Synthesis of Nano-Metric Gold Complexes with New Schiff Bases Derived from 4-Aminoantipyrene, Their Structures and Anticancer Activity

Article abstract of DOI:10.1134/S1070363217120519

Two new Schiff bases derived from combination of 4-aminoantipyrine with ethylenediamine (L₁) or benzaldehyde (L₂), gave Au(III) complexes. Their structures were elucidated from microanalytical, magnetic, conductance, and FT-IR, UV-Vi

Full text of DOI:10.1134/S1070363217120519

ISSN 1070-3632, Russian Journal of General Chemistry, 2017, Vol. 87, No. 12, pp. 3043–3051. © Pleiades Publishing, Ltd., 2017.
Synthesis of Nano-Metric Gold Complexes
with New Schiff Bases Derived from 4-Aminoantipyrene,
Their Structures and Anticancer Activity1
K. S. A. Abou Melhaa*, G. A. A. Al-Hazmib,c, and M. S. Refatd,e
a Chemistry Department, Faculty of Science of Girls, Abha, King Khalid University, Abha, Saudi Arabia
*e-mail: dr.khlood@hotmail.com
b Chemistry Department, Faculty of Science, King Khalid University, Abha, Saudi Arabia
c Chemistry Department, Faculty of Applied Sciences, Taiz University, Taiz, Yemen
d Chemistry Department, Faculty of Science, Taif University, P.O. Box 888, Al-Hawiah, Taif, 21974 Saudi Arabia
e Department of Chemistry, Faculty of Science, Port Said, Port Said University, Egypt
Received October 19, 2017
Abstract―Two new Schiff bases derived from combination of 4-aminoantipyrine with ethylenediamine (L1)
or benzaldehyde (L2), gave Au(III) complexes. Their structures were elucidated from microanalytical,
1
magnetic, conductance, and FT-IR, UV-Vis, Mass, and H and 13C NMR spectral data. High conductance
values indicated electrolytic nature of the complexes. Magnetic moments and electronic spectral data indicated
that two synthesized Au(III) Schiff base complexes had a square planar geometry. FT-IR spectroscopic data
demonstrated that the Schiff bases were coordinated to Au(III) ions in a tetradentate manner with NNNN donor
sites of two 4-amino antipyrine and two azomethine (L1), while L2 Schiff base ligand coordinated to Au(III)
ions via its four azomethine nitrogen, which was further supported by the appearance of new bands in IR
spectra due to ν(M–N). Activation thermodynamic parameters (E*, ΔH*, ΔS*, and ΔG*) were calculated on the
basis of TG curves. Crystalline structures of Schiff bases and their Au(III) complexes were characterized by X-
ray diffraction (XRD), their morphology was characterized by scanning electron microscopy (SEM) and
transmission electron microscopy (TEM). The Schiff base ligands and their Au(III) chelates were screened for
their antimicrobial activity. Cytotoxic activity of those was tested against the human breast cancer (MCF-7) and
human hepatocellular carcinoma (HepG-2) tumor cell lines.
Keywords: 4-aminoantipyrine, gold, Schiff base, chelates, nanoscale, spectroscopic, morphology, antimicrobial
activity
DOI: 10.1134/S1070363217120519
INTRODUCTION
thesized and characterized by elemental, molar con-
ductance, magnetic, SEM, TEM, and thermal analyses,
and a variety of spectral methods including Mass, UV-
Vis, FT-IR, 1H and 13C NMR spectrum, and XRD. The
results of their antibacterial and anticancer activity
tests are reported herein.
Transition metal complexes of 4-aminoantipyrine
and its derivatives have been extensively studied due
to their potential in biology [1].
The literature survey reveals that close attention has
been payed to Schiff bases derived from 4-amino-
antipyrine with several aldehydes or ketones. Less
efforts were directed towards condensation of 4-amino-
antipyrine with ethylenediamine in the presence of
benzaldehyde condensed with the NH2 group in the
position 4. In the present study two new tetradentate
Schiff bases and their Au(III) complexes were syn-
EXPERIMENTAL
4-Aminoantipyrine (Aldrich), ethylenediamine
(Sigma-Aldrich), benzaldehyde (Aldrich), gold(III)
chloride (Sigma-Aldrich), and all other chemicals and
solvents were of analytical grade and used without
further purifications.
The elemental analyses were carried out on a
Perkin Elmer CHN 2400 (USA). Molar conductivity of
1 The text was submitted by the authors in English.
3043

3044
ABOU MELHA et al.
Scheme 1.
Me
Me
N
N
Me
NH2
Me
NH2
NH2
N
N
+
2
N
N
NH2
NH2
Me
O
N
N
Me
Scheme 2.
Me
Me
Me
Me
N
N
+
O=C
N
N
H
N=
C
H
NH2
N
O
Me
Me
N
N
Me
N= C
H
Me
N=
N
NH2
NH2
N
2
N
+
N
C
H
O
N=
Me
C
H
N
N
Me
freshly prepared 1.0×10–3 mol/cm3 DMSO solutions
was measured using a Jenway 4010 conductivity
meter. IR spectra were recorded on a Bruker FT-IR
Spectrophotometer (4000–400 cm–1). UV-Vis absorp-
tion spectra were recorded in DMSO in the range of
800–200 nm on a UV2 Unicam UV/Vis Spectrophoto-
meter fitted with a quartz cell of 1.0 cm path length.
Magnetic moments were measured on a Magnetic
Susceptibility Balance, Sherwood Scientific, Cambridge
up to 800°C. Scanning electron microscopy (SEM)
images were taken with a Quanta FEG 250 equipment.
The X-ray diffraction patterns were recorded on an
X'Pert PRO PANanalytical X-ray powder diffracto-
meter. Transmission electron microscopy images
(TEM) were generated using a JEOL 100s microscope.
Synthesis of 4-aminoantipyrine ethylenediamine
Schiff base chelate (L1) (Scheme 1). 4-Amino-
antipyrine (2.03 g, 0.02 mol, 20 mL methanol) was
mixed with ethylenediamine (0.6 g, 0.01 mol, 20 mL
methanol) and refluxed for 2 h at 60°C. The precipitate
was washed, filtered off, recrystallized from methanol,
and dried in a vacuum desiccator over anhydrous
calcium chloride. The product was obtained as a
1
Science Park, England, at 25oC. H and 13C NMR
spectra were measured on a Varian Mercury VX-300
NMR spectrometer in DMSO-d6. Chemical shifts were
related to those of the solvent. Purity of Schiff base
ligands (L1 and L2) was tested by mass spectra
measured on a AEI MS 30 Mass Spectrometer. The
thermal studies, TG/DTG–50H, were carried out on a
Shimadzu thermo-gravimetric analyzer under nitrogen
1
yellow solid, yield 61%, mp 220°C. H NMR spec-
trum, δ, ppm: 1.77 s (6H, 2CH3, C3); 2.1 s (4H, 2CH2);
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 12 2017

SYNTHESIS OF NANO-METRIC GOLD COMPLEXES WITH NEW SCHIFF BASES
(a) (b)
3045
C
C
C
C
C
N
C
C
C
C
C
N
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
N
N
C
C
C
C
C
C
N
C
C
C
C
N
C
C
C
C
C
C
C
C
C
C
C
C
N
C
C
C
C
C
N
C
Fig. 1. (a) HOMO and (b) LUMO structures of Schiff base ligand L2.
2.74 s (6H, 2NCH3); 3.99 br (4H, 2NH2); 7.21 t (2H,
phenyl, C4); 7.40 m (8H, phenyl, C2, C3). 13C NMR
spectrum, δ, ppm: 10.35, 23.76 (2CH3), 38.73 (CH2),
120.5, 122.3, 125.6, 129.6, 136.0, 161.8, 169.8, 174.2
(N–C, C=C, C=N). MS, m/z (Irel, %), [M]+: 430 (4.7),
401 (2.5), 243 (2.7), 216 (41.3), 201 (31.7), 186 (22.5),
185 (52.1), 134.8 (48.6), 124 (22.8), 109 (22.4), 105
(36.4), 78 (100), 57 (80). Found, %: C 66.80; H 6.87;
N 25.79. C24H30N8. Calculated, %: C 66.95; H 7.02; N
26.03.
122.7, 123.3, 126.8, 127.2, 130.3, 132.2, 133.6, 133.8,
135.9, 146.4, 158.0, 162.5 (N–C, C=C, C=N). MS, m/z
(Irel, %), [M]+: 606 (14.4), 591 (12.3), 503 (10.5), 318
(43.9), 290 (35.7), 289 (25.4, 213 (24.5), 198 (22.7),
187 (48.9), 186 (28.8), 172 (30.2), 105 (15.3), 104
(11.2), 95 (54.4), 77 (100). Found, %: C 75.09; H 6.22;
N 18.41. C38H30N8. Calculated, %: C 75.22; H 6.31; N
18.47.
Synthesis of Au(III) Schiff base (L1–L2) com-
plexes. The mixture of a Schiff base ligand (L1 or L2)
(0.02 mol) with gold(III) chloride (0.02 mol) was
dissolved in 50 mL methanol and refluxed for 2 h.
Then, the red (L1) or brown (L2) solution was eva-
porated to half of its original volume to make the
product precipitate. The precipitate was filtered off,
washed with methanol and dried in a vacuum
desiccator over anhydrous CaCl2.
Synthesis of 4-aminoantipyrine–benzaldehyde–
ethylenediamine Schiff base chelate (L2) (Scheme 2).
The Schiff base chelate (L2) was synthesized in two
steps. Solution of 4-aminoantipyrine (2 mmol) in
methanol was mixed with benzaldehyde (2 mmol) and
gently heated for 2 h upon constant stirring. The
precipitate obtained was filtered off and recrystallized
from methanol. Fine pale yellow powder was washed
with alcohol, ether and dried in vacuum desiccator
over anhydrous calcium chloride. The precursor
(2 mmol) was mixed with methanol solution of
ethylenediamine (1 mmol) and refluxed for 2 h with
constant stirring at 60°C. The reaction mixture was
poured in to crushed ice. The yellow solid product (L2)
was filtered off and recrystallized from methanol.
[Au(L1)]·Cl3. Yield 60%, decomposition tempera-
1
ture 260–280°C. H NMR spectrum, δ, ppm: 1.90 s
(6H, 2CH3, C3); 2.5 s (4H, 2CH2); 2.84 s (6H, 2NCH3);
4.81 br (4H, 2NH2); 7.38–7.59 m (10H, phenyl). 13C
NMR spectrum, δ, ppm: 15.73, 27.08 (2CH3), 45.95
(CH2), 122.5, 123.5, 126.6, 129.0, 137.5, 160.6, 170.5,
179.8 (N–C, C=C, C=N). MS, m/z (Irel, %): 376 (26.9),
375 (55.7), 361 (24.5), 204 (46.7), 203 (73.9), 202
(28.8), 120 (17.4), 93 (74.4), 84 (31.2), 83 (38.5), 76
(58.1), 56 (100). Found, %: C 39.10; H 4.03; N 15.14;
Cl 14.33. Calculated, %: C 39.28; H 4.12; N 15.27; Cl
14.49.
1
Yield 63%, mp 209°C. H NMR spectrum, δ, ppm:
2.18 s (6H, 2CH3, C3); 2.69 s (4H, 2CH2); 3.11 s (6H,
2NCH3); 7.35–7.83 m (20H, phenyl). 13C NMR
spectrum, δ, ppm: 12.59, 34.83 (2CH3), 52.16 (CH2),
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 12 2017

3046
ABOU MELHA et al.
Scheme 3. The proposed structures of [Au(L1)]·Cl3 and [Au(L2)]·Cl3 complexes.
Me
Me
Me
Me
N
N
N
N
NH
N= C
H
Au
N
Au
.
N
.
Cl3
Cl3
N
N
NH2
N=C
H
N
N
N
Me
N
Me
Me
Me
[Au(L2)]·Cl3. Yield 64%, decomposition tempera-
ture 260–274°C. Found, %: C 49.89; H 4.12; N 12.08;
Cl 11.48. Calculated, %: C 50.15; H 4.21; N 12.31; Cl
11.69.
Anti-cancer activity. Human breast cancer (MCF-7)
cell line and human hepatocellular carcinoma (HepG-2)
cells were obtained from the American type culture
collection ATCC, Rockvill, MD). The cells were
grown on RPMI-1640 medium supplemented with
10% inactivated fetal calf serum and 50 µg/mL of
gentamycin. The cells were maintained at 37°C in a
humidified atmosphere with 5% CO2 and were
subcultured two to three times a week. The cells were
grown as monolayers in growth RPMI-1640 medium
supplemented with 10% inactivated fetal calf serum
and 50 µg/mL of gentamycin. The monolayers of
10000 cells adhered at the bottom of the wells in a
96-well micro titer plate were incubated for 24 h at 37°C
in a humidified incubator (5% CO2). The monolayers
were then washed with sterile phosphate buffered
saline (0.01 M pH 7.2) and simultaneously the cells
were treated with 100 µL of the test sample different
Antimicrobial assessment. Antimicrobial activity of
the samples was tested using the modified Kirby-Bauer
disc diffusion method [2]. Briefly, 100 μL of the best
bacteria (gram negative (Escherichia coli and
Klebsiella) and gram positive (Staphylococcus aureus
and Staphylococcus epidermidis) were grown in 10 mL
of fresh media until they reached a count of
approximately 108 cells/mL for bacteria [3]. Microbial
suspension (100 μL) was spread onto agar plates,
corresponding to the broth in which they were
maintained. Isolated colonies of each organism were
selected from primary agar plates and tested for
susceptibility by the disc diffusion method [4].
Table 2. FT-IR spectral data (cm–1) for L1, L2 and their
Table 1. Quantum chemical parameters of the Schiff base
ligands L1 and L2
gold(III) complexes
Parameter
LUMO, eV
L1
L2
E
–23.5691
4.2669
–29.4767
22.62484
52.10154
3.42593
26.05077
0.038387
–3.42593
0.019193
0.225272
0.13151
ν(N–H);
ν(NH2)
Compounds
ν(C=O) ν(C=N) ν(C–N) ν(M–N)
EHOMO, eV
ΔE, kJ/mol
χ, kJ/mol
27.836
9.6511
L1
3436,
3322
1649
1649,
1585
1274
–
–
η, kJ/mol
13.918
σ, kJ/mol
Pi, kJ/mol
S, kJ/mol
0.071849
–9.6511
0.035925
3.346161
0.693426
[Au(L1)]Cl3
L2
3423,
3135
–
–
1636
499
–
1649,
1561
1298
1286
ω, kJ/mol
ΔNmax, kJ/mol
[Au(L2)]Cl3
1623,
1511
499
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 12 2017

SYNTHESIS OF NANO-METRIC GOLD COMPLEXES WITH NEW SCHIFF BASES
3047
Table 3. Kinetic parameters deduced from the Coats–Redfern equation for the gold(III) complexes
Thermodynamic parameters
Complexe
DTGmax, °C
277
Steps
2
parameter
value
[Au(L1)]·Cl3
E, J/mol
4.49×104
4.61×101
–2.18×102
4.02×104
1.64×105
0.9995
A, s–1
ΔS, J mol–1 K–1
ΔH, J/mol
ΔG, J/mol
r
[Au(L2)]·Cl3
300
E, J/mol
A, s–1
6.25×104
6.60×103
–1.77×102
5.80×104
1.52×105
0.9950
2
ΔS, J mol–1 K–1
ΔH, J/mol
ΔG, J/mol
r
dilutions in fresh medium and incubated at 37°C.
Control of untreated cells was made in the absence of
the test sample. Six wells were used for each con-
centration of the test sample. Every 24 h observations
under an inverted microscope were made. Number of
the surviving cells was determined by staining the cells
with crystal violet [5] followed by cell lysing using
33% glacial acetic acid and the absorbance was
determined at 490 nm using an ELISA reader (Sun
Rise, TECAN, Inc, USA) after intensive mixing. The ab-
sorbance values from untreated cells were considered
as 100% proliferation. The number of viable cells was
determined using an ELISA reader as mentioned
before and the percent of viability was calculated as
powerful donation character. Molecular modeling
allowed to estimate three dimensional arrangements of
atoms in free Schiff base and their Au(III) complexes.
As an example, structures of HOMO and LUMO for
the Schiff base ligand L2 are presented in Fig. 1.
Stoichiometry and molar conductance results.
Two tetradentate Schiff base ligands and their gold(III)
complexes have been synthesized by a 1 : 1 molar
condensation of 4-aminoantipyrine with ethylenedi-
amine or benzaldehyde. The complexes were stable in
the air at room temperature, slightly soluble in polar
solvents and soluble in organic solvents (DMF,
DMSO). Molar conductances of the complexes were
59 and 72 μs/cm for gold(III) complexes of L1 and L2,
respectively. These results indicated that gold(III)
complexes were 1 : 1 electrolytes in DMSO solutions
(1×10–3 M). The electrolytic nature of Au(III)
complexes suggested that the chloride anions of the
salts were localized outside the coordination spheres
[9] (Scheme 3). This was supported by the reaction of
the synthesized gold(III).
[1 – (ODt/ODc)]×100%,
where ODt is the mean optical density of wells treated
with the test sample and ODc is the mean optical
density of untreated cells. The 50% inhibitory
concentration (IC50) was estimated from graphic plots.
RESULTS AND DISCUSSION
IR spectra. IR spectra of the ligands as well as
those of Au(III) complexes had similar profiles (Table 2).
Condensation of 4-aminoantipyrine with ethylenedi-
amine was indicated by disappearance of the band ν
(C=O), presence of the NH2 group stretching bands
[10] and a band at 1585 cm–1 assigned to the ν(C=N)
group (Table 2). The band at 1649–1585 cm–1 (C=N)
of the ligand L1 disappeared or shifted to lower
frequencies (1636 cm–1) in the spectrum of the cor-
responding gold(III) complex, which indicated
participation of C=N nitrogen in coordination with
Molecular modeling. The Schiff base chelates and
their gold(III) complexes single crystals data were
supported by quantum chemical calculations and
molecular modeling studies [6,7]. The geometry
optimization and conformation analysis were performed
using semi-empirical PM3 level [7] as implemented in
software of Hyperchem 7.5 program [8] (Table 1).
The negative data of ELUMO and EHOMO indicated
stability of the synthesized complexes. High values of
EHOMO confirmed that the Schiff base ligands had a
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 12 2017

3048
ABOU MELHA et al.
(a)
(b)
20 μm
10 μm
Fig. 2. SEM images of Schiff base ligand (a) L1 and (b) [Au(L1)]·Cl3 complex.
Au(III). Stretching vibrations of the NH2 group were
shifted to lower wavenumbers in the spectra of the
complex due to participation of nitrogen atoms of the
terminal amino groups in chelation. The ligand acted
as tetradentate chelating agents bonded to gold(III) ion
via four nitrogen atoms of the Schiff base (C=N and
NH2). Appearance of the weak band at 499 cm–1
confirmed the M…N coordination in the complex.
(1.77 and 2.74 ppm) shifted in the spectrum of the
corresponding complex to 1.90 and 2.84 ppm ac-
cordingly. The signals of the NH2 group shifted from
3.99 to 4.81 ppm, accordingly, indicating lower
electronic density over the nitrogen atom upon com-
plexation. The 13C NMR spectrum demonstrated clear
downfield shift for the sp3 carbon atoms.
Thermogravimetric analyses and kinetic
calculations. Decomposition temperature of the syn-
thesized gold(III) complexes was above 200°C which
indicated formation of stable coordination compounds.
Electronic and magnetic measurements. Au(III)
Complexes of L1 and L2 Schiff bases had diamagnetic
nature (μeff = 0.21 and 0.19) as expected for low spin
d8 complexes, which was assigned to square planar
geometry [11].
In the current study, the integral method of Coats
and Redfern [13] was used to evaluate the kinetic
parameters and thermal behavior of gold(III) Schiff
base complexes (Table 3). The accumulated data
allowed to make the following remarks:
Electronic spectra of free Schiff base ligands
exhibited bands at 292 and 352 nm, assignable to π–π*
and n–π* transitions in the benzene rings, NH2 and
azomethine groups. The electronic spectra of gold(III)
complexes gave three distinguished absorption bands
(1) The gold(III) Schiff base complexes demon-
strated the first order decomposition stages in all cases.
1
at 383–379, 354, and 292–280 nm due to A1g→1A2g,
1
1A1g→1Β1g, A1g→1Eg and charge transfer transitions,
(2) The value of ∆G increased significantly for the
subsequent decomposition stages of a given complex.
This was due to increased values of T∆S from one
stage to another that were higher than the values of ∆H
[14, 15].
respectively. The bands were attributed to the low-spin
square planar configuration [12].
1H and 13C NMR spectra. Two methyl groups
1
signals of the free L1 recorded in H NMR spectrum
(3) The negative values of activation entropy (∆S)
indicated the more ordered activation complexes than
the reactants and/ or the reactions were slow [16].
Table 4. Crystallite sizes (D), dislocation density (δ) and
strain (ε) data for [Au(L1)]Cl3
Complex
D, nm
δ×1012, lin/m2
ε×10–4
(4) The positive values of ∆H indicated that the
decomposition processes were endothermic.
[Au(L1)]·Cl3
12
0.0069
1.65
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SYNTHESIS OF NANO-METRIC GOLD COMPLEXES WITH NEW SCHIFF BASES
3049
Table 5. Inhibition zone diameter for Schiff bases and their gold(III) complexes against some kinds of bacteria
Inhibition zone diameter, mm/mg sample
Samples
Escherichia
coli (g–)
Staphylococcus
Epidermidis (g+)
Staphylococcus Aureus
Klebsiella (g–)
(g+)
Control: DMSO
0.0
0.5
0.0
0.3
0.0
1.0
0.0
0.4
Standards
Augmentin
Unasyn
0.2
0.3
0.2
0.2
0.1
0.1
0.1
0.2
0.0
0.0
1.0
0.0
0.0
0.0
0.0
0.2
0.0
0.0
0.0
0.0
L1
Au–L1 complex
L2
Au–L2 complex
Morphological studies (XRD, SEM and TEM).
Crystallinity of the Schiff base chelate (L1) and its
Au(III) complex were deduced from the major
diffraction patterns based on the Deby–Scherrer [17]:
Antibacterial and anticancer assessments.
Antibacterial activity of the Schiff base ligands (L1 and
L2) and their gold(III) complexes was screened in vitro
against gram negative (Escherichia coli and
Klebsiella) and gram positive (Staphylococcus aureus
and Staphylococcus epidermidis) bacteria (Table 5).
The accumulated data indicated that the gold(III)
complexes exhibited higher growth inhibition potential
than that of the ligand. The [Au(L1)]·Cl3 complex
demonstrated antibacterial activity against Escherichia
coli that inhibited multiplication process of the
microbes by blocking their active sites. Mechanism of
higher toxicity of the gold(III)–L1 complex compared
to that of the L1 ligand could be ascribed to the
increase of lipophilicity of the complex due to
chelation [23]. Chelation reduced polarity of the metal
atom mostly due to partial sharing of its positive
D = Kλ/βcos θ,
where λ is the wavelength of X-ray (1.5418 Å) for
CuKα radiation, K is constant taken as 0.94, β full
width at half maximum (FWHM) of prominent
intensity peak (100% relative intensity peak), θ is a
peak position.) The calculated grain sizes were found
to be 12 nm for [Au(L1)]·Cl3 complex. The lower grain
size of Au(III)–L1 complex (12 nm) could be attributed
to the increase of Schiff base chelates around metal
ions as tetradentate cavity [18]. The evaluated
dislocation density (δ) [19] and is listed in Table 4.
Four diffraction patterns peaks at 2θ = 38.14°,
44.30°, 64.59°, and 77.63°, were assigned to the planes
(111), (200), (220), and (311) of face centered cubic
crystal lattice structure of AuNPs [20]. The average
particle size was found to be 12 nm, which cor-
responded to the planes (111), (200), (220), and (311)
deduced from the Scherrer’s equation [21, 22].
According to the SEM images (Fig. 2) the
synthesized gold(III) complex was NPs, grown as
uniform shape with diameter size range 0.3–3.0 μm.
The TEM analysis of the complex [Au(L1)]·Cl3
(Fig. 3) confirmed the presence of nanomeric gold(III)
ions inclusion in Schiff base molecules. The TEM
photograph demonstrated spherical NPs of gold(III)
that appeared as dark spots. The diameter of Au(III)
complex was ca 10 nm. These data matched with the
XRD data.
200 nm
Fig. 3. TEM image of [Au(L1)]·Cl3 complex.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 12 2017

3050
ABOU MELHA et al.
Table 6. Inhibitory activity of the Schiff base ligand L1 and complexes [Au(L1)]·Cl3 and [Au(L2)]·Cl3 against MCF-7 and
HepG-2 cell lines
Viability
Sample concentration, μg
HepG-2 cell line
Au–L1
6.39
MCF-7 cell line
Au–L1
8.94
L1
Au–L2
8.62
L1
Au–L2
12.45
24.56
39.72
58.19
79.04
94.18
99.72
100
500
250
125
62.5
31.25
15.60
7.80
3.90
2
11.78
24.02
32.76
46.28
71.39
86.23
94.12
99.47
100
24.47
37.56
59.21
80.46
95.28
99.72
100
16.47
28.92
37.54
45.23
68.96
82.37
90.49
97.51
100
19.73
28.65
39.51
48.62
70.38
86.29
97.02
100
17.25
28.19
37.85
60.94
78.15
92.47
98.42
100
100
100
100
1
100
100
100
100
100
0
100
100
100
100
100
100
IC50
57.9
28.1
30.2
178
46.1
90.2
charge with the donor groups and possible π-electron
delocalization within the whole chelate ring. Chelation
could also increase lipophilic nature of the central
metal atom, which subsequently favored permeation
through the lipid layer of cells membrane [24]. The
mode of action of complexes could involve formation
of hydrogen bonds with the imino group leading to
interference with the cell wall synthesis. H-Bond
formation would have damaged the cytoplasmic
membrane and the cell permeability could also be
altered leading to cells death.
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