In situ alkaline media: Synthesis, spectroscopic, morphology and anticancer assignments of some transition metal ion complexes of 1-((2-aminophenylimino) methyl) naphthalen-2-ol Schiff base

Article abstract of DOI:10.1016/j.molstruc.2019.01.083

Four Schiff base complexes of Cu(II), Co(II), Ni(II) and Zn(II) metal ions were synthesized by reaction of 1-((2-aminophenylimino)methyl)naphthalen-2-ol (HL) with metal(II) chloride salts. The geometric structures of these complexes were elucidated based

Full text of DOI:10.1016/j.molstruc.2019.01.083

Journal of Molecular Structure 1183 (2019) 190e201
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: http://www.elsevier.com/locate/molstruc
In situ alkaline media: Synthesis, spectroscopic, morphology and
anticancer assignments of some transition metal ion complexes of
1
-((2-aminophenylimino) methyl) naphthalen-2-ol Schiff base
Jehan Y. Al-Humaidi
Department of Chemistry, College of Science, Princess Nourah Bint Abdulrahman University, Riyadh 11671, Saudi Arabia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 13 October 2018
Received in revised form
Four Schiff base complexes of Cu(II), Co(II), Ni(II) and Zn(II) metal ions were synthesized by reaction of 1-
(
(2-aminophenylimino)methyl)naphthalen-2-ol (HL) with metal(II) chloride salts. The geometric struc-
tures of these complexes were elucidated based on different types of analyses like elemental analyses
31 December 2018
and spectroscopic instruments (FT-IR, UVeVis., mass and 1H NMR). Microanalytical analysis was
Accepted 25 January 2019
Available online 26 January 2019
confirmed the 1:1 stoichiometry ratio (metal: HL). The molar conductance values (3.80e5.59
that all HL complexes have an electrolytic behavior in comparable with free HL data (1.35 S) except for
non-electrolytic copper(II) complex (1.46 S). The general formulas of the synthetic complexes were
mS) referred
m
m
Keywords:
þ
ꢀ
2þ
2þ
þ ꢀ
2 2 2
O)] .Cl and [Cu(L)(Cl)(H O) ]. The assignments of
[
M(L)(H O (M ¼ Co & Ni ), [Zn(L)(H
FTIR spectra confirmed that the deprotonated HL Schiff base ligand acts as a tridentate NNO chelate
through oxygen eO of phenolic group and both nitrogen atoms of eNH and C]N azomethine groups.
2
O)
3
] .Cl .3H
2
Schiff base
Transition metal ions
XRD
2
Morphology
Anticancer
The electronic, magnetic and electron spin resonance analyses revealed that all complexes are six co-
ordinated but zinc(II) complex is four coordinated geometry. The thermogravimetric analyses (TGA/DTG)
and differentially thermal analyses (DTA) of the free HL chelate and its complexes have been performed
2
under N atmosphere. The final thermal decomposition residue of metal-Schiff base complexes has been
MO formula. The crystalline surface morphology of the solid products were investigated dependent on X-
ray diffractometer and scanning electron microscopy. The efficiency of antimicrobial (bacteria & fungi)
and anticancer of colon carcinoma HCT-116 cell lines were assessed against free HL Schiff base ligand and
their four complexes.
©
2019 Elsevier B.V. All rights reserved.
1
. introduction
literature due the fact that the ligands around central metal ions in
natural systems are asymmetrical [9e11]. Asymmetric Schiff-base
ligands have many advantages over their symmetrical counter-
parts in the composition and geometry of transition metal com-
plexes and properties [12]. Asymmetric Schiff base compounds
have been widely studied in connection with catalysis of many
reactions [13] due to the versatility of their steric and electronic
properties and are promising materials for optoelectronic applica-
tions [14] and models of relevance for biologically important spe-
cies [15,16] and their industrial applications [17].
Schiff bases are one of the organic compounds which have an
important significant in the field of pharmaceutical industry, bio-
logical activities (antibacterial, antifungal and antitumor) [1e3].
The transition metal Schiff base complexes with their biological
activity have been widely studied in literature [4e6]. Schiff bases of
aromatic amines have a wide role in a biological and pharmaco-
logical activities [7]. Aromatic aldehydes with an effective conju-
gation system than aliphatic aldehydes form stable Schiff bases and
Schiff base ligands with oxygen or nitrogen donor atoms are a good
class of organic capable of binding to different metal ions [8]. The
coordination chemistry of transition metal complexes of asym-
metrical Schiff base ligands has attracted much attention in
In this research paper, the NNO Schiff base and their copper(II),
cobalt(II), nickel(II) and zinc(II) complexes have been prepared and
discussed using elemental analyses, magnetic, molar conductance,
1
SEM, UVeVis, FTIR, H NMR, ESR and XRD spectroscopic analyses. In
addition, the results of their antimicrobial and anticancer activities
were also scanned.
E-mail address: al-hamidij@hotmail.com.
https://doi.org/10.1016/j.molstruc.2019.01.083
0
022-2860/© 2019 Elsevier B.V. All rights reserved.

J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
191
2
. Experimental
ꢀ Infrared spectra were recorded on
Spectrophotometer.
a
Bruker FT-IR
2
.1. Reagents
ꢀ Electronic spectra were scanned using Perkin-Elmer Precisely
Lambda 25 UV/Vis double beam Spectrometer.
1
In this study, the CoCl
2
.6H
2
O, NiCl
2
2
.6H O, CuCl
2
.2H
2
O, and ZnCl
2
ꢀ
H NMR spectra were scanned using 200 MHz Varian Gemini
Spectrophoto-meters.
were received from Sigma-Aldrich (Taufkirchen, Germany) but o-
phenylenediamine and 2-hydroxy-1-naphthaldehyde were
received from BDH chemical company. Solvents such as methanol
and diethyl ether were used without purification.
ꢀ Thermal analyses were performed using a Shimadzu thermog-
ravimetric analyzer.
ꢀ Mass spectra were scanned using AEI MS 30 mass spectrometer
at 70 eV.
ꢀ
ꢀ
X-ray diffraction patterns were recorded using Bruker AXS X-ray
powder diffraction.
Scanning electron microscopy was performed using Joel JSM-
2
.2. Synthesis of 1-((2-aminophenylimino)methyl)naphthalen-2-ol
(
HL) Schiff base
639OLA with an accelerating voltage of 20 KV.
The Schiff base (HL) ligand has been synthesized by refluxing
both of 2-hydroxy-1-naphthaldehyde (0.172 g, 1 mM) and o-phe-
nylenediamine (0.108 g, 1 mM) in 20 mL methanol for 3hrs [18,19].
Orange yellow solid precipitate (Scheme 1) was isolated, filtered
and recrystallized from methanol solvent. The purity of the HL
Schiff base ligand was checked using TLC technique. Yield, 88%, m.p
2
.5. Antimicrobial assessments
ꢁ
ꢀ1
ꢀ1
ꢀ1
2.5.1. Antibacterial assay
1
44e146 C. IR: 3470 cm (OH), 3372 cm (NH
2
), 3020 cm (CH
aromatic), 1618 cm (C]N). 1HNMR (300 MHz, DMSO‑d
ꢀ
1
Antibacterial inhibition was tested by using diffusion method
6
, ppm)
), 6.70 (s, 1H, CH]N), 7.02e7.97 (m, 10H, Ar-H),
, ppm)
¼ 99.99,
[21], this biological experiment was performed three times to take
d
¼ 5.07 (s, 2H, NH
2
3
.70 (s, 1H, OH), 1 CNMR (75 MHz, DMSO‑d
total average data. The ciprofloxacin pure drug was used as anti-
bacterial standard. The tested samples were assessed at 10 and
5
9
6
d
¼
d
117.8, 126.8,127.0, 127.8, 128.7, 129.0,131.7, 132.4,133.4, 133.9, 134.0,
0 mg concentrations. The antibacterial activity of free HL ligand
1
34.4, 145.6, 158.2, 164.3, 170.7 ppm due to C]C, C]N, CeN and
þ
þ
þ
and its complexes were applied against:
CeO). Mass spectra, [M ]m/z ¼ [M þ2] 264 (0.97%), [M þ1] 263
þ
(4.53%), [M ] 262.1 (68%), 171 (0.79%), 170 (1.04%), 153 (1.15%), 152
(1.87%), 144 (8.33%), 127 (1.85%), 126 (2.85%), 119 (100%), 118
(7.40%), 93 (8.00.4%), 92 (10.84%), 77 (5.33%). Anal. Calc. for
ꢀ
ꢀ
Gram positive bacteria: Bacillus Subtillus (RCMB 00010) and
Staphylococcus aureas (RCMB 000106).
Gram negative bacteria: Escherichia Coli (RCMB 000103) and
Pseudomanas aeruginose (RCMB 000102).
17 14 2
C H N O: C, 77.84; H, 5.38; N, 10.68. Found: C, 77.21; H, 5.25; N,
10.60%.
2.3. Synthesis of complexes
2
.5.2. Antifungal assay
General procedure: a warmed dissolved solution of HL Schiff
A 100 L of the tested samples which dissolved in a dime-
m
base ligand (1 mmol) in methanol (30 mL) was mixed slowly with
warmed aqueous solutions (10 mL distilled water) of CoCl .6H O,
NiCl .6H O, CuCl .2H O, or ZnCl (1 mmol). The pH of the resulting
thylsulfoxide with different concentrations 10 mg/mL and 50 mg/
mL were assessed against two kinds of fungi (A. Niger and Penicil-
lium sp.). The free sample of DMSO was used as control and also
fluconazole drug was used as antifungal standard.
2
2
2
2
2
2
2
mixtures were adjusted to the range 7e8 with ammonia solution,
ꢁ
then stirred under refluxed at 70 C for 1 h. The reaction mixture
then concentrated to half its initial volume and left to cooling for
one day. The isolated solid complexes were separated, washed with
few drops of methanol and dried under vacuum over silica gel.
2.6. Cytotoxic assay
The cytotoxic activities (IC50) of HL free ligand and its metal
complexes were checked against human colon carcinoma HCT-
16 cell lines using Masmann and Vijayen et al. colorimetric
method [22,23]. The HCT-116 cell lines were received from the
American type culture collection (ATCC, Rock, Villa, and MD). The
inhibitory activity was determined at different concentrations (50,
2
.4. Analyses
1
ꢀ
The percentage of %C, %H and %N elements were determined
using Perkin-Elmer CHN 2400 analyzer.
Percentage of cobalt, nickel, copper and zinc ions was estimated
gravimetrically.
Chloride ions were determined gravimetrically based on well
known method [20].
Molar conductivities were scanned using Jenway 4010 conduc-
tivity meter.
ꢀ
2
5, 12.5, 6.25, 3.125 and 1.65 mg). The equation was used to calculate
the percentage of viability as follows:
ꢀ
ꢀ
ꢀ
% viability ¼ ½1 ꢀ ðODt=ODcÞꢂx100
Magnetic measurements were calculated using magnetic bal-
ance (Sherwood Scientific), Cambridge, England.
(ODt ¼ mean optical density of wells treated with the test sample
and ODc ¼ mean optical density of untreated cells).
H
H
C
methanol, refluxing
C
+
O
H N
N
2
90 min.
NH2
NH2
OH
OH
Scheme 1. Synthesis of HL Schiff base ligand.

192
J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
3
. Results and discussion
H
C
N
H
C
3
.1. Microanalyses and physical properties
2
Cl.3H O
NH
2
N
O
Cu
NH
2
The 1:1 condensation of o-phenylenediamine with 2-hydroxy-
-naphthaldehyde under certain condition yielded the 1-((2-
O
H
2
O
Cl
Co
1
OH
2
aminophenylimino)methyl)naphthalen-2-ol (HL) Schiff base.
Elementary analyses (%C, %H, and %N) of the synthesized Cu(II),
Co(II), Ni(II) and Zn(II) complexes are summarized in Table 1. An
elemental analyses values are agreement with the suggested for-
mulas of the synthetic HL Schiff base complexes. The synthetic
Schiff base complexes are shown in Fig. 1. The HL ligand can be
H O
OH
2
2
OH
2
H
C
H
C
2
Cl.3H O
N
II
II
II
II
Cl
chelated to central metal ions (Cu , Co , Ni and Zn ) through more
N
NH
2
1
O
than one donating sites. However, the IR and HNMR spectra of the
NH2
Ni
O
ligand (HL) and its complexes indicate that in neutralization system
the deprotonated HL Schiff base ligand exists as tridentate fashion.
The chemical composition and molecular structure of the HL ligand
are assigned in (section 2-2) and depicted in Scheme 1. The mi-
croanalyses and physical results confirmed that the complexes
synthesized under the alcoholic/aqueous alkaline media have a 1:1
stoichiometry (M:L). The deprotonated HL Schiff base ligand acts as
a negative tridentate binding agent chelated toward the central
Zn
OH
2
2
H O
OH
2
OH
2
þ
ꢀ
(M ¼ Co2þ
2þ
Ni ),
Fig. 1. Suggested structures of [M(L)(H
2
O)
3
] .Cl .3H
2
O
&
þ
ꢀ
[Zn(L)(H O)] .Cl and [Cu(L)(Cl)(H O) ] Schiff base complexes.
2
2
2
1
00
2
metal ion, while H O and chlorine acts as coordinated ligand spe-
cies in order to complete the coordination number around the
respected metal ions. Hence Schiff base ligand and these complexes
80
are fully characterized by different techniques, viz. elemental
1
analysis, molar conductance, magnetic, SEM, UVeVis, FTIR,
H
NMR, ESR and XRD spectroscopic analyses as well as thermal an-
alyses. The prepared Schiff base complexes are colored, non-
hygroscopic and insoluble in water but soluble in DMF and DMSO
solvents. The experimental data of molar conductance values of
60
4
0
0
HL
ꢀ
3
II
II
II
Cu(II)
Co(II)
Zn(II)
10
M solutions of the prepared Co , Ni and Zn Schiff base
Cu(II) complex
Co(II) complex
Ni(II) complex
Zn(II) complex
complexes in DMSO were found within 3.80e5.59 S range, which
m
2
is in agreement with the electrolytic statement of the complexes.
Therefore, one chlorine atom in cobalt(II), nickel(II) and zinc(II)
Schiff base complexes is existed outside the coordination sphere.
On the other hand, the copper(II) complex has a non electrolytic
650 600 550 500 450 400 350
0
4
000 3500 3000 2500 2000 1500 1000 500
property (1.35
as coordinated ligand [24].
mS), hence, the chlorine atom in this case exhibited
-
1
Wavenumbers, cm
Fig. 2. Infrared spectra of HL Schiff base and complexes (I-IV).
3.2. Infrared spectra
Fig. 2 is refer to the FT-IR spectra of the free HL Schiff base and
ꢀ
ꢀ
Regarding HL free ligand, the stretching vibration of n(OeH)
synthesized metal complexes. The distinguish IR spectral peaks and
their interpretations are tabulated in Table 2. Essential information
about attachment between central metal ions and the donation
sites of the Schiff base ligand were discussed dependent on the
reported research in literature [25e29].
ꢀ1
band is presence at 3470 cm , this band is disappeared after
complexation due to the deprotonation of eOH group and then
coordinated of oxygen atom towards metal ions.
ꢀ1
The new infrared bands exhibited within 3462e3371 cm
range in case of metal complexes are assigned to the stretching
vibrations of uncoordinated water molecules.
ꢀ
The infrared spectrum of HL Schiff base chelate showed distin-
ꢀ
1
ꢀ The
n(CeO) stretching vibration of phenolic group display at
guish band of the eCH]N azomethine group at 1618 cm , this
ꢀ
1
ꢀ1
1287 cm in case of HL Schiff base ligand. This band is shifted to
band was shifted to lower wavenumbers (1606-1611 cm ) in
case of the spectra of synthesized transition metal complexes,
this result confirmed that the eCH]N nitrogen atom partici-
pated in the coordination towards metal ions [25].
ꢀ1
lower wavenumbers (1285-1280 cm
) after complexation
because of participation of phenolic group oxygen atom in the
coordination by associated of the CeOeM bond [27,28].
Table 1
Microanalyses and physicochemical values of the Schiff base complexes.
Chemical formulas
Color
L
m
(
mS)
Elemental analyses, % Found/(Calcd.%)
C
H
N
Cl
M
[
[
[
[
Cu(L)(Cl)(H
2
O)
2
] (I)
Green
Brown
Green
Brown
1.46
4.62
5.59
3.80
51.46 (51.52)
44.01 (44.03)
44.03 (44.05)
53.68 (53.71)
4.30 (4.32)
5.41 (5.43)
5.41 (5.44)
3.94 (3.98)
7.04 (7.07)
6.02 (6.04)
6.00 (6.04)
7.28 (7.37)
8.77 (8.95)
7.61 (7.64)
7.61 (7.65)
9.27 (9.33)
16.00 (16.03)
12.62 (12.71)
12.59 (12.66)
17.11 (17.20)
þ
ꢀ
Co(L)(H
2
O)
3
] .Cl .3H
2
O (II)
O (III)
þ
ꢀ
ꢀ
Ni(L)(H
Zn(L)(H
2
O)
3
] .Cl .3H
2
þ
2
O)] .Cl (IV)

J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
193
2
1
1
0
0
.0
.5
.0
.5
.0
0
0
0
0
.15
.10
.05
.00
-
-
-
-
-
0.05
0.10
0.15
0.20
0.25
-0.5
DPPH standard sample
Complex
I
-1.0
1000
2000
3000
4000
5000
6000
Magnetic field Gause
Fig. 3. ESR spectra of copper(II) complex I.
Table 2
Infrared spectra assignments of the HL Schiff base and metal complexes.
their copper, cobalt, nickel and zinc(II) were scanned in DMSO
solvent. The free HL chelate has three absorption bands at 32258,
ꢀ
1
2
7778 and 24390 cm , these electronic transition bands are
Compounds
n(OH)
2
n(NH )
n(C]N)
d
(NH
2
)
n(CeO)
n(M-N)
n(M-O)
*
*
assigned to
p/p and n/p of aromatic rings (phenyl and
HL
I
3470
3391
3372
e
1618
1606
1565
1574
1287
1280
e
e
naphthalene) [30,31], azomethine group and intermolecular LCT of
aromatic rings, respectively. Electronic transitions of phenyl rings
have been affected in case of synthesized metal complexes spectra.
557
499
4
67
501
46
II
3454
3363
1608
1575
1283
561
4
This is because of the attached of aromatic ring with the place of
III
IV
3462
3371
e
e
1609
1611
1574
1581
1282
1285
570
554
429
479
*
chelation. The n/
p
electronic transition bands were shifted after
coordinated of metal ions toward HL Schiff base ligand, this can be
attributed to the participation of chromophore azomethine group
in the coordination toward metal ions [30].
410
Table 3
ESR parameters of Cu(II) complex I.
3.3.1. Copper(II) complex (I)
Hamiltonian parameters
ꢃ10ꢀ
4
a2
0.6047
b2
0.0644
ꢀ1
and
/ T2g and B1g/ A1g
g
2
k
g
t
g
0
G
A
173
k
ꢀ It has two electronic transition bands at 16807 cm
ꢀ1
2
2
2
2
.1227
1.9176
1.9860
1.4891
21276 cm , these can be attributed to E
g
transitions, respectively.
ꢀ
The experimental effective magnetic moment (meff/B.M.) of
Cu(II) complex is 2.09 BM, this value is agreement with an
octahedral geometry [32e34].
ꢀ
The
n
(NeH) stretching frequency of eNH
2
group is presence at
ꢀ1
3
372 cm in the free HL ligand. This band is disappeared or
shifted to lower wavenumbers in case of chelation. This results
confirm that the nitrogen atom of the amino group coordinated
to metal ions.
ꢀ The ESR spectrum of solid Cu(II) complex is displayed in Fig. 3.
The experimental values of g and g are 2.1227 and 1.9176,
k
t
respectively (see Table 3). These data are assigned to distortion
octahedral geometry of the Cu(II) complex. Based on Hathaway
ꢀ
ꢀ
The bending vibration motion
d
(NH
2
) of eNH
2
group at
ꢀ1
ꢀ1
1565 cm (free HL ligand) is shifted to 1581-1574 cm in case
interpretations [32,33], if G > 4 (where, G ¼ (g
k
ꢀ 2)/(g ꢀ 2)),
t
of complexes. This result is due to the sharing of NH
complexation [29].
2
group in
the exchange interaction is negligible but G < 4 indicates
considerable exchange interaction in the solid complexes.
ꢀ Regarding, synthesized copper(II) complex discussed in this
paper the ‘G’ value is < 4 which indicated to the exchange
interaction in solid complex.
ꢀ1
There are new infrared bands presence at 570-554 cm and
ꢀ
1
5
n
01-410 cm ranges with medium-to-weak intensities due to
(M ꢀ N) and (M ꢀ O) stretching motions [29], respectively.
This results refer to the coordination of center metal ions to-
wards phenolic eO and eN atoms (NH and eCH]N groups).
n
ꢀ The molecular orbital coefficients a2 (covalence inꢀplane
2
2
s
ꢀbonding) and
b
(covalence inꢀplane
p
ꢀbonding) are esti-
mated using the following mentioned equations [34];
ꢀ
ꢁ
ꢂ
ꢃ
A
:036
ꢀ 2:0023 þ 3 ðg⊥ ꢀ 2:0023Þ þ 0:04
2
k
3.3. Electronic, magnetic and ESR measurements
a
¼
þ g
k
0
7
UVeVis electronic spectra of the free HL Schiff base ligand and

194
J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
ꢀ
The physical electronic parameters data of (B), (b b ) are
), and ( o
assigned to the covalency nature of synthesized nickel(II) Schiff
base HL complex.
ðg ꢀ 2:9923ÞE
b2
¼
2
ꢀ8la
ꢀ1
(
Where,
l
¼ ꢀ828 cm for the free Cu(II) ion and E is the electronic
transition energy.
3.3.4. Zinc(II) complex (IV)
ꢀ
ꢀ
Lower b2 value in comparison with a2 confirmed that inꢀplane
The zinc(II) metal ion has a d10 electronic configuration, so, it
ꢀ
p
ꢀbonding is more covalent than inꢀplane ꢀbonding [32,33].
s
hasn't take part in the electronic transitions. Therefore the
electronic spectrum of zinc(II) complex (IV) is referred only to
the intra-ligand electronic transitions. These electronic transi-
tions mainly occur at the ultraviolet region [40,41], which
confirmed the absence of the ded transitions [42].
2
The
a value of Cu(II) complex assigned to the covalency in the
bonding between the Cu(II) ion and HL Schiff base ligand.
ꢀ
The UVeVis absorption spectrum of zinc(II) complex (IV)
display three absorption bands at 34482 and 25000 cm , these
3.3.2. Cobalt(II) complex (II)
ꢀ1
are assigned to intr-ligand charge transfer, whereas the third
electronic transition band at 21053 cm is assigned to LMCT
ꢀ
UVeVis. electronic absorption spectrum of Co(II) complex(II)
octahedral geometrical structural has two ded transition bands
ꢀ1
[40e42].
ꢀ1
4
at 19047 and 23529 cm , these can be attributed to T
1
g (F) /
4
4
g (F) / 4T
A
2
g (F)
n
2
and T
1
1
g (P)
n
3
, respectively [30].
3
.4. Mass spectra
ꢀ
Practical magnetic moment data is 4.64 BM, this is assigned to
octahedral geometry.
The mass spectrum technique gives a good discussion about the
consecutive degradation of the synthesized ligand with numerous
peaks recorded with different fragment patterns. The mass spec-
ꢀ
Ligand field parameters of Dq, B, LFSE, and
7369, and 1.0808 respectively. These values agreement with
cobalt(II) octahedral geometry [35].
b are 1447, 1065,
1
trum of HL Schiff base ligand (Fig. 4) refer to the molecular ion peak
þ
M
at m/z ¼ 262.1 (68%), which confirms strongly the proposed
structure and also confirms the purity of the synthesized ligand.
The mass spectrum has prominent peaks at m/z ¼ 263.0 (4.53%),
3.3.3. Nickel(II) complex (III)
2
64.1 (0.97%), 171 (0.79%), 170 (1.04%), 153 (1.15%), 152 (1.87%), 144
(
9
8.33%), 127 (1.85%), 126 (2.85%), 119 (100%), 118 (7.40%), 93 (8. 4%),
2 (10.84%), 77 (5.33%) as shown in the fragmentation Scheme 2.
þ ꢀ
2 3 2
meff experimentally of [Ni(L)(H O) ] .Cl .3H O complex
ꢀ
The
located at low spin octahedral (0.75 BM). The Ni(II) complex has
The mass fragmentation patterns along with the base peak at m/
z ¼ 119 prove that, the essential cleavage of the ligand molecule is
2
3
magnetic moment values at zero data with d sp hybrid orbital
which is matched with an octahedral geometry.
shown in the bond between the carbon atom at position 1 of the
naththol ring and the ring.
b-
ꢀ
The electronic absorption spectrum of Ni(II) complex(III) octa-
hedral geometry has three distinguish bands at 16949, 20408
þ
ꢀ
FAB
mass
spectra
of
[Ni(L)(H
2
O)
3
] .Cl .3H
2
O
and
ꢀ
1
3
3
3
3
and 25974 cm due to A2g/ T2g (F), (
n
1); A2g/ T1g (F), (
3) transitions, respectively.
3) transition band is occurring at
5974 cm due to organic fraction of the Schiff base complex.
n2)
[Cu(L)(Cl)(H
2
O)
2
] complexes have been done. The distinguish
3
3
and A2g/ T2g (P), (
n
fragments referred to the peaks of metal ions and fragmentation
patterns of HL ligand.
3
3
ꢀ
ꢀ
The
2
A2g/ T2g (P), (n
ꢀ1
The fragmentation pattern of the Zn(II) complex (Fig. 5) has
ꢀ
1
The divide
n
2/
n
1 ratio value is 1.2041 cm which is located
þ
prominent peaks at m/z [M ] ¼ 280 (18.24%), 359 (10.4%), 327
within the limit of octahedral geometry [36e39]. The ligand
field parameters like Racah interelectronic repulsion parameter
(19.2%), 261 (1.04%), 269 (100%), 247 (1.3%), 241 (12.8%), 169 (3.3%),
1
43 (7.3%),129 (35.8%),121 (5.4%),105 (6.7%), 93 (4.8%), 78 (1.3%), 28
(
B), ligand field splitting energy (10Dq), covalency factor (
b),
(4.7%) as shown in the fragmentation Scheme 3.
ligand field stabilization energy (LFSE) and percentage lowering
o
of energy in free gaseous ion (
b
) have an experimental values at
3.5. 1HNMR spectra
ꢀ
1
ꢀ1
ꢀ1
1
308 cm ,16949 cm , 0.297, 20.338 kcal mol , and 70%. These
parameters were estimated based on the following equations
37,38];
The structure of the HL Schiff base ligand was discussed through
[
the 1H and C NMR spectra (Fig. 6A). The HNMR spectrum dis-
13
1
3A2g/3T2g (F), (
played a singlet peak at
azomethine proton is shown at
due to the aromatic protons are presence within the range of
d
¼ 5.07 ppm attributed to NH
2
group. The
¼ 6.70 ppm. The multiplet peaks
n
1) ¼ 10Dq
d
3A2g/3T1g (F), (
2
2
n
2) ¼ 7.5B þ 15Dq - ½(225B þ 100Dq e 180DqB)½
d
¼ 7.02e7.97 ppm. The phenolic OH proton recorded at
3A2g/3T2g (P), (
n
3) ¼ 7.5B þ 15Dq - ½(225B þ 100Dq e 180DqB)½
2
2
2
22 - 3
B
complex¼ (2
n
1 þ
n
n
1
n
2) / (15
n
2 - 27
n
1)
0
ꢀ1
b
¼ B/B' (B is the free nickel ion ¼ 1038 cm
)
LFSE ¼ 12Dq
bo ¼ 100 e (
b
x
100)
Fig. 4. Mass fragmentation spectrum of HL Schiff base ligand.

J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
195
o
o
+
o
+
o
+
+
OH
H
C
+
N
C
N
NH2
NH2
m/z = 118
m/z = 119
Base peak
m/z = 144
m/z = 127
b
a
o
+
H
C
b
N
NH2
NH2
OH
m/z = 262
o
+
m/z = 92
o
+
H
C
b
a
a
+H
N
a
NH2
O
H
m/z = 93
b
m/z = 171
a
o
o
+
+
o
+
H
C
a
N
C
c
N
b
OH
O
m/z = 77
m/z = 170
a
m/z = 170
b
b+c
o
o
+
+
o
+
N
C
C
N
OH
m/z = 144
m/z = 152
m/z = 153
o
o
+
+
m/z = 127
m/z = 126
Scheme 2. The fragmentation pattern proposed for HL Schiff base ligand.
The downfield shift of the signal due to NH
2
take place from
5.07 ppm (HL ligand) to 6.96 (complex) and the azomethane proton
shifted from 6.70 to 7.19 ppm. The spectrum showed the absence of
OH signal, which proves that the chelation of the Zn(II) cation
carried out with oxygen of the OH group.
3.6. thermal analysis
Fig. 5. Mass fragmentation patterns of Zn(II) complex.
Figs. 7 and 8 are referred to the TGA and DTA thermograms of HL
Schiff base and its complexes (Cu, Co, Ni and Zn(II)) under nitrogen
atmosphere at heating rate 10 C/min.
ꢁ
d
¼ 9.70 ppm. The 13C NMR spectrum of the HL Schiff base ligand
has some signals at
1
due to C]C, C]N, CeN and CeO bands, respectively. H NMR
spectrum of Zn(II) complex (Fig. 6B) has distinguish signals at
d
¼ 99.99, 117.8, 126.8, 127.0, 127.8, 128.7, 129.0,
31.7, 132.4, 133.4, 133.9, 134.0, 134.4, 145.6, 158.2, 164.3, 170.7 ppm
3.6.1. HL schiff base ligand
1
The HL Schiff base ligand is simultaneous decomposed in six
ꢁ
DTAmax peaks within temperature range 25e800 C. The decom-
ꢁ ꢁ
position steps are exhibited within 25e135 C, 135e197 C,
d
¼ 6.96 (s, 2H, NH
2
), 7.19 (s, 1H, CH]N), 7.22e8.51 (m, 10H, Ar-H),
1
ꢁ
ꢁ
ꢁ
respectively. The HNMR spectrum of Zn(II) complex showed a
downfield shifts for all signals due to the change in electronic
environment of the ligand after complexation with positive metal.
197e283 C, 283e435 C and 435e683 C ranges at different DTA
maximum peaks as 154 (endo), 236(exo), 290(exo), 351(exo),
ꢁ
438(exo) and 610 C(exo), respectively. The observed of total mass

196
J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
H
H
C
C
a
C
O
N
a
Cl
N
a
N
NH
2
N
O
Zn
O
Zn
m/z = 169
m/z = 327
m/z = 359
-
H3
-
Cl
-OH2
-OH2
NH
m/z = 93
- NH2
2
H
C
-Cl
H
C
N
-
OH2
a
NH
2
Cl
N
O
- Zn
NH
2
m/z = 261
O
Zn
OH
m/z = 380
-
-
O
4 H
m/z = 78
a
2
H
C
- NH2
H
N
+
H C
2
NH
2
N
NH
2
m/z = 241
+
O
H
m/z = 143
m/z = 121
C
N
-
O
-
NH2
O
H
C
m/z = 247
N
N
N
HC
C
N
m/z = 105
m/z = 129
H
m/z = 269
HC
N
m/z = 28
Scheme 3. Fragmentation pattern of Zn(II) complex.
loss is 100%, this confirm the purity of synthesized HL Schiff base
3.6.4. Nickel(II) complex (III)
ligand.
Thermal decomposition of nickel(II) complex pass through two
degradation steps. The first one occurs at exothermic DTA-
ꢁ
ꢁ
max ¼ 81 C (25e274 C), the observed mass loss associated as
3.6.2. Copper(II) complex (I)
(obs. ¼ 48.991%) and the second step occurs at the maximum
ꢁ
ꢁ
Thermal decomposition of the copper(II) complex take place
temperature exothermic DTA
¼ 201 C (274e538 C). The mass
max
ꢁ
ꢁ
within mainly three stages of DTAmax at 67 C(exo), 201 C(exo),
4
5
loss at this step (obs. ¼ 25.625%). These sages are associated with
ꢁ
ꢁ
01 C(endo) and 659 C(endo) with observed mass losses 6.226,
5.379 and 16.726%, respectively, due to losses of organic moiety of
the loss of HL Schiff base ligand, six (coord. and uncoord.) H O
2
molecules and chlorine atom. Final residue is NiO oxide polluted
with residual carbon atoms.
HL, coordinated H
position residue resulted at 800 C is CuO which has agreement
between observed and theoretical calculations.
2
O molecules and chlorine atom. Final decom-
ꢁ
3.6.5. Zinc(II) complex (IV)
Thermal decomposition of Zn(II) complex take place in definite
ꢁ
ꢁ
four differential thermal peaks DTAmax ¼ 68 C (exo), 232 C (exo),
3
.6.3. Cobalt(II) complex (II)
ꢁ
ꢁ
5
69 C (endo) and 795 C (endo). The degradation stages occurs at a
temperature ranges 25e379 and 379e519 C. The found weight loss
Cobalt(II) complex thermally destroyed in two steps. The first
ꢁ
ꢁ
step located at 25e346 C and the second step occurred at
3
ꢁ
associated with these steps are (obs. ¼ 79.822%) and due to loss of
46e800 C corresponding to the loss of HL Schiff base ligand, six
ꢁ
H
2
O, Cl and HL thermal species. Final thermal product at 800 C is
(
coordinated and uncoordinated) water molecules and chlorine
zinc oxide.
atom, the weight loss associated with these stages (obs. ¼ 79.224%
%
). DTA curve has two peaks with exothermic and endothermic
ꢁ
behavioral at 73 and 599 C, respectively. The CoO with polluted
with few carbons produced from the thermal decomposition of
cobalt(II) complex.
3.7. Kinetic thermodynamic parameters
The kinetic thermodynamic parameters (Table 4) viz. E*, A, H*, S*

J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
197
1
13
1
þ ꢀ
Fig. 6. A H and C NMR spectra of HL Schiff base. B HNMR spectrum of [Zn(L)(H O)] .Cl Schiff base complex.
2
and G* as activation energy, frequency factor, enthalpy of activation,
entropy of activation and free energy of activation, respectively,
were estimated dependent on the TGA beside DTA curves. Coats-
Redfern and Horowitz-Metzger [43,44] methods were employed
to calculate these parameters. The increasing values of E*
(I-IV) have a crystalline phase (Fig. 9A and B). The XRD spectrum of
Ni(II) complex (Fig. 9B) has a sharp peak due to higher crystallinity.
The crystalline behavior for the synthesized complexes can be
attributed to amalgamation of water molecules inside coordination
sphere [48] and the inherent crystalline nature of the metallic
compounds. The grain sizes of the synthesized Schiff base com-
plexes were estimated from XRD patterns by calculated the full
width at half maximum (FWHM) of the highest peaks using Deby-
Scherrer equation [49]. The complexes I-IV have the average grain
size of 17, 29, 12 and 4 nm, respectively suggesting that the com-
plexes are nano-crystalline.
ꢀ
1
ꢀ
1
(
80e123 kJ mol ) and lower values of frequency factor (S ) are
assigned to the slowest reactions of copper, cobalt, nickel and
zinc(II) Schiff base complexes than normal [45,46]. The negative
ꢀ
1
ꢀ1
values of entropy of activation (ꢀ32.2e139 J mol
K ) confirmed
that the activated of synthesized Schiff base solid complexes has a
more ordered [47] than the preliminary reactants.
SEM micrographs of the free HL, Co(II) and Ni(II) complexes are
shown in Fig. 10. It is seen from the photos that the HL Schiff base
ligand shows an agglomeration with different rectangle-like
structure sizes. The nickel(II) complex shows compacted platelet-
3
.8. XRD and SEM studies
X-ray powder diffraction patterns of free HL and its complexes

198
J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
5
4
3
2
1
0
HL
Cu(II)
Co(II)
Ni(II)
Zn(II)
0
100
200
300
400
500
600
700
o
Temp [ C]
Fig. 7. TGA curves of HL and its M(II) Schiff base complex.
7
6
5
4
3
2
1
0
8
6
4
2
0
HL
0
0
0
0
0
0
0
Cu(II)
Co(II)
Ni(II)
Zn(II)
-
-
-
2
4
6
-
10
0
200
400
600
800
1000
o
Temp [ C]
Fig. 8. DTG curves of HL and its M(II) Schiff base complex.
Table 4
Kinetic thermodynamic parameters of free HL Schiff base ligand and its complexes.
Compound
Stage
Methoda
Parameter
r
Ea (J molꢀ1
)
A (s
ꢀ1
)
D
Sa (J mol
ꢀ1 ꢀ1
K
)
D
Ha (J molꢀ1
)
D
Ga (Jmolꢀ1
)
2nd
2nd
2nd
2nd
2nd
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
8.72 ꢃ 10
4
6.59 ꢃ 10
1.29 ꢃ 10
4.24 ꢃ 10
3.17 ꢃ 10
1.40 ꢃ 10
2.11 ꢃ 10
3.40 ꢃ 10
5.98 ꢃ 10
2.44 ꢃ 10
4.11 ꢃ 10
5
ꢀ1.39 ꢃ 10
ꢀ1.14 ꢃ 10
ꢀ6.47 ꢃ 10
ꢀ4.80 ꢃ 10
ꢀ5.48 ꢃ 10
ꢀ3.22 ꢃ 10
ꢀ1.24 ꢃ 10
ꢀ1.00 ꢃ 10
ꢀ5.00 ꢃ 10
ꢀ2.65 ꢃ 10
2
8.25 ꢃ 10
9.33 ꢃ 10
1.05 ꢃ 10
1.11 ꢃ 10
1.10 ꢃ 10
1.19 ꢃ 10
7.60 ꢃ 10
8.55 ꢃ 10
1.10 ꢃ 10
1.18 ꢃ 10
4
1.60 ꢃ 10
1.57 ꢃ 10
1.37 ꢃ 10
1.35 ꢃ 10
1.37 ꢃ 10
1.34 ꢃ 10
1.36 ꢃ 10
1.34 ꢃ 10
1.34 ꢃ 10
1.31 ꢃ 10
5
0.9849
0.9836
0.9991
0.9979
0.9966
0.9965
0.9946
0.9975
0.9928
0.9897
HL
I
4
7
2
1
1
1
1
2
2
1
1
4
5
5
5
5
4
4
5
5
5
5
5
5
5
5
5
5
5
9.80 ꢃ 10
5
9
1.09 ꢃ 10
5
10
10
11
6
1.15 ꢃ 10
5
II
1.14 ꢃ 10
5
1.23 ꢃ 10
4
III
IV
8.00 ꢃ 10
4
7
8.95 ꢃ 10
5
1.14 ꢃ 10
5
11
1.22 ꢃ 10
a
CoatseRedfern (CR) and HorowitzeMetzger (HM).

J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
199
Fig. 9. AXRD patterns of free HL Schiff base ligand. B. XRD patterns of nickel(II) Schiff base complex.
like structure. Cobalt(II) complex has a gelatinized form with
different sized electrodes-like structure. The surface morphology
differentiations between HL and both cobalt(II) and nickel(II)
complexes in shapes and size of grains can be assigned to the as-
sociation of new chelation behavior, that metal ions play an
important roles for the difference in surface morphology.
base ligand (Table 5). The increasing of biological activity con-
cerning the metal complexes based on Tweedy's chelation theory,
that the chelation make to reduce the polarity of the central metal
ions which favors the permeation of the complexes through the
lipid layer of cell membranes [50]. Furthermore, hydrogen bonding
may affect the mode of action of compound probably through the
azomethine group and the active centers of cell constituents
resulting in the interference with normal cell processes [51]. In vitro
antifungal activities of the synthesized complexes were carried out
against Aspergillus niger and penicillium sp. using fluconazole as
standard drug and inhibition activity were assessed at 10 and
50 mg concentrations. Significant improvement of antifungal effi-
ciency after complexation was listed in Table 6. The increase in
3.9. Biological assay
The biological assay resulted showed that the synthesized HL
complexes have efficient inhibition on the metabolic growth of the
investigated bacteria (Table 5). The synthesized Schiff base com-
plexes have significant activity compared with the free HL Schiff

200
J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
Herein, the anticancer effectiveness of the synthesized com-
pounds as free HL ligand and its metal complexes have been eval-
uated on human HCT-116 cell line of colon carcinoma cells using to
Masmann and Vijayen et al. method [22,23]. The inhibitory activity
against HCT-116 carcinoma cells was performed using various
concentrations (50, 25, 12.5, 6.25, 3.125 and 1.65
tested samples. The 50% inhibitory concentration (IC50) of cop-
per(II) complex g) and zinc(II) complex
(IC50 ¼ 10.5
IC50 ¼ 6.13 g) have a good antitumor activity rather than free
Schiff base ligand HL and nearly from the standard antitumor drug
vinblastine (IC50 ¼ 2.38 g) against human colon carcinoma cells
HCT-116). In conclusion, Zn(II)-HL complex can nominate as anti-
cancer agent against colon carcinoma.
mg) (Table 7) from
m
(
m
m
(
4. Conclusions
Schiff base HL ligand derived from the condensation reaction
between 1-naphthaldehyde and o-phenylenediamine and its cop-
per, cobalt, nickel and zinc(II) complexes in a molar ratio of 1:1
were synthesized and characterized using elemental and spectro-
scopic analyses. The molar conductance values showed an elec-
trolytic nature for all metal complexes except the copper(II)
complex. Electronic, magnetic and molecular formula data have
been suggested an octahedral geometry for the copper(II), cobal-
t(II), and nickel(II) complexes. The XRD patterns showed a
Fig. 10. SEM images of HL Schiff base ligand (A), cobalt(II) complex (B) and nickel(II)
complex (C).
activity with increasing concentration of the samples is due to the
impermeability of the microbial cells or ribosomal difference in the
microbial cells [52,53].
Table 5
Antibacterial activities of HL ligand and metal complexes with (10 and 50 mg) concentrations.
Compound
Gram Positive Bacteria
Gram Negative Bacteria
Bacillus sub.
Staphylococcus
E. Coli
Pseudomonas sp.
10 mg
50 mg
10 mg
50 mg
10 mg
50 mg
10 mg
50 mg
HL
Cu(II)
Co(II)
Ni(II)
Zn(II)
Ciprofloxacin
e
5
4
e
1
8
7
3
5
9
5
2
10
9
4
6
8
1
9
9
5
7
13
7
19
16
6
8
25
20
18
6
9
23
15
11
6
8
19
19
14
9
11
20
e
1
11
15
Table 6
Antifungal activity of HL ligand and metal complexes with (10 and 50 mg) concentrations.
Compound no.
A. Niger
0 mg
Penicillium sp.
1
50 mg
10 mg
50 mg
HL
Cu(II)
Co(II)
Ni(II)
Zn(II)
Fluconazole
e
7
3
2
7
15
8
8
13
16
10
22
12
10
16
28
19
15
9
11
21
e
5
10
Table 7
Cytotoxicity of HL ligand and metal complexes against HCT-116 cell line of colon carcinoma cells.
Sample concentration (mg)
Viability (%)
HL
Cu(II)
Co(II)
Ni(II)
Zn(II)
Vinblastine standard
5
2
1
6
3
1
0
0
5
84.97
91.43
97.92
99.08
100
8.98
82.74
93.82
98.16
100
100
100
46.56
5.89
14.38
16.13
24.25
45.13
55.00
72.13
100
17.52
38.74
74.29
89.65
95.87
100
66.32
84.21
93.78
98.24
100
12.76
23.85
48.74
81.27
93.69
100
2.5
.25
.125
.65
.00
100
100
100
100
IC50
(m
g)
>50
10.5
>50
45.6
6.13
2.38

J.Y. Al-Humaidi / Journal of Molecular Structure 1183 (2019) 190e201
201
crystalline nature for the metal complexes with nano grain sizes.
The free Schiff base and its complexes were screened against Gram-
positive bacteria (Bacillus Subtillus and Staphylococcus aureas) and
Gram-negative bacteria (Escherichia Coli and Pseudomanas aerugi-
nose) and two fungal species (A. Niger and Penicillium sp.). The data
showed that most complexes had activity more than that of Schiff
base HL. The metal complexes showed IC50 values higher than that
of Schiff base HL free ligand, and the Zn(II) complex showed the
[20] I.M. El-Deen, A.A.M. Belal, N.Y. Farid, Rosan Zakaria, Moamen S. Refat, Spec-
trochim. Acta, Part A 149 (2015) 771.
[
21] A.I. Vogel, A Text Book of Quantitative Inorganic Analysis, Longmans, London,
994.
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93.
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23] T. Musmann, J. Imunol. Methods 65 (1983) 55.
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mg) against HCT-116 cell line of colon carcinoma
(2006) 1208.
cell. The anticancer activity of HL and its complexes were compa-
rable with Vinblastine standard drug IC50 (2.38 mg) (Table 7).
[27] S. Brooker, S.S. Iremonger, P.G. Plieger, Polyhedron 22 (5) (2003) 665.
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