Synthesis, spectral studies and antimicrobial activities of some 2-naphthyl pyrazoline derivatives

Article abstract of DOI:10.1016/j.saa.2012.04.082

A series of 2-naphthyl pyrazolines were synthesized by the cyclization of 2-naphthyl chalcones and phenylhydrazine hydrochloride in the presence of sodium acetate. The yields of pyrazoline derivatives are more than 80%. The synthesized pyrazolines were characterized by their physical constants, IR, ¹H, ¹³C and MS spectra. From the IR and NMR spectra the CN (cm^-1) stretches, the pyrazoline ring proton chemical shifts (ppm) of δH_a, H_b and H_c and also the carbon chemical shifts (ppm) of δCN are correlated with Hammett substituent constants, F and R, and Swain-Lupton's parameters using single and multi-regression analyses. From the results of linear regression analysis, the effect of substituents on the group frequencies has been predicted. The antimicrobial activities of all synthesized pyrazolines have been studied.

Full text of DOI:10.1016/j.saa.2012.04.082

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 693–700
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Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Synthesis, spectral studies and antimicrobial activities of some 2-naphthyl
pyrazoline derivatives
S.P. Sakthinathan a, G. Vanangamudi a, G. Thirunarayanan b,
⇑
a PG & Research Department of Chemistry, Government Arts College, C-Mutlur 608102, Chidambaram, India
b Department of Chemistry, Annamalai University, Annamalainagar 608002, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of 2-naphthyl pyrazolines were synthesized by the cyclization of 2-naphthyl chalcones and phen-
ylhydrazine hydrochloride in the presence of sodium acetate. The yields of pyrazoline derivatives are
more than 80%. The synthesized pyrazolines were characterized by their physical constants, IR, 1H, 13C
and MS spectra. From the IR and NMR spectra the C@N (cmꢀ1) stretches, the pyrazoline ring proton
Received 3 February 2012
Received in revised form 13 April 2012
Accepted 18 April 2012
Available online 25 April 2012
chemical shifts (ppm) of dH , Hb and Hc and also the carbon chemical shifts (ppm) of dC@N are correlated
a
with Hammett substituent constants, F and R, and Swain–Lupton’s parameters using single and multi-
regression analyses. From the results of linear regression analysis, the effect of substituents on the group
frequencies has been predicted. The antimicrobial activities of all synthesized pyrazolines have been
studied.
Keywords:
2-Naphthyl pyrazolines
IR and NMR spectra
Hammett correlation
Antimicrobial activities
Ó 2012 Elsevier B.V. All rights reserved.
Introduction
the corresponding pyrazoline derivatives [11,12]. The reaction of
hydrazine and its derivatives with
,b-epoxy ketones is one of the preparative methods for the syn-
thesis of pyrazolines and pyrazoles [13]. Alternatively, the reaction
of substituted hydrazines with ,b-unsaturated ketones has been
reported to form regioselective pyrazolines [14]. The synthesis of
pyrazoline rings from chalcone derivatives containing anisole and
the 3,4-methylenedioxyphenyl ring by the conventional method
using acetic acid was reported with low yields [15]. Some 1-(4-
arylthiazol-2-yl)-3,5-diaryl-2-pyrazoline derivatives have been
synthesized by the reaction of 1-thiocarbamoyl-3,5-diaryl-2-pyr-
azoline derivatives with phenacetylbromide in ethanol. The struc-
tural elucidations of the compounds were performed by IR, 1HNMR
and mass spectral data and elemental analysis [16]. Semicarbazide
a,b-unsaturated ketones and
Pyrazoline refers to both the classes of simple aromatic ring or-
ganic compounds of the heterocyclic series characterized by a 5-
membered ring structure composed of three carbon atoms and
two nitrogen atoms in adjacent positions, and the unsubstituted
parent compound. So these compounds with pharmacological ef-
fects on humans, they are classified as alkaloid, although they are
rare in nature. Many pyrazolines show various pharmacological
properties [1]. Some pyrazoline derivatives are used as pesticides
[2], fungicides [3], antibacterial [4], antifungal [5], antiamoebic
[6], and antidepressant activity [7] and insecticides. Heterocyclic
of the type 3-hetaryl-1H-4,5-dihydropyrazoles arouse particular
interest because the properties determined by the pyrazoline
fragment are combined with the features of the corresponding het-
arene [7,8]. Therefore, it should be noted that 3-(4-hydroxy-3-cou-
marinyl)-1H-4,5-dihydropyrazoles are structural analogues of
3-substituted 4-hydroxy-coumarins some representatives of which
are effective blood anticoagulants. The pyrazoline function is quite
stable, and has inspired chemists to utilize the mentioned stable
fragment in bioactive moieties to synthesize new compounds pos-
sessing biological activity. Some related compounds were evalu-
ated for anticonvulsant activity [9]. The antidepressant activity of
these compounds was evaluated by the ‘‘Porsolt Behavioural Des-
a
a
(hydrochloride) and thiosemicarbazide on reaction with a,b-unsat-
urated ketones of the ferrocene series in excess of t-But-OK gave
1-carbamoyl and 1-thiocarbamoyl (ferrocenyl)-4,5-dihydropyraz-
oles. Ten new fluorine-containing 1-thiocarbamoyl-3,5-diphenyl-
2-pyrazolines have been synthesized in 80–85% yields by a
microwave-promoted solvent-free condensation of 2,4-dichloro-
5-fluoro chalcones with thiosemicarbazide over potassium carbon-
ate[17]. Nanoparticles of 1-phenyl-3-naphthyl-5-(dimethylamino
phenyl)-2-pyrazolines ranging from tens to hundreds of nanome-
tres have been prepared by the reprecipitation method [18]. Five
new 1,3,5-triphenyl-2-pyrazolines have been synthesized by
reacting 1,3-diphenyl-2-propene-1-one with phenylhydrazine
hydrochloride and another five new 3-(200-hydroxy naphthalen-
100-yl)-1,5-diphenyl-2-pyrazoline have been synthesized by
reacting 1-(20-hydroxylnaphthyl)-3-phenyl-2-propene-1-one with
pair Test’’ on Swiss-Webster mice [10]. The
a,b-unsaturated ke-
tones can play the role of versatile precursors in the synthesis of
⇑
Corresponding author. Tel.: +91 4144 220015.
E-mail address: drgtnarayanan@gmail.com (G. Thirunarayanan).
1386-1425/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.saa.2012.04.082

694
S.P. Sakthinathan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 693–700
Scheme 1. Synthesis of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines.
Table 1
Analytical and mass spectral data of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines.
Entry
X
Mol. formula
Mol. weight
Yield (%)
m.p. (°C)
Mass (m/z)
1
2
3
4
5
6
7
8
9
H
C25 H20N2
348
426
456
382
382
382
366
378
362
85
80
85
83
83
87
80
85
85
116–117
64–65
110–111
81–82
91–92
62–63
65–66
104–105
70–71
348[M+], 272, 271, 195, 181, 168, 167, 154, 147, 127, 77, 68, 41
426[M+], 428[M2+], 299, 271, 155, 154, 145, 127, 79, 77
3-Br
4-Br
2-Cl
3-Cl
4-Cl
4-F
C25 H19BrN2
C25 H19BrN2
C25 H19ClN2
C25 H19ClN2
C25 H19ClN2
C25 H19 FN2
C26 H21N2O
C26 H21N2
426[M+], 428[M2+], 299, 271, 194, 168, 154, 145, 127, 77
382[M+], 384[M2+], 347, 271, 195, 154, 111, 77, 68, 35
382[M+], 384[M2+], 346, 271, 197, 195, 154, 145, 77, 68, 43, 35
382[M+], 384[M2+], 345, 270, 197, 195, 155, 154, 145, 77, 68, 35, 28
366[M+], 368[M2+], 347, 289, 244, 239, 163, 155, 127, 122, 95, 77, 41, 28, 18
378[M+], 347, 301, 271, 251, 225, 145, 127, 107, 105, 91, 77, 31, 27
362[M+], 347, 285, 271, 257, 235, 195, 167, 165, 127, 91, 77, 28
2-OCH3
4-CH3
Table 2
IR and NMR spectral data of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines.
Entry
X
m
CN (cmꢀ1
)
dH (ppm)
dH (ppm)
dH (ppm)
dCN (ppm)
a
c
b
1
2
3
4
5
6
7
8
9
H
1671.38
1590.34
1677.78
1681.12
1683.12
1677.88
1678.88
1596.70
1681.12
3.286
3.254
3.253
3.187
3.248
3.243
3.253
3.252
3.256
3.954
3.960
3.955
4.082
3.962
3.963
3.953
3.906
3.935
5.333
5.290
5.303
5.705
5.278
5.316
5.319
5.294
5.304
153.01
169.77
153.14
159.07
152.81
153.16
153.10
159.07
153.26
3-Br
4-Br
2-Cl
3-Cl
4-Cl
4-F
2-OCH3
4-CH3
phenylhydrazine hydrochloride [19]. Also some new 1,3,5-tri-
phenyl-2-pyrazolines have been synthesized by reacting 1,3-di-
phenyl-2-propene-1-one with phenylhydrazine hydrochloride
and another five new 3-(200-hydroxy naphthalen-100-yl)-1,5-diphe-
nyl-2-pyrazoline have been synthesized by reacting 1-(20-hydrox-
ylnaphthyl)-3-phenyl-2-propene-1-one with phenylhydrazine
hydrochloride [20]. The effect of substituents on the group fre-
quencies have been studied, through UV–vis, IR, 1H and 13C NMR
spectra of ketones [21] unsaturated ketones [22–24], acid chlorides
[14] acyl bromides, and their esters [25]. The effect of substituents
on the infrared, proton and carbon-13 group frequencies of pyraz-
oline derivatives are not been studied so far. Hence the authors
have taken efforts to synthesise some 2-naphthyl pyrazoline deriv-
atives by cyclization of 2-naphthyl chalcones and phenylhydrazine
hydrochloride in the presence of anhydrous sodium acetate and to
study the spectral linearity and also the antimicrobial activities.
and are uncorrected. Infrared spectra (KBr, 4000–400 cmꢀ1) have
been recorded on BRUKER (Thermo Nicolet) Fourier transform
spectrophotometer. The NMR spectra of all pyrazolines have been
recorded on JEOL-400 spectrometer operating at 400 MHz for
recording 1H spectra and 100 MHz for 13C spectra in CDCl3 sol-
vent using TMS as internal standard. Mass spectra have been re-
corded on SHIMADZU spectrometer using chemical ionization
technique.
Synthesis of 2-naphthyl pyrazolines derivatives: [1-phenyl-3-(2-
naphthyl)-5-(substituted phenyl)-2-pyrazolines]
An appropriate equi-molar quantities of substituted styryl 2-
naphthyl ketones (0.20 mmol), phenylhydrazine hydrochloride
(0.20 mmol) and anhydrous sodium acetate (0.5 g) was refluxed
[26] in (15 mL) ethanol for 8 h (Scheme 1). The completion of the
reaction was monitored by TLC. The reaction mixture was cooled,
and poured into ice cold water. The precipitate was filtered, dried
and subjected to column chromatography using hexane and ethyl
acetate (3:1) as eluent. The analytical and mass spectral data are
presented in Table 1. The IR and NMR spectral data are given in
Table 2.
Experimental
All chemicals used were procured from Sigma–Aldrich and E-
Merck. Melting points of all pyrazoles have been determined in
open glass capillaries on Mettler FP51 melting point apparatus

S.P. Sakthinathan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 693–700
695
Table 3
Results of statistical analysis of IR and NMR spectral data of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines with Hammett substituent constants
r
,
r+
,
rI,
rR and F
and R parameters.
Frequency
Constants
r
I
q
s
n
Correlated derivatives
H, 3-Br, 2-Cl, 3-Cl, 4-Cl, 4-F, 2-OCH3, 4-CH3
mCN (cmꢀ1
)
r
0.901
0.900
0.800
0.810
0.871
0.819
1656.50
1657.14
1662.21
1680.68
1649.93
1898.95
29.537
23.092
7.971
8.164
8.329
9.321
3.91
3.90
3.90
3.20
3.01
3.00
8
8
9
9
9
9
r+
rI
rR
F
H, 3-Br, 4-Br, 2-Cl, 3-Cl, 4-Cl, 4-F, 2-OCH3, 4-CH3
R
dH (ppm)
r
0.801
0.821
0.791
0.851
0.842
0.815
3.255
3.654
3.251
3.268
3.512
3.812
2.251
2.092
7.978
8.166
8.264
9.002
3.91
6.90
6.98
10.23
9.23
8.36
9
9
9
9
9
9
H, 3-Br, 4-Br, 2-Cl, 3-Cl, 4-Cl, 4-F, 2-OCH3, 4-CH3
a
r+
rI
rR
F
R
dH (ppm)
r
r
rI
rR
F
0.904
0.913
0.803
0.851
0.862
0.880
3.954
3.954
3.937
3.268
3.262
3.541
0.089
0.917
0.077
8.166
8.021
9.922
0.31
0.89
0.73
10.23
10.03
9.96
8
6
9
9
9
9
H, 3-Br, 4-Br, 3-Cl, 4-Cl, 4-F, 2-OCH3, 4-CH3
H, 2-Cl, 4-Cl, 4-F, 2-OCH3, 4-CH3
H, 3-Br, 4-Br, 2-Cl, 3-Cl, 4-Cl, 4-F, 2-OCH3, 4-CH3
b
+
R
dH (ppm)
r
r
rI
rR
F
0.811
0.831
0.817
0.802
0.871
0.808
5.343
5.335
5.331
5.351
5.921
5.624
6.123
1.131
2.102
3.201
4.021
5.027
1.40
1.32
1.52
1.41
2.03
2.30
9
9
9
9
9
9
H, 3-Br, 4-Br, 2-Cl, 3-Cl, 4-Cl, 4-F, 2-OCH3, 4-CH3
c
+
R
dCN (ppm)
r
0.902
0.822
0.722
0.818
0.881
0.821
155.79
155.96
154.40
154.92
156.34
159.32
4.568
3.826
5.372
5.611
4.521
5.116
0.57
0.86
0.88
0.95
1.02
1.11
7
9
9
9
9
9
H, 3-Br, 4-Br, 2-Cl, 4-Cl, 4-F, 4-CH3
H, 3-Br, 4-Br, 2-Cl, 3-Cl, 4-Cl, 4-F, 2-OCH3, 4-CH3
r+
rI
rR
F
R
r, correlation co-efficient; I, intercept; q, slope; s, standard deviation; n, number of substituents.
single parameter correlation are shown in Table 3. The correlation
of
C@N (cmꢀ1) frequencies of pyrazolines with Hammett and r+
substituent constants is found to be satisfactory. All correlations
produce positive values. This implies that there is a normal sub-
stituent effect operates in all systems. The Hammett I and R con-
m
r
q
r
r
stants fail in correlation. This is due to the absence of inductive and
resonance effects of the substituent and is associated with the con-
jugated structure shown in (Fig. 1). In short some of the single
N
N
H
H
C
parameter correlations of m
C@N (cmꢀ1) frequencies with Hammett
H
H+
substituent constants of resonance and inductive effects fail. So,
the authors think that it is worthwhile to seek the multi regression
analysis and which produce a satisfactory correlation with reso-
nance, field and Swain–Lupoton’s [27] constants. The correspond-
ing equations are given in (2) and (3).
Ha
Hb
Fig. 1. The resonance conjugative structure.
mCN ðcmꢀ1Þ ¼ 1673:93ðꢁ26:670Þ þ 29:957rIðꢁ0:694Þ
þ 104:181rRðꢁ8:148Þ
Results and discussion
IR spectral study
ðR ¼ 0:916; P > 90%; n ¼ 9Þ
ð2Þ
The synthesized 2-naphthyl pyrazoline derivatives are shown in
Scheme 1.The infrared C@N stretching frequencies (cmꢀ1) of these
pyrazolines have been recorded and are presented in Table 2. These
data are correlated with Hammett substituent constants and
Swain–Lupoton’s [27] parameters. In this correlation the structure
parameter Hammett equation employed is as shown in Eq. (1).
mCN ðcmꢀ1Þ ¼ 1669:21ðꢁ26:617Þ þ 44:895Fðꢁ7:681Þ
þ 96:718Rðꢁ9:194Þ ðR ¼ 0:939; P > 90%; n ¼ 9Þ
ð3Þ
1H NMR spectral study
The 1H NMR spectra of nine pyrazoline derivatives under inves-
tigation have been recorded in deuteriochloroform solution
employing tetramethylsilane (TMS) as internal standard. The sig-
nals of the pyrazoline ring protons have been assigned. They have
been calculated as AB or AA0 systems, respectively. The chemical
shifts (ppm) of Ha are at higher fields than those of Hb and Hc in
this series of pyrazolines. This is due to the deshielding of Hb and
m
¼
q
r
þ
mo
ð1Þ
where mo is the frequency for the parent member of the series.
The observed
C@N stretching frequencies (cmꢀ1) are corre-
lated with various Hammett substituent constants and F and R
parameters through single and multi-regression analyses including
Swain–Lupoton’s parameters. The results of statistical analysis of
m

696
S.P. Sakthinathan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 693–700
PLATE-1
PLATE-2
PLATE-3
PLATE-5
PLATE-4
PLATE-6
PLATE-7
PLATE-9
PLATE-8
PLATE-10
Fig. 2. Antibacterial activities of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines.

S.P. Sakthinathan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 693–700
697
Table 4
Antibacterial activities of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines.
S. No.
Compound
X
Zone of Inhibition (mm)
Gram positive bacteria
Gram negative bacteria
B. subtilis
M. luteus
S. aureus
E. coli
K. pneumoniae
1
2
3
4
5
6
7
8
9
K1
K2
K3
K4
K5
K6
K7
K8
H
3-Br
4-Br
2-Cl
3-Cl
4-Cl
4-F
2-OCH3
4-CH3
Ampicillin
DMSO
–
–
8
8
7
8
9
–
6
20
–
7
7
8
8
7
7
7
–
–
18
–
8
7
7
8
8
–
6
6
–
18
–
6
6
7
7
6
10
9
10
12
18
–
7
8
7
8
–
7
7
7
7
12
–
K9
Standard
Control
Fig. 3. Clustered column chart of antibacterial activities of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines.
Hc which are in different chemical as well as magnetic environ-
ment. These Ha protons gave an AB pattern and the Hb proton dou-
blet of doublet in most cases was well separated from the signals
Hc and the aromatic protons. The assigned chemical shifts (ppm)
of the pyrazoline ring Ha, Hb and Hc protons are presented in Table
2.
The results of statistical analysis of Hb proton chemical shifts
(ppm) with Hammett substituents are shown in Table 3. The Hb
proton chemical shifts with Hammett
satisfactory correlation excluding 2-Cl, 3-Cl, 3-Br and 4-Br sub-
stituents. The rI and rR constants fail in correlation. This is
due to the absence of inductive and resonance effect of substit-
uents and it is associated with the conjugative structure shown
in Fig. 1.
r
and r+ constants give
In nuclear magnetic resonance spectra, the 1H or the 13C chem-
ical shifts (d) (ppm) depend on the electronic environment of the
nuclei concerned. These chemical shifts have been correlated with
reactivity parameters. Thus the Hammett equation may be used in
the form as shown in (4).
The results of statistical analysis of Hc proton chemical shifts
(ppm) with Hammett substituents are presented in Table 3. The
Hc proton chemical shifts with Hammett
r constants and F and R
parameters fail in correlation. All correlations produce positive
q
Logd ¼ Logd0 þ
q
r
ð4Þ
values. This means that the normal substituent effect operates in
all systems. This failure in correlation is associated with conjuga-
tive structure shown in Fig. 1.
where d0 is the chemical shift of the corresponding parent
compound.
In view of the inability of the Hammett
individually satisfactory correlation, the authors think that it is
worthwhile to seek multiple correlations involving either I andrR
r constants to produce
The assigned Ha, Hb and Hc proton chemical shifts (ppm) of pyr-
azoline ring have been correlated with various Hammett sigma
constants. The results of statistical analysis are presented in Table
3.The Ha proton chemical shifts (ppm) with Hammett substituent
constants and F and R parameters fail in correlation. All correla-
r
constants or Swain–Lupton’s [27] F and R parameters. The correla-
tion equations for Ha–Hc protons are given in (5)–(10).
dðHppmÞ ¼ 3:268ðꢁ0:018Þ þ 0:059ðꢁ0:004ÞrI þ 0:184ðꢁ0:005ÞrR
tions give positive
effect operates in all systems. The failure in correlation is associ-
ated with the conjugative structure shown in Fig. 1.
q values. This shows that the normal substituent
a
ðR ¼ 0:905; P > 90% n ¼ 9Þ
ð5Þ

698
S.P. Sakthinathan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 693–700
PLATE-1
PLATE-2
PLATE-3
PLATE-4
Fig. 4. Antifungal activity of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines.
13C NMR spectra
Table 5
Antifungal
pyrazolines.
activities
of
1-phenyl-3-(2-naphthyl)-5-(substituted
phenyl)-2-
Organic chemists and researchers [25,28,29]have made exten-
sive study of 13C NMR spectra for a large number of different ke-
tones, styrenes and keto-epoxides. They have studied linear
S. No.
Compound
X
Zone of Inhibition (mm)
A. niger
T. viride
correlation of the chemical shifts (ppm) of C , Cb and CO carbons
a
with Hammett
r constants in alkenes, alkynes, acid chlorides and
1
2
3
4
5
6
7
8
9
K1
K2
K3
K4
K5
K6
K7
K8
H
3-Br
4-Br
2-Cl
3-Cl
4-Cl
4-F
2-OCH3
4-CH3
Miconazole
DMSO
–
–
–
–
–
9
9
8
8
14
–
7
8
8
10
10
–
7
–
styrenes. In the present study, the chemical shifts (ppm) of pyraz-
oline ring C@N carbon, have been assigned and are presented in
Table 1. Attempts have been made to correlate the dC@N chemi-
cal shifts (ppm) with Hammett substituent constants, field and
resonance parameters, with the help of single and multi-regres-
sion analyses to study the reactivity through the effect of
substituents.
The chemical shifts (ppm) observed for the dC@N have been
correlated with Hammett constants and the results of statistical
analysis are presented in Table 3. The dC@N chemical shifts
K9
Standard
Control
–
16
–
(ppm) give satisfactory correlation with Hammett
r constants ex-
dðHppmÞ ¼ 3:261ðꢁ0:018Þ þ 0:049ðꢁ0:003ÞF þ 0:158ðꢁ0:006ÞR
cept 3-Cl and 2-OCH3 substituents. When these are included in the
correlation they reduce the correlation co-efficient considerably.
a
ðR ¼ 0:908; P > 90% n ¼ 9Þ
ð6Þ
The remaining Hammett r+
, rI, rR, F and R parameters fail in cor-
relation. This is due to the reason stated earlier with resonance
conjugative structure shown in Fig. 1.
dðHppmÞ ¼ 3:954ðꢁ0:033Þ þ 0:1159ðꢁ0:008ÞrI þ 0:111ðꢁ0:001ÞrR
b
In view of inability of some of the
vidually satisfactory correlation, the authors think that it is
worthwhile to seek multiple correlation involving all rI R, F
r constants to produce indi-
ðR ¼ 0:951; P > 95%; n ¼ 9Þ
ð7Þ
,
r
dðHppmÞ ¼ 3:960ðꢁ0:031Þ þ 0:122ðꢁ0:009ÞF þ 0:158ðꢁ0:001ÞR
b
and R parameters. The correlation equations are given in (11)
and (12).
ðR ¼ 0:950; P > 95%; n ¼ 9Þ
ð8Þ
ð9Þ
dðHppmÞ ¼ 5:319ðꢁ0:105Þ þ 1:135ðꢁ0:027ÞrI þ 0:621ðꢁ0:003ÞrR
ðppmÞ
d
¼ 154:008ðꢁ4:452Þ þ 4:07ðꢁ1:150ÞrI þ 3:565ðꢁ0:100ÞrR
c
CN
ðR ¼ 0:901; P > 90%; n ¼ 9Þ
ðR ¼ 0:922; P > 90%; n ¼ 9Þ
ð11Þ
dðppmÞ ¼ 5:319ðꢁ0:105Þ þ 0:121Fðꢁ0:002Þ þ 0:154ðꢁ0:003ÞR
ðppmÞ
Hc
d
¼ 154:995ðꢁ4:361Þ þ 3:401ðꢁ1:025ÞF þ 2:205ðꢁ0:054ÞR
CN
ðR ¼ 0:900; P > 90%; n ¼ 9Þ
ð10Þ
ðR ¼ 0:914; P > 90%; n ¼ 9Þ
ð12Þ

S.P. Sakthinathan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 693–700
699
Fig. 5. Clustered column chart of antifungal activities of 1-phenyl-3-(2-naphthyl)-5-(substituted phenyl)-2-pyrazolines.
Microbial activities
The antifungal activity of substituted pyrazoline synthesized in
the present study are shown in Fig. 4 for plates (1–4) and the zone
of inhibition values of the effect is given in Table 5. The clustered
column chart, shown in Fig. 5 reveals that all the compounds K6,
K7, K8, K9 have moderate antifungal activity against Aspergillus ni-
ger and K2, K3, K4, K5 have good antifungal activity against Tricho-
derma viride. The pyrazoline with 3-Cl, 4-Cl and 4-F, substituents
have shown greater antifungal activity than those with the other
substituents present in the series.
Pyrazoline derivatives possess a wide range of biological activ-
ities [2,4,6,8–10,29–31]. These multipronged activities are associ-
ated with different pyrazoline rings. Hence, it is intended to
examine their activities against respective microbes-bacteria’s.
Antibacterial sensitivity assay
The antibacterial screening effect of synthesized pyrazoline is
shown in Fig. 2 (plates 1–10). The antibacterial activities of all
the synthesized pyrazolines have been studied against three gram
positive pathogenic strains Micrococcous luteus, Bacillus substilis
Staphylococcus aureus and two gram negative strains Escherichia
coli and Klebsiella species. The disc diffusion technique was followed
Acknowledgement
The authors thank to SAIF, IIT Chennai-600036 for recording
NMR spectra of all compounds.
using the Kirby–Bauer [32]method, at a concentration of 250 lg/
mL with Ampicillin taken as the standard drug. The measured zone
of inhibition is shown in Table 4 and the clustered column chart is
shown in Fig. 3. All the compounds showed moderate to high activ-
ity against S. aureus, E. coli and Klebsiella. While weak to moderate
activity was observed against M. luteus and B. substilis. The com-
pounds K6, K7, K8 and K9 were high activity against E. coli and B.
substilis. The compounds K3 and K4 were highly activity against
M. luteus. K1, K2 and K5 were highly active against S. aureus,
whereas compounds K1, K2, K7, K8 and K9 were moderately active
against B. substilis, S. aureus and E. coli. The rest of the compounds
displayed weak activity against all the microorganisms. However
the activities of the test compounds are less than that of standard
antibacterial agent used.
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