Multi-Step Synthesis, Physicochemical investigation and optical properties of pyrazoline derivative: A Donor-π-Acceptor chromophore

Article abstract of DOI:10.1016/j.molstruc.2020.129667

The new extended π-bond pyrazoline derivative (ENTD) was prepared from heterocyclic chalcone with 2-hydrazinylbenzo[d] thiazole. The spectroscopic methods established the structure of the ENTD, and the elemental analysis established the purity of the ENTD. In ten different solvents, physicochemical ENTD parameters such as the molar absorption coefficient, transition dipole moments, Stokes shift, oscillator intensity and fluorescence quantum yield were determined to see the effect of the solvent with pyrazoline derivative (ENTD) on the basis of different polarity. In addition, the interaction of ENTD chromophore with the cationic and anionic surfactants have been studied. The intensity of fluorescence spectrum of the ENTD was found to increase with an increase in the surfactant concentration. This indicates that there is a strong interaction between ENTD and surfactants. The ENTD chromophore can therefore be used as a probe to define the surfactants' CMC.

Full text of DOI:10.1016/j.molstruc.2020.129667

Journal Pre-proof
Multi-Step Synthesis, Physicochemical investigation and optical
properties of pyrazoline derivative: A Donor-π-Acceptor chromophore
Salman A. Khan , Qasim Ullah , Salauddin Syed , Alimuddin ,
Abdulraheem S.A. Almalki , Rami J. Obaid , Meshari A. Alsharif ,
S.Y. Alfaifi , Sanjay Kumar
PII:
S0022-2860(20)31980-3
DOI:
Reference:
https://doi.org/10.1016/j.molstruc.2020.129667
MOLSTR 129667
To appear in:
Journal of Molecular Structure
Received date:
Revised date:
Accepted date:
17 August 2020
6 November 2020
20 November 2020
Please cite this article as: Salman A. Khan , Qasim Ullah , Salauddin Syed , Alimuddin ,
Abdulraheem S.A. Almalki , Rami J. Obaid , Meshari A. Alsharif , S.Y. Alfaifi , Sanjay Kumar ,
Multi-Step Synthesis, Physicochemical investigation and optical properties of pyrazoline
derivative: A Donor-π-Acceptor chromophore, Journal of Molecular Structure (2020), doi:
https://doi.org/10.1016/j.molstruc.2020.129667
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Highlights
► Synthesis of Novel pyrazoline derivative (ENTD) with extended π-bond
► Physicochemical investigation and optical properties of pyrazoline derivative.
► Pyrazoline derivative used as a probe to conclude the CMC of the surfactants.
1

Multi-Step Synthesis, Physicochemical investigation and optical properties of pyrazoline derivative: A
Donor-π-Acceptor chromophore
Salman A. Khan1,*, Qasim Ullah1, Salauddin Syed1, Alimuddin1, Abdulraheem S. A. Almalki2,
Rami J. Obaid3, Meshari A. Alsharif4, S. Y. Alfaifi 5, Sanjay Kumar6
1Physical Sciences Section, School of Sciences, Maulana Azad National Urdu University,
Hyderabad 500032, Telangana, India
2Department of Chemistry, Faculty of Science, Taif University, Taif 210974, Saudi Arabia
3Chemistry Department, Faculty of Applied Science, Umm Al-Qura University, Makkah, Saudi
Arabia
4Department of Chemistry, Faulty of Science, University of Tabuk, Tabuk, Saudi Arabia,
5Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah
21589, Saudi Arabia
6Department of Chemistry, Multani Mal Modi College Patiala 147001, Punjab, India
Corresponding Authors e-mail: sahmad_phd@yahoo.co.in (S. A. Khan)
Abstract:
The new extended π-bond pyrazoline derivative (ENTD) was prepared from heterocyclic
chalcone with 2-hydrazinylbenzo[d] thiazole. The spectroscopic methods established the
structure of the ENTD, and the elementary analysis established the purity of the ENTD. In ten
different solvents, physicochemical ENTD parameters such as the molar absorption coefficient,
transition dipole moments, stoke shift, oscillator intensity and fluorescence quantum yield were
determined to see the effect of the solvent with pyrazoline derivative (ENTD) on the basis of
different polarity. In addition, the interaction of ENTD chromophore with the cationic and
anionic surfactants. The intensity of fluorescence spectrum of the ENTD was found to increase
with an increase in the surfactant concentration. This indicates that there is a strong interaction
between ENTD and surfactants and those electrostatic forces emerge from this interaction. The
ENTD chromophore can therefore be used as a probe to define the surfactants' CMC.
Keywords: Chalcone; Pyrazoline; Stokes shift; Surfactants; CMC
2

1. Introduction
In the current year, a various number of organic molecules with the extended π-bond conjugated
arrangement containing with donor group (N-CH3, O-CH3, -OH) and acceptor group (CN, NO2,
CF2), mainly donor-π-acceptor chromophores, have established a lot of importance owed to their
applications in an extensive variety optoelectronic and electronic devices [1]. The D-π-A
organization confirms effective intermolecular charge transfer (ICT) from the electron-donating
group to the electron-accepting group via π-bong conjugation and creates the donor-π-acceptor
system [2]. Based on the structural and π-bond conjugation of chromophores with different
substituted of donor and acceptor group organic compounds are significant attention because of
their prospective application in the numerous fields of the applied organic chemistry such as
organic light-emitting diodes (OLED) [3], dye-sensitized solar cell (DSSC) [4], non-linear optics
(NLO) [5], fluorescent chemosensor for the detection of various toxic metal ions as well as
organic field-effect transistors (OFET) [6, 7]. Alongside these extensively used applications
donor-π- acceptor chromophores are also used in solar photovoltaics, biochemical sensors, and
concerned substantial attention on the action of numerous infections by photodynamic therapy
[8]. Direct contact in the donor-π-acceptor chromophore provides additional photophysical
properties to the π-conjugated molecules, such as dipole movement, transition dipole moments,
fluorescence quantum yields, oscillator strength, and photostability [9]. Therefore, widespread
research exertions have been focused on the modification of donor-π-acceptor and π-bond
conjugated framework.
3

Pyrazoline represents an important class of the two adjacent nitrogen atoms and a single double
bond containing heterocyclic compounds [10]. Polycyclic aromatic hydrocarbon in π-bond
conjugated pyrazolines has been accomplished preferred photophysical properties such as solid-
state emission, higher fluorescence quantum yields in solid as well as solution stage, longer and
shorter lifetime fluorescence [11-14]. In addition, carbazole is another group of the heterocyclic
compound act as an electron donor group with many interesting photophysical properties and is
useful in making laser dyes, chemosensor, fluorescence probes for envisaging the various
infected living cells and organic light-emitting diodes [15, 16]. Owing to the material science
significance of both type compounds our amine to design the donor acetone chromophore
containing both types of framework pyrazoline and carbazole which have the good π-bond
conjugation and can be used as heterocyclic donor-π- acceptor chromophore. In the present, we
define the synthesis of pyrazoline via the multi-step reaction and its optical properties.
2. Experimental
2.1.Chemical
All the chemical and reagents used in this experiment were purchased from Sigma-Aldrich
Chemical Pvt. Ltd., and Merck Specialties Pvt. Ltd., and used without additional
decontamination. Cetyltrimethyl ammonium bromide (CATB) and sodium dodecyl sulfate
surfactants were also purchased from Merck. All the solvents were used spectroscopic grade to
measure the UV-visible absorption spectra and fluorescence spectra of the pyrazoline derivative.
9-Ethyl-9H-carbazole-3-carbaldehyde, 2-hydrazinylbenzo [d] thiazole and chalcone have been
synthesized according to the reported literature (Scheme 1 & 2) [17-19].
2.2.Instrumental
4

The improvement of the reaction was examined by the silica gel 60F254 pre-coated aluminum
sheets thin layer chromatography (TLC) from Merck. Some steps of the product were purified
the Column chromatography. Proton-NMR (600MHz) and Carbon-NMR (125MHz) spectrum of
the pyrazoline were recorded in DMSO-d6 on Bruker spectrometer. Elemental analysis of the
pyrazoline compound was performed on an Elemental analyzer. FT-IR spectrum of pyrazoline
was recorded on the Perkin-Elmer 100 FT-IR spectrometer and the maximum of absorption (vmax)
is given in cm-1. A Shimadzu Uv-16550PC UV / Vis spectrophotometer and a Shimadzu RF
5301PC spectrofluorophotometer with 1.0 cm optical path length quartz cuvettes were used to
record UV-visible absorption and fluorescence spectra of the pyrazoline derivative in different
solvents at room temperature.
2.3. Synthesis of Pyrazoline derivative (ENTD)
A mixture of the 3-(9-ethyl-9H-carbazol-3-yl)-1-(naphthalen-2-yl) prop-2-en-1-one (2.0 g,
0.0053 mol), 2-hydrazinylbenzo[d] thiazole (1.32 g, 0.0079 mol) and sodium hydroxide (0.42g,
0.106 mol) in 15 ml absolute alcohol was refluxed for 16 h. The progress of the reaction was
monitored by the TLC. After completing the reaction, Crushed ice was added to the reaction
mixture, then again was stirred for 25 min. The resulting precipitous was filtered by the vacuum
pump, washed with cold distilled water, dry and recrystallization in ethanol [20].
Brown solid; Yield: 68%; FT-IR (vmax, cm-1): 3056 (CHAromatic), 2991 (CHAliphatic), 1728 (C=N),
1
1586 (C=C), 1438 (C=S), 1332 (C-N), 1012 (N-N); H-NMR (600MHz, DMSO-d6) (δ/ppm):
8.73-6.18 (m, 18H, CHAromatic), 5.76 (dd, 1H, CHX, JXA = 3.6 Hz, JXB = 12.8 Hz), 3.54 (dd,1H,
CHA, JAB = 5.6 Hz, JAX = 17.4 Hz), 4.02 (dd, 1H, CHB, JBA = 12.03Hz, JBX = 18.2 Hz), 4.11 (q,
3H,N-CH2-CH3, J = 6.2Hz), 1.26 (t, 2H, N-CH2-CH3, J = 4.2Hz); 13C-NMR (125MHz, DMSO-
5

d6) (δ/ppm): 161.56 (C=N, benzothiazoyl), 156.12, 152.18 (C=N, pyrazoline ring), 149.18,
144.75, (C-N), 137.23, 130.25, 125.22, 125.08, 124.05, 122.62, 121.18, 121.28, 120.56, 119.38,
118.83, 117.98, 112.98, 109.48, 107.28, 105.78, 65.56 (C-Cpyra), 46.85 (CH2,pyra), 41.87 (N-CH2-
CH3), 12.56 (N-CH2-CH3); Anal. calc for C34H26N4S; C, 78.13, H, 5.0, N, 10.72, Found: C,
78.08, H, 4.96, N, 10.67.
3. Result and discussion
3.1.Chemistry
ENTD has been synthesized by reaction 3-(9-ethyl-9H-carbazol-3-yl)-1-(naphthalen-2-yl) prop-
2-en-1-one with 2-hydrazinylbenzo[d] thiazole (Scheme 3). The spectroscopic methods and
elementary analysis established the structure of the ENTD. IR spectra showed an absorption
band in the regions of 1332 cm-1 and 1012 cm-1 for C-N and N-N groups and the absence of two
important peaks in the regions 3300-3400 cm-1 and 1675 cm-1 for the (C=O) carbonyl group of
the chalcone and primary amine group (NH2) of the 2-hydrazinylbenzo[d] thiazole indicating the
formation of pyrazoline ring from chalcone. The structure of the pyrazoline derivative additional
1
1
conformed by the H-NMR spectra. H-NMR spectrum of ENTD derivative showed three
doublets of doublets peaks for pyrazoline ring protons Ha, Hb and Hx as existing in Scheme 3,
That emerged because of the germinal-vicinal coupling between Ha and Hb, of which protons are
equal at position 4 of the methylene group and at position 5 of the pyrazoline ring of the methane
group Hx proton. The doublet of doublet peaks at δ 3.54 ppm (Jax = 5.6 Hz, Jab = 17.4 Hz) was
given by Proton Ha trans to Hx while the doublet of doublet peaks at δ 4.02 ppm was distributed
to proton Hb where its higher J value was due to the vicinal cis coupling at Hx (Jbx = 12.03 Hz,
Jba = 18.2 Hz). Finally, at δ 5.76 ppm (Jxa = 3.6 Hz, Jxb = 12.8 Hz), the doublet of doublets peak
downfield of these two peaks was dispensed to proton Hx, approving the existence of vicinal
6

coupling between methylene and methine protons and the existence of a trans configuration.
Furthermore, the structure of the pyrazoline was confirmed by the 13C-NMR spectra, with
pyrazoline derivative carbon atoms such as C = N, CH-pyrazoline ring and CH2 of the pyrazoline
ring giving upsurge to peaks of 152.18 ppm, 65.56 ppm and 46.85 ppm respectively. The signals
in the 137.23-112.98 ppm range were shown by other aromatic carbons.
3.2.Optical properties
The absorption spectrum of the pyrazoline derivative was recorded in ten different polarities of
the solvents at normal temperature. The spectrum of the pyrazoline in different solvents
exhibited broad, intense absorption band. The absorption maxima of the pyrazoline derivative
slightly shifted red shift (14 nm) as mentioned in Table 1, when solvent polarity increase n-
Hexane (339 nm) to DMSO (353nm), the red may be accredited to the stronger electron donating
group (N-CH2-CH3), which cause an intermolecular charge transfer (ICT) character of the
transition [21]. The polarity of the solvents also affected on the molar absorption coefficient and
its value were accessible in table 1. On excitation 345 nm, the emission spectrum of the
pyrazoline derivative sturdily stimulated with solvents polarity. As shown in Figure 1, the
pyrazoline derivative exhibited one broad band and emission maxima with large red shift (35
nm) when the solvent polarity increases n-Hexane (432 nm) to DMSO (467 nm). The red shift
could be attributed to photoinduced intramolecular charge transfer (PICT) state formed by
intramolecular charge transfer from the donor group (N-CH2-CH3) carbazole to the acceptor
group pyrazoline ring at single excited state [22].
7

The empirical Dimroth polarity parameters ET (30) of the various solvents associated with the
absorption energy (Ea) and emission energy (Ef) of the pyrazoline derivative in different solvents
as accessible in Figure 2 [23].
One dimensional association between absorption energy (Ea), emission energy (Ef) and different
polarity of the solvents were acquired by the following equations
Ea = 89.49 – 0.018 x ET(30)
(1)
(2)
Ef = 69.68 -0.078 x ET(30)
3.3.Determination of transition dipole-moments and stokes shift
The physicochemical parameters such as stokes shift transition dipole moments, oscillator
strength of the pyrazoline derivative have been stimulated on the basis of the different polarity of
the solvents. Different diploe-moments in different solvents of the pyrazoline derivative were
determined between single excited state and ground state ∆μ = μe–μg [24].
Lippert-Mataga equation (3) can be used to determine the various physicochemical parameters of
the pyrazoline derivative in different solvents [25].
22
h ca3
st abs em

f Const.
(3)

Where ( st ) is epitomize the stokes shift as mentioned in the Table 1, the value to the stokes
shift decreases when the polarity of the solvents decreases DMSO to n-Hexane, representing
strong steadiness of excited state in polar solvents, a is the radius cavity, c is the velocity of the
light, h is the Plank constant and ∆f is the orientation polarizability of the different solvent have
explained by following equation [26].
8

 1
2 1
2 1
22 1
f 

(4)
where ε and η are the molar absorption coefficient and refractive index of the different solvent
respectively.
The plot of orientation polarizabilty (∆f) versus stokes shift () as showed Figure 3. The linear
correlation between orientation polarizabilty versus stokes shift identified that stokes shift was
dependent on the solvent polarity or polarizabilty.
Lippert-Matga equation (3) was used to calculate the dipole moment between the ground and
excited state of the pyrazoline derivatives. In the equation 3, a is the cavity radius of the
pyrazoline derivative was appraised by the following equation.

1/ 3
3M




a 
(5)
4N d


Where M is molecular mass, N is the Avogadro number and d is the estimated density of the
pyrazoline derivative in 1g/cm3. The different dipole moment of the pyrazoline derivative has
been calculated from the slop of stokes shift versus polarizabilty and it was found 0.54 Debye.
This value reveals that intramolecular charge transfer character of the excited state and sudden
creation of a giant dipole (due to photoinduced ICT) result in a strong interface with the
adjoining medium to cause solvent reformation [27].
9

The transition dipole-moments of the pyrazoline derivative in different solvent have calculated
by using following equation and the values are listed in the Table 1, indicating the dipole-
moments increasing with increases solvent polarity.
f
2 
(6)
4.72 107 Emax
Where f is the oscillator strength and Emax is the energy maximum of the absorption in cm-1.
The oscillator strength of the pyrazoline derivative in different solvent has been calculated by the
following equation (7) [28].
f  4.32 109



d
(7)

-1
-1
the wavenumber (cm-1). The

where Ɛ is the coefficient of molar absorption (M cm ) and
calculated oscillator intensity (f) values for different solvents are given in table 1. The oscillator
strength was directly dependent on the solvent polarity of the pyrazoline derivative.
3.4.Fluorescence quantum yields of the ENTP in various solvents
In the following equation, the fluorescence quantum yield of the pyrazoline derivative in various
solvents was determined using the standard dye comparison (Quinine Sulphate ɸr = 0.55 in 0.1
M H2SO4 solution) (8). [29]
2
I x A x n
r
Ir x Axn

 
(8)
r
f
2
r
ɸr is the fluorescence quantum yield of the reference due Quinine Sulphate, ɸf is the
Where
fluorescence quantum yield of the pyrazoline derivative in different solvent. I is the fluorescence
10

intensity of the pyrazoline and reference dye in the DMSO, A is the absorbance of the pyrazoline
and reference dye in DMSO and n is the refractive index of the solvent.
The fluorescence quantum yield of the pyrazoline derivative also changed depending on the
solvent polarity, the fluorescence spectrum prejudiced from the polarity of the solvent. The
values in interrogation for the pyrazoline derivative in different solvents were listed in Table 1.
The acquired data showed that meaningfully reliant to the property of the solvents such as
hydrogen bonding with electron donor group, hydrogen bonding with electron acceptor group
and polarizability. I addition the plot between fluorescence quantum yields of the pyrazoline
derivative in different solvents versus ET(30) of the different solvent were shown in Figure 4,
where ET(30) is the solvent polarity parameter identify by Reichardt [30]. The fluorescence
quantum yield increased with increased the polarity of the solvents. On the other hand the
fluorescence quantum yield showed poorer values in strong polar solvents such as ethanol and
methanol as compared to the other less polar solvent. This occurrence can be expounded by
positive solvatokinetic effects. In the durable polar solvents durable interaction between the
pyrazoline molecule and solvent occur when the polarity of the solvent increased in the excited
state. When interaction of the hydrogen bonding between the proton donor solvent and
pyrazoline molecule took place, decreases the fluorescence quantum yield of the pyrazoline
derivative [31].
3.5. Effect of the surfactants on the emission spectrum pyrazoline derivative
Two different charged surfactants such as cetyltrimethyl ammonium bromide (CTAB) as
cationic and sodium dodecyle sulphate (SDS) as anionic were used to see the effect on the
emission spectrum of the pyrazoline derivative. The selected of these two precise surfactants due
11

to the ionic charged preoccupied by the pyrazoline derivative can be opinionated by the
positively and negatively charged surfactants. Thus, the fluorescence spectrum of the pyrazoline
derivative was based on the interaction of the pyrazoline with CTAB or SDS. The emission
spectrum of the pyrazoline derivative was measured in the absence of the CTAB and SDS. When
increasing the concentration of the CTAB (2.0 x 10-4 to 1.8 x 10-3 M) the emission intensity of
the pyrazoline increases and as same behavior with SDS, increase the concentration of the SDS
(2.0 x 10-3 to 1.8 x 10-2 M) the fluorescence intensity of the pyrazoline derivative increases [32].
Such enhancement of the fluorescence asset of 1 x 10-5 M of pyrazoline derivative at an
inflexible molar concentration with cumulative the concentration of CTAB and SDS might
probably be predictable to the overtone mechanism of the pyrazoline derivative with CTAB and
SDS as existing in the Figure 5 and 6. The emission intensity of the pyrazoline derivative
sudden changed in the presence of different concentration of the CTAB and SDS takes place at
concentration of the surfactants, 9.74 x 10-4 and 6.13 x 10-3 mol dm-3, which are very close to the
critical micelle concentration (CMC) of CTAB and SDS surfactants as mentioned in the Figure
7 and 8 [33]. The pyrazoline derivative can be used as a probe to evaluate the CMC of the
surfactants of both types.
Conclusions
The New pyrazoline derivative has been prepared by the multi-steps reaction and it's
1
configuration was determined by the detailed of FT-IR, H-NMR and 13C-NMR spectroscopic
techniques and purity of the compound was inveterate by the elemental analysis.
Physicochemical properties of the pyrazoline derivative were studied by using ten different
solvents on the basis of the different polarity. It was observed that the energy of the excited state
of the pyrazoline derivative unnatural from the increase in the polarity of the solvents associated
12

with the energy of the ground state of the pyrazoline derivative. This state proposed the existence
of substantial variances between excited and ground state charge dissemination of the pyrazoline
derivative. In addition, the pyrazoline derivative also used as a probe to conclude the CMC of the
surfactants.
Acknowledgement
Taif University Researches Supporting Project number (TURSP-2020/44) Taif University, Taif,
Saudi Arabia.
Credit Author Statement
To this manuscript, all the authors contributed equally.
Declaration of interests
The authors declare that they have no known competing financial interests or personal relationships
that could have appeared to influence the work reported in this paper.
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Scheme 2: Preparation of Carbazole aldehyde
Scheme 2: Preparation of 2-Hydrazinobenzothiazole
18

O
O
O
NaOH
EtOH
H
C
H
3
+
N
N
H
C
3
H
3C
H
N
N
S
2
H
N
Ha
Hb
CH3
N
N
Hx
N
S
N
(ENDT)
Scheme 3: Preparation of ENDT
19

Physicochemical parameters of ENTD in various solvents
Table 1:
Solvent
ETN
ET (30)
Kcal
ε
f
μ 12
Debye
Φf
st
(cm-1)
f
ab(nm) em(nm)
M -1cm-1
mol-1
DMSO
0.263
0.441
45.1
353
467
27070
0.74
6.32
6915
0.36
DMF
EtOH
MeOH
CHCl3
CH2Cl2
CH3CN
Dioxane 0.148
FHT
n-Hexane 0.0014 0.0002
0.274
0.305
0.308
0.217
0.255
0.274
0.404
0.654
0.762
0.259
0.472
0.164
0.210
43.8
51.9
55.4
39.1
41.1
45.6
36.0
35.09
31.1
351
350
351
348
346
345
343
341
339
462
453
455
447
448
449
440
438
432
25870
21870
22000
23450
22050
21780
22830
20780
19070
0.70
0.56
0.57
0.59
0.56
0.58
0.58
0.53
0.48
6.18
6.03
5.93
6.10
5.91
5.83
5.71
5.87
5.39
5486
6496
6512
6364
6714
6427
6494
5848
6350
0.39
0.41
0.28
0.40
0.43
0.28
0.31
0.22
0.10
0100.8 01005
20

500
400
300
200
100
0
DMSO
DMF
EtOH
MeOH
CHCl
3
CH Cl
2
2
Dioxane
CH CN
3
THF
n-Hexane
400
450
500
550
600
Wavelength (nm)
Figure 1: Emission spectra of 1 x 10-5 M of ENTD in various solvents.
85
80
75
70
65
60
E
E
a
b
30
35
40
45
50
55
-1
E (30) Kcal mol
T
Figure 2: Absorption (Ea) and emission (Ef) plot of energy versus ET(30) of the various solvent.
21

7000
6900
6800
6700
6600
6500
6400
6300

30
35
40
45
 f
50
55
Figure 3: Plot of ∆f versus stokes shift
0.5
0.4
0.3
0.2
0.1
30
35
40
45
50
55
-1
E (30) Kcal mol
T
Figure 4: Plot of Φf versus ET(30) of the different solvents
22

450
400
350
300
250
200
150
100
50
0
400
450
500
550
600
650
Wavelength (nm)
Figure 5: Fluorescence spectra of 1 x 10-5 M mol dm-3 of ENTD at different concentration of
CTAB.
150
125
100
75
50
25
0
400
450
500
550
600
650
Wavelength (nm)
Figure 6: Fluorescence spectra of 1 x 10-5 M mol dm-3 of ENTD at different concentration of
SDS.
23

450
400
350
300
250
200
150
100
50
CMC
0.0000 0.0004 0.0008 0.0012 0.0016 0.0020
-1
[CTAB] mol dm
Figure 7: Plot If versus the concentration of CTAB.
160
140
CMC
120
100
80
60
0.000
0.004
0.008
0.012
-3
0.016
0.020
[SDS] mol dm
Figure 8: Plot If versus the concentration of SDS.
24

Graphical Abstract:
500
400
300
200
100
0
DMSO
DMF
EtOH
MeOH
CHCl
3
CH Cl
2
2
Dioxane
CH CN
3
THF
n-Hexane
400
450
500
550
600
Wavelength (nm)
450
400
350
300
250
200
150
100
50
CMC
0.0000 0.0004 0.0008 0.0012 0.0016 0.0020
-1
[CTAB] mol dm
25