Preparation, characterization and biological activity of silver nanoparticles and silver(I) complex using the new compound 2,2′-(2-phenyl acetylazanediyl)diacetic acid

Article abstract of DOI:10.1016/j.ica.2015.02.012

Silver nanoparticles (AgNPs) were prepared by the reduction of AgNO₃ using 2,2′-(2-phenyl acetylazanediyl)diacetic acid in dilute aqueous Na₂CO₃ solution. On the other hand, the Ag(I)-complex was prepared by reacting AgNO₃ with the ligand in a 1:1 M ratio. The nanoparticles and complex formed were characterized using IR, UV-Vis and ¹H NMR spectroscopy, whereas thermal studies were performed for the Ag(I) complex. The particle sizes of the AgNPS were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Photographs showed that the silver sol consisted of well dispersed spherical shaped nanoparticles with particle size ranging between 6.24 and 7.84 nm. A typical plasmon absorption band at 430 nm was observed for the silver nanoparticles. 2,2′-(2-phenyl acetylazanediyl)diacetic acid acted as a reducing as well as adsorbing agent in the preparation of these spherical, silver nanoparticles. Both silver nanoparticles and Ag(I) complex proved to have antibacterial as well as antifungal activities.

Full text of DOI:10.1016/j.ica.2015.02.012

Inorganica Chimica Acta 429 (2015) 257–265
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Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Preparation, characterization and biological activity of silver
nanoparticles and silver(I) complex using the new compound
2,20-(2-phenyl acetylazanediyl)diacetic acid
⇑
Amina A. Soayed
Alexandria University, Faculty of Science, Department of Chemistry, P.O. Box 426, Ibrahimia, 21321 Alexandria, Egypt
a r t i c l e i n f o
a b s t r a c t
Silver nanoparticles (AgNPs) were prepared by the reduction of AgNO3 using 2,20-(2-phenyl acety-
lazanediyl)diacetic acid in dilute aqueous Na2CO3 solution. On the other hand, the Ag(I)-complex was
prepared by reacting AgNO3 with the ligand in a 1:1 M ratio. The nanoparticles and complex formed were
characterized using IR, UV–Vis and 1H NMR spectroscopy, whereas thermal studies were performed for
the Ag(I) complex. The particle sizes of the AgNPS were determined by scanning electron microscopy
(SEM) and transmission electron microscopy (TEM). Photographs showed that the silver sol consisted
of well dispersed spherical shaped nanoparticles with particle size ranging between 6.24 and 7.84 nm.
A typical plasmon absorption band at 430 nm was observed for the silver nanoparticles. 2,20-(2-phenyl
acetylazanediyl)diacetic acid acted as a reducing as well as adsorbing agent in the preparation of these
spherical, silver nanoparticles. Both silver nanoparticles and Ag(I) complex proved to have antibacterial
as well as antifungal activities.
Article history:
Received 8 December 2014
Received in revised form 4 February 2015
Accepted 12 February 2015
Available online 26 February 2015
Keywords:
Silver nanoparticles
2,20-(2-phenyl acetylazanediyl)diacetic acid
Scanning electron microscopy (SEM)
Transmission electron microscopy (TEM)
Antimicrobial studies
Thermal analyses
Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
membrane. The coordinating ligands of the silver(I) complexes
play the role of carrier for the silver(I) ion to the biological system.
The treatment of infectious diseases is one of the most impor-
tant and challenging issues because of the increasing number of
Silver nanoparticles as well, having the nanometer scale range
1–100 nm, proved to be effective in controlling and suppressing
bacterial growth. They were also used as chemical and biological
sensors [8,9] and have very good antimicrobial effect against var-
ious pathogenic organisms. The silver nanoparticles can be benefi-
cial in delayed diabetic wound healing [10]. It is also known that
Ag-NPs have unusual optical, electronic, and chemical properties
[11–14]. Spectral characteristics of silver nanoparticles are
strongly dependent on their size, shape, inter particle spacing
and environment [15]. Optical scattering was shown to be useful
in detecting bio-systems and have been applied to the diagnostics
of cancer cells [16,17].
The aim of the present work was to synthesize and characterize
a novel ligand 2,20-(2-phenyl acetylazanediyl)diacetic acid as well
as its Ag(I) complex and use it as a reducing agent to synthesize
AgNPs that would become the next generation in the fight against
microbial infections.
resistant microbial pathogens. Although
a large number of
antibiotics and chemotherapeutics are used nowadays in medical
treatment, new classes of antimicrobial agents are required.
There is a real need for the discovery of new compounds having
antimicrobial activity which acts differently from those of well-
known classes of antimicrobial agents to which many clinically
pathogens are now resistant. That is why, new antimicrobial
agents and nano-compounds have to be synthesized.
Silver and its compounds have long been used as antifungal,
antibacterial agents for antibiotic resistant bacteria [1], preventing
infection, healing wounds and anti-inflammatory [2]. Silver is toxic
to microorganisms by poisoning respiratory enzymes and compo-
nents of electron transport system, and it also binds to bacterial
surface, altering the membrane function and inhibiting replication
[3–7]. Silver complexes of oxygen donor ligands have also dis-
played a wide range and effective activities against some bacteria,
yeasts and molds due to the direct interaction between the
silver(I) ion and biological ligands such as protein, enzymes and
2. Experimental
The chemicals used were of high purity. The methanol and sil-
ver nitrate used were (99.5%) and were obtained from Cicarelli
and Fluka, respectively.
⇑
Mobile: +20 1005297350; +966 545996300.
E-mail addresses: amsoayed@yahoo.com, aasaid@uod.edu.sa
http://dx.doi.org/10.1016/j.ica.2015.02.012
0020-1693/Ó 2015 Elsevier B.V. All rights reserved.

258
A.A. Soayed / Inorganica Chimica Acta 429 (2015) 257–265
2.1. Synthesis of 2,20-(2-phenyl acetylazanediyl)diacetic acid 4
(25 mL) to a hot solution (60 °C) of the ligand (10 mmol) in the
same solvent (25 mL). The resulting mixture was stirred under
reflux for 2–3 h whereupon the complex precipitated. It was col-
lected by filtration, washed with a 1:1 ethanol–water mixture fol-
lowed by diethyl ether and then dried in vacuum over anhydrous
calcium chloride. Elemental analysis for the complex are as fol-
lows: calculated (found); C 38.32 (38.02); H 3.22 (3.36); N 3.72
(3.48); Ag 28.68 (28.48).
Thionyl chloride (74 mL) was added drop wise to a suspension
of 2-phenylacetic acid 1, (13.6 g, 100 mmol), during a period of
time 30 min at ꢀ20 °C. The reaction mixture was stirred at
ꢀ20 °C for 1 h and then overnight at rt. The solvent and the excess
of SOCl2 were removed under vacuum and then diethyl ether was
added and removed in vacuum, this process was repeated three
times. The crude acid chloride was added to a mechanically stirred
cold (ice bath) solution of dimethyl iminodiacetate hydrochloride 2
(19.7 g, 100 mmol) in dry CH2Cl2 (20 mL) in presence of Et3N
(13.9 mL, 100 mmol) under nitrogen. The reaction mixture was
stirred overnight, diluted with 100 mL CH2Cl2, washed with 1 N
HCl (twice), saturated NaCl (twice), and then dried over MgSO4.
The solvent was evaporated at 30 °C. The crude ester 3 was dis-
solved in 10% KOH in ethanol (20 mL). The reaction mixture was
refluxed for 3 h and then neutralized with 1 N HCl solution. The
precipitate formed was filtered off and washed with water to give
the acid. The product was further recrystallized from MeOH/ether
to give off white solid in 93.2% yield (23.4 g), m.p. 74–75 °C. IR
(KBr): 3664 (br, OH), 3490 (br, OH), 2987–2901 (C–H stretching),
1744 (CO, acid), 1696 (CO, amide), 1475 (C–N), 1407 (O–H defor-
2.4. Instruments used
2.4.1. Scanning electron microscopy of silver nanoparticles (SEM)
Surface morphology of the synthesized silver nanoparticles was
done using an Oxford Instrument attached to JSM-5300 scanning
microscope equipment. The thin coating of the silver nano-synthe-
sized particles were prepared on a carbon coated copper grid by
dropping a very small amount of the sample on the grid, excess
solution was removed using a blotting paper. The film is then
placed on the SEM grid which was allowed to dry by putting it
under a mercury lamp for several minutes.
2.4.2. Transmission electron microscopy of silver nanoparticles (TEM)
The morphological examination and particle sizes of the silver
nanoparticles were also determined by transmission electron
microscopy (TEM). The TEM images were performed with a JEOL
100-CX transmission electron microscope with an acceleration
voltage of 80 kV. A drop of the prepared sample was placed on a
carbon copper grid and dried before placing it into the TEM sample
chamber.
.
mation), 1056 (C–OH stretching) cmꢀ1 1H NMR (500 MHz,
DMSO-d6): d 3.62 (2H, s, CH2), 3.97 (2H, s, CH2), 4.20 (2H, s, CH2),
7.16–7.19 (3H, m, Ar–H), 7.25 (2H, t, Ar–H), 12.1 (2H, br.s, 2 O–
H). 13C NMR (125 MHz, DMSO-d6): d 48.86 (CH2), 50.72 (CH2),
126.95 (Ar–H), 128.70 (Ar–H), 129.77 (Ar–H), 135.77 (Ar–H),
171.15 (C@O), 171.39 (C@O), 171.76 (C@O). Elemental analysis:
Anal. Calc. for C12H13NO5: C, 57.37; H, 5.22; N, 5.58. Found: C,
57.66; H, 4.94; N, 5.49% (see Scheme 1).
2.4.3. FTIR, UV–Vis and 1H NMR spectroscopy
The FTIR spectra were recorded on a Perkin-Elmer 1600 series
Fourier transform instrument as KBr pellets spectrophotometer
covering a scan range 4000–500 cmꢀ1. Nuclear magnetic resonance
spectrum (1H NMR spectra) was recorded on a JOEL 500 MHz spec-
trometer with chemical shift values reported in d units (ppm) rela-
tive to an internal standard. UV–Vis measurements were carried
out using an automated spectrophotometer UV–Vis Perkin-Elmer
Model Lambda 20, and ranged from 200 to 1200 nm using metha-
nol as solvent and blank.
2.2. Synthesis of Ag nanoparticles
2.12 g (20 mmol) of Na2CO3 were dissolved in the least amount
of distilled water and 30 mL of methanol. A solution of (2.51 g,
10 mmol) of 2,20-(2-phenyl acetylazanediyl)diacetic acid in metha-
nol was added to the Na2CO3 solution with constant stirring at a
temperature of 40 °C. 0.17 g (1 mmol) of AgNO3 was dissolved in
30 mL of methanol and added to the previous mixture in a glass
container at 40 °C, under constant stirring to obtain a 1:10
(AgNO3:ligand) ratio. The mixture was left overnight with stirring
at room temperature. The color of solution changed from white to
grey and finally black. The black precipitate was decanted and
dried.
2.4.4. Elemental and thermal analyses (TGA, DTG and DTA) of Ag-
complex
Thermal analyses (TGA, DTG and DTA) were carried out in N2
atmosphere with a heating rate 10 °C minꢀ1 using a Shimadzu
TGA 50H and DTA 50 thermal analyzer. Elemental analyses were
performed on Perkin-Elmer 2400 elemental analyzer, and the val-
ues found were within 0.3% of the theoretical values. The metal
ion content was determined using atomic absorption method with
a spectrophotometer 850-Fisher Jarrell ash computer controlled.
2.3. Synthesis of the Ag(I) complex
The silver(I) complex was prepared by the addition of a hot
solution (60 °C) of AgNO3 salt (10 mmol) dissolved in ethanol
O
SOCl2
O
O
2.5. Antimicrobial studies
OH
Cl
2
1
The silver nanoparticles and complex were tested for their
antimicrobial and antifungal effects using agar diffusion method
against pathogenic bacteria Staphylococcus aureus, S, Escherichia
coli (E. coli), and Candida albicans, C fungus. The pure bacterial cul-
tures were periodically sub cultured on Nutrient agar. The paper
disc diffusion method was used to test for antimicrobial activity,
described by standard procedure [18]. The paper disc was cut
down into a small disc (4 mm diameter) and sterilized at 150 °C
for 45 min in hot air oven. Approximately 20 mL of molten
Nutrient agar was poured in sterilized petri plates which were left
overnight at room temperature. The sterilized discs were impreg-
nated with the silver nanoparticles or the Ag(I) complex solutions
and a positive control drug. Then the discs were dried in sterile
O
H
N
H
Cl
O
O
Et3N/DCM
10% KOH
O
O
O
O
O
O
N
N
HO
O
OH
O
4
3
Scheme 1. Synthesis of 2,20-(2-phenyl acetylazanediyl)diacetic acid 4.

A.A. Soayed / Inorganica Chimica Acta 429 (2015) 257–265
259
condition. The bacterial species were grown in 100 mL nutrient
50.72 ppm. The aromatic carbons showed 4 signals at 126.95,
128.70, 129.77, 135.77 ppm. The carbon signals of the three car-
bonyl groups were observed at 171.15, 171.39, and 171.76 ppm.
broth for 24 h. 100
l
l of the diluted cultures (1 ꢁ 106) of test
organisms were spread on nutrient agar plates. The silver nanopar-
ticles or complex impregnated discs were placed on the plates and
incubated at 37 °C for 24 h. After incubation, the different levels of
zone of inhibition of bacteria were measured in mm and the mean
values were presented.
3.1. Characterization of silver nanoparticles
Previously, it was shown that silver nanoparticles which show
interaction with bacteria are normally those having small particle
sizes which have the ability to react with and penetrate the cell
membrane and also due to the higher surface to volume ratio of
smaller particles which enhances the reactivity of the nanoparticle
surfaces. When the size of the silver nanoparticles decreases, the
percentage of the interacting atoms increases, and this could be
the explanation to why small (1–10 nm) silver nanoparticles are
able to interact with the bacteria [4].
Nam et al. [22] have shown that complexation of Ag ions with
carboxyl groups enhances the reduction of silver ions by lowering
the energy barrier of reduction as compared to unbound silver ions
and also by lowering the Fermi level of the silver cluster due to the
electron donation of the carboxyl group.
3. Results and discussion
2-phenylacetyl chloride 2 was first prepared by the reaction of
2-phenylacetic acid 1 with thionyl chloride. The acid chloride 2
formed was allowed to react with dimethyl iminodiacetate
hydrochloride in dry CH2Cl2 in presence of Et3N as base to afford
the corresponding ester 3. The ester 3 was hydrolyzed by alcoholic
potassium hydroxide to give the corresponding dicarboxylic acid 4.
The structure of 2,20-(2-phenyl acetylazanediyl) diacetic acid 4 was
established by IR, 1H NMR, 13C NMR, and elemental analyses. The
IR spectra of 4 showed two broad bands at 3664 and 3490 cmꢀ1
attributed to the lattice hydroxyl stretching mode [19] and hydro-
gen bonded OH, respectively. The C@O (carboxylic) band [20]
appeared at 1744 cmꢀ1 whereas C@O amide band was shown at
1696 cmꢀ1, Fig. 1. Researches had shown that with no hydrogen
bond, the C@O bond would be strong and its stretching frequency
is high and appears at 1776 cmꢀ1. If one hydrogen bond is formed
with either the carbonyl oxygen (HO–C@O) or the hydroxyl hydro-
gen (HO–C@O), the C@O stretching frequency would be downshift-
ed to 1740–1746 cmꢀ1 [21], from which it is indicated that the
carboxylic groups in the present ligand were involved in H-
bonding.
3.1.1. UV–Vis and FTIR spectroscopy
UV–Vis spectrophotometric technique was applied to confirm
the formation of silver nanoparticles. It is well known that silver
nanoparticles exhibit different sizes and colors which arise due
to excitation of surface plasmon resonance (SPR) in the silver
nanoparticles [23]. The distinctive color is due to a phenomenon
known as plasmon absorbance. Incident light creates oscillations
in conduction electrons on the surface of the nanoparticles and
electromagnetic radiation is absorbed.
The plasmon resonance produces a peak in the wavelength
range 380–450 nm depending on the complex dielectric constant
of the metal, the cluster size and the environment [24]. For the
Ag nanoparticles obtained in this study, the characteristic surface
plasmon broad band was found to be at 430 nm, Fig. 3. This band
is indicative of the presence of spherical nanoparticles in the reac-
tion mixture [25,26].
The 1H NMR spectrum of 4, Fig. 2, showed three singlet peaks at
3.62, 3.97, and 4.20 ppm corresponding to the three CH2 groups, a
multiplet peak at the range 7.16–7.19 ppm corresponding to three
of the aromatic protons, a triplet at 7.25 ppm corresponding to two
aromatic protons, and a broad singlet peak at 12.1 ppm corre-
sponding to 2 OH protons of carboxylic group. The 13C NMR spec-
trum of compound 4 showed 9 resolved carbon signals. The carbon
signals of the three CH2 groups were observed at 48.86 and
Fig. 1. FTIR spectrum of 2,20-(2-phenyl acetylazanediyl)diacetic acid.

260
A.A. Soayed / Inorganica Chimica Acta 429 (2015) 257–265
1
Fig. 2. H NMR of 2,20-(2-phenyl acetylazanediyl)diacetic acid.
Fig. 4 shows the FTIR spectra of the ligand capped silver
The elemental analysis of the silver nanoparticles was per-
formed using the Energy Dispersive X-ray Spectroscopy (EDX) on
the TEM, Fig. 7. The EDX spectrum confirmed that the nanoparti-
cles suspension contains nothing but silver. The peaks at 3.00–
3.40 keV correspond to the binding energy of Ag to the organic
compound [30]. Throughout the scanning range of binding ener-
gies, no obvious peak was observed to belong to impurity. This
indicates that the synthesized product is composed of high purity
Ag nanoparticles.
nanoparticles where the disappearance of the peaks at 1744 and
1696 cmꢀ1 (C@O) in the ligand and the presence of a peak at
596 cmꢀ1 supports the bridging bidentate linkage involving silver
surface and oxygen atoms of carboxyl groups [27,28]. This bonding
between AgNPs with carboxylate groups is an important clue to
the understanding of the role of the Ag NPs to the biological system
[25].
Fig. 8, depicts a proposed scheme that shows a single molecule
of 2,20-(2-phenyl acetyl-azanediyl)diacetic acid linking two Ag
nanoparticles. In this model, the COOꢀ group is linked to the Ag
particles by the oxygen atoms and no direct contact is established
between the silver nanoparticles [30].
3.1.2. Scanning electron microscopy analysis (SEM) of synthesized
silver nanoparticles
SEM is a valuable instrument, where high-resolution images of
the surface are detected. The SEM micrograph, Fig. 5, shows that
the particles have a spherical nature which is in agreement with
the shape of the surface plasmon resonance band of the UV–Vis
spectra [29].
3.2. Characterization of the Ag(I) complex
3.1.3. Transmission electron microscopy (TEM) analysis of synthesized
silver nanoparticles
Multi-carboxylate ligands, are known for their ability to act as
hydrogen-bond acceptors and donors in an assembly of supramo-
lecular structures [31–35].
In the present research paper, a Ag(I) complex has been pre-
pared and characterized using spectrophotometric methods as
well as studying its stability using thermal analyses and its
antibacterial and antifungal activities. Silver(I) complexes can
exhibit linear, seesaw, trigonal, square-pyramidal, trigonal-bipyra-
midal, square-planar, tetrahedral, and octahedral coordination
The sizes of the prepared Ag-NPs were determined using a
transmission electron microscope (TEM). TEM micrograph of
ligand capped silver nano-particles is presented in Fig. 6. From
the figure it is obvious that the particles shapes are perfectly sphe-
rical with particle sizes less than 10 nm. Silver particles sizes range
from 6.24 nm to 7.84 nm. It is believed that the sample prepared
has good morphology.

A.A. Soayed / Inorganica Chimica Acta 429 (2015) 257–265
261
Fig. 3. UV–Vis absorption spectra of silver nanoparticles.
Fig. 4. FTIR spectrum of ligand capped silver nanoparticles.
geometries [36,37] and has high affinity for hard donor atoms such
as nitrogen or oxygen atoms [36], and is apt to form short Agꢂ ꢂ ꢂAg
contact.
molecules which usually lie in the 3000–3800 cmꢀ1 region. The
position and intensity of water bands are very sensitive to the
water environment and to the state of water association via H-
bonding. Those in the range 3330–3474 cmꢀ1 are the OH stretches
of
3750 cmꢀ1 are OH stretches of H-bonded H2O molecules [38,39].
The bands in the range
= 3000–2800 cmꢀ1 are assignable to
stretching modes of the C–Harom, and the CH2- chromophores.
a coordinating H2O molecule and those between 3600–
3.2.1. FTIR and UV–Vis spectroscopy
The FTIR of the Ag(I) complex under investigation, [Ag L]2ꢂ2H2O,
Fig. 9, showed a band at 3672 cmꢀ1 due to antisymmetric (
m3) and
m
symmetric (m1) stretching modes of vibrations of the water

262
A.A. Soayed / Inorganica Chimica Acta 429 (2015) 257–265
Fig. 5. SEM micrograph of silver nanoparticles synthesized by the reaction of silver nitrate with 2,20-(2-phenyl acetylazanediyl)diacetic acid 4.
Fig. 6. TEM micrograph of silver nanoparticles synthesized by the reaction of silver nitrate with 2,20-(2-phenyl acetylazanediyl)diacetic acid 4.
The disappearance of the
C–O stretching modes in the complex compared to the ligand,
assigned the contribution of these groups in complex formation.
m
OH,
m
C@O bands and the shift in the
m
The coordination geometry around a Ag+ ion is preferentially
linear, giving either one dimension coordination polymers or
dimeric structures [42,43].
Characteristic bands were observed at
m
= 1604; 1560 cmꢀ1 and
Since no d–d transitions are expected for a d10 complex, the
UV–Vis band of [Ag L]2ꢂ2H2O at 410 nm is assigned to metal to
at
m
= 1475; 1409 cmꢀ1 assigned to asymmetric and symmetric
stretching modes of vibrations of the carboxylic groups, respective-
ly [19,39,40]. The absence of characteristic bands at ꢃ1700 cmꢀ1
attributed to the protonated carboxylic groups, indicated complete
deprotonation of the carboxylate groups upon complex formation
with Ag(I) ion. The difference between asymmetric and symmetric
ligand charge transfer (MLCT) or ligand-centered p–
p⁄ transitions.
3.2.2. 1H NMR of the Ag-complex
The diamagnetic [Ag L]2ꢂ2H2O showed highly resolved 1H NMR
spectrum, Fig. 10. The –OH peak (of the carboxylic groups) at
12.1 ppm in the ligand disappeared in case of the complex, indicat-
ing their chelation to Ag(I) ions. The three singlet peaks at 3.69,
stretching
carboxylic groups to the Ag(I) ions [41].
Dm
= 84 cmꢀ1 assigned a bidentate coordination of the

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263
Fig. 7. TEM–EDX spectra of silver nanoparticles synthesized by 2,20-(2-phenyl acetylazanediyl)diacetic acid.
N
Ag
COO
3.3. Antimicrobial studies
COO
O
Scientists [3–7,44,45] have shown that silver nanoparticles
attach to the surface of the cell membrane of different types of bac-
teria and disturb its function, penetrate bacteria, and release silver
ions.
N
OOC
Ag
However, from the point of view of the ligand exchange reac-
tions of Ag(I) complexes, several possible mechanisms have been
suggested for the bioactivity of the aqueous Ag(I) ion. The first
mechanism involves the interference of the Ag(I) ion with electron
transport, the second possible mechanism is the binding of the
Ag(I) ion to DNA [46]. The third mechanism is the interaction of
Ag(I) ions with the cell membrane’s protein synthesis pathways
[47]. Chelated Ag(I) was found to be more effective by several
orders of magnitude than the free silver ions and it has been pro-
posed that Ag(I) ions are actively transported intra-cellular by
the chelating ligand(s) in a protected complex and not as a free
ion [48].
Fig. 8. A schematic diagram of silver nanoparticles linked to 2,20-(2-phenyl
acetylazanediyl)diacetic acid.
4.03, and 4.23 ppm corresponding to the three CH2 groups in the
ligand were shifted to 3.49, 3.83 and 3.95 ppm, respectively. A
multiplet peak in the region 7.120–7.125 ppm corresponds to the
aromatic protons.
It has been suggested that activity of Ag(I) complexes towards
Gram-negative (such as E. coli) and Gram-positive bacteria is
dependent on the nature of the bonding atom, with superior activ-
ity for the complexes containing the more weakly bonded Ag(I)–N
moiety and to a lesser extent, Ag(I)–O. This suggests that the more
weakly bonded metal-complexes may allow easier ligand
exchange with biological ligands, thus facilitating the interruption
of the fungal cells normal biochemical pathways.
In the present work, the silver nanoparticles prepared using
2,20-(2-phenyl acetylazanediyl)diacetic acid as a reducing agent,
were tested for their antimicrobial activity by using agar diffusion
method against pathogenic gram positive bacteria, S. aureus, S, and
3.2.3. Thermal analyses (TGA, DTG and DTA) of the Ag complex
The thermogravimetric analysis (TGA) of the [Ag L]2ꢂ2H2O com-
plex, Fig. 11, showed that decomposition started at ꢃ67.74 °C
where a water molecule (found: 4.400; calc.: 4.675%) was lost
(DTG = 81.74 °C) followed by the loss of a CO2 molecule between
100 and 255 °C; DTG = 230.72 °C (found: 11.600; calc.: 11.428%).
It then suffered pyrolytic processes between (255 and 400 °C) with
DTG = 294.87 °C, then between (400 and 600 °C); DTG = 489.46
and 565.41 °C due to the loss of COꢂN(CH2)CH2 COO, (found:
26.121; calc.: 25.974%) and 6C atoms of phenyl ring, (found:
19.004; calc.: 18.700%) respectively, leaving a residue of Ag (found:
28.484; calc.: 28.052%).
Fig. 9. FTIR spectrum of the silver complex.

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A.A. Soayed / Inorganica Chimica Acta 429 (2015) 257–265
Fig. 10. 1H NMR spectrum of [Ag L]2ꢂ2H2O.
Fig. 11. Thermal analyses (a) TGA and (b) DTA of [Ag L]2ꢂ2H2O.
gram negative bacteria, E. coli (E. coli) E, and C. albicans C fungus.
The diameter of inhibition zones around the disk containing silver
nanoparticles in S. Aureus, C. albicans were 14 mm, whereas no dif-
fusion was observed for E. coli. The minimum inhibitory concentra-
that silver nanoparticles had a great antibacterial and antifungal
efficacy.
On the other hand, the inhibition zone (IZ) of the Ag(I) complex
showed that it possesses remarkable antimicrobial and antifungal
activities, Table 1.
tion (MIC) was 62.5 lg/ml against both S and C which indicated

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265
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Test
compound
Inhibition zone diameter growth (mm/mg sample)
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Escherichia
coli
IZ
Staphylococcus
aureus
IZ
Aspergillus
flavus
IZ
Candida
albicans
IZ
Ag NPs
[AgL]2ꢂ2H2O 32
–
14
30
–
10.0
14
20
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Silver nanoparticles were obtained via the chemical reduction
of AgNO3 using the newly prepared 2,20-(2-phenyl acety-
lazanediyl)diacetic acid. The FTIR and UV–Vis. spectra confirmed
the formation of the silver nanoparticles. Spherical shapes were
observed in TEM with particle sizes ranging from 1.02 to
4.75 nm. The prepared Ag nanoparticles have antibacterial effect
on the gram positive S. aureus, S bacteria and Candida albicans C
fungus but no effect on E. Coli gram negative bacteria was
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The author would like to express her deepest thanks to
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in this research as the ligand.
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