Synthesis of new tridentate 5-(arylazo) salicylaldimine ligands and their Cu (II) complexes

Article abstract of DOI:10.1016/j.molstruc.2013.07.033

New tridentate Schiff base ligands (H₂L) were synthesized via condensation of 5-(arylazo)salicylaldehydes and 2-aminophenol or 2-aminothiophenol. When the new salicylaldimines were subjected to react with CuCl₂ in the presence of N(E

Full text of DOI:10.1016/j.molstruc.2013.07.033

Journal of Molecular Structure 1050 (2013) 192–196
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Synthesis of new tridentate 5-(arylazo) salicylaldimine ligands
and their Cu (II) complexes
⇑
Samir Y. Abbas , Wahid M. Basyouni, Khairy A.M. El-Bayouki
Organometallic and Organometalloid Chemistry Department, National Research Centre, Cairo, Egypt
h i g h l i g h t s
ꢀ
ꢀ
ꢀ
ꢀ
Synthesis of 5-(arylazo)salicylaldehydes as preligands.
New tridentate Schiff base ligands were synthesized via condensation of preligand and 2-aminophenol or 2-aminothiophenol.
The new ligands were subjected to react with CuCl2.
The structures of the ligands and metals complexes were established.
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 31 May 2013
Received in revised form 8 July 2013
Accepted 19 July 2013
Available online 26 July 2013
New tridentate Schiff base ligands (H2L) were synthesized via condensation of 5-(arylazo)salicylaldehy-
des and 2-aminophenol or 2-aminothiophenol. When the new salicylaldimines were subjected to react
with CuCl2 in the presence of N(Et)3 yield the new complexes. The structure of the metal complexes
was established by microanalyses, IR, UV spectra and thermal analyses. The results suggest that the
ligands were coordinated to the copper ion in tridentate manner with ONO (or ONS) donor sites of the
deprotonated phenolic-OH, azomethine-N, and deprotonated phenolic-OH (or deprotonated thiophenol-
ic-SH). Furthermore, one water molecule was coordinated to the central metal atom. The composition of
complexes can be represented as CuLÁH2O.
Keywords:
Salicylaldimine
Schiff’s base
Tridentate ligand
Copper (II) complexes
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
sulfur chelating groups in their structures have received much
attention and for further studies during the past few years because
In the recent years, there has been considerable interest in the
chemistry of transition metal complexes of Schiff’s bases [1,2].
They have played a key role in the development of coordination
chemistry, resulting in an enormous number of publications, rang-
ing from pure synthetic work to modern physicochemical and bio-
chemically relevant studies of metal complexes [3]. This is due to
the fact that Schiff’s bases offer opportunities for inducing sub-
strate chirality, tuning the metal centered electronic factor,
enhancing the solubility and stability of either homogeneous or
heterogeneous catalysts [4–9], light emitting diode [10], corrosion
inhibitor [11], potentiometric sensor [12,13], intermediates to ob-
tain of some heterocyclic compounds [14], to synthesize of conju-
gate polymers containing azomethine bond [15] and their wide
spectrum biological activities [16,17]. Salicylaldimine-based
ligands have found applications in preparation of metallo-meso-
gens, optical metal ion detection and enantioselective catalysis
[18,19]. In addition, Schiff bases containing nitrogen, oxygen and
of their specific properties e.g. electrochemically active compounds
[20] catalytically active materials in asymmetric catalysis [21],
photo-chromism [22], complexing towards heavy metals [23],
determining of some cations [24], intermediates for heterocyclic
compounds containing sulfur and nitrogen atoms [25] and antimi-
crobial activities [26].
Moreover much attention has been paid to photonic materials
based on light-induced phase transitions because these types of
materials are very useful in new information processing technol-
ogy. Azo moiety is suitable for this research field because these
materials are able to change molecular shape via reversible cis–
trans isomerization upon photo-irradiation. These compounds
have potential applications in optical switching, high-density opti-
cal data storage and optical computing [27,28]. Due to the clean
photochemistry of azobenzene, and substantial change in material
properties during light irradiation, it has been investigated as an
active component for a variety of applications, such as lithography,
non-linear optical devices and optical switches [29]. From a basic
point of view, azo dyes belong to the simplest physical systems
in which light illumination induces cis–trans isomerization and a
⇑
Corresponding author. Tel.: +20 1003790232.
E-mail address: samiryoussef98@yahoo.com (S.Y. Abbas).
0022-2860/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2013.07.033

S.Y. Abbas et al. / Journal of Molecular Structure 1050 (2013) 192–196
193
local change in the structure of the liquid crystalline phases. These
changes can be responsible for the variation of the different elec-
tro-optical applications.
Copper (II) complexes of Schiff base derivatives are an impor-
tant class of bioactive compounds as they exhibit good antibacte-
rial and anti-malarial activities [30]. Recently, copper (II)
complexes were employed as catalysts in the aerobic oxidation
of benzylic alcohols and the corresponding ligand structures in
solution and solid state [31].
So far, there are several metal complexes with differently
substituted salicylaldimine ligands. However, metal complexes
having azo moiety in the salicylaldimines are still rare. Based on
the aforementioned properties of Schiff’s bases and azo com-
pounds, the search for new and effective derivatives is of para-
mount importance. Therefore, the present work described the
preparation and characterization of a new type of 5-(arylazo) sali-
cylaldimines as tridentate ligands and their copper (II) complexes
with uncomplexed azo moiety.
gave satisfactory results. Also, indicated the absence of chlorine
atoms in the metal complexes and were in perfect agreement with
a 1:1 ratio metal/ligand. Elemental analyses of these isolated com-
plexes indicated that they can be represented as CuL1–8ÁH2O.
The IR spectra of the ligands were compared with those of the
metal complexes in order to confirm the binding mode of the Schiff
base ligands to the corresponding metal ion in the complexes. The
free Schiff base ligands H2L1–8 showed a strong bands in the region
1618–1614 cmÀ1, which are the characteristic frequency of the
azomethine v C@N group. The v C@N band is shifted to lower fre-
quency in all the complexes and displayed at 1606–1600 cmÀ1 re-
gion, indicating coordination of the Schiff bases through the
azomethine nitrogen atom. In all of these complexes a medium
and/or weak band was observed at the 550–415 cmÀ1 range which
can be attributed to the
m (CuAN) and m (CuAO) modes. IR spectra
showed that H2L1–8 was coordinated to the metal ions in tridentate
manner with ONS donor sites of the azomethine-N, deprotonated
phenolic-OH and thiophenolic-SH. The main infrared bands of
the ligands and their metal complexes are showed in Table 1.
The electronic spectra data of the Schiff bases H2L1–8 and their
complexes Cu(L1–8)ÁH2O are summarized in Table 1. The spectra
of the Schiff base H2L1–8 exhibit two main peaks: around 350
and 490 nm. This bands corresponding to intraligand transition.
The spectra of the complexes CuL1,3,5,7ÁH2O show intense bands
in the high-energy region about 433 nm which can be assigned
to charge transfer L ? Cu bands. The spectra of the complexes
CuL2,4,6,8ÁH2O show intense bands about 392, 482 nm.
2. Results and discussion
5-(Arylazo) salicylaldehyde derivatives A1–4 as pre-ligands were
prepared via coupling salicyladehyde with the appropriate substi-
tuted benzene diazonium chloride (obtained in situ by diazotization
of the desired aromatic amines using a mixture of sodium nitrite and
HCl) in presence of sodium hydroxide. Structural elucidation of A1–
4 derivatives was accomplished by their correct elemental analysis
and carful inspection of their spectral data. In the IR spectra, the car-
bonyl group was observed at 1669–1649 cmÀ1 because the intramo-
lecular hydrogen bonding between OH and the formyl group in
structure A1–4 leads to a decrease of the stretching frequency of
TGA: In order to fully characterize the metal complexes in terms
of thermal stability, their thermal behaviors were studied. To
understand the thermal decomposition process, the copper CuL3-
ÁH2O (as a representative example) was examined. Thermo gravi-
metric (TGA) and differential thermo gravimetric (DTG) analyses
for this metal complex were carried out within the temperature
range from ambient temperature up to 1000 °C. It is seen three
thermal reactions from thermograms for all complexes (Fig. 1).
The first decomposition step of estimated mass loss 3.7% (calcu-
lated mass loss 3.9%) is due to the elimination of one water mole-
cule in the temperature ranges 200–250 °C. The DTG curve gives an
exothermic peak at 230 °C (the maximum peak temperature). The
second step occurs within the temperature range 250–290 °C with
the estimated mass loss 13.3% (calculated mass loss 13.5%) may is
due to the elimination of two moieties of methoxy group. The DTG
curve gives an exothermic peak at 276 °C (the maximum peak tem-
perature). The third step of the thermal decomposition was in the
temperature range 280–749 °C with the estimated mass loss 65.3%
(calculated mass loss 65.0%) which is due to the complete decom-
position of the organic ligand and loss of the remaining organic
moiety as molecule of ligand. The DTG curve gives an exothermic
peak at DTG 660 °C (the maximum peak temperature). The remain-
ing weight of 17.1% corresponds to the percentage of the one CuO
component.
C@O, and the hydroxyl group was observed at 3446–3423 cmÀ1
.
Their 1H NMR spectra displayed signal about d = 10.32 ppm charac-
teristic for CH of aldehydic group and signal about d = 11.73 ppm
indicating the presence of OH group; which disappeared in D2O
solution. Moreover, mass spectrum of A3 (as a representative exam-
ple): showed a molecular ion peaks at: m/z = 310.
Schiff’s base ligands H2L1–8 were synthesized via condensation
of salicylaldehyde derivatives A1–4 with 2-aminophenol and 2-
aminothiophenol. The imines prepared in this way are formed in
nearly quantitative yields and being of high purity. Structure of
these Schiff’s bases was elucidated by their IR, NMR and mass spec-
tra. IR spectra of HL1–8 showed disappearance of bands for carbonyl
group and the presence bands in 1618–1614 cmÀ1 region for
CH@N group. Also, showed bands in 3447–3410 cmÀ1 region for
OH grouping. According to the 1H NMR spectra, the Ar-OH proton
of these ligands displayed as a singlet at: 12.85 ppm due to effect of
phenolic OH and hydrogen bonding (D2O-exchangeable). The azo-
methine proton of H2L1–8 appeared as a singlet at 8.60 ppm. Addi-
tional structural information can be deduced from mass
spectroscopy (C.F Experimental Part).
Due to the successful preparation of Schiff’s bases H2L1–8 the
attention was directed, in the present work, to investigate their
chemical behavior towards metal cation. Therefore, it was encour-
aged to synthesize some new copper complexes starting from the
Schiff’s bases H2L1–8. Thus, when a solution of the divalent CuCl2
3. Conclusion
The present study deals with the synthesis of novel 5-(arylazo)
salicylaldimine derivatives as ligands to investigate their complex-
ing behavior with Cu ion. The elemental analyses indicated the ab-
sence of chlorine atoms in the metal complexes. Also, elemental
analyses are in perfect agreement with a 1:1 ratio metal/ligand.
IR spectra showed that the ligands were coordinated to the copper
ion in tridentate manner with ONO (or ONS) donor sites of the
deprotonated phenolic-OH, azomethine-N, and deprotonated phe-
nolic-OH (or deprotonated thiophenolic-SH). The TGA of the syn-
thesized complexes indicated the presence of one molecule of
water coordinated with metal ion. Based on spectroscopic data
(0.01 mol) was added to
a
stirred hot solution of H2L1–8
(0.01 mol) in ethanol in presence of triethylamine, at reflux tem-
perature, the corresponding complexes CuL1–8ÁH2O were formed
(Scheme 1). All the synthesized copper (II) complexes are air-stable
at room temperature and non-hygroscopic, colored solids, insolu-
ble in water, partially soluble in ethanol and methanol, and soluble
in DMSO and DMF. Decomposition occurs with conc. nitric acids,
and the resultant solution was used after suitable dilution for
metal analysis. The elemental analyses for these new compounds

194
S.Y. Abbas et al. / Journal of Molecular Structure 1050 (2013) 192–196
NH2
XH
OH
N=N-Cl
OH
R
N
N
CHO
R
CHO
A1 R = 3-Br
A2 R = 3,5-(OCH3)2
A3 R = 4-OCF3
A4 R = 2-OC2H5
H2O
O
OH
Cu
N
X
HX
R
N
CuCl2
R
N
N
N
C
H
N
CuL1-8.H2O
H2L1-8
H2L1 R = 3-Br
L2 R = 3-Br
X = O H2L5 R = 4-OCF3 X = O
X = S
L6 R = 4-OCF3 X = S
L7 R = 2-OC2H5 X = O
L8 R = 2-OC2H5 X = S
L3 R = 3,5-(OCH3)2 X = O
L4 R = 3,5-(OCH3)2 X = S
Scheme 1. Proposed structures of the tridentate ligands and their metal complexes.
Table 1
and the elemental analyses results, it was conclude that the ligands
were coordinated to the copper ion in tridentate manner with ONO
(or ONS) donor sites. Furthermore, one water molecule was coordi-
nated to the central metal atom. The composition of complexes can
be represented as CuLÁH2O.
IR and UV of synthesized compounds.
Compd. no.
Stretching vibration in cmÀ1
Wave length kmax (nm)
mCH@N
mMAO
mMAN
H2L1
1618
1614
1617
1615
1618
1614
1616
1618
1605
1604
1604
1603
1601
1604
1600
1605
–
–
–
–
–
–
–
–
490
500
515
550
522
531
512
512
–
–
–
–
–
–
–
–
421
421
435
435
435
435
416
406
356, 487
351, 494
354, 483
355, 497
350, 485
358, 492
353, 487
351, 490
436
396, 487
434
398, 484
433
H2L2
H2L3
H2L4
4. Experimental
H2L5
H2L6
Melting points were determined on a digital Gallen-Kamp MFB-
595 instrument and are uncorrected. Infrared spectra (KBr-disc)
H2L7
H2L8
were recorded using a FTIR 5300 spectrometer (m
, cmÀ1). NMR
CuL1ÁH2O
CuL2ÁH2O
CuL3ÁH2O
CuL4ÁH2O
CuL5ÁH2O
CuL6ÁH2O
CuL7ÁH2O
CuL8ÁH2O
spectra were recorded on a Bruker instrument at 500 MHz with
DMSO as solvent. Mass spectra were recorded on GC/MS finnigan
SSQ 7000 spectrophotometer & GC Ms-QP 1000 EX mass spectrom-
eter at 70 eV. UV spectra were recorded on UV-2401PC, UV–Vis
Recording spectrophotometer. TGA–DTA curves were obtained
using a Schimatzu DTG-60H instrument. Platinum pans were used
for thermograms obtained between room temperature and
1000 °C. The heating rate was 10 °C/min. Microanalyses were car-
ried out by the Microanalytical Laboratory, National Research Cen-
tre, Cairo, Egypt and the Microanalytical Research Center, Faculty
of Science, Cairo University.
391, 482
437
393, 480
100
80
60
40
20
0
4.1. Synthesis of 5-(arylazo)salicylaldehyde derivatives A1–4
The appropriate aniline derivative (3-bromoaniline, 3,5-dime-
thoxyaniline,
4-trifluoromethylaniline
or
2-ethoxyaniline)
(54 mmol) was dissolved in a mixture of concentrated hydrochloric
acid (16 ml) and water (50 ml) and cooled to 0–5 °C. Sodium nitrite
(58 mmol) was dissolved in water (16 ml) and cooled. The cold so-
dium nitrite solution was added in small volumes to the cold ani-
line hydrochloride solution, and the mixture was well shaken
(solution A). The temperature was not allowed to rise above
10 °C. A solution of the salicylaldehyde (54 mmol) in 5% NaOH
(90 ml) was cooled to 5 °C (solution B). Solution A was added very
slowly to solution B; a dark-red solution was produced. When all
the diazonium salt solution had been added, the mixture was al-
lowed to stand in an ice bath for 30 min with occasional stirring.
The dark-red precipitate was filtered off, washed well with water,
dried and crystallized from ethanol to give A1–4.
200
400
600
800
1000
Temperature (°C)
Fig. 1. TGA of CuL3ÁH2O.

S.Y. Abbas et al. / Journal of Molecular Structure 1050 (2013) 192–196
195
4.1.1. 5-((3-Bromophenyl)diazenyl)-2-hydroxybenzaldehyde (A1)
4.2.2. 4-((3-Bromophenyl)diazenyl)-2-((2-
mercaptophenylimino)methyl)phenol (H2L2)
Yield 85%; mp 146–145 °C; IR: m
/cmÀ1: 3446 (OH), 1649 (C@O);
1H NMR: d/ppm = 7.14 (d, 1H, J = 9.24 Hz, Ar-H), 7.50 (m, 1H, Ar-H),
7.67 (d, 1H, J = 6.9 Hz, Ar-H), 7.83 (d, 1H, J = 6.9 Hz, Ar-H), 7.90 (s,
1H, Ar-H), 8.05 (d, 1H, J = 9.24 Hz, Ar-H), 8.14 (s, 1H, Ar-H), 10.32
(s, 1H, CHO), 11.73 (br, 1H, OH); Anal Calcd for C13H9BrN2O2
(305): C, 51.17; H, 2.97; N, 9.18; Found: C, 51.17; H, 2.97; N, 9.18%.
Yield 89%; m.p. 199–201 °C; 1H NMR: d/ppm = 6.91–7.83 (m,
8H, Ar-H), 7.91 (s, 1H, Ar-H), 7.97 (d, 1H, J = 9.14, Ar-H), 8.23 (s,
1H, Ar-H), 9.23 (s, 1H, CH@N), 11.78 (br, 1H, SH), 14.02 (br, 1H,
OH); 13C NMR: 119.4, 122.4 (2C), 123.8, 127.3, 128.3, 130.2 (2C),
130.5, 131.9, 133.7, 144.9, 149.5, 152.4, 153.4, 161.3 (2C), 163.0,
165.1; Anal Calcd for C19H14BrN3OS (412.30): C, 55.35; H, 3.42;
N, 10.19; Found: C, 55.30; H, 3.30; N, 10.20%.
4.1.2. 5-((3,5-Dimethoxyphenyl)diazenyl)-2-hydroxybenzaldehyde
(A2)
4.2.3. 4-((3,5-Dimethoxyphenyl)diazenyl)-2-((2-
Yield 89%; mp 118–119 °C; IR: m
/cmÀ1: 3321(OH), 1679 (C@O);
hydroxyphenylimino)methyl)phenol (H2L3)
1H NMR: d/ppm = 3.79 (s, 6H, 2OCH3), 6.63 (s, 1H, Ar-H), 7.00 (s,
2H, Ar-H), 7.15 (d, 1H, J = 8.4 Hz, Ar-H), 8.04 (d, 1H, J = 8.5 Hz, Ar-
H), 8.14 (s, 1H, Ar-H), 10.33 (s, 1H, CHO), 11.48 (br, 1H, OH); 13C
NMR: 55.8 (2OCH3), 100.9 (2C), 103.6, 118.7, 122.9, 124.7, 130.0,
145.1, 154.1, 161.3 (2C), 163.8, 191.3 (CHO); Anal Calcd for
Yield 91%; m.p. 227–229 °C; 1H NMR: d/ppm = 3.83 (s, 6H,
2OCH3), 6.61 (s, 1H, Ar-H), 6.89 (t, 1H, J = 8.4 Hz, Ar-H), 6.95–7.09
(m, 4H, Ar-H), 7.14 (t, 1H, J = 8.4 Hz, Ar-H), 7.47 (d, 1H, J = 6.9 Hz,
Ar-H), 7.92 (d, 1H, J = 9.2 Hz, Ar-H), 8.20 (s, 1H, Ar-H), 9.15 (s,
1H, CH@N), 10.05 (br, 1H, OH), 14.95 (br, 1H, OH); 13C NMR: 56.0
(2OCH3), 100.8 (2C), 103.3, 117.1, 119.1, 119.6, 119.8, 120.3,
127.2, 129.1, 130.1, 133.1, 144.1, 151.4, 154.4, 160.7, 161.4 (2C),
167.7; Anal Calcd for C21H19N3O4 (377.39): C, 66.83; H, 5.07; N,
11.13; Found: C, 66.90; H, 5.00; N, 11.30%.
C15H14N2O4 (286.28): C, 62.93; H, 4.93; N, 9.79; Found: C, 62.80;
H, 4.80; N, 9.90%.
4.1.3. 2-Hydroxy-5-((4-
(trifluoromethoxy)phenyl)diazenyl)benzaldehyde (A3)
Yellow crystals; yield 85%; mp 132–133 °C; IR:
4.2.4. 4-((3,5-Dimethoxyphenyl)diazenyl)-2-((2-
m
/cmÀ1: 3423
mercaptophenylimino)methyl)phenol (H2L4)
(OH), 1669 (C@O); 1H NMR: d/ppm = 6.96 (d, 1H, J = 9.25 Hz, Ar-
H), 7.51 (d, 2H, J = 8.4, AB system), 7.88 (d, 2H, J = 8.4, AB system),
7.99 (d, 1H, J = 9.25 Hz, Ar-H), 8.08 (s, 1H, Ar-H), 10.29 (s, 1H, CHO),
11.75 (br, 1H, OH); MS, m/z (%): 310 (M+; 15.19), 311 (M + 1; 15.2),
161 (C6H4OCF3; 68.4), 153 (24.1), 149 (M-C6H4OCF3; 54.5) 120
(19), 95 (100), 94.4 (19), 93 (54.5), 92 (29); Anal Calcd for C14H9F3-
N2O3 (310): C, 54.20; H, 2.92; N, 9.03; Found: C, 54.20; H, 2.92; N,
9.03%.
Yield 83%; m.p. 150–152 °C; 1H NMR: d/ppm = 3.84 (s, 6H,
2OCH3), 6.62 (s, 1H, Ar-H), 6.87 (t, 1H, J = 8.4 Hz, Ar-H), 6.95–7.09
(m, 4H, Ar-H), 7.13 (t, 1H, J = 8.4 Hz, Ar-H), 7.43 (d, 1H, J = 6.9 Hz,
Ar-H), 7.95 (d, 1H, J = 9.2 Hz, Ar-H), 8.21 (s, 1H, Ar-H), 9.15 (s,
1H, CH@N), 11.78 (br, 1H, SH), 14.95 (br, 1H, OH); 13CNMR: 56.1
(2OCH3), 100.7 (2C), 103.2, 117.3, 119.2, 119.4, 119.8, 120.3,
127.2, 129.1, 130.1, 130.3, 133.1, 144.2, 151.4, 160.7, 161.4 (2C),
167.8; Anal Calcd for C21H19N3O3S (393.46): C, 64.10; H, 4.87; N,
10.68; Found: C, 64.30; H, 4.70; N, 10.80%.
4.1.4. 5-((2-Ethoxyphenyl)diazenyl)-2-hydroxybenzaldehyde (A4)
4.2.5. 2-((2-Hydroxyphenylimino)methyl)-4-((4-
Yield 93%; mp 146–145 °C; IR: m
/cmÀ1: 3321(OH), 1679 (C@O);
(trifluoromethoxy)phenyl)diazenyl)phenol (H2L5)
1H NMR: d/ppm = 1.37 (t, 3H, J = 6.85 Hz, CH3), 4.19 (q, 2H,
J = 6.85 Hz, CH2), 6.96–7.20 (m, 3H, Ar-H), 7.40–7.45 (m, 2H, Ar-
H), 7.68 (d, 1H, J = 8.4 Hz, Ar-H), 8.14 (s, 1H, Ar-H), 10.32 (s, 1H,
CHO), 11.73 (br, 1H, OH); 13C NMR: 15.3 (CH3), 65.0 (CH2), 115.0,
117.4, 117.3, 121.1, 121.6, 122.6, 125.4, 132.6, 138.7, 142.3,
146.3, 156.4, 163.5, 191.1 (CHO); Anal Calcd for C15H14N2O3
(270.28):: C, 66.66; H, 5.22; N, 10.36; Found: C, 66.80; H, 5.10; N,
10.50%.
Yield 79%; m.p. 224–226 °C; 1H NMR: d/ppm = 6.85–7.02 (m,
3H, Ar-H), 7.15 (d, 1H, Ar-H), 7.45–7.56 (m, 3H, Ar-H), 7.85–7.97
(m, 3H, Ar-H), 8.22 (s, 1H, Ar-H), 9.19 (s, 1H, CH@N), 10.08 (br,
1H, OH), 15.04 (br, 1H, OH); Anal Calcd for
(401.34): C, 59.85; H, 3.52; N, 10.47; Found: C, 59.90; H, 3.60; N,
10.30%.
C20H14F3N3O3
4.2.6. 2-((2-Mercaptophenylimino)methyl)-4-((4-
(trifluoromethoxy)phenyl)diazenyl)phenol (H2L6)
Yield 85%; m.p. 254–256 °C; 1H NMR: d/ppm = 7.10–8.14 (m,
10H, Ar-H), 8.33 (s, 1H, Ar-H), 9.23 (s, 1H, CH@N), 11.78 (br, 1H,
SH), 14.02 (br, 1H, OH); Anal Calcd for C20H14F3N3O2S (417.40):
C, 57.55; H, 3.38; N, 10.07; Found: C, 57.40; H, 3.50; N, 10.20%.
4.2. Synthesis of tridentate ligands H2L1–8
Equimolar amounts of 5-(arylazo) salicylaldehyde A1–4
(0.01 mol) and the proper amine (2-aminophenol or 2-aminothio-
phenol) in ethanol (20 ml) was heated under reflux for 1 h and the
reaction mixture was left to cool. The resulting solid product ob-
tained was filtered off and recrystallized from ethanol to give the
4.2.7. 4-((2-Ethoxyphenyl)diazenyl)-2-((2-
hydroxyphenylimino)methyl)phenol (H2L7)
Yield 90%; m.p. 146–145 °C; 1H NMR: d/ppm = 1.37 (t, 3H,
J = 6.85 Hz, CH3), 4.23 (q, 2H, J = 6.85 Hz, CH2), 6.90–8.10 (m, 10H,
Ar-H), 8.19 (s, 1H, Ar-H), 9.18 (s, 1H, CH@N), 10.02 (br, 1H, OH),
13.92 (br, 1H, OH); Anal Calcd for C21H19N3O3 (361.39): C, 69.79;
H, 5.30; N, 11.63; Found: C, 69.60; H, 5.20; N, 11.50%.
Schiff base ligands H2L1–8
.
4.2.1. 4-((3-Bromophenyl)diazenyl)-2-((2-
hydroxyphenylimino)methyl)phenol (H2L1)
Yield 80%; m.p. 229–231 °C; 1H NMR: d/ppm = 6.89 (t, 1H,
J = 6.9, Ar-H), 6.95–7.07 (m, 2H, Ar-H), 7.15 (t, 1H, J = 8.4, Ar-H),
7.51 (m, 2H, Ar-H), 7.67 (d, 1H, J = 7.6, Ar-H), 7.83 (d, 1H, J = 7.65,
Ar-H), 7.91 (s, 1H, Ar-H), 7.97 (d, 1H, J = 9.14, Ar-H), 8.23 (s, 1H,
Ar-H), 9.18 (s, 1H, CH@N), 10.10 (br, 1H, OH), 15.06 (br, 1H, OH);
13C NMR: 119.6, 122.3 (2C), 123.9, 127.2, 128.2, 130.0 (2C),
131.9, 133.7, 144.9, 149.5, 152.0, 153.6, 157.6, 161.6 (2C), 163.4,
165.0; Anal Calcd for C19H14BrN3O2 (396.24): C, 57.59; H, 3.56; N,
10.60; Found: C, 57.70; H, 3.40; N, 10.70%.
4.2.8. 4-((2-Ethoxyphenyl)diazenyl)-2-((2-
mercaptophenylimino)methyl)phenol (H2L8)
Yield 88%; m.p. 162–164 °C; 1H NMR: d/ppm = 1.38 (t, 3H,
J = 6.85 Hz, CH3), 4.21 (q, 2H, J = 6.85 Hz, CH2), 6.94–8.12 (m,
10H, Ar-H), 8.28 (s, 1H, Ar-H), 9.17 (s, 1H, CH@N), 10.32 (br, 1H,
SH), 13.92 (br, 1H, OH); 13C NMR: 15.3 (CH3), 65.0 (CH2), 115.2,
117.0, 118.3, 119.7, 121.1, 122.5, 122.8, 125.7, 126.0, 126.8,
127.0, 128.6, 132.7, 142.3, 145.9, 151.9, 156.2, 161.6, 164.5; Anal

196
S.Y. Abbas et al. / Journal of Molecular Structure 1050 (2013) 192–196
Calcd for C21H19N3O2S (377.46): C, 66.82; H, 5.07; N, 11.13; Found:
C, 66.90; H, 5.20; N, 11.30%.
4.3.8. CuL8ÁH2O
Yield 77%; Anal Calcd for C21H19CuN3O3S (456.04): C, 55.19; H,
4.19; Cu, 13.90; N, 9.19; Found: C, 55.19; H, 4.19; Cu, 13.90; N,
9.19%;
4.3. Preparation of the complexes CuL1–8ÁH2O
To a hot solution of H2L1–8 (0.01 mol) in ethanol (50 ml), a solu-
tion of CuCl2Á2H2O (0.01 mol) in 3 ml ethanol (70%) was added
then a catalytic amount of triethylamine was added. The reaction
mixture was heated under reflux while stirring for 3 h then. The so-
lid product that formed while hot was separated by filtration,
washed with ethanol and dried to give CuL1–8ÁH2O as colored
greenish crystals.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.molstruc.2013.07.
033.
References
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Yield 74%; Anal Calcd for C19H14BrCuN3O3 (473.95): C, 47.96; H,
2.97; Cu, 13.36; N, 8.83; Found: C, 47.96; H, 2.97; Cu, 13.36; N,
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N, 8.54%;
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Yield 81%; Anal Calcd for C21H19CuN3O5 (456.06): C, 55.20; H,
4.19; Cu, 13.91; N, 9.20; Found: C, 55.20; H, 4.19; Cu, 13.91; N,
9.20%;
4.3.4. CuL4ÁH2O
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Yield 78%; Anal Calcd for C21H19CuN3O4S (472.04): C, 53.32; H,
4.05; Cu, 13.43; N, 8.88; Found: C, 53.32; H, 4.05; Cu, 13.43; N,
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4.3.5. CuL5ÁH2O
Yield 77%; Anal Calcd for: C20H14CuF3N3O4 (480.02): C, 49.95; H,
2.93; Cu, 13.21; N, 8.74; Found: C, 49.95; H, 2.93; Cu, 13.21; N,
8.74%;
4.3.6. CuL6ÁH2O
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N, 8.46%;
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4.3.7. CuL7ÁH2O
Yield 75%; Anal Calcd for C21H19CuN3O4 (440.07): C, 57.20; H,
4.34; Cu, 14.41; N, 9.53; Found: C, 57.20; H, 4.34; Cu, 14.41; N,
9.53%;