, respectively, which are shorter than that
of N(2)-C(7) (1.3511(19) Å) in the free ligand. These bond lengths are in agreement with that of
other acylhydrazone complexes in which the acylhydrazone ligand takes enolic form.[18]
However, the C(7)–O(1) and C(26)–O(2) bond length of 1.284(6) and 1.285(6) nm are longer
than that of C(7)–O(1) (1.2203(18) Å) in HL. These data approach the value of 1.282(6) Å
expected for an enolic form of the acylhydrazone ligand.[19] The bond angles of O(2)–Cu(1)–N(4)
(81.12(15)o), N(2)–Cu(1)–N(4) (110.05(16)o) and O(2)–Cu(1)–O(1) (104.20(14)o) indicate
distortion
from
perfect
tetrahedron
angle.
The
dihedral
angle
between
O(1)–C(7)–N(1)–N(2)–Cu(1) plane (plane 1) and O(2)–C(26)–N(3)–N(4)–Cu1 plane (plane 2) is
of 47.97°.
While in ZnL2, the bond distances for Zn–N(1) and Zn–N(2) are 1.995(5) and 2.009(5) Å,
respectively, which are comparable to the bond lengths reported for similar
bis[N-(1-pyrenylmethyl)salicylideneaminato]zinc (2.005 Å) in the literature.[20] The bond
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distances for Zn–O(1) and Zn–O(2) are 1.943(4) and 1.946(4) Å, respectively, which are longer
than that of bis[N-(1-pyrenylmethyl)salicylideneaminato]zinc (1.912 Å).[20] The N(1)–N(4) and
N(2)–N(3) distances are 1.377(6) and 1.395(6) Å for Zn(II) complex, while the N(1)-N(2)
distance of the ligand is 1.3876(16) Å. These N-N distances can be comparable with those of
zinc(II) acylhydrazone complexes reported in literatures.[21, 22] The double bond of N(3)–C(6)
and N(4)–C(3) are 1.313(7) and 1.340(8) Å, respectively, which are shorter than that of N(2)-C(7)
(1.3511(19) Å) in the free ligand. However, the C(6)–O(2) and C(3)–O(1) bond length of 1.293(6)
and 1.292(7) Å are longer than that of C(7)–O(1) (1.2203(18) Å) in the free ligand. The angles of
N(1)–Zn–O(1) and N(2)–Zn–O(2) are 81.30(19) and 81.49(18)°, respectively, which are smaller
than that of the ideal tetrahedron angle. However, the angles of N(1)–Zn–N(2) and O(1)–Zn–O(2)
are much larger up to 116.9(2) and 117.89(17)°, respectively. The N(1)–N(4)–C(3)–O(1)–Zn
plane (plane 1) and N(2)–N(3)–C(6)–O(2)–Zn plane (plane 2) are roughly perpendicular to each
other with a dihedral angle of 73.67°. The copper and zinc ions have an N2O2 tetrahedral
coordination sphere as reported for some bis(schiff-base)zinc complexes.[23] All these data
indicate the 2-acetonaphthonebenzoylhydrazone ligand has coordinated to Cu and Zn center
successfully.
Thermal Properties of Complexes
The melting point temperature (Tm) of ZnL2 was 263-264 oC, which is 30 oC higher than that of
o
CuL2 (Tm = 223-224 C). Thermogravimetric (TG) analysis was performed under an N2
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atmosphere on complex samples (Figure 6). The TG curve of CuL2 shows the first weight loss of
o
30 % in the temperature range from 271 to 360 C, associated with the exclusion of two phenyl
and methyl groups (calcd. 29 %); then, from 360 to 600 oC, the residual ligands are released in a
featureless process. ZnL2 started to lose weight at 268 oC and completed at 458 oC. The observed
weight loss of 62% is corresponding to the loss of the phenyl and naphthyl groups (calcd. 64%).
o
And then, the curve shows further decomposition in the temperature range 458-618 C with an
11% weight change, corresponding to loss of the coordinated ligand parts (calcd. 12%). These
results indicate that both of the complexes possess excellent thermally stability as is commonly
observed for the conventional Schiff-base metal complexes.
UV-Vis Absorption and Photoluminsecence Properties
The UV-Vis spectra of the free ligand (2×10-4 M), CuL2 and ZnL2 (1×10-4 M) in chloroform
solution were presented in Figure 7. For the free ligand, the absorption maxima appeared at 309
nm was attributed to π→π* transition.[24] While for the complexes, the maximum band was
shifted to 318 nm and the intensity increased because of the extension of the larger conjugated
system after coordination.[25] Unfortunately the expected weak d-d transition in the visible region
for the one-electron paramagnetic (meff = 1.69 and 1.64 BM) complexes cannot be detected even
with concentrated solutions. It may be lost in the low energy tail of the charge transfer
transition.[2, 3, 26]
Photoluminescence emission spectra were measured at the same concentration, as shown in
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Figure 7. Under 318 nm UV light excitation, the emission spectrum for ligand shows one broad
blue emission band around at 422 nm. However, CuL2 shows relatively weak emission at 438 nm,
while ZnL2 exhibits a very strong emission band centered at 450 nm. The reason could be due to
the quenching effect from the Cu(II) ion. Possible mechanism which accounts for the quenching
effect is collisional quenching of the excited-state fluorophore by the Cu2+ quencher which may
proceed via a multitude of interactions like heavy atom effect, paramagnetic interaction as well
as the electron transfer process.[27] The strong blue luminescence of ZnL2 may be attributed to
the coordination of the ligand to the zinc center, which increases the rigidity of the ligand that
prevents a photo-induced electron transfer (PET) process and reduces the loss of energy via a
un-radiation pathway, thus enhancing the π→π* transition of the ligand.[28, 29] Furthermore, the
luminescence quantum yield for the ZnL2 was determined to be φ = 0.10 with a reference
solution of quinine sulfate in 0.5 mol/L sulfuric acid (φ = 0.546) [30] and were corrected by the
refractive index of the solvent at 298 K.
Energy Levels of Complexes
As is well known, theoretical calculations based on density functional theory are usually
employed to rationally obtain the optimized geometries and electronic structures of organic and
inorganic compounds.[31] Herein, to better understand the geometric and spectroscopic
parameters of these complexes, the molecular orbital energy levels were also studies by
theoretical calculation. The ground state geometries of the Cu(II) and Zn(II) complexes were
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fully optimized at the B3LYP/6-311G(d,p) level of theory[32] using the Gaussian09 program
package.[33] As shown in Figure 5, the calculated bond lengths of Zn–N1 and Zn–N2 in Zn(II)
complex are 2.115 and 2.122 Å, respectively, and it is consistent with the X-ray data with the
value of 1.995(5) and 2.009(5) Å, which proves the reliability of the calculated method used in
this work. Based on the optimized structures, the energy levels and the molecular orbital
distributions of the highest occupied molecular orbital (HOMO) and the lowest unoccupied
molecular orbital (LUMO), as well as the energy gap between HOMO-LUMO can be obtained
as illustrated in Figure 9. It is obvious that the different central metal ions lead to the variation of
their frontier molecular orbital energy levels. ZnL2 has a smaller ∆Egap (3.766 eV) than CuL2
(3.834 eV). Furthermore, it is also clearly showed that both complexes have their HOMOs
mainly localized on the naphthyl group and the coordinated N-N=C moiety. Meanwhile for their
LUMOs, the naphthyl group has much more orbital contributions than any other moieties of the
ligand. All these results can lead to an electronic transition from the ground state to the excited
state due to a transfer of electrons from the HOMO to LUMO level, which is mainly a …
transition.[34]
CONCLUSION
A 2-acetonaphthonebenzoylhydrazone ligand and its Cu(II) and Zn(II) complexes were
synthesized and characterized by FTIR, NMR, thermogravimetric analysis, UV-Vis and emission
spectroscopy. The molecular structure of HL, the Cu(II) and Zn(II) complex were further
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investigated by X-ray crystallography. These results indicate a distorted tetrahedral geometry for
both complexes. The electronic structures of both complexes have been determined using DFT
method. On the basis of our analysis, it has been demonstrated that the differences in the central
metal ions have major influences on their spectroscopic properties and the energy levels of
complexes.
ACKNOWLEDGMENTS
The authors acknowledge financial support from the National Natural Science Foundation of
China (grant no. 51303084).
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TABLE 1. Crystal data for HL and CuL2 and ZnL2
Compound
Formula
HL
CuL2
ZnL2
C19H16N2O
288.34
Monoclinic
P21 / n
C38H30N4O2Cu
638.20
C38H30N4O2Zn
640.03
FW
Crystal system
Space group
a (Å)
Monoclinic
P21 / c
Monoclinic
P21 / c
5.5829(3)
7.8387(4)
33.2247(17)
90.196(2)
1453.99(13)
4
13.409(7)
15.452(8)
14.905(7)
101.257(10)
3029(3)
4
13.460(3)
15.673(3)
14.828(3)
99.74(3)
3083.0(11)
4
b (Å)
c (Å)
β (°)
V (Å3)
Z
Dcalc (g cm-3)
μ(mm-1)
1.31712
0.08
3029 (3)
0.76
1.379
0.838
F (000)
608
1324
1328
T (K)
277
296
293(2)
Goodness of fit on F2
R1,wR2 [I>2σ(I)]*
ρmax, ρmin (e·Å-3)
1.01
1.01
0.932
0.051, 0.143
0.23, -0.18
2
0.065, 0.173
0.78, -0.57
2
0.0758, 0.1614
0.36, -0.43
*R1 = (||Fo|–|Fc||)/|Fo|; wR2 = [(w(Fo –Fc2)2)/(wFo )]1/2
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TABLE 2. Selected bond distances (Å) and bond angles (°) for HL, CuL2 and ZnL2
HL
N1–C3
1.2867(18)
1.3876(16)
1.3511(19)
115.50(13)
123.52(14)
C3–C4
1.4843(19)
1.2203(18)
1.501(2)
N1–N2
C7–O1
N2–C7
C7–C10
C7–N2–N1
C3–N1–N2
N1–C3–C4
O1–C7–N2
119.32(12)
116.02(12)
CuL2
Cu1–O1
1.907 (3)
1.897(3)
1.942(4)
1.967(4)
1.284(6)
1.294(6)
1.494(7)
104.20(14)
149.54(17)
81.38(16)
81.12(15)
148.28(16)
110.05(16)
125.8(4)
116.6(5)
117.5(4)
109.6(3)
108.6(4)
117.6(4)
N3–C26
N3–N4
N4–C27
N2–C8
N2–N1
O2–C26
1.303(6)1
1.404(5)
1.273(6)
1.294(6)
1.398(5)
1.285(6)
Cu1–O2
Cu1–N2
Cu1–N4
C7–O1
C7–N1
C7–C4
O2–Cu1–O1
O2–Cu1–N2
O1–Cu1–N2
O2–Cu1–N4
O1–Cu1–N4
N2–Cu1–N4
O1–C7–N1
O1–C7–C4
N1–C7–C4
C7–O1–Cu1
C26–N3–N4
C27–N4–N3
ZnL2
C27–N4–Cu1
N3–N4–Cu1
C8–N2–N1
130.0(3)
112.3(3)
119.3(4)
128.0(4)
112.5(3)
111.1(3)
108.7(4)
125.4(4)
116.8(5)
117.8(4)
115.9(5)
122.3(5)
C8–N2–Cu1
N1–N2–Cu1
C26–O2–Cu1
C7–N1–N2
O2–C26–N3
O2–C26–C23
N3–C26–C23
N2–C8–C10
N2–C8–C9
Zn–O1
1.943(4)
1.995(5)
1.290(7)
1.340(8)
Zn–O2
Zn–N2
C3–O1
N4–N1
1.946(4)
2.009(5)
1.292(7)
1.377(6)
Zn–N1
N2–C5
N4–C3
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N3–N2
1.395(6)
1.313(7)
117.89(17)
134.6(2)
81.49(18)
109.8(4)
129.1(4)
126.7(4)
116.0(6)
126.2(6)
123.4(6)
114.6(6)
115.2(6)
110.0(5)
C2–C38
1.472(8)
1.293(6)
81.30(19)
132.56(19)
116.9(2)
109.5(4)
112.0(4)
113.5(4)
117.8(6)
109.0(5)
118.3(5)
117.9(6)
126.9(6)
122.7(6)
C6–N3
C6–O2
O1–Zn–O2
O2–Zn–N1
O2–Zn–N2
C3–O1–Zn
C5–N2–Zn
C2–N1–Zn
N4–C3–C7
O1–C3–N4
N1–C2–C1
N1–C2–C38
O2–C6–C13
C6–N3–N2
O1–Zn–N1
O1–Zn–N2
N1–Zn–N2
C6–O2–Zn
N3–N2–Zn
N4–N1–Zn
O1–C3–C7
C3–N4–N1
N2–C5–C19
N3–C6–C13
O2–C6–N3
N2–C5–C4
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HL
ZnL2
CuL2
4000 3500 3000 2500 2000 1500 1000
-1
500
Wavenumbers (cm
)
Figure 1. FTIR spectra of the free ligand and the complexes.
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Figure 2. 1H NMR spectra of HL and Zn(II) complex.
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Figure 3. ORTEP drawing of HL, showing 40 % probability displacement ellipsoids. The
hydrogen atoms are omitted for clarity.
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Figure 4. ORTEP drawing of CuL2, showing 40 % probability displacement ellipsoids. The
hydrogen atoms are omitted for clarity.
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Figure 5. ORTEP drawing of ZnL2, showing 40 % probability displacement ellipsoids. The
hydrogen atoms are omitted for clarity.
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100
80
ZnL2
60
40
20
0
CuL2
0
100 200 300 400 500 600 700 800 900
o
Temperature ( C)
Figure 6. TG curves of CuL2 and ZnL2 at a scan rate of 10 oC min-1 under nitrogen.
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