Synthesis and biocidal activity of some naphthalene-based cationic surfactants

Article abstract of DOI:10.1007/s11743-011-1286-z

In this study, different cationic surfactants were prepared by reacting dodecyl bromide with tertiary amines to produce a series of quaternary ammonium salts that were converted subsequently to stannous and cobalt cationic complexes via complexing them with stannous (II) or cobalt (II) ions. Surface properties such as surface- and interfacial-tension, and the emulsifying power of these surfactants were investigated. The surface parameters including critical micelle concentration, maximum surface excess, minimum surface area, tension lowering efficiency and effectiveness were studied. The free energy of micellization and adsorption were calculated. Antimicrobial activity was determined via the inhibition zone diameter of the prepared compounds, which was measured against six strains of a representative group of microorganisms. The antimicrobial activity of some of the prepared surfactants against sulfate reducing bacteria was determined by the dilution method. FTIR spectra, elemental analysis and a H¹ NMR spectrum were examined to confirm compound structure and purity. The results obtained indicate that these compounds have good surface properties and good biocidal effect on broad spectrum of micro organisms. AOCS 2011.

Full text of DOI:10.1007/s11743-011-1286-z

J Surfact Deterg (2012) 15:223–234
DOI 10.1007/s11743-011-1286-z
ORIGINAL ARTICLE
Synthesis and Biocidal Activity of Some Naphthalene-Based
Cationic Surfactants
Ismail A. Aiad
Mohammed M. El-Sukkary
Ahmed I. Adawy
•
Abdelfatah M. Badawi
•
•
Abdallah A. El-Sawy
•
Received: 11 October 2010 / Accepted: 9 July 2011 / Published online: 30 July 2011
Ó The Author(s) 2011. This article is published with open access at Springerlink.com
Abstract In this study, different cationic surfactants were
prepared by reacting dodecyl bromide with tertiary amines
to produce a series of quaternary ammonium salts that were
converted subsequently to stannous and cobalt cationic
complexes via complexing them with stannous (II) or
cobalt (II) ions. Surface properties such as surface- and
interfacial-tension, and the emulsifying power of these
surfactants were investigated. The surface parameters
including critical micelle concentration, maximum surface
excess, minimum surface area, tension lowering efficiency
and effectiveness were studied. The free energy of micel-
lization and adsorption were calculated. Antimicrobial
activity was determined via the inhibition zone diameter of
the prepared compounds, which was measured against six
strains of a representative group of microorganisms. The
antimicrobial activity of some of the prepared surfactants
against sulfate reducing bacteria was determined by the
Introduction
Cationic surfactants are used for quite different purposes
than anionic surfactants. They have a greater affinity for
various surfaces and could play an important role in the
textile industry. Surfactants are usually employed for
wetting or emulsifying and it has been reported by many
investigators [1–3] that cationic surfactants, especially
those having quaternary ammonium groups, display these
activities. Quaternary ammonium salts also show biocidal
properties [4]. Surfactant metal complexes are expected to
provide a wide range of interesting phenomena on aggre-
gation in aqueous solution due to variations in charge
numbers, size and extent of hydrophobicity through com-
bination of the central metal and ligands [5]. However,
their physical properties in solution have not been studied
extensively [6–9].
1
dilution method. FTIR spectra, elemental analysis and a H
Metalloaggregates are made of surfactants that combine
a metal-coordinating polar head with a hydrophobic tail
[10]. Surfactants micellize in solution after the critical
micelle concentration (CMC) is reached, depending on
their molecular structure and the environmental conditions
NMR spectrum were examined to confirm compound
structure and purity. The results obtained indicate that
these compounds have good surface properties and good
biocidal effect on broad spectrum of micro organisms.
[
11].
The antimicrobial action of cationic surfactants is based
Keywords Cationic surfactant ꢀ Critical micelle
concentration ꢀ Antimicrobial activity
on their ability to disrupt and disorganize the integral
bacterial membrane by combined hydrophobic and elec-
trostatic adsorption phenomena at the membrane–water
interface [12].
AI ..AI .. AA id aa dw (y &) ꢀ A. M. Badawi ꢀ M. M. El-Sukkary ꢀ
Petrochemicals Department, Egyptian Petroleum Research
Institute, Nasr City, Cairo, Egypt
e-mail: yiaiad@yahoo.co.uk
The cell membrane of pathogenic bacteria is predomi-
nantly negatively charged as compared with eukaryotic
cells [13]. Hence, the positive charge of the cationic
amphiphile facilitates their interaction with the bacterial
membrane.
A. A. El-Sawy
Faculty of Science, Chemistry Department, Benha University,
Al Qalyubiyah, Egypt
This study aimed to prepare some novel metallocationic
surfactants based on naphthalene, and to determine their
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24
J Surfact Deterg (2012) 15:223–234
surface properties including the CMC, the maximum sur-
Structural Confirmation of the Prepared Compounds
face excess (Cmax), and the minimum surface area
(
Amin), as well as their efficiency (PC ) and effectiveness
20
The chemical structure of the synthesized compounds was
characterized as follows. Elemental analysis of the
obtained surfactants was carried out using an Elemental
Analyzer Model Varioelemenrar. The measurements were
carried out at the Micro Analytical Center, Faculty of
Science, Cairo University. Fourier transform infrared
(FTIR) spectra were obtained using an ATI Mattsonm
(
pCMC).
Experimental Procedure
Materials
TM
TM
Infinity series , Bench top 961 controlled by Win First
The chemicals used in this study were of pure grade from
Aldrich and were used without further purification. The
solvents used were of pure grade.
V2.01 software (Egyptian Petroleum Research Institute).
1
HNMR was measured in DMSO-d in a Spect Varian,
6
1
GEMINI 200 ( H 200 MHz). (Micro Analytical Center,
Cairo University, Egypt).
Synthesis
Evaluation Method of Surface Active Properties
(
(
(
A) Piperidine-1-yl methyl naphthalene (I ) was synthe-
b
sized by refluxing 1-chloromethyl naphthalene (Ia)
Surface and Interfacial Tension
(
(
1 mol) and piperidine (4 mol) for 6 h in benzene
30 ml).
Surface and interfacial tension of solutions of the prepared
compounds were measured using Du-Nouy Tensiometer
(Kr u¨ ss type 6). The surface tension of different concen-
B) Dipiperidine-1-yl dimethyl naphthalene (II ) was
b
synthesized by refluxing 1,5-bis- dichloromethyl
-
2
-3
naphthalene (II ) (1 mol) and piperidine (4 mol) for
a
trations ranging from 5 9 10 to 1 9 10 mol/L was
measured at different temperatures (25, 35 and 45 °C). The
interfacial tension between 0.1% surfactants solution and
light paraffin oil was also measured at 25 °C.
6
h in benzene (30 ml).
0
C) Dipyridine- 4, 4 -yl -1,5 bis-disulphonamide naph-
thalene (III ) was synthesized by refluxing 1,5
b
disulphony dichloride naphthalene (III ) (1 mol),
a
4
4
-amino pyridine (2 mol) and pyridine (2 mol) for
h in ethanol (30 ml).
Emulsification Power
Emulsification power of the synthesized surfactants was
measured by vigorous shaking of 10 ml surfactant solution
(0.1%) and 10 ml paraffin oil for 5 min at 25 °C. The
emulsification power was expressed as the time required
for separation of 9 ml pure water.
The reaction mixtures were left to cool then filtered.
(
D) Quaternary ammonium compounds were synthesized
by refluxing 1 mol of (I ), (II ) and (III ) with 1, 2
b
b
b
and 2 mol dodecyl bromide (R), respectively, in
ethanol for 12 h. The solid product was filtered off
and recrystallized from ethanol to obtain the cationic
Surface Parameters of the Prepared Compounds
surfactants
N-methyl
naphthalene—N-dodecyl
0
pipyridinium bromide (I ), N, N -1,5 bis dimethyl
c
Critical Micelle Concentration The CMC values of the
prepared compounds were determined using surface ten-
sion techniques, i.e., the surface tension measurements
were plotted against the logarithm of the surfactant con-
centration. As is usual, the interrupt change in the curve
slope is taken as the CMC.
0
naphthalene—N, N -didodecyl dipipyridinium bro-
0
mide (II ) and 4,4 -1,5 bis disulfonamide naphtha-
c
0
lene—N, N -didodecyl dipyridinium bromide (III ),
c
respectively.
(
E) Metal complexes (metallosurfactants) were synthe-
sized by refluxing 2, 1 and 1 mol of (I ), (II ) and
c
c
(III ) in ethanol, respectively, with 1 mol of each of
c
Effectiveness Effectiveness (pCMC) is the difference
stannous chloride (SnCl ꢀ2H O) and cobalt chloride
between the surface tension of pure water (c ) and the
2
2
o
(
CoCl ꢀ6H O) in ethanol, respectively to obtain metal
surface tension of the surfactant solution (c) at the CMC.
pCMC ¼ c ꢁ c
2
2
complexes M, N, X, Y, A and B, respectively
Schemes 1, 2; Figs. 1, 2). And metal complex Z was
o
CMC
(
obtained by refluxing 1 mol of (II ) in ethanol with
c
Efficiency Efficiency (PC20) is determined by the con-
centration (mol/L) of the surfactant solution capable of
suppressing the surface tension by 20 dyne/cm.
half a mole each of stannous chloride and cobalt
chloride in ethanol (Fig. 3).
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J Surfact Deterg (2012) 15:223–234
225
Cl
OH
P
+
H2C
O
HCl
+
HO
OH
+
+
CH COOH
3
O
+
HN
N
+
C H Br
12 25
1
+
1
+
C H
1
2
25
N
C H
1
2
25
N
2-
Br
+
Sn Cl2 Br2 2H O
2
2
SnCl 2H O
2 2
2
Scheme 1 Chloromethylation of naphthalene to produce complex (M)
2
Maximum Surface Excess The values of the maximum
surface excess (Cmax) calculated from surface or interfacial
data by the use of Gibbs equation [14].
Cmax maximum surface excess in mole/cm
Avogadro’s number
N
Cmax ¼ ꢁ1=2:303 RTðdc=d log CÞT
where
Thermodynamic Parameters of Micellization and Adsorp-
tion The thermodynamic parameters of adsorption and
micellization of the synthesized cationic surfactants were
calculated according to Gibb’s adsorption equations as
follows [16]:
2
Cmax
R
maximum surface excess in mole/cm
7
universal gas constant 8.31 9 10 ergs
-
1
-1
mole
K
O
mic
DG ¼ RT lnðCMCÞ
T
absolute temperature (273.2 ? °C)
surface pressure in dyne/cm
surfactant concentration
O
ads
O
mic
ꢁ1 ꢂ pCMC ꢂ Amin
DG ¼ DG ꢁ 6:023 ꢂ 10
dc
C
O
mic
DSmic ¼ ꢁdðDG =DTÞ
(
dc/dlog C)T is the slope of a plot surface tension versus
log concentration curves below CMC at
constant temperature
O
ads
-
DSads ¼ ꢁdðDG =DTÞ
O
mic
DHmic ¼ DG þ T ꢀ DSmic
O
ads
DHads ¼ DG þ T ꢀ DSads
Minimum Surface Area The area per molecule at the
interface provides information on the degree of packing
and the orientation of the adsorbed surfactant molecule.
The average minimum surface area (Amin; in square ang-
strom) occupied by each molecule adsorbed on the inter-
face [15] is given by:
Antimicrobial Activity of the Prepared Compounds
The antimicrobial activity of the prepared metallocationic
surfactants (M, N, X, Y, Z, A and B) was measured indi-
vidually using the diffusion agar technique against a wide
range of microorganisms previously isolated in the
1
6
Amin ¼ 10 =CmaxN
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J Surfact Deterg (2012) 15:223–234
Scheme 2 Chlorosulphonation
of naphthalene to produce
complex (A)
O
OH
S
O
Cl
S
+
O
O
S
O
Cl
O
Cl
naphthalene-1,5-disulfonyl dichloride
+
N
N
O
O
NH
2
H
2
N
N
S
S
O
HN
O
N
+
2
+
2
C H Br
12 25
R
N
2-
O
O
NH
Br
S
S
HN
O
O
N
R
+
SnCl 2H O
2
2
2
+
R
2
-
N
O
O
NH
Sn Cl Br 2H O
2 2 2
S
S
HN
O
O
N
R
Biotechnology Laboratory of the EPRI from different oil
polluted environments using a dose equal to 5 mg/l.
The microorganisms include Gram-positive bacteria
(Staphylococcus gallinarum NK1, Bacillus maroccanus
I.1.1.3 and Brevibacterium casei I.2.1.7), Gram-negative
bacteria (Pseudomonas synxantha I.1.1.1), yeast (Candida
parapsilosis NSh45) and fungi (Aspergillus terreus I.1.3.1).
The antimicrobial activity of some of the synthesized
compounds at different doses (800; 1,000; 1,200 ppm) was
measured against sulfate reducing bacteria (SRB) using the
dilution method.
h
g
m
n
i
N
f
k
h
e
2-
d
b
g
j
c
l
c
Sn Cl2 Br 2 2H2 O
k
c
l
c
c
c
c
c
a
2
Fig. 1 Complex (M), N-methyl naphthalene-N-dodecyl pipyridinium
dibromo-dichloro tinate complex
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J Surfact Deterg (2012) 15:223–234
227
g
f
j
FTIR Spectra
h
i
k
e
O
HN
N
O
d
2-
f
g
S
c
g
f
c
FTIR spectroscopy was used to identify the functional
groups of prepared metallocationic surfactants. The FTIR
spectra of complex M showed an absorption band at
e
h
S
O
c
N
N
Sn Cl2 Br2 2H2O
d
O
i
c
H
k
c
c
g
j
c
f
c
c
c
c
c
c
-1
b
778 cm corresponding to adjacent H atom of naphtha-
-1
a
c
-
lene, and absorption bands at 1,450 cm and 2,847 cm
1
c
c
b
corresponding to CH aliphatic asymmetric bending and
symmetric stretching, respectively. An absorption band at
a
0
0
-1
2,920 cm corresponds to ammonium ion (R N ; Fig. 4).
?
Fig. 2 Complex (A), 4, 4 -1,5 bis disulfonamide naphthalene-N, N -
didodecyl pyridinium dibromo-dichloro tinate complex
4
The FTIR spectrum of complex Z showed an absorption
-
1
band at 720 cm corresponding to the adjacent H atom of
-
1
naphthalene, and absorption bands at 1,455 cm
and
corresponding to CH aliphatic asymmetric
bending and symmetric stretching, respectively. An addi-
b
a
c
-1
2,851 cm
c
h
c
g
c
k
l
l
i
c
c
N
2-
-1
f
tional absorption band at 2,922 cm
?
ammonium ion (R N ; Fig. 5).
corresponds to
h
c
j
e
1/2 Sn Cl2 2H2O 1/2 Co Cl2 6H2O Br2
d
h
d
e
g
j
4
N
c
c
i
h
k c
c
c
The FTIR spectra of complex A showed an absorption
-1
band at 758 cm corresponding to adjacent H atom of
g
c
g
f
c
c
-
1
naphthalene, and an absorption band at 1,189 cm cor-
b
a
responding to the SO -NH group. An additional absorption
2
-
band at 2,927 cm corresponds to ammonium ion (R N ;
1
?
0
0
Fig. 3 Complex (Z),N, N -1, 5 bis dimethyl naphthalene–N, N -
didodecyl pipyridinium dibromo-dichloro tinate-cobaltate complex
4
Fig. 6).
1
HNMR Spectra
Results and Discussion
1
HNMR spectra of complex M showed signal triplet at d =
0
.87 ppm for (H ), sextet at d = 0.9 ppm for (H ), quintet at
Chemical Structure
a
b
d = 1.29 ppm for (H ), quintet at d = 1.8 ppm for (H ),
c
d
triplet at d = 3.07 ppm for (H ), quintet at d = 1.29 ppm for
The chemical structure of the prepared cationic surfactants
was confirmed by elemental analysis, and their FTIR and
e
(
H ), quintet at d = 2.56 ppm for (H ), triplet at d =
f
g
1
3.44 ppm for (H ), singlet at d = 4.83 ppm for (H ), doublet
HNMR spectra.
h
i
at d = 7.1 ppm for (H ), triplet at d = 7.65 ppm for (H ),
j
k
doublet at d = 7.93 ppm for (H ), doublet at d = 8.09 ppm
Elemental Analysis
l
for (H ) and triplet at d = 8.44 for (H ) (Fig. 7).
m
n
1
HNMR spectra of complex Z showed signal triplet at
As shown in Table 1, there is very close agreement
between the theoretical and experimental values of
microanalysis, meaning that these products are rather pure,
and their work up was done properly.
d = 0.85 ppm for (H ), sextet at d = 1.1 ppm for (H ),
a
b
quintet at d = 1.24 ppm for (H ), quintet at d = 1.7 ppm for
c
(
H ), triplet at d = 3 ppm for (H ), quintet at d = 1.24 ppm
d
e
Table 1 Micro elemental analysis of the prepared metallosurfactants
Complex
C (%)
M
N
X
Y
Z
A
B
Th.
57.25
56.75
7.84
7.7
56.66
56.25
8.43
8.2
52.79
52.4
8
52.18
51.8
8.69
8.5
52.48
52.1
8.36
8.2
45.37
45.2
6
44.9
44.5
6.6
Exp.
Th.
H (%)
N (%)
Exp.
Th.
7.9
5.9
6.5
2.38
2.2
2.36
2.1
2.68
2.5
2.6
2.66
2.5
4.8
4.7
Exp.
2.4
4.6
4.5
Th. Theoretical, Exp. experimental
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J Surfact Deterg (2012) 15:223–234
Fig. 4 Fourier transform infrared (FTIR)-spectrum of the metallocationic surfactant complex M
Fig. 5 FTIR-spectrum of the metallocationic surfactant complex Z
for (H ), quintet at d = 2.56 ppm for (H ), triplet at d =
triplet at d = 7.4 ppm for (H ) and doublet at d = 7.5 ppm
f
g
j
3
.79 ppm for (H ), singlet at d = 4.7 ppm for (H ), doublet
for (H ) (Fig. 9).
k
h
i
at d = 7.61 ppm for (H ), triplet at d = 7.85 ppm for (H )
j
k
and doublet at d = 8.02 ppm for (H ) (Fig. 8).
Surface Properties
l
1
HNMR spectra for complex A showed signal triplet at
d = 0.85 ppm for (H ), sextet at d = 1.24 ppm for (H ),
Surface and Interfacial Tension
a
b
quintet at d = 1.53 ppm for (H ), quintet at d = 1.49 ppm
c
for (H ), triplet at d = 2.53 ppm for (H ), doublet at d =
Surface Tension The surface tension of aqueous solutions
of the prepared metallocationic surfactant with different
concentrations (0.05, 0.025, 0.01, 0.005, 0.0025, 0.00125
d
e
8
.9 ppm for (H ), doublet at d = 6.8 ppm for (H ), singlet at
f
g
d = 4.6 ppm for (H ), doublet at d = 8.1 ppm for (H ),
h
i
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J Surfact Deterg (2012) 15:223–234
229
Fig. 6 FTIR-spectrum of the metallocationic surfactant complex A
1
Fig. 7 H-NMR-Spectrum of the metallocationic surfactant complex M
and 0.001 mol/L) and at different temperatures (25, 35 and
dehydration of the hydrophobic chain as the temperature
increases.
4
5 °C) was measured. The data are represented in surface
tension-concentration curves as shown in Figs. 10, 11, and
2. It is clear that surface tension decreases with increasing
The surface tension values of the cationic complexes
(M, N, X, Y, Z, A and B) are expected to have lower
values than the parent cationic surfactants (I , II and
1
concentration due to increasing migration of the surfactant
molecules from the bulk to the interface of the solution.
The figures also show that surface tension values decrease
as the temperature increases from 25 to 45 °C; this is
because the surfactants become less soluble due to
c
c
III ). This is possible because of the increase in the
c
hydrophobicity of these complexes in comparison to the
parent cationics, which is due to the presence of two
ligands coordinated to the metal-ion-like (M and N)
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J Surfact Deterg (2012) 15:223–234
1
Fig. 8 H-NMR-Spectrum of the metallocationic surfactant complex Z
1
Fig. 9 H-NMR-spectrum of the metallocationic surfactant complex A
complexes, i.e., more non-polar chains. Interactions
between the water/surfactant molecules increase, which
forces them to the air–water interface [17]. Hence, the
surface tension was depressed considerably. Also, the
presence of two alkyl chains in one molecule linked by a
metal-ion-like (X, Y, Z, A and B) complex enhances the
adsorption and aggregation properties by strengthening
inter- or intra-molecular hydrophobic interactions [18],
i.e., the complexes adsorb more efficiency at air/water
interfaces than their parent salts. So, the structures of the
synthesized surfactants play an important role in their
surface properties.
6
5
5
4
4
3
3
2
0
5
0
5
0
5
0
5
o
25
C
M
N
X
Y
Z
A
B
3.5
3
2.5
2
1.5
1
0.5
0
-
log C (mole/liter)
Fig. 10 Surface tension versus -log concentration of complexes at
25 °C
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J Surfact Deterg (2012) 15:223–234
231
o
5
5
4
4
3
3
2
5
0
5
0
5
0
5
3
5 C
Table 2 Interfacial tension and emulsion stability of the synthesized
metallosurfactants
M
N
X
Y
Z
Emulsion stability (s)
Interfacial tension, mN/m
Surfactant
20
18
4
5
5
3
5
3
5
M
N
X
Y
Z
A
B
2
1
1
9
3
.5
3
2.5
2
1.5
1
0.5
0
25
-
Log C (mole/liter)
142
A
B
8
5
Fig. 11 Surface tension versus -log concentration of complexes at
5 °C
3
Critical Micelle Concentration
o
CMC values of the prepared metallocationic surfactants
were determined by plotting the surface tension (c) of
surfactant solutions versus their bulk concentrations in
mole/L at 25 °C, 35 °C and 45 °C. The CMC values
listed in Tables 3, 4 and 5 show a decrease in CMC with
increasing temperature and number of hydrophobic
chains. The rise in temperature probably decreases the
hydration of the hydrophilic group, favoring micelliza-
tion. On the other hand, a rise in temperature causes
disruption of the structured water surrounding the
hydrophobic group, an effect that disfavors micellization.
The relative magnitude of these two opposing effects
determines whether the CMC increases or decreases over
a particular temperature range. The data in Tables 3, 4
and 5 reveal that CMC decreases with rising tempera-
ture, i.e., micellization is enhanced.
5
4
4
3
3
2
2
0
5
0
5
0
5
0
45 C
M
N
X
Y
Z
A
B
3.5
3
2.5
2
1.5
1
0.5
0
-
Log C (mole/liter)
Fig. 12 Surface tension versus -log concentration of complexes at
5 °C
4
The higher number of uniqueness of the metal–surfac-
tant coordination complexes lies in the fact that the bond
between the head group and the tail part of the surfactant is
a coordinate bond, and the surfactant contains a higher
charge on the head group, which leads to more repulsion in
the bulk of the aqueous solution and thus increasing
adsorption onto the surface.
Increasing the number of hydrophobic chains decreases
the solubility and consequently increases the free energy of
the system, leading to concentration of the surfactant
molecules at the surface and formation of micelles.
Effectiveness
Interfacial Tension The interfacial tension of the oil/0.1%
surfactant systems at (25 °C) was measured (Table 2). It is
clear from the data that the synthesized surfactants (M, N,
X, Y, Z, A and B) have good interfacial tension values
against paraffin oil. Also, the lower values of the interfacial
tension indicate the potential to use these surfactants in
several applications as corrosion inhibitor and biocides.
The most efficient surfactant is one that gives the greatest
lowering in surface tension for a given CMC. According to
the results of the effectiveness (GCMC) shown in Tables 3,
4 and 5, complex Y was found the most effective at 25 °C,
with a reduction of 38.4 mN/m at CMC. Complexes M and
Y were very close in terms of effectiveness, being most
effective at 35 °C, with 41.62 and 41.17 dyne/cm,
respectively. Complex M achieved the best effectiveness at
Emulsion Stability
45 °C, with 42.4 dyne/cm.
The emulsifying power of the prepared cationic surfactants
Efficiency
(
M, N, X, Y, Z, A and B) is listed in Table 2 as a function
of time. All the prepared cationic surfactants have, in
general, low emulsion stability as a function of time, so that
these surfactants cannot be used as long-term emulsion
stabilizers.
Efficiency (Pc ) values of the prepared metallocationic
2
0
surfactants are given in Tables 3, 4 and 5. From these data
it was observed that increasing the number of alkyl chains
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J Surfact Deterg (2012) 15:223–234
and temperature together produce a decrease in efficiency.
This is due to the fact that the efficiency of adsorption at
interfaces increases linearly with an increase in the number
of carbon atoms in the hydrophobic group and temperature.
Minimum Surface Area
The minimum area per molecule at the aqueous solution/air
interface for the prepared surfactants is listed in Tables 3, 4
and 5. The minimum surface area (Amin) decreases with an
increase in the number of hydrophobic chains in the sur-
factant molecules due to the higher accumulation of these
molecules at the interface and a smaller available area per
molecule.
Maximum Surface Excess
The values of Cmax are represented in Tables 3, 4 and 5.
Cmax increases by increasing the number of hydrophobic
chains on the head group or by the presence of two ligands
(
depending on the metal ion) due to the increase of the
Standard Free Energies of Micellization and Adsorption
interaction with the water phase so the surfactant molecules
are directed to the interface, which decreases the surface
energy of the solution.
From Tables 6 and 7 values of the standard free energies of
o
o
micellization and adsorption (DGmic, DGads) are always
Table 3 Surface properties of
the synthesized metallocationic
surfactants at 25 °C
-3
-3
-10
2
Surfactant
CMC910
mol/L
p
CMC
mN/m
,
Pc20910
mole/L
,
C
max910
Amin, nm
2
mol/cm
M
N
X
Y
Z
2.37
2.86
2.71
2.48
2.4
36.35
38.15
36.23
38.4
1.0
1.352
1.617
1.296
1.188
1.336
0.842
0.732
1.228
1.027
1.281
1.397
1.243
1.972
2.269
1.0
1.12
1.1
CMC Critical micelle
concentration, pCMC
effectiveness, Pc20 efficiency,
36.17
26.77
27.66
1.02
1.2
A
B
1.87
1.82
C
A
max maximum surface excess,
min minimum surface area
1.12
Table 4 Surface properties of
the synthesized metallocationic
surfactants at 35 °C
2
Surfactant
CMC 9
-3
p
CMC
,
mN/m
Pc20
9
10 mol/L
C
10
max
-10
9
mol/cm
Amin, nm
-4
2
1
0
, mole/L
M
N
X
Y
Z
2.1
41.62
39.94
38.16
41.17
39.2
4.75
4.05
4.17
5.48
8.22
0.1
1.419
1.297
0.968
1.250
0.941
0.558
0.424
1.170
1.280
1.716
1.328
1.764
2.975
3.919
2.38
2.39
2.05
2.19
1.32
1.25
A
B
35.93
32
0.1
Table 5 Surface properties of
the synthesized metallocationic
surfactants at 45 °C
-3
-4
-10
2
min nm
Surfactant
CMC910
mol/L
p
CMC
,
mN/m
Pc20 9 10
mole/L
,
C
mol/cm
max 9 10
,
A
2
M
N
X
Y
Z
1.74
2.1
42.4
40.97
39.88
41.7
41
0.656
1.76
1.0
1.600
1.287
1.060
1.256
1.184
0.492
0.410
1.037
1.290
1.567
1.322
1.402
3.372
4.046
2.23
1.78
1.7
0.26
2.8
A
B
0.9
37
0.1
1.08
34.73
0.1
1
23

J Surfact Deterg (2012) 15:223–234
233
Table 6 Thermodynamic parameters of micellization of the synthe-
sized metallosurfactants at 25 °C
negative, indicating that these two processes are sponta-
neous; however, there is a greater increase in the negative
value of DGads compared to those of micellization. This
suggests the tendency of the molecules to be adsorbed at
the interface.
O
Surfactant
DGmic kJ/mol
DSmic, kJ/mol.K
DHmic, kJ/mol
M
N
X
Y
Z
-14.982
-14.516
-14.650
-14.870
-14.951
-15.569
-15.637
-0.081
-0.096
-0.081
-0.099
-0.074
-0.142
-0.149
-39.196
-43.084
-38.923
-44.302
-36.898
-57.765
-59.979
Antimicrobial Activity of the Prepared Compounds
It is well known that the activity toward a variety of bac-
terial species for numerous structural variations of a lot of
cationic surfactants is optimal when the carbon chain
length is between 10 and 14 atoms [19–23]. The antimi-
crobial activity results of the prepared compounds are in
Table 8. The results indicate that the synthesized metallo-
surfactants have good antimicrobial activity, and the dif-
ferences in their activity depend on the structure of the
complex.
A
B
Table 7 Thermodynamic parameters of adsorption of the synthe-
sized metallosurfactants at 25 °C
O
Surfactant
DGads, kJ/mol
DSads, kJ/mol K
DHads, kJ/mol
M
N
X
Y
Z
-41.867
-38.092
-42.603
-47.180
-42.030
-47.365
-53.421
-0.105
-0.168
-0.196
-0.105
-0.219
-0.467
-0.526
-73.298
-88.159
-101.110
-78.431
-107.425
-186.714
-210.333
When the cationic site of the surfactant binds to the
anionic sites of the cell wall surface, the surfactant mole-
cules are able to diffuse through the cell wall then disrupt
the membrane and permit the release of electrolytes and
nucleic materials, leading to cell death. The membrane
activity of the surfactants depends on the character of the
polar head groups (size and electric charge distribution)
and hydrocarbon chains (length, number, saturation and
multiple chains).
A
B
Table 8 Microbial inhibition zone of the tested complexes (mm)
Surfactant Microorganism
The antimicrobial activity of the synthesized biocides
(X, Y and Z) against SRB was determined by dilution
method and the results are listed in Table 9.
NK1 I.1.1.3 I.2.1.7 I.1.1.1 NSh45 I.1.3.1
The results indicate that the synthesized metallocationic
surfactants have antimicrobial activity against the tested
organisms (SRB), and that their activity depends on their
chemical structure, mainly the number of hydrophobic
chains and the length and type of metal.
M
N
X
Y
Z
26
20
24
20
18
16
Nil
38
25
21
24
20
11
Nil
23
20
15
16
18
Nil
Nil
22
20
20
18
18
Nil
Nil
22
16
18
16
17
Nil
Nil
18
14
14
16
14
Nil
Nil
Open Access This article is distributed under the terms of the
Creative Commons Attribution Noncommercial License which per-
mits any noncommercial use, distribution, and reproduction in any
medium, provided the original author(s) and source are credited.
A
B
Table 9 Antimicrobial activity of some synthesized surfactants against sulfate reducing bacteria (SRB) using the dilution method
Bacteria count (SRB)
Surfactant X
800
Surfactant Y
800
Surfactant Z
800
Dose (ppm)
Days
1,000
1,200
1,000
1,200
1,000
1,200
1
2
3
4
5
6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
10
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
10
2
10
2
3
10
3
3
10
3
10
2
10
10
10
2
2
10
3
10
3
3
10
3
10
3
10
2
10
10
10
2
2
10
3
10
3
3
10
3
10
3
10
3
10
10
10
10
3
3
10
3
10
3
10
3
3
10
3
10
3
10
3
10
10
10
1
23

2
34
J Surfact Deterg (2012) 15:223–234
References
cationic amphiphilic compounds from arginine. Langmuir
1
2:5296–5301
1
2
9. Nagamune H, Maeda T, Ohkura K, Yamamoto K, Nakajima M,
Kourai H (2000) Evaluation of the cytotoxic effects of bis–qua-
ternary ammonium antimicrobial reagents on human cells. Tox-
icol In Vitro 14:139–147
0. Birnie CR, Malamud D, Schnaare RL (2000) Antimicrobial
evaluation of N-alkyl betaines and N-alkyl-N, N dimethyl amine
oxides with variations in chain length. Am Soc Microbiol
1
2
. Koshy LL, Pegiadou-Koemtjopoulou S, Rakshit AK (1991)
Thermodynamics of micellization of some new pyridinium cat-
ionic surfactants. Colloids Surf 59:1–6
. Fisicaro EE, Pelizzetti M, Barbier P, Savarino G, Viscardi R
(1990) Aqueous micellar of some N-alkyl nicotinamide and N-N-
alkyl pyridinium halide surfactants and partial molar enthalpies.
Thermochim Acta 168:43–59
. Gad E, El-Sukkary EM, Azzam E (1997) Surface and thermo-
dynamic studies of N-(octyl, dodecyl, and cetyl) oxycarbonyl
methyl pyridinium bromide. Monatshafte Chemie 128:1237–
4
4:2514–2517
3
2
2
2
1. Viscardi G, Quagliotto P, Barolo C, Savarino P, Barni E, Fisciaro
E (2000) Synthesis and surface and antimicrobial properties of
novel cationic surfactants. J Org Chem 65:8197–8203
2. Pernak J, Kalewska J, Ksycinska H, Cybulski J (2001) Synthesis
and antimicrobial activities of some pyridinium salts with alk-
oxymethyl hydrophobic group. Eur J Med Chem 36:899–907
3. Campanac C, Pineau L, Payard A, Baziard-Mouysset G, Roques
C (2002) Interactions between biocide cationic agents and bac-
terial bioflms. Antimicrob Agents Chemother 46:1469–1474
1
246
4
5
6
. Badawi AM, El-Marazibanl MM, Haroun B, Soliman H (1983)
Quaternary ammonium salts of potential biological activity. Curr
Sci 52:1169–1171
. Sierra T (1996) Low molecular weight lyotropic metallomeso-
gens. In: Serrano JL (ed) Metallomesogens, chap 2. VCH,
Weinheim
. Iida M, Yonezawa A, Tanaka A (1997) A novel reverse micellar
system composed of bis (octylethylenediamine) zinc (II) chloride
in aqueous benzene and chloroform solutions. J Chem Lett
Author Biographies
2
6:663–664
7
8
9
. Iida M, Sakai T, Koine N, Kaizaki S (1993) Anisotropic aggre-
gation of A 1, 10-phenanthroline dinuclear chromium (III)
complex bridged by two L-tartrates in aqueous solution. J Chem
Soc Faraday Trans 89:1773–1778
. Iida M, Yamamato M, Fujita N (1996) Multinuclear NMR studies
on micellar formation of aqueous [Co(N-octyl- or N-dodecyl
ethylene diamine)(3, 7-diazanonane-1, 9-diamine)]3, solutions.
Bull Chem Soc Jpn 69:3217–3224
Ismail A. Aiad received his PhD in physical chemistry from Zagazig
University. He is Professor of Applied Organic Chemistry at the
Egyptian Petroleum Research Institute (EPRI; Applied Surfactant
Laboratory), and a member of the board of the Chemical Services and
Development Center for Oil Field Chemicals. He is interested in the
synthesis and applications of surfactants materials.
Abdelfattah M. Badawi has a PhD degree in Applied Chemistry
from Azhar University and a DSc degree in Applied Organic
Chemistry from Toronto University. He is currently Professor of
Applied Organic Chemistry at the EPRI (Applied Surfactant Labo-
ratory) and scientific consultant to the Center of Excellence and
Technology, Ministry of Military Production. His research interests
are in the areas of both environmental and medicinal chemistry, with
special emphasis on antitumor agents.
. Jaeger DA, Reddy VB, Arulsamy N, Bohle DS, Grainger DW,
Berggren B (1998) Micellization model for multivalent ionic
surfactants. Langmuir 14:2589–2592
1
0. Menger FM, Gan LH, Johnson E, Durst DH (1987) Phosphate
ester hydrolysis catalyzed by metallomicelles. J Am Chem Soc
1
09:2800–2803
1
1
1
1. Moulik SP (1996) Micelles: self-organized surfactant assemblies.
Curr Sci 71:368–376
2. McDonnell G, Russell AD (1999) Antiseptics and disinfectants:
activity, action, and resistance. Clin Microbiol Rev 12:147–179
3. Oren Z, Hong J, Shai YJ (1997) A repertoire of novel antibac-
terial diastereomeric peptides with selective cytolytic activity.
Biol Chem 272:14643–14649
4. Takeshita T, Shimohara T, Maeda S (1982) Synthesis of EDTA
monoalkyl amide chelates and evaluation of the surface-active
properties. J Am Oil Chem Soc 59:104–107
5. Shuichi M, Kazayasu I, Sadao Y, Kazuo K, Tsuyoshi Y (1990)
Surface activities, biodegradability and antimicrobial properties
of n-alkyl glucosides, mannosides and galactosides. J Am Oil
Chem Soc 67:996–1001
Mohammed M. El-Sukkary received his PhD in Applied and
Organic Chemistry from Al-Azhar University. He is the supervisor of
Scientific Affairs and Relations at the EPRI and a member of the
board of directors. At EPRI, he has been Head of the Surfactants
Laboratory and of the Petrochemicals Department, as well as Deputy
Director.
1
1
Abdallah A. El-Sawy has a PhD in Organic Chemistry, and is
currently Professor of Organic Chemistry at Benha University, Benha
City, Egypt. His research interests are in surfactants science and
applications.
1
1
6. Rosen MJ (1987) Surfactants and interfacial phenomena. Wiley,
New York, p 72
7. Gad EAM, El-Sukkary MMA, Ismail DA (1997) Surface and
thermodynamic parameters of sodium N-acyl sarcosinate sur-
factant solutions. J Am Oil Chem Soc 74:43–47
Ahmed I. Adawy received his MSc and PhD from Banha University,
Benha City, Egypt. He is a researcher in the Surfactants and
Applications Laboratory at the EPRI. His interest is in surfactant
science and applications.
1
8. Lourdes P, Josep LT, Angeles M, Conxitra S, Rosa MI (1996)
Synthesis and biological properties of a new class of gemini
1
23