Solvent and substituent effect on the photophysical properties of pyrazoline derivatives: A spectroscopic study

Article abstract of DOI:10.1016/j.jphotochem.2017.10.010

Pyrazoline derivatives are among solvatochromic dyes and they are the most widely used in many fields such as sensors, labeling agent and optoelectronic devices. Therefore, synthesis of new pyrazoline derivatives and determination of their optical behavior in different solvents are a very important research area. In this study, the solvatochromic behaviors of seven new synthetic pyrazoline derivatives, (4-[3-(4-Hydroxyphenyl)-5-aryl-4,5-dihydro-pyrazol-1-yl]benzenesulfonamides, compound 1-7), were determined in different solvents. As a result of the measurements, a large red shifts in the fluorescence spectra of the compounds studied were observed for each compound, when the polarity of the solvent increased. Kamlet-Taft and Catalan parameters were used to describe the solvent-soluble interactions. The obtained results showed that the solvatochromic behavior of the compounds is dependent on their solvent polarity as well as the effect of the hydrogen-bonding properties of the solvents. It was also found that the increases in the polarity of the solvent was facilitated the non-radiative transition. Furthermore, the changes in the dipole moments of compounds 1-7 in different solvents at room temperature were calculated by using the Lippert–Mataga equation. It was very impressive that calculated fluorescence quantum yield values of the compounds studied here by using different solvents were remarkably high than the ones reported in the literatures for pyrazolines. In addition, the effect of substituent on the photo-physical properties of the compounds was also investigated. It was observed that the fluorescence intensity of the substituted compounds 2-6 increased comparing to the compound 1, which is a non-substituted derivative. These changes were not dependent on electronic nature of the substituent on phenyl ring (i.e. electron donating and electron withdrawing substituent). According to data obtained it can be stated that these novel solvatochromic dyes studied here can be find application in pharmaceutical industry, as labeling agent, sensor applications as biosensors or analytical sensors and/or optoelectronic devices.

Full text of DOI:10.1016/j.jphotochem.2017.10.010

Accepted Manuscript
Title: Solvent and Substituent Effect on the Photophysical
Properties of Pyrazoline Derivatives: A Spectroscopic Study
Authors: Ebru Bozkurt, Halise Inci Gul, Ebru Mete
PII:
S1010-6030(17)31279-0
DOI:
Reference:
https://doi.org/10.1016/j.jphotochem.2017.10.010
JPC 10934
To appear in:
Journal of Photochemistry and Photobiology A: Chemistry
Received date:
Revised date:
Accepted date:
30-8-2017
30-9-2017
7-10-2017
Please cite this article as: Ebru Bozkurt, Halise Inci Gul, Ebru Mete,
Solvent and Substituent Effect on the Photophysical Properties of Pyrazoline
Derivatives: A Spectroscopic Study, Journal of Photochemistry and Photobiology A:
Chemistry https://doi.org/10.1016/j.jphotochem.2017.10.010
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Solvent and Substituent Effect on the Photophysical Properties of
Pyrazoline Derivatives: A Spectroscopic Study
a*
b
c
Ebru Bozkurt , Halise Inci Gul , Ebru Mete
aProgram of Occupational Health and Safety, Erzurum Vocational Training School, Ataturk
University, 25240 Erzurum, Turkey
b
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ataturk University, 25240
Erzurum, Turkey
c
Department of Chemistry, Faculty of Science, Ataturk University, TR-25240 Erzurum, Turkey
*
Corresponding Author. Tel: +90(442)231 2667; Fax #: +90(442)231 2503
e-mail: ebrubozkurt@atauni.edu.tr (Ebru Bozkurt)
GRAPHICAL ABSTRACT
Highlights
1




Seven pyrazoline derivatives (compound 1-7) were synthesized and their photo-physical
properties were investigated.
The effect of solvent and substituent on the photo-physical properties of new pyrazoline
derivatives was determined.
It suggested that the photo-physical properties of these biologically active novel molecular
probes may be useful in some areas, such as labeling, sensor applications in different
environments.
ABSTRACT
Pyrazoline derivatives are among solvatochromic dyes and they are the most widely used in
many fields such as sensors, labeling agent and optoelectronic devices. Therefore, synthesis of
new pyrazoline derivatives and determination of their optical behavior in different solvents are
a very important research area. In this study, the solvatochromic behaviors of seven new
synthetic pyrazoline derivatives, (4-[3-(4-Hydroxyphenyl)-5-aryl-4,5-dihydro-pyrazol-1-
yl]benzenesulfonamides, compound 1-7), were determined in different solvents. As a result of
the measurements, a large red shifts in the fluorescence spectra of the compounds studied were
observed for each compound, when the polarity of the solvent increased. Kamlet-Taft and
Catalan parameters were used to describe the solvent-soluble interactions. The obtained results
showed that the solvatochromic behavior of the compounds is dependent on their solvent
polarity as well as the effect of the hydrogen-bonding properties of the solvents. It was also
found that the increases in the polarity of the solvent was facilitated the non-radiative transition.
Furthermore, the changes in the dipole moments of compounds 1-7 in different solvents at room
temperature were calculated by using the Lippert–Mataga equation. It was very impressive that
calculated fluorescence quantum yield values of the compounds studied here by using different
solvents were remarkably high than the ones reported in the literatures for pyrazolines. In
addition, the effect of substituent on the photo-physical properties of the compounds was also
investigated. It was observed that the fluorescence intensity of the substituted compounds 2-6
increased comparing to the compound 1, which is a non-substituted derivative. These changes
were not dependent on electronic nature of the substituent on phenyl ring (i.e. electron donating
and electron withdrawing substituent). According to data obtained it can be stated that these
novel solvatochromic dyes studied here can be find application in pharmaceutical industry, as
labeling agent, sensor applications as biosensors or analytical sensors and/or optoelectronic
devices.
Keywords: Pyrazoline; Absorption; Fluorescence; Solvent effect; Kamlet-Taft and Catalan
parameters
1
. Introduction
2

Synthesis and the photo-physical characterization of new fluorogenic probes provide important
contributions to many fields such as analytical, biochemical and optoelectronic [1-7].
Especially, solvatochromic fluorescent dyes have been extensively studied due to their potential
applications as polarity-sensitive molecular probes. Several the optical properties of
solvatochromic dyes (SD) such as the fluorescence intensity, color, the fluorescence quantum
yield or lifetime are sensitive to the solvent medium in which SD are solved. The properties of
SD lead their uses in several chemical, biological events in addition to their finding application
in multimolecular systems as labeling agent, sensor ext. [8]. Pyrazoline derivatives are a widely
used solvatochromic dye [9, 10]. Pyrazoline is a five-membered heterocyclic ring containing
two nitrogen atoms can be considered as the best examples of this type of probes among
fluorogenic probes. These type of compounds show strong fluorescence property due to
conjugation available between pyrazoline and two phenyl rings. Pyrazolines and their
complexes are also used in organic electroluminescent devices (OLEDs) due to high
fluorescence quantum yield and strong fluorescence properties [11-16]. Furthermore, these
compounds also have importance in medicinal chemistry because of their several bioactivities
such as antimicrobial [17, 18], antiamoebic [19], antinociceptive [20], anticancer [21],
antidepressant [22] and anti-inflammatory [23].
Pyrazoline derivatives are typical intramolecular charge transfer (ICT) compounds owing to
charge transfer from the nitrogen atom at the 1-position of pyrazoline to the carbon atom at the
3
-position of the pyrazoline ring (Scheme 1). The effects of the solvents used on the absorbance
and fluorescence properties of these ICT materials take attention to the researchers working in
the fields [24-27]. The interactions between fluorescent probes and solvent molecules occur as
either specifically (hydrogen bond etc.) or non-specifically. Multiple linear regression analysis
suggested by Kamlet-Taft and Catalan is used to characterize the solvent–solute interactions.
These approaches can be described by the following equations:
3

∗
푦 = 푦 + 푎훼 + 푏훽 + 푐휋 (Kamlet-Taft)
(1)
(2)
0
푦 = 푦 + 푎푆퐴 + 푏푆퐵 + 푐푆푃 + 푑푆푑푃 (Catalan)
0
where y is the desired spectral property and y
0
stands spectral property in a vacuum or the gas
phase. α, β and π* denote the hydrogen bond donor (HBD) acidity, hydrogen bond acceptor
HBA) basicity and dipolarity/polarizability of the solvents respectively. Catalan model
(
parameters SA, SB, SP and SdP characterize the solvent acidity, basicity, polarizability and
dipolarity respectively. a–d are the regression coefficients describing the sensitivity of the
respective property to the different types of solvent–solute interactions [28-31].
In this study, it was aimed to investigate the spectral behaviors of the novel synthesized
pyrazoline
derivatives
(4-[3-(4-Hydroxyphenyl)-5-aryl-4,5-dihydro-pyrazol-1-
yl]benzenesulfonamides, 1-7, Scheme 1) in different solvents. The substituents on the 4-
position of phenyl ring were changed as hydrogen (1), methyl (2), methoxy (3), bromine (4),
chlorine (5), flour (6), nitro (7). For this purpose, to take UV-Vis absorption, steady-state and
time-resolved fluorescence measurements for all compounds in different solvents were planned.
Since the changes in the optical properties of pyrazolines may find application in several areas
such as chemical, biological and multimolecular systems as previously mentioned above. It was
also considered to explain the interactions between the solvents used and solute, i.e. the
compound by using multiple linear regression analysis. Additionally, the influences of the
solvents used on the photo-physical parameters such as the fluorescence quantum yield,
fluorescence lifetime, radiative (k ) and non-radiative (knr) rate constants and the effects of the
r
substituents available at the 4-position of phenyl (Scheme 1) on the photo-physical behavior
were considered to investigate.
2
. Experimental
2
.1. Material
4

All the solvents (Sigma and Merck), quinine sulfate (Fluka) and H
2
SO (Sigma) were purchased
4
and used without further purification. The physical properties, polarity parameters, Kamlet-Taft
and Catalan parameters of all solvents used in the study are listed in Table 1 and 2 [32, 33]. The
stock solution of all compounds was prepared in ethanol. A certain amount of fresh probe
samples in different solution was obtained from this stock solution by evaporating the solvent.
-6
For all measurements, the concentrations of compounds were 2.0x10 M. All the experiments
were performed at room temperature.
2
.2. Equipment
The UV-Vis absorption and fluorescence spectra of the samples were recorded with Perkin
Elmer Lambda 35 UV/VIS spectrophotometer and Shimadzu RF-5301PC
spectrofluorophotometer, respectively. Fluorescence and absorption measurements were taken
for all sulfonamide derivatives at room temperature. For the steady-state fluorescence
measurements, all the samples were excited at 350 nm and fluorescence intensity were recorded
between 355 nm and 650 nm. The fluorescence lifetime measurements were carried out with a
LaserStrobe model TM3 spectrofluorophotometer from Photon Technology International (PTI).
The excitation source combined a pulsed nitrogen laser/tunable dye laser. The samples were
excited at 366 nm. The decay curves were collected over 200 channels using a nonlinear time
scale with the time increment increasing according to arithmetic progression. The fluorescence
decays were analyzed with the lifetime distribution analysis software from the instrument
2
supplying company. The quality of fits was assessed by χ values and weighed residuals [34].
The Fluorescence quantum yields of donor molecules were calculated through the Parker-Rees
equation:
2
ꢃ푂ꢄꢁ
퐷
휂
1−10
ꢀ
ꢂ
∅푠 = ∅ ( ) ( ) ( )
1−10ꢃ푂ꢄ
ꢂ
(3)
푟
2
퐷
휂
ꢁ
ꢁ
where D is the integrated area under the corrected fluorescence spectrum, n is the refractive
index of the solution, and O
D
is the optical density at the excitation wavelength (λex= 350 nm).
5

The subscripts s and r refer to the sample and reference solutions, respectively. Quinine sulfate
in 0.5 M H SO solution was used as the reference. The fluorescence quantum yield of quinine
sulfate was 0.55 in 0.5 M H SO solution [35].
2
4
2
4
The rate constants of the radiative (k
using the following equations.
r
) and non-radiative (knr) deactivation were calculated by
Φ
푘푟 =
휏ꢅ푣
(4)
(5)
1
=
푘푟 + 푘푛푟
휏ꢅ푣
where Φ is fluorescence quantum yield and τav is average fluorescence lifetime of samples [36].
.3.Synthesis of pyrazoline derivatives
The compounds were synthesized and characterized as described in our previous study [37].
2
1
13
The synthesis of the compounds has been summarized in Scheme 2. H NMR, C NMR, HRMS
data, yield of the reactions and melting points of the compounds for compound 1-7 can be found
in the supplementary file.
3
. Results and discussion
3
.1. Effect of solvents on absorption and fluorescence spectra
The absorption and fluorescence spectra of seven pyrazoline derivatives (Scheme 1) were
recorded in ten different solvents such as 1,4-dioxane, tetrahydrofuran (THF), ethyl acetate,
dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile (ACN), isopropanol (i-
PrOH), ethanol (EtOH), methanol (MeOH), water at room temperature (Figs. 1-2). Maximum
absorption band for the compound 1 used were at about 350-360 nm (Fig. 1). The bands at issue
*
were attributed to the π→π transitions of conjugated skeleton localized on the pyrazoline ring.
The changes in the absorption maxima of the compounds depending on solvent polarity were
presented in Table 3. The absorption maxima for each molecule shifted to longer wavelength
6

(bathochromic shift) and the intensity of absorbance decreased (hypochromic shift) when the
solvent polarity increased. The bathochromic shifts are result from the increase in the dipole
moment of the probe whereas the hypochromic shifts are result from the hydrogen-bond
formation [38, 39]. It was observed that the shifts in absorption maxima were minimal
comparing to maxima of fluorescence spectra of the compounds depending on solvent polarity.
This suggested that there was no charge transfer in the ground state of the compounds.
The steady-state fluorescence and normalized fluorescence spectra of compound 1 were shown
in Figs. 2 and 3. As shown in Fig. 2, the compound studied exhibited one broad band which
represented S
1
→S electronic transition. It was observed that the red shifts in the fluorescence
0
maxima with the increase in solvent polarity were greater than red shifts in the absorption
maxima (Figs. S1 and S2). The energies of excited state of compounds were more affected from
the increases in the solvent polarity comparing to the energies of the ground state of the
compounds since there were differences between the shifts of fluorescence maxima and the
shifts of absorption maxima in red region (Table 3) [26, 40]. The red shift observed depending
*
on the solvent polarity indicated the presence of π → π transition. The shifts of fluorescence
band maxima to the longer wavelength proved the presence of significant differences between
excited and ground state charge distributions of the molecules. The reason of differences in
charge distributions of the molecules was stronger intermolecular interactions in polar solvents
in the excited state of the compounds [41]. The molar absorption coefficient (ε) values of the
studied compounds were presented in Table 3. These values were remarkably high suggesting
that the electronic transitions in the solvents from the ground state to the excited state had π →
π* character [10, 39].
The fluorescence quantum yield and lifetime values of fluorophores also changed depending
on solvent polarity because the emission spectra influenced from solvent polarity. The values
in question for the compounds in different solvents were listed in Table 3. The data obtained
7

revealed that significantly dependent to the solvent properties such as hydrogen bond donor
ability, hydrogen bond acceptor ability and polarizability. The fluorescence quantum yields
increased when solvent polarity increased in both polar aprotic (except for acetonitrile) and
polar protic solvents. On the other hand, the fluorescence quantum yields had lower values in
strongly polar solvent such as acetonitrile and alcohols comparing to the other solvents having
less polarity. This phenomenon can be explained by positive solvatokinetic effects. In strong
polar solvents, strong interactions between molecule and solvents occur when solvent polarity
increased in excited state. When hydrogen bond interaction between a molecule and a proton
donor solvent took place, the quantum yield of the compound decrease. The decreases in the
quantum yield result from the fluorescence quenching whose reasons are the enhancement of
intersystem crossing, strong internal conversion and vibrational deactivation all the reasons
mentioned led to intramolecular charge transfer (ICT). This situation caused to increases in the
rate of non-radiative relaxation of an excited state. This suggested that the positive
solvatokinetic effect was taking place [10, 42].
To understand the dependence of the absorption and fluorescence spectra to the solvent, the
solvent polarity parameter (E
versus E (30) were plotted (Fig. 4). A linear variation was obtained between the Stokes shift
and the E (30) values for the compounds studied. The linear variations implied potential
T
(30)) approach has been used. The Stokes shift (Δν =νabs-νflu)
T
T
application of these parameters to explain the microenvironment of the compounds which are
new pyrazoline derivatives [43, 44].
Lippert–Mataga equation can be used to determine the influence of solvent polarity on the
optical properties of a fluorophore [45-48]:
ꢉΔ휇2
ℎꢊꢆ3
∆
휈 = 휈ꢆꢇ푠 ꢈ 휈푓푙푢
=
ꢋꢌ + 푐표ꢍꢎ푡푎ꢍ푡
(6)
−
1
where Δν is the Stokes shift in wavenumber (cm ), νabs and νflu are the wavenumbers of the
absorption and fluorescence maximum wavelengths, respectively, h is the Planck constant, c is
8

the light velocity, a is the cavity radius, and Δf is the orientation polarizability of the solvent
defined as follows (Eq. 7):
휀−1
휂2−1
ꢋꢌ =
ꢈ
(7)
2
ꢉ휀ꢏ1
ꢉ휂 ꢏ1
where ε and η are the dielectric constant and refractive index of the solvent, respectively. Fig.
showed the plot of Stokes shift versus the orientation polarizability (∆f). The polar protic
5
solvents were not included when the Fig. 5 was drawing due to specific solute–solvent
interactions such as hydrogen bonding and the acidity and basicity of solvents. The linear
relationships between Stokes shift versus the orientation polarizability indicated that the Stokes
shift was dependent to the solvent dipolarity and/or polarizability. For all compounds, the
differences in between dipole moments (Δμ) of the ground and excited states were calculated
from the Lippert–Mataga equation. At this equation, the cavity radius a for all compounds was
estimated by using Eq. (8)
1
)
/ꢐ
ꢐ푀
푎 = (4
(8)
푁ꢑꢒ
where M is the molecular weight, N is Avogadro’s number, and d is an assumed molecular
−
3
density of 1 g cm . The estimated dipole moment differences were 19.93, 27.18, 28.90, 15.77,
1
7.21, 18.36 and 27.81 of compounds 1-7, respectively. These large dipole moment differences
indicated that the intramolecular charge transfer (ICT) state occurred by the effect of the solvent
used after the excitation of the compounds [38].
3
.2. Multiple regression analysis
Multiple linear regression analysis suggested by Kamlet-Taft (Eq.1) and Catalan (Eq.2) were
also employed to discuss the solvent effects in more detail. The regression coefficients, their
standard deviations and the multiple linear correlation coefficient r for the pyrazoline
derivatives were summarized in Tables 4 and 5. It was noticed that the largest contribution to
the interactions between a solute and a solvent belonged to the solvent dipolarity/polarizability
*
(
cπ and cSP). This indicated that the dominant factor on the solvatochromic changes in
9

absorption wavelength (λabs) and fluorescence wavelength (λflu) was the solvent polarizability.
However, the contributions of hydrogen bond donor (HBD) acidity and hydrogen bond acceptor
(HBA) parameters in solvent cannot be neglected. The multiple regression analysis of νabs and
νflu indicated that HBD/solvent acidity (α/SA) much more contributed to interaction between a
solute and a solvent than HBA/solvent basicity (β/SB) for all compounds tested. The low values
*
of α and β compared to π supported that spectroscopic properties of these pyrazoline
derivatives were less sensitive to hydrogen bonding characteristics of solvents. These results
were supported by those obtained from the E
T
(30) approach and the Lippert–Mataga approach
[
41, 49]. Negative values of regression coefficients indicated that the regression parameters
considered contributed to the stabilization of the compounds both the ground state and the
excited state [50].
3
.3. Substituent effect
Seven novel pyrazoline derivatives synthesized and studied here had different at the substituents
groups 4- position of phenyl ring (Scheme 1). The compounds 1-6 exhibited very high
fluorescence properties in the blue-green region. The intensity in fluorescence spectra of each
compound in DMSO changed depending on the nature of substituents on phenyl rings (Fig. 6).
Increases in fluorescence intensity of the substituted compounds (2-6) were observed
comparing to compound 1 which is non-substituted derivative without dependent the electronic
nature of the substituent on phenyl ring (i.e. electron donating and electron withdrawing
substituent), exception was the compound 7 which has nitro substituent on phenyl ring. In the
case of the compound 7, the efficient intersystem crossing process occur due to the existence
of a low-lying n → π* transition. The presence of detectable fluorescence decrease results from
high rate of S
considerable charge transfer character of the excited state of nitro bearing compound, since
NO group has strong electron-withdrawing nature [51]. The fluorescence quantum yield
1
→S
0
internal conversion. S
1
→S internal conversion may be related to the
0
−
2
1
0

values of the compounds 2-6 were higher than the compound 1’s, which is non-substituted
compound, without dependent the nature of substituents (i.e. electron donating and electron
withdrawing substituent) except the compound 7. This situation was similar to the situation
fluorescence intensity as mentioned before.
The values as the fluorescence intensities and quantum yields obtained in this study were
remarkably higher than the ones reported in literatures for the compounds having pyrazoline
moiety [10, 39, 52-56]. The data obtained from the present study may be useful in
pharmaceutical industry, in labeling and sensor applications as biosensors or analytical sensors.
4
. Conclusions
The photo-physical behaviors of newly synthesized seven pyrazoline derivatives 1-7 (Scheme
1
) were described in different solvents. All compounds (except for 7) exhibited very high
fluorescence properties depending on the solvent polarity in the blue-green region. It was
observed that the energy of excited state for every compound was more affected from the
increases in the solvent polarity compared to the energy of ground state of the same compound.
This situation suggested the presence of significant differences between excited and ground
state charge distributions of the molecules. The solvent dependence of the absorption and
fluorescence spectra was discussed using the solvent polarity parameter (E (30)) approach,
T
Lippert–Mataga equation, and multiple linear regression analysis. All results shown in Fig. 4,
Fig. 5 and Table 4, Table 5 pointed out that the dominant factor affecting the interaction
between a solute (compound) and a solvent was the solvent polarizability on the solvatochromic
changes in λabs and λflu. In addition, the fluorescence quantum yield values calculated for
compounds 1-7 comparing to the previous values of several compounds having pyrazoline ring
in literatures in different solvents were quite impressive and high. Moreover, the effects of the
substituent at 4-position of phenyl ring on the photo-physical properties of the compounds 1-7
were evaluated. The increases in fluorescence intensities and the fluorescence quantum yields
were noticed in compounds 2-6 without dependent to the electronic nature of the substituents
1
1

comparing to non-substituent compound, except compound 7 which has nitro group. The photo-
physical properties of these biologically active novel molecular probes may be useful in some
areas, such as labeling, sensor applications in different environments.
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1
5

Figr-1FIGURES CAPTION
Scheme 1. Structure of the pyrazoline derivatives 1-7
Scheme 2. Synthesis of the pyrazoline derivatives 1-7
Fig. 1. The absorption spectra of compound 1 in different solvents.
Fig. 2. The fluorescence spectra of compound 1 in different solvents.
Fig. 3. Normalized fluorescence spectra of compound 1 in different solvents.
Fig. 4. The plot of Stokes shift versus the solvent polarity, E (30)
T
−
1
Fig. 5. Stokes shift (Δν =νabs-νflu /cm ) versus orientation polarizability function (Δf).
Fig. 6. The fluorescence spectra of pyrazoline derivatives, 1-7 in DMSO.
Scheme 1.
Reagents and conditions.
Hydrazinobenzenesulfonamide hydrochloride, EtOH, glacial acetic acid, reflux 6-12 h. Ar:
for 1′, 1; 4-CH for 2′, 2; 4-CH OC for 3′, 3; 4-BrC for 4′, 4; 4-ClC for 5′,
; 4-FC for 6′, 6; 4-NO for 7′, 7.
(i) 10% aq NaOH, EtOH, 0-5 oC, 12 h; (ii) 4-
C
6
H
5
3
C
6
H
4
3
6
H
4
6
H
4
6
H
4
5
6
H
4
2
C
6
H
4
Scheme 2.
1
6

Fig. 1.
Fig. 2.
1
7

Fig. 3.
Fig. 4.
1
8

Fig. 5.
Fig. 6.
1
9

TABLES
Table 1. The physical properties and polarity parameters of selected solvents
Table 2. Kamlet-Taft and Catalan parameters of selected solvents
Table 3. Spectroscopic and photo-physical properties of compounds 1-7 in selected solvents
*
Table 4. Estimated coefficients (y
0
, aα, bβ, cπ for νabs, νflu) and correlation coefficients (r) for
regression analysis of the pyrazoline derivatives 1-7 according to the Kamlet-Taft solvent
parameters
Table 5. Estimated coefficients (y , aSA, bSB, cSP and dSdP for νabs, νflu) and correlation
0
coefficients (r) for regression analysis of the pyrazoline derivatives 1-7 according to the Catalan
solvent parameters
Table 1.
2
0

Table 2.
Table 3.
2
1

Table 3. Continued
2
2

Table 4.
2
3

Table 5.
2
4

SUPPLEMENTARY MATERIAL
Solvent and Substituent Effect on the Photophysical Properties of
Pyrazoline Derivatives: A Spectroscopic Study
a*
b
c
Ebru Bozkurt , Halise Inci Gul , Ebru Mete
aProgram of Occupational Health and Safety, Erzurum Vocational Training School, Ataturk
University, 25240 Erzurum, Turkey
bDepartment of Pharmaceutical Chemistry, Faculty of Pharmacy, Ataturk University, 25240
Erzurum, Turkey
cDepartment of Chemistry, Faculty of Science, Ataturk University, TR-25240 Erzurum, Turkey
*
Tel: +90(442)231 2667; Fax #: +90(442)231 2503
e-mail: ebrubozkurt@atauni.edu.tr (Ebru Bozkurt)
4
-[3-(4-Hydroxyphenyl)-5-phenyl-4,5-dihydro-pyrazol-1-yl]benzenesulfonamide (1)
0
1
M.p. 208–210 C. Yield: 47%. H NMR (400 MHz, CD3OD, ppm) d ¼ 7.65 (d, 2H, J ¼ 8.8
Hz), 7.64 (d, 2H, J ¼ 9.0 Hz), 7.36–7.24 (m, 5H), 7.08 (d, 2H, J ¼ 9.0 Hz), 6.84 (d, 2H, J ¼
8
1
1
.8 Hz), 5.43 (dd, 1H, J ¼ 12.0, 5.7 Hz), 3.92 (dd, 1H, J ¼ 17.4, 12.0 Hz), 3.13 (dd, 1H, J ¼
13
7.4, 5.7 Hz); C NMR (100 MHz, CD OD, ppm) d ¼ 160.2, 151.5, 148.7, 143.5, 132.8,
3
30.3, 128.9, 128.8, 128.5, 126.9, 125.0, 116.5, 113.3, 64.5, 44.7; HRMS (ESI-MS): calcd.
+
for C21
H
20
N
3
O
3
S [M + H] 394.1225; found 394.1217.
4
-[3-(4-Hydroxyphenyl)-5-p-tolyl-4,5-dihydro-pyrazol-1-yl]benzenesulfonamide (2)
0
1
M.p. 163–164 C. Yield: 75%. H NMR (400 MHz, CD3OD, ppm) d ¼ 7.62 (d, 2H, J ¼ 8.8
Hz), 7.61 (d, 2H, J ¼ 9.1 Hz), 7.20–7.10 (m, 4H), 7.05 (d, 2H, J¼8.8 Hz), 6.82 (d, 2H, J¼8.8
Hz), 5.37 (dd, 1H, J¼12.1, 5.5 Hz), 3.87 (dd, 1H, J¼17.4, 12.1 Hz), 3.08 (dd, 1H,
2
5

1
3
J¼17.4, 5.5 Hz), 2.28 (s, 3H, –CH3); C NMR (100 MHz, CD
3
OD, ppm) d¼159.0, 150.3,
1
47.5, 139.2, 137.4, 131.5, 129.6, 127.7, 127.3, 125.6, 123.8, 115.3, 112.1, 63.1, 43.5, 19.9;
+
HRMS (ESI-MS): calcd. for C22
H
22
N
3
O S [M + H] 408.1382; found 408.1367.
3
4
-[3-(4-Hydroxyphenyl)-5-(4-methoxyphenyl)-4,5-dihydropyrazol-1-
yl]benzenesulfonamide (3)
0
1
M.p. 176–178 C. Yield: %23. H NMR (400 MHz, CD3OD, ppm) d¼7.62 (d, 2H, J¼8.8
Hz), 7.61 (d, 2H, J¼8.8 Hz), 7.16 (d, 2H, J¼8.8 Hz), 7.06 (d, 2H, J¼8.8 Hz), 6.86 (d, 2H,
J¼8.8 Hz), 6.82 (d, 2H, J¼8.8 Hz), 5.36 (dd, 1H, J¼12.1, 5.5 Hz), 3.86 (dd, 1H, J¼17.2,
13
1
2.1 Hz), 3.74 (s, 3H, -OCH3), 3.09 (dd, 1H, J¼17.2, 5.5 Hz); C NMR (100 MHz, CD OD,
3
ppm) d¼159.5, 159.0, 150.3, 147.6, 134.1, 131.4, 127.7, 127.2, 126.9, 123.9, 115.3, 114.4,
+
1
4
12.1, 62.9, 54.5, 43.5; HRMS (ESI-MS): calcd. for C22
24.1312.
H
22
N
3
O
4
S [M + H] 424.1331; found
4
-[5-(4-Bromophenyl)-3-(4-hydroxyphenyl)-4,5-dihydro-pyrazol-1-
yl]benzenesulfonamide (4)
0
1
M.p. 174–175 C. Yield: 38%. H NMR (400 MHz, CD3OD, ppm) d¼7.64 (d, 2H, J¼8.8
Hz), 7.63 (d, 2H, J¼8.8 Hz), 7.48 (d, 2H, J¼8.4 Hz), 7.19 (d, 2H, J¼8.4 Hz), 7.05 (d, 2H,
J¼9.1 Hz), 6.82 (d2H, J¼8.8 Hz), 5.42 (dd, 1H, J¼12.1, 5.5 Hz), 3.91 (dd, 1H, J¼17.6, 12.1
13
Hz), 3.12 (dd, 1H, J¼17.6, 5.5 Hz); C NMR (100 MHz, CD
3
OD, ppm) d¼159.1, 150.3,
1
47.3, 141.5, 132.1, 131.9, 127.8, 127.7, 127.4, 123.6, 121.2, 115.3, 112.1, 62.7, 43.3; HRMS
+
(
ESI-MS): calcd. for C21
H
19BrN
3
O
3
S [M + H] 472.0330; found 472.0317.
4
-[5-(4-Chlorophenyl)-3-(4-hydroxyphenyl)-4,5-dihydro-pyrazol-1-
yl]benzenesulfonamide (5)
2
6

0
1
M.p. 152–154 C. Yield: 62%. H NMR (400 MHz, CD3OD, ppm) d¼7.64 (d, 2H, J¼8.8
Hz), 7.63 (d, 2H, J¼8.8 Hz), 7.32 (d, 2H, J¼8.4 Hz), 7.26 (d, 2H, J¼8.4 Hz), 7.05 (d, 2H,
J¼9.2 Hz), 6.82 (d, 2H, J¼8.8 Hz), 5.45 (dd, 1H, J¼12.1, 5.5 Hz), 3.91 (dd, 1H, J¼17.2,
1
3
1
1
2.1 Hz), 3.12 (dd, 1H, J¼17.2, 5.5 Hz); C NMR (100 MHz, CD OD, ppm) d¼159.1, 150.3,
3
47.3, 141.0, 133.3, 131.9, 129.1, 127.8, 127.5, 127.4, 123.6, 115.3, 112.1, 62.6, 43.3; HRMS
+
(
ESI-MS): calcd. for C21
H
19
C
N
l 3
O
3
S [M + H] 428.0836; found 428.0824.
4
-[5-(4-Fluorophenyl)-3-(4-hydroxyphenyl)-4,5-dihydro-pyrazol-1-
yl]benzenesulfonamide (6)
0
1
M.p. 243–244 C. Yield: 72%. H NMR (400 MHz, CD3OD, ppm) d¼7.63 (d, 4H, J¼8.8
Hz), 7.30–7.26 (m, 2H), 7.07–7.03 (m, 4H), 6.82 (d, 2H, J¼8.8 Hz), 5.45 (dd, 1H, J¼12.1, 5.5
13
Hz), 3.90 (dd, 1H, J¼17.6, 12.1 Hz), 3.11 (dd, 1H, J¼17.6, 5.5 Hz); C NMR (100 MHz,
CD
3
OD, ppm) d¼159.1, 150.3, 147.4, 138.2, 131.8, 127.8, 127.7, 127.3, 123.7, 115.8, 115.6,
+
1
15.3, 112.1, 62.6, 43.5; HRMS (ESI-MS): calcd. for C21
found 412.1115.
-[3-(4-Hydroxyphenyl)-5-(4-nitrophenyl)-4,5-dihydro-pyrazol-1-yl]benzenesulfonamide
7)
H19FN
3
3
O S [M + H] 412.1131;
4
(
0
1
M.p. 173–176 C. Yield: 61%. H NMR (400 MHz, CD3OD, ppm) d¼8.20 (d, 2H, J¼8.8
Hz), 7.65 (d, 2H, J¼9.2 Hz), 7.64 (d, 2H, J¼8.8 Hz), 7.51 (d, 2H, J¼8.8 Hz), 7.05 (d, 2H,
J¼9.2 Hz), 6.82 (d, 2H, J¼8.8 Hz), 5.60 (dd, 1H, J¼12.1, 5.5 Hz), 3.97 (dd, 1H, J¼17.6,
1
3
1
1
2.1 Hz), 3.17 (dd, 1H, J¼17.6, 5.5 Hz); C NMR (100 MHz, CD OD, ppm) d¼159.2, 150.3,
3
49.5, 147.7, 147.2, 132.3, 127.9, 127.5, 127.1, 124.2, 123.4, 115.4, 112.1, 62.6, 43.1; HRMS
+
(
ESI-MS): calcd. for C21
H
18
N
4
O
5
S [M + H] 437.0920; found 437.0931.
2
7

2
8

Fig. S1. The absorption spectra of pyrazoline derivatives 2-7 in different solvents.
2
9