New trifluoromethyl-containing (E)-N′-arylidene-[3-alkyl(aryl/ heteroaryl)-4,5-dihydro-1H-pyrazol-1-yl]carbohydrazides: Synthesis, crystal structure and antimicrobial/antioxidant activity

Article abstract of DOI:10.1016/j.jfluchem.2011.12.010

A new series of twenty-one trifluoromethyl-containing (E)-N′- arylidene-1H-pyrazole-1-carbohydrazides (4) was synthesized by the cyclocondensation reactions of six 3-alkyl(aryl/heteroaryl)-5-trifluoromethyl-5- hydroxy-4,5-dihydro-1H-pyrazole-1-carbohydraz

Full text of DOI:10.1016/j.jfluchem.2011.12.010

Journal of Fluorine Chemistry 135 (2012) 303–314
Contents lists available at SciVerse ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
New trifluoromethyl-containing (E)-N0-arylidene-[3-alkyl(aryl/heteroaryl)-4,5-
dihydro-1H-pyrazol-1-yl]carbohydrazides: Synthesis, crystal structure and
antimicrobial/antioxidant activity
a
a
a
a
Helio G. Bonacorso a, , Susiane Cavinatto , Patrick T. Campos , Liliane M.F. Porte , Jussara Navarini ,
*
Gisele R. Paim a, Marcos A.P. Martins a, Nilo Zanatta a, Caroline Z. Stuker b
a Nu´cleo de Quı´mica de Heterociclos – NUQUIMHE, Departamento de Quı´mica, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil
b
´
´
Nucleo de Pesquisas de Produtos Naturais – NPPN, Departamento de Quımica, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil
A R T I C L E I N F O
A B S T R A C T
A new series of twenty-one trifluoromethyl-containing (E)-N0-arylidene-1H-pyrazole-1-carbohydra-
zides (4) was synthesized by the cyclocondensation reactions of six 3-alkyl(aryl/heteroaryl)-5-
trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazole-1-carbohydrazides (2) with eleven aryl/hetero-
aryl aldehydes and acetophenone (3) in 52–97% yields and six new carbohydrazides 2 were easily
obtained from the reaction of 1,1,1-trifluoro-4-alkyl(aryl/heteroaryl)-4-methoxy-3-alken-2-ones (1)
with carbohydrazide. Subsequently, four examples of carbohydrazides 4 were fully studied by X-ray
diffraction and the twenty-seven pyrazolyl-carbohydrazides 2 and 4 screened for their antioxidant and
antimicrobial proprieties and evaluated by DPPH and MIC methods, respectively. Both series 2 and 4
Article history:
Received 3 November 2011
Received in revised form 13 December 2011
Accepted 19 December 2011
Available online 26 December 2011
Keywords:
Pyrazoles
Semicarbazones
X-ray
showed ability to capture DPPH free radical for IC50 from 47.57 to 487
mg/mL. Most of the compounds
presented fungistatic and bacteriostatic activity only for high MIC levels ranging from 0.25 mg/mL to
Carbohydrazides
DPPH activity
Antimicrobial activity
MIC
0.5 mg/mL.
ß 2011 Elsevier B.V. All rights reserved.
1. Introduction
1H-pyrazoles and derivatives are known to exhibit important
biological activities in medicinal and agricultural scientific fields
Convenient synthetic routes to aromatic heterocycles have been of
ongoing interest. Especially desirable are methods of placing fluorine
selectively on heterocycle moieties since these derivatives often
exhibit bioactivity [1]. Fluorocarbon systems, with minor exceptions,
do not occur in nature and, in general, present no peculiar handling
difficulties; e.g. the familiar and powerful techniques of isolation,
purification, and identification are applicable in similar ways to those
for corresponding hydrocarbon systems. However, because fluorine is
unique in that it can replace hydrogen in a wide range of hydrocarbon
systems without gross distortion of the geometry of the system and
because the difference between hydrogen and fluorine creates
entirely different electronic environments for functional groups in
the fluorocarbon system, new fluorinated compounds become
available with reactions and properties quite different from their
hydrocarbon analogues [2]. Moreover, many trifluoromethylated
[3]. Therefore, much attention has been paid to the development of
new methods for the synthesis of fluorine containing pyrazoles.
Another class of relevance is the semicarbazones, which are of
considerable pharmacological interest since a number of deriva-
tives has shown a broad spectrum of chemotherapeutic properties
[4]. Also, they are associated with diverse pharmacological
activities, such as antibacterial and antifungal, antihypertensive,
hypolipidemic, antineoplasic, hypnotic and anticonvulsant [5].
Thus, in an effort to synthesize new fluorinated 1H-pyrazoles
containing a fluorinated fragment as well as the semicarbazone
moiety in their structures, the aim of this work is to synthesize, to
study the new structures via X-ray diffraction and to evaluate the
antioxidant and antimicrobial activity of a series of six pyrazo-
lylcarbohydrazides and twenty-one new semicarbazones (Scheme
1). These new heterocyclic systems are of interest principally for
antioxidant properties due to the presence of a conjugated
p-
system. Some similar molecules might be important in preventing
the treatment of diseases related to the imbalance between
formation and detoxification [6].
* Corresponding author. Tel.: +55 55 3220 8756; fax: +55 55 3220 8756.
E-mail address: heliogb@base.ufsm.br (H.G. Bonacorso).
0022-1139/$ – see front matter ß 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2011.12.010

304
H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
2. Results and discussion
2.1. Synthesis and structure
reactions, there was a remain of aldehyde which could not be
removed by extraction or distillation.
The structures of all compounds 2 were determined by 1H, 13
C
NMR and by comparison with data of other compounds previously
synthesized [9]. The structures of new semicarbazones (4) were
deduced from NMR experiments, X-ray diffraction studies and by
comparison based on the interpretation of literature data [8].
Compounds 4 showed the 1H NMR chemical shifts of the
diastereotopic methylene protons (H4) as a characteristic AB
A review of the literature [7,8] shows that the methodologies
that have been used until now, though efficient for the synthesis of
similar compounds such 2 and 4, require drastic conditions and
long reaction times, which vary from 12 h to 4 days, involving
several reactions steps with yields from 20% to 50%. Therefore, it
was developed a simple method, where it is possible to obtain new
trifluoromethyl-containing semicarbazones (4), in good yields. The
present method in general allows the convenient synthesis of a
series of ligands in which the substituents at the position 3 (R1) of
the 5-trifluoromethyl-5-hydroxy-2-pyrazoline ring and two sub-
stituents (R2, R3) of the semicarbazone moiety can be varied.
Based on the literature data previously described by us [9], the
reactions of 1,1,1-trifluoro-4-alkyl(aryl/heteroaryl)-4-methoxy-3-
alken-2-ones (1a–f) [10] with carbohydrazide to obtain the
pyrazolyl-carbohydrazide system (2) were carried out in a 1:1
molar ratio, in ethanol as solvent at 0–50 8C, for 4 h with yields of
44–86%. Herein, in a reinvestigation we found that better results
were obtained when the reactions were performed under room
temperature for 18–20 h with chromatographic accompaniment
(TLC), followed by a simple filtration and evaporation of the
residual solvent under reduced pressure after the reaction time.
The known products 2a–b, 2d–e and the new carbohydrazides 2c
(R1 = p-tolyl) and 2f (R1 = 1-naphthyl) were obtained as pure and
stable solids in better yields (62–92%).
Subsequently, the reactions of 3-alkyl(aryl/heteroaryl)-5-tri-
fluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazolyl-1-carbohy-
drazides (2a–f), with the respective aldehydes 3a–j or
acetophenone 3k were carried out in 1:1 molar ratio in ethanol
and the reactions were also monitored by TLC. The first results for
aldehyde derivative 3a were obtained when the reactions were
carried out at 60 8C for 7 h using 1–2 drops of 37% concentrated
hydrochloric acid as catalyst (82% yield). The optimal condition to
isolate the 4aa (93% yield) was accessed when the reaction was
performed by the same time, solvent and temperature but without
the concentrated HCl catalyst.
system with a doublet in average at
3.41 ppm, respectively with a geminal coupling constant in
average at 19 Hz. The hydroxy protons are shown in the 1H spectra
in average at 7.82 ppm. Moreover, NH shows signs in the range of
10.39 ppm and the protons for the arylidene moiety R2CH55N0N in
average of 8.64 ppm. Compounds 4 present the typical 13C
chemical shifts of the pyrazoline ring at 148.1 ppm (C3) and
45.85 ppm (C4). C5 presents a characteristic quartet at 91.25 ppm
with JCF = 34 Hz due to the attached CF3 group. The CF3 group
d 3.78 and the other doublet at
d
d
d
d
d
d
2
1
shows a typical quartet at
carbonyl carbon showed signal around of
d
122.9 ppm with JCF = 285 Hz. The
151 ppm. The arylidene
d
substituents show signs for the non-aromatic carbon
(R2HC55N0NH–) in average of 146.7 ppm and (R2CH3C55N0NH–)
of 149.4 ppm.
In parallel, for a full structural elucidation, the X-ray diffraction
measurements were carried out for the compounds 4aa, 4ae, 4af
and 4df.
These four compounds are constituted by the 4,5-dihydro-1H-
pyrazole ring with a hydroxy and a trifluorometyl group in
position-5 and still a phenylsemicarbazone group present in
position-1 (Fig. 1). Also, these 2-pyrazolines crystallized in
monoclinic system and space group P21/n for 4aa, P21/c (4af and
4ae) and P(1) for 4df. The overall view and labeling of the molecule
are displayed in Figs. 2 and 3. The lengths and angles of the
compounds are showed in Table 1.
For each molecule, the five-membered ring showed r.m.s.
˚
deviations from the plane of 0.0278, 0.0122, 0.0946 and 0.1006 A
and the torsion angle of N(2)–N(1)–C(11)–O(12)– are 159.67(18),
158.3(2), 179.7(3) and ꢀ179.09(16)8 for compounds 4aa, 4af, 4df
and 4ae, respectively. The geometry of the 1-carbonyl-4,5-dihydro-
1H-pyrazole system is similar to that reported in the literature [11].
Also, the fragment [O(12)55C(11)–N(12)–N(13)55C(14)] showed a
r.m.s. deviations from the plane of 0.0422, 0.0484, 0.0430 and
In order to test a possible solvent-free reaction condition, we
carried out reactions using pure liquid aldehydes as solvent.
However, a lot of starting material (2) was observed by 1H NMR
spectrum probably due to the difficulty of homogenization of the
reagents. When the amount of aldehydes was added to the
˚
0.0189 A for compounds 4aa, 4af, 4df and 4ae, respectively and the
geometry of the phenylsemicarbazone system is similar to that
R3
R2
F3C
F3C
OH
OH
O
OMe
NHNH2
O
HN
O
N
R2R3C(O) 3a-k, ii
i
N
N
52 - 97 %
F3C
R1
62-92%
N
N
R1
R1
4aa-fe (R1/R2R3)
1a-f
2a-f
(21 examples)
i = (NH2NH)2CO, EtOH, 18 - 20 h, r.t.; ii = EtOH, 7 h, 60ºC
1,2,4
a
b
c
d
e
f
R1 Me Ph 4-MePh 2-Furyl 2-Thienyl 1-Naphthyl
3,4
a
b
c
d
e
f
g
h
i
j
k
R2 Ph 3-NO2Ph 4-NO2Ph 2-BrPh 4-ClPh 4-Tolyl 4-OMePh 1,3-Benzodioxol-5-yl 1-Naphthyl 2-Furyl Ph
R3
H
H
H
H
H
H
H
H
H
H
Me
Scheme 1.

H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
305
Fig. 1. Planar structures of (E)-N0-Benzylidene-(5-trifluoromethyl-5-hydroxy-3-methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4aa), (E)-N0-(4-Methylbenzylidene)-
(5-trifluoromethyl-5-hydroxy-3-methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4af), (E)-N0-(4-Methylbenzylidene)-[5-trifluoromethyl-3-(2-furyl)-5-hydroxy-4,5-
dihydro-1H-pyrazol-1-yl]carbohydrazide (4df) and (E)-N0-(4-Chlorobenzylidene)-(5-trifluoromethyl-5-hydroxy-3-methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide
(4ae).
reported in the literature [12]. The least square plane angle between
the fragment [O(12)55C(11)–N(12)–N(13)55C(14)] and the pyrazole
ring showed values of 18.71(5), 24.27(14), 9.26(26) and 13.56(12)8
for 4aa, 4af, 4df and 4ae respectively. Moreover, the least square
plane angle between the fragment [O(12)55C(11)–N(12)–
N(13)55C(14)] and the phenyl ring showed values of 8.28(9),
39.88(9), 21.77(24) and 9.61(11)8 for 4aa, 4af, 4df and 4ae
respectively. The values referred to 4aa, 4af, 4df and 4ae release
that the pyrazole ring, the fragment O(12)55C(11)–N(12)–
N(13)55C(14) and phenyl ring are close to the same plane. All this
planarity may be associated to a small electronic resonance
involving the pyrazole ring, the fragment O(12)55C(11)–N(12)–
N(13)55C(14) and phenyl ring.
These patterns generated pseudo six membered rings geminated
to pyrazole ring (Fig. 4), similar to other 4,5-dihydro-1H-pyrazole
derivatives already reported in the literature [13]. Still in
compound 4aa was found an intramolecular hydrogen bond
˚
O(101)–H(101)ꢁ ꢁ ꢁO(62) with interatomic distance of 2.666(2) A for
O(101)ꢁ ꢁ ꢁO(62) with a second independent molecule presents in
the asymmetric unit of these compound.
The crystalline structures of compounds are stabilized by
intermolecular hydrogen bond (Table 2) determining the crystal-
line packing type. Hydrogen bonds containing highly electronega-
tive atoms in both donor and acceptor groups in systems such as
N–Hꢁ ꢁ ꢁO and O–Hꢁ ꢁ ꢁO showed dominant electrostatic character
and have been considered strong interactions [14], which will be
discussed in this work. On the other hand, in C–Hꢁ ꢁ ꢁO or C–Hꢁ ꢁ ꢁN
gradually decreases the electrostatic character while the disper-
sion character increases, making the weak hydrogen bonding [14],
which are also present in the crystal packing of compounds, but it
The presence of intramolecular hydrogen bonds O(51)–
H(51)ꢁ ꢁ ꢁO(61) were shown to stabilize the position of the carbonyl
group in molecules 4aa and 4af with interatomic distance of
´
˚
2.729(2) and 2.697(3) A for O(51)ꢁ ꢁ ꢁO(61), respectively (Table 2).
Fig. 2. View of the asymmetric unit of the compounds 4aa and 4af, showing the atom labeling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms
are represented by circles of arbitrary radii.

306
H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
Fig. 3. View of the asymmetric unit of the compounds 4df and 4ae, showing the atom labeling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms
are represented by circles of arbitrary radii.
will not be discussed in detail. These interactions occur when
donor groups or acceptor protons have low electronegativity.
For the four compounds the crystal packing occurred in the
form of infinite chains along of the plane. For compound 4aa the
infinites chains were formed (Fig. 4) through the intermolecular
hydrogen bonds N(62)–H(62)ꢁ ꢁ ꢁO(12) and N(12)–H(12)ꢁ ꢁ ꢁO(62)
respectively, involving two independent molecules. For compound
4af (Fig. 4), appears only the intermolecular hydrogen bond N(12)–
´
˚
H(12)ꢁ ꢁ ꢁO(12) with interatomic distances of 2.943(3) A for
N(12)ꢁ ꢁ ꢁO(12) (x, ꢀy + 1/2, z + 1/2). Although compound 4aa has
two independent molecules in the asymmetric unit of the crystal
packing, it occurred in the same way that the two compounds
involving the same atoms in hydrogen bonding. This observation
shows that the presence of the methyl group in the benzene ring
does not cause a molecular change in 4af, which would be able to
alter the proton acceptor or donor in a strong hydrogen bond
N(12)H(12)ꢁ ꢁ ꢁO(12).
´
˚
with interatomic distances of the 2.883(2) and 2.966(2) A,
Table 1
˚
Bond lengths [A] and angles [8] for compounds 4.
Compounds
4aa
1.407(2)
4af
1.399(3)
4df
1.401(4)
4ae
1.409(2)
On the other hand, for 4df and 4ae (Fig. 5) the crystalline
packing occurred through intermolecular hydrogen bond O(51)–
N(1)–N(2)
C(3)–N(2)
1.273(3)
1.499(3)
1.276(3)
1.492(4)
1.523(3)
1.462(3)
1.395(3)
1.523(4)
1.484(3)
1.383(3)
1.230(3)
1.336(3)
1.378(3)
1.281(3)
1.458(4)
1.285(4)
1.490(5)
1.535(4)
1.462(4)
1.412(4)
1.518(6)
1.441(5)
1.377(4)
1.218(4)
1.341(5)
1.379(3)
1.267(5)
1.456(5)
1.272(2)
1.493(2)
˚
H(51)ꢁ ꢁ ꢁO(12) with interatomic distance of 2.882(4) A for
C(4)–C(3)
˚
O(51)ꢁ ꢁ ꢁO(12) (x + 1, y, z) in 4df and of 2.6475(18) A for
C(4)–C(5)
1.530(3)
1.534(2)
O(51)ꢁ ꢁ ꢁO(12) (ꢀx + 3, y ꢀ 1/2, ꢀz ꢀ 1/2) in 4ae. We have described
the interaction between the same hydroxyl and carbonyl groups in
1-carbonyl-5-hydroxy-4,5-dihydropyrazoles, but leading to for-
mation of supramolecular dimers [13]. Moreover, it was observed
in 4ae a hydrogen bond [O(1)–H(1B)ꢁ ꢁ ꢁO(51)] involving a water
C(5)–N(1)
1.463(3)
1.476(2)
C(5)–O(51)
1.388(2)
1.395(2)
C(51)–C(5)
1.517(3)
1.530(2)
C(31)–C(3)
1.490(3)
1.486(3)
N(1)–C(11)
1.368(2)
1.379(2)
O(12)–C(11)
1.232(2)
1.222(2)
˚
N(12)–C(11)
1.348(3)
1.353(2)
molecule with interatomic distance of 2.908(2) A for O(1)ꢁ ꢁ ꢁO(51)
N(12)–N(13)
1.372(2)
1.377(2)
(ꢀx + 3, y ꢀ 1/2, ꢀz ꢀ 1/2). Now, the presence of a bulky group
(furan) in position-3 of the pyrazole ring in compound 4df and the
presence of a water molecule in the asymmetric unit in the
structure 4ae were able to alter the proton donor in the strong
hydrogen bonding in the crystal packing of these structures, being
the hydroxyl O(51) interacting with carbonyl proton acceptor
O(12). Whole interatomic distance showed to be less than the sum
of Van der Waals radii of the acceptors and donors (Dꢁ ꢁ ꢁA) atoms of
proton involved in the interaction [15].
N(13)–C(14)
1.272(3)
1.272(2)
C(141)–C(14)
C(3)–N(2)–N(1)
N(2)–C(3)–C(4)
C(3)–C(4)–C(5)
N(1)–C(5)–C(4)
N(2)–N(1)–C(5)
N(2)–C(3)–C(31)
N(1)–C(5)–C(51)
O(51)–C(5)–N(1)
O(51)–C(5)–C(51)
C(11)–N(1)–N(2)
O(12)–C(11)–N(1)
N(12)–C(11)–N(1)
O(12)–C(11)–N(12)
C(11)–N(12)–N(13)
C(14)–N(13)–N(12)
N(13)–C(14)–C(141)
1.457(3)
1.461(2)
107.28(16)
114.81(17)
102.72(17)
101.57(15)
113.21(15)
121.6(2)
107.9(2)
107.1(3)
107.94(14)
113.63(15)
102.23(14)
99.91(13)
110.92(13)
122.05(17)
113.90(14)
113.39(14)
105.16(14)
117.87(14)
120.56(16)
114.64(15)
124.78(16)
118.13(15)
115.66(15)
121.35(17)
114.3(2)
103.0(2)
101.97(18)
112.77(18)
121.9(2)
108.5(2)
114.3(2)
109.2(2)
119.5(2)
120.9(2)
114.1(2)
125.0(2)
118.3(2)
115.5(2)
120.2(3)
114.1(3)
101.7(2)
100.5(3)
111.8(2)
122.3(3)
114.2(3)
111.6(3)
106.4(4)
118.7(3)
121.5(3)
114.7(3)
123.7(3)
118.2(3)
116.5(3)
121.2(4)
108.32(17)
113.90(17)
109.60(16)
121.07(16)
120.79(18)
114.30(16)
124.91(18)
118.69(16)
115.06(17)
121.86(18)
A notable difference observed was that the compounds 4aa and
4af, which containing the intramolecular hydrogen bond O(51)–
H(51)ꢁꢁꢁO(12) and the intermolecular hydrogen bond N(12)–
H(12)ꢁꢁꢁO(12), showed the pyrazole rings more plane when
compared with 4df and 4ae. On the other hand, compounds 4df
and 4ae that contained the intermolecular hydrogen bond O(51)–
H(51)ꢁꢁꢁO(12) showed the fragment N(2)–N(1)–C(11)55O(12) more

H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
307
Table 2
Hydrogen bonding geometry in structures [A],8.
˚
Compounds
D–HꢁꢁꢁA
D–H
HꢁꢁꢁA
DꢁꢁꢁA
D–HꢁꢁꢁA
Symmetry codes
4aa
O(51)–H(51)ꢁꢁꢁO(12)
O(101)–H(101)ꢁꢁꢁO(62)
N(62)–H(62)ꢁꢁꢁO(12)
N(12)–H(12)ꢁꢁꢁO(62)
0.82
2.19
2.729(2)
2.666(2)
2.883(2)
2.966(2)
123.6
122.8
151(2)
153(2)
0.82
2.13
0.92(2)
0.83(2)
2.04(2)
2.20(2)
x + 1, y, z
4af
O(51)–H(51)ꢁꢁꢁO(12)
N(12)–H(12)ꢁꢁꢁO(12)
O(51)–H(51)ꢁꢁꢁO(12)
0.82
2.16
2.697(3)
2.943(3)
2.882(4)
123.1
147(2)
161.0
0.91(3)
0.82
2.14(3)
2.10
x, ꢀy + 1/2, z + 1/2
x + 1, y, z
4df
4ae
O(51)–H(51)ꢁꢁꢁO(12)
O(1)–H(1B)ꢁꢁꢁO(51)
0.82
1.83
2.6475(18)
2.908(2)
173.6
ꢀx + 3, y ꢀ 1/2, ꢀz ꢀ 1/2
ꢀx + 3, y ꢀ 1/2, ꢀz ꢀ 1/2
0.9143(17)
2.0072(13)
168.29(14)
plane when compared to 4aa and 4af. These data demonstrate the
effect of the interactions present in the crystal packing affecting
the molecular structure.
2.2. Antioxidant activity
Antioxidants are considered important nutraceuticals on
account of many health benefits [6]. Antioxidants may be classified
according to their mode of action as free radical scavengers,
chelators of metal ions involved in catalyzing lipid oxidation, or
oxygen scavengers that react with oxygen in closed systems [6,16].
Several different methods are available and have been used to
assess the total antioxidant capacity of numerous molecules. The
commonly used antioxidant evaluation method, DPPH (1,1-
diphenyl-2-picrylhydrazyl) radical scavenging was applied to
determine the antioxidant capacity. The target carbohydrazides
2 and 4 were compared with BHT (Butylated hydroxytoluene) and
Quercetin, as reference compounds.
The DPPH antioxidant assay measures the hydrogen donating
capacity of the molecules in the sample. When the free radical
DPPH is reduced by the sample its color changes from violet to
yellow. This absorbance decline is measured and the antioxidant
capacity can be determined.
Compounds 2 and 4 were active as free radical DPPH trapping
for screening. By determining the IC50, it was found that the
compounds of series 2 demonstrated value in the range from 77.47
to 109.42
range from 47.57 to 487
active at the concentration of 47.57
m
g/mL and the new series of semicarbazones 4 in the
g/mL (Table 3). Compound 4bf was
g/mL, being the lowest value
m
m
able to inhibit 50% of DPPH for the tested samples.
In this work, we also obtained the percentages of inhibition of
compounds 2 and 4 to evaluate free radical scavenging activity
DDPH (Table 2). The percentage of inhibition at various concen-
trations measured through the absorbance of the samples shows
that the compounds 2a–f reached relevant data on the concentra-
tions of 250
mg/mL, which approached the standard BHT (Table 4).
Samples of the new series of semicarbazones (4bf, 4bg and 4bj)
from the precursor 2b showed a greater ability to capture DPPH
free radical when compared with the other compounds, especially
the 4bf, which was capable of inhibiting a higher percentage of
97.7% at a concentration of 250
mg/mL (Table 4).
2.3. Antimicrobial activity
Numerous recent publications have documented the fact that
despite growing problems with resistance to antimicrobial agents
amongst important bacterial pathogens, the number of new
antibiotics being brought to the market has shown a precipitous
decline over the past several decades, with only five new
antibacterial agents approved for clinical use in the USA between
2003 and 2007 [17]. The use of antimicrobial drugs to treat public
health is growing and it is possible to see an emergence of bacterial
Fig. 4. A stereoview of part of the crystal structure of 4aa and 4af showing the
formation of a hydrogen bonded.

308
H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
Table 3
Antioxidant activity IC50 for 4,5-dihydro-1H-pyrazolyl-1-carbohydrazides (2) and
(E)-N0-arylidene-[4,5-dihydro-1H-pyrazol-1-yl]-carbohydrazides (4).
Compounds 2a 2b 2c 2d 2e 2f
IC50 g/mL) 96.28 101.89 109.42 96.4 102.92 77.47
4aa
(
m
238.46
Compounds 4ab
IC50 g/mL) 487.0
4ac
4ad
4ae
4af
4ag
4ah
(
m
259.55 145.83 235.71 219.69 256.39 363.63
Compounds 4ai
4aj
4ak
4bf
4bg
4bj
4ce
IC50 g/mL) 254.21 206.58 72.44
(
m
47.57
84.28
82.09
270.59
Compounds 4df
4dh
4ea
4ef
4fb
4fe
BHT
IC50(mg/mL) 270.37 216.67 194.26 451.11 220.79 167.03 21.55
The best results, but not satisfactory, refer to the compound 2f,
which presented bacteriostatic for gram-positive bacterium S.
pyogenes and for gram-negative bacterium E. coli, MIC = 0.125 mg/
mL. This compound was also bactericidal against the bacterium E.
coli at the concentration of 0.25 mg/mL (Table 5).
3. Experimental
3.1. Synthesis and structure
3.1.1. General procedures
Unless otherwise indicated all common reagents and solvents
were used from commercial suppliers without further purification.
All melting points were determined using open capillaries on an
Electrothermal Mel-Temp 3.0 apparatus and are uncorrected. 1H
and 13C NMR spectra were acquired on a Bruker DPX 200 MHz or
DPX 400 MHz spectrometers, 5 mm sample tubes, 298 K, digital
resolution ꢂ 0.01 ppm, in DMSO-d6 (2, 4) and CDCl3 (1) using TMS as
internal reference. The CHN elemental analyses were performed on a
Perkin-Elmer 2400 CHN elemental analyzer (Universidade de Sa˜o
Paulo, USP/Brazil).
Table 4
Antioxidant activity for 4,5-dihydro-1H-pyrazolyl-1-carbohydrazides (2) and (E)-
N0-arylidene-[4,5-dihydro-1H-pyrazol-1-yl]carbohydrazides (4).
Compounds
% Inhibition
250a
125a
62.5a
31.25a
15.62a
7.81a
2a
80.2
84
51.2
61.1
54.6
64.4
59.1
78.9
26.4
13.8
18.5
28
22.6
31.3
26.7
33.1
33.4
40.9
10.1
9.3
11.6
20.4
16.8
14.6
18.5
20.8
5.4
6.8
10.1
10
4.9
6.8
8.2
6.4
7
2b
2c
65.8
87.2
83.6
90.4
52.4
26.3
40.8
64
2d
9.4
2e
11.4
13
2f
10.3
0.26
1.4
3
4aa
4ab
4ac
4ad
4ae
4af
4ag
4ah
4ai
4aj
4ak
4bf
4bg
4bj
4ce
4df
4dh
4ea
4ef
4fb
4fe
BHT
2.1
7.8
3.6
11.1
10.4
2.2
9.2
7.3
4.3
2.2
1.4
–
31.8
56
10.7
31.8
40.5
29
1.9
–
20.8
23.7
19.8
17.2
13
16.7
17.1
19.2
15.5
9.9
15.4
11.3
18
14
78.8
40
5.7
16.7
10
49.3
54.3
92.5
97.7
86
25.5
25.7
67
11.8
7.5
Fig. 5. A stereoview of part of the crystal structure of 4df and 4ae showing the
5
formation of a hydrogen bonded.
46.8
54.3
42.4
39.5
10.7
30.8
16.5
15
34
18.2
36.1
18
10.6
25.9
9.6
4.3
1.1
24
70
45.3
23.5
17.8
5.5
64.3
73
resistance. To maintain the efficiency of the treatment of diseases
caused by bacteria, new active compounds are always being
searched for [18].
90.8
38.6
48
10.8
3.2
17.3
34.4
29.2
33.1
20.7
30.7
29.8
89.2
29.5
12.3
5.9
26.6
10.1
4.7
57.8
63.6
32
9.7
4.5
12.3
4.1
1.7
33.2
The compounds 2a, 2c, 2d and 2e forward to microorganisms
and tested concentrations were active in the yeast Candida albicans
MIC = 0.25 mg/mL. Compounds 4aa, 4ab, 4ad, 4ae, 4af, 4ag, 4ah,
4aj, 4ak, 4bf, 4bg, 4bj, 4ce, 4df, 4dh, 4ea, 4ef and 4fe presented
fungistatic activity, whose minimal inhibitory concentration (MIC)
level ranged from 0.25 to 0.5 mg/mL (Table 5).
15.8
15.3
14.6
71.2
14.4
9
13.8
6.9
56
64
4.6
2.6
91.2
56.9
45.8
a
Concentration in
mg/mL.

H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
309
Table 5
Antimicrobial activity for 4,5-dihydro-1H-pyrazolyl-1-carbohydrazides (2) and (E)-N0-arylidene-[4,5-dihydro-1H-pyrazol-1-yl]carbohydrazides (4).
Sample
MICa/MLCa
Microorganismc
E. coli
K. pneumonia
S. pyogenes
S. aureus
S. epidermidis
B. subtilis
S. cerevisiae
C. Albicans
2a
0.25/>0.5
>0.5
0.25/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.25/>0.5
>0.5
>0.5
0.25/>0.5
>0.5
2b
>0.5
2c
>0.5
>0.5
0.25/>0.5
0.5/>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
0.25/>0.5
0.25/>0.5
0.25/>0.5
>0.5
2d
0.25/>0.5
>0.5
0.25/>0.5
>0.5
0.25/>0.5
>0.5
0.25/>0.5
>0.5
0.25/>0.5
>0.5
>0.5
2e
>0.5
2f
0.125/0.25
>0.5
>0.5
0.125/>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
4aa
4ab
4ac
4ad
4ae
4af
4ag
4ah
4ai
4aj
4ak
4bf
4bg
4bj
4ce
4df
4dh
4ea
4ef
4fb
4fe
>0.5
>0.5
>0.5
>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.25/>0.5
0.25/>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.25/>0.5
0.25/>0.5
0.5/>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.25/>0.5
0.25/>0.5
0.25/>0.5
0.25/>0.5
0.25/>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.25/>0.5
0.25/>0.5
0.25/>0.5
0.5/>0.5
0.25/>0.5
0.5/>0.5
0.5/>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.25/>0.5
0.25/>0.5
0.25/>0.5
0.25/>0.5
0.5/>0.5
0.25/>0.5
0.25/>0.5
0.5/>0.5
0.5/>0.5
0.25/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
0.5/>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
0.5/>0.5
>0.5
>0.5
0.5/>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
0.5/>0.5
0.25/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.25/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.25/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.25/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.5/>0.5
0.5/>0.5
>0.5
0.5/>0.5
0.5/>0.5
0.5/>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
0.25/>0.5
0.25/>0.5
Standardb
3.12 ꢃ 10ꢀ3
3.12 ꢃ 10ꢀ3
6.25 ꢃ 10ꢀ3
3.12 ꢃ 10ꢀ3
3.12 ꢃ 10ꢀ3
3.12 ꢃ 10ꢀ3
10.3 ꢃ 10ꢀ3
10.3 ꢃ 10ꢀ3
a
mg/mL.
b
Chloramphenicol for bacteria and Nistatin for yeast.
ATCC (American Type Culture Collection).
c
4-Alkyl(aryl/heteroaryl)-4-methoxy 1,1,1-trifluoroalk-3-en-2-
13C NMR (100.61 MHz, DMSO-d6):
d = 154.7 (C55O), 149.5 (C-3),
ones (1a–f) were prepared according to the previous publications
[10] from the trifluoroacetylation reactions of the respective
enolether (1a) or acetals (1b–f) with trifluoroacetic anhydride in
the presence of pyridine. The pure compounds 1 were obtained by
distillation under reduced pressure.
139.9, 137.9, 129.0, 126.5, (6 C, Ar), 123.2 (q, 1J = 285, CF3), 91.1 (q,
2J = 33, C-5), 44.1 (C-4), 20.8 (Me).
Anal. Calc. for C12H13F3N4O2 (302.25): C, 47.68; H, 4.34; N,
18.54%.
Found: C, 47.82; H, 4.31; N, 18.75%.
General procedure for synthesis of 3-alkyl(aryl/heteroaryl)-5-
trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazolyl-1-carbohydra-
zides (2a-f).
5-Trifluoromethyl-3-(2-furyl)-5-hydroxy-4,5-dihydro-1H-pyrazo-
lyl-1-carbohydrazide (2d). Yellow solid; yield 85%; mp 217–219 8C. Lit.
[9]: yield 44%; mp 216–217 8C.
General procedure: To the corresponding and pure 4-alkyl(aryl/
5-Trifluoromethyl-5-hydroxy-3-(2-thienyl)-4,5-dihydro-1H-pyra-
zolyl-1-carbohydrazide (2e). White solid; yield 92%; mp 229–231 8C.
Lit. [9]: yield 80%; mp 230–231 8C.
heteroaryl)-1,1,1-trifluoro-4-methoxy-3-alken-2-ones
(1a–f)
(10 mmol) at room temperature, a solution of carbohydrazide
(0.9009 g, 10 mmol) in ethanol (10 mL) was added. The mixtures
were stirred for an additional 18–20 h at room temperature. Then,
the crude products were filtered, washed with cold ethanol and
recrystallized from ethanol. Subsequently, the pure products 2a–f
were submitted to reduced pressure to eliminate any trace of the
residual solvents, and isolated as white or yellow solids (yields 62–
92%).
5-Trifluoromethyl-5-hydroxy-3-methyl-4,5-dihydro-1H-pyrazo-
lyl-1-carbohydrazide (2a). White solid; yield 62%; mp 161–162 8C. Lit.
[9]: yield 49%; mp 161–162 8C.
5-Trifluoromethyl-5-hydroxy-3-phenyl-4,5-dihydro-1H-pyrazo-
lyl-1-carbohydrazide(2b). White solid; yield 88%; mp 234–236 8C. Lit.
[9]: yield 86%; mp 234–235 8C.
5-Trifluoromethyl-5-hydroxy-3-(1-naphthyl)-4,5-dihydro-1H-
pyrazolyl-1-carbohydrazide (2f). Yellow solid; yield 65%; mp 214–
215 8C.
1H NMR (400.13 MHz, DMSO-d6):
d = 9.16 (d, 1H, Ar, J = 8), 8.30
(s, 1H, NH), 8.04 (d, 1H, Ar, J = 8), 8.00 (d, 1H, Ar, J = 8), 7.75 (s, 1H,
OH), 7.70–7.66 (m, 1H, Ar), 7.63–7.55 (m, 2H, Ar), 4.27 (s, 2H, NH2),
4.02 (d, 1H, H-4a, 2J = 18), 3.71 (d, 1H, H-4b, 2J = 18).
13C NMR (100.61 MHz, DMSO-d6):
d = 154.9 (C55O), 150.6 (C-3),
133.5, 130.8, 129.6, 128.8, 128.4, 127.7, 126.5, 126.2, 124.9 (10C,
Ar), 123.4 (q, 1J = 285, CF3), 90.1 (q, 2J = 33, C-5), 46.7 (C-4).
Anal. Calc. for C15H13F3N4O2 (338.28): C, 53.26; H, 3.87; N,
16.56%.
Found: C, 53.31; H, 3.84; N, 16.69%.
5-Trifluoromethyl-5-hydroxy-3-(4-methylphenyl)-4,5-dihydro-
1H-pyrazolyl-1-carbohydrazide (2c). White solid; yield 67%; mp 240–
242 8C.
General procedure for the synthesis of new (E)-N0-arylidene-[3-
alkyl(aryl/heteroaryl)-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-
pyrazol-1-yl]carbohydrazides (4).
General procedure: To a stirred solution of the respective 3-
alkyl(aryl/heteroaryl)-5-trifluoromethyl-5-hydroxy-4,5-dihydro-
1H-pyrazol-1-yl-carbohydrazides 2a–f (5 mmol) in ethanol (5 mL)
1H NMR (400.13 MHz, DMSO-d6):
d
= 8.34 (s, 1H, NH), 7.76 (s,
1H, OH), 7.75 (d, 2H, Ar, J = 8), 7.26 (d, 2H, Ar, J = 8), 4.14 (s, 2H,
NH2), 3.74 (d, 1H, H-4, 2J = 19), 3.44 (d, 1H, H-4, 2J = 19).

310
H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
was added the aldehydes 3a–j or desired ketone 3k (5 mmol). The
mixtures were subjected to magnetic stirring for 7 h at 60 8C. After
the reaction time, the mixtures were stored for 48 h at room
temperature. The precipitates were filtered under reduced pressure
and washed with cold ethanol. The solids 4 were recrystallized from
Anal. Calc. for C13H12ClF3N4O2ꢁH2O (366.72): C, 42.58; H, 3.85;
N, 15.28%.
Found: C, 42.57; H, 3.95; N, 15.57%.
(E)-N0-(4-Methylbenzylidene)-(5-trifluoromethyl-5-hydroxy-3-
methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4af). White
solid; yield 75%; mp 155–156 8C.
a
mixture of ethanol:acetone:di-iso-propyl ether (2:1:2) and
isolated as white to yellow solids (yields 52–97%).
(E)-N0-Benzylidene-(5-trifluoromethyl-5-hydroxy-3-methyl-4,5-
dihydro-1H-pyrazol-1-yl)carbohydrazide (4aa). White solid; yield
93%; mp 164–165 8C.
1H NMR (400.13 MHz, DMSO-d6):
d = 10.65 (s, 1H, NH), 8.33 (s,
1H, CH), 7.57 (s, 1H, OH), 7.50 (d, 2H, Ar, J = 8), 7.24 (d, 2H, Ar, J = 8),
3.42 (d, 1H, H-4, J = 19), 3.05 (d, 1H, H-4, J = 19), 2.33 (s, 3H, Me–Ar),
2.05 (s, 3H, Me).
1H NMR (400.13 MHz, DMSO-d6):
d
= 10.73 (s, 1H, NH), 8.38 (s,
13C NMR (100.61 MHz, DMSO-d6):
d = 152.4 (C55O), 149.8 (C-3),
1H,CH), 7.62–7.60(m, 2H,Ar), 7.61(s, 1H,OH), 7.43–7.41(m, 3H,Ar),
145.4 (C55N), 139.1, 132.0, 129.3, 124.7 (6C, Ar), 123.3 (q, 1J = 284,
CF3), 90.6 (q, 2J = 33, C-5), 47.9 (C-4), 20.9 (Me–Ar), 15.1 (Me).
Anal. Calc. for C14H15F3N4O2 (328.29): C, 51.22; H, 4.61; N,
17.07%.
3.43 (d, 1H, H-4, J = 19), 3.06 (d, 1H, H-4, J = 19), 2.05 (s, 3H, Me).
13C NMR (100.61 MHz, DMSO-d6):
d = 152.3 (C55O), 149.8 (C-3),
145.4 (C55N), 134.6, 129.2, 128.5, 126.4 (6C, Ar), 123.2 (q, 1J = 285,
CF3), 90.6 (q, 2J = 33, C-5), 47.7 (C-4), 14.9 (Me).
Anal. Calc. for C13H13F3N4O2 (314.26): C, 49.68; H, 4.17; N,
17.83%.
Found: C, 51.27; H, 4.11; N, 17.29%.
(E)-N0-(4-Methoxybenzylidene)-(5-trifluoromethyl-5-hydroxy-3-
methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4ag). White
solid; yield 97%; mp 152–153 8C.
Found: C, 49.74; H, 4.03; N, 17.99%.
(E)-N0-(3-Nitrobenzylidene)-(5-trifluoromethyl-5-hydroxy-3-
methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4ab). Yellow
solid; yield 66%; mp 191–192 8C.
1H NMR (400.13 MHz, DMSO-d6):
d = 10.57 (s, 1H, NH), 8.31 (s,
1H, CH), 7.56 (s, 1H, OH), 7.55 (d, 2H, Ar, J = 9), 6.99 (d, 2H, Ar, J = 9),
3.79 (s, 3H, OMe), 3.42 (d, 1H, H-4, J = 19), 3.06 (d, 1H, H-4, J = 19),
2.05 (s, 3H, Me).
1H NMR (200.13 MHz, DMSO-d6):
d = 11.04 (s, 1H, NH), 8.49 (s,
1H, CH), 8.43 (s, 1H, Ar), 8.22 (d, 1H, Ar, J = 8), 8.02 (d, 1H, Ar, J = 8),
7.76–7.72 (m, 1H, Ar), 7.69 (s, 1H, OH), 3.45 (d, 1H, H-4, J = 19), 3.07
(d, 1H, H-4, J = 19), 2.06 (s, 3H, Me).
13C NMR (50.32 MHz, DMSO-d6):
d = 152.4 (C55O), 150.0 (C-3),
145.3 (C55N), 160.4, 128.1, 127.4, 114.2 (6C, Ar), 123.4 (q, 1J = 285,
CF3), 90.6 (q, 2J = 33, C-5), 55.2 (OMe), 47.9 (C-4), 15.2 (Me).
Anal. Calc. for C14H15F3N4O3 (344.29): C, 48.84; H, 4.39; N,
16.27%.
13C NMR (100.61 MHz, DMSO-d6):
d = 152.8 (C55O), 149.6 (C-3),
148.2 (C55N), 142.8, 136.6, 132.8, 130.3, 123.58, 120.2 (6C, Ar),
123.3 (q, 1J = 285, CF3), 90.6 (q, 2J = 33, C-5), 47.9 (C-4), 15.1 (Me).
Anal. Calc. for C13H12F3N5O4 (359.26): C, 43.46; H, 3.37; N,
19.49%.
Found: C, 49.07; H, 4.01; N, 16.31%.
(E)-N0-(1,3-Dioxobenzyliden-5-yl)-(5-trifluoromethyl-5-hydroxy-
3-methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4ah). White
solid; yield 83%; mp 167–168 8C.
Found: C, 43.21; H, 3.71; N, 19.45%.
(E)-N0-(4-Nitrobenzylidene)-(5-trifluoromethyl-5-hydroxy-3-
methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4ac). Yellow
solid; yield 82%; mp 252–253 8C.
1H NMR (200.13 MHz, DMSO-d6):
d = 10.66 (s, 1H, NH), 8.28 (s,
1H, CH), 7.61 (s, 1H, OH), 7.20 (s, 1H, Ar), 7.01–6.94 (m, 2H, Ar), 6.07
(s, 2H, dioxol), 3.44 (d, 1H, H-4, J = 19), 3.05 (d, 1H, H-4, J = 19), 2.05
(s, 3H, Me).
1H NMR (400.13 MHz, DMSO-d6):
d = 11.09 (s, 1H, NH), 8.50 (s,
1H, CH), 8.28 (d, 2H, Ar, J = 8), 7.87 (d, 2H, Ar, J = 8), 7.70 (s, 1H, OH),
3.46 (d, 1H, H-4, J = 19), 3.08 (d, 1H, H-4, J = 19), 2.07 (s, 3H, Me).
13C NMR (100.61 MHz, DMSO-d6):
d = 152.3 (C55O), 149.8 (C-3),
148.5 (C55N), 147.8, 145.1, 129.15, 122.5, 108.3, 104.6, 101.3 (7C, Ar),
123.3 (q, 1J = 283, CF3), 90.6 (q, 2J = 33, C-5), 47.8 (C-4), 15.1 (Me).
Anal. Calc. for C14H13F3N4O4 (358.27): C, 46.93; H, 3.66; N,
15.64%.
13C NMR (50.32 MHz, DMSO-d6):
d = 152.9 (C55O), 149.5 (C-3),
147.4 (C55N), 142.8, 141.2, 127.4, 124.0, (6C, Ar), 123.3 (q, 1J = 285,
CF3), 90.7 (q, 2J = 33, C-5), 48.0 (C-4), 15.2 (Me).
Anal. Calc. for C13H12F3N5O4 (359.26): C, 43.46; H, 3.37; N,
19.49%.
Found: C, 46.91; H, 3.64; N, 15.61%.
(E)-N0-(1-Naphythylidene)-(5-trifluoromethyl-5-hydroxy-3-
methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4ai). White
solid; yield 85%; mp 182–183 8C.
Found: C, 43.48; H, 3.39; N, 19.39%.
(E)-N0-(2-Bromobenzylidene)-(5-trifluoromethyl-5-hydroxy-3-
methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide
(4ad).White
1H NMR (400.13 MHz, DMSO-d6):
d = 10.86 (s, 1H, NH), 9.10 (s,
solid; yield 54%; mp 172–173 8C.
1H, CH), 8.85 (d, 1H, Ar, J = 8), 8.00–7.97 (m, 2H, Ar), 7.86 (d, 1H, Ar,
J = 8), 7.68 (s, 1H, OH), 7.66–7.57 (m, 3H, Ar), 3.47 (d, 1H, H-4,
J = 19), 3.10 (d, 1H, H-4, J = 19), 2.09 (s, 3H, Me).
1H NMR (200.13 MHz, DMSO-d6):
d = 11.20 (s, 1H, NH), 8.75 (s,
1H, CH), 7.90 (d, 1H, Ar, J = 8), 7.68 (s, 1H, Ar), 7.65 (s, 1H, OH), 7.43
(t, 1H, Ar, J = 7), 7.35–7.28 (m, 1H, Ar), 3.44 (d, 1H, H-4, J = 19), 3.06
(d, 1H, H-4, J = 19), 2.06 (s, 3H, Me).
13C NMR (50.32 MHz, DMSO-d6):
d = 152.6 (C55O), 149.9 (C-3),
145.2 (C55N), 133.5, 130.2, 130.1, 129.9, 128.7, 127.0, 126.7, 126.1,
125.5, 124.3 (10C, Ar), 122.4 (q, 1J = 285, CF3), 90.7 (q, 2J = 33, C-5),
48.0 (C-4), 15.2 (Me).
Anal. Calc. for C17H15F3N4O2 (364.32): C, 56.04; H, 4.15; N,
15.38%.
13C NMR (100.61 MHz, DMSO-d6):
d = 152.4 (C55O), 149.7 (C-3),
143.6 (C55N), 133.6, 133.0, 131.0, 127.8, 126.8, 123.0 (6C, Ar), 123.3
(q, 1J = 284, CF3), 90.6 (q, 2J = 33, C-5), 47.9 (C-4), 15.1 (Me).
Anal. Calc. for C13H12BrF3N4O2 (393.16): C, 39.71; H, 3.08; N,
14.25%.
Found: C, 56.13; H, 4.15; N, 15.30%.
Found: C, 39.72; H, 2.92; N, 14.41%.
(E)-N0-(Furan-2-ylmethylene)-(5-trifluoromethyl-5-hydroxy-3-
methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4aj). White
solid; yield 61%; mp 166–167 8C.
(E)-N0-(4-Chlorobenzylidene)-(5-trifluoromethyl-5-hydroxy-3-
methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4ae). White
solid; yield 74%; mp 133–134 8C.
1H NMR (200.13 MHz, DMSO-d6):
d = 10.76 (s, 1H, NH), 8.28 (s,
1H NMR (400.13 MHz, DMSO-d6):
d
= 10.80 (s, 1H, NH), 8.36 (s,
1H, CH), 7.78 (s, 1H, Fur), 7.60 (s, 1H, OH), 6.74 (s, 1H, Fur), 6.59 (s,
1H, Fur), 3.42 (d, 1H, H-4, J = 19), 3.06 (d, 1H, H-4, J = 19), 2.05 (s,
3H, Me).
1H, CH), 7.63 (d, 2H, Ar, J = 8), 7.62 (s, 1H, OH), 7.48 (d, 2H, Ar, J = 8),
3.43 (d, 1H, H-4, J = 19), 3.06 (d, 1H, H-4, J = 19), 2.05 (s, 3H, Me).
13C NMR (100.61 MHz, DMSO-d6):
d
= 152.4 (C55O), 149.8 (C-3),
13C NMR (100.61 MHz, DMSO-d6):
d = 152.6 (C55O), 149.9 (C-3),
144.1 (C55N), 133.8, 133.5, 128.6, 128.0 (6C, Ar), 123.2 (q, 1J = 284,
CF3), 90.6 (q, 2J = 34, C-5), 47.7 (C-4), 14.8 (Me).
149.8 (C55N), 144.4, 135.5, 112.0, 111.7, (4C, Fur), 123.4 (q, 1J = 285,
CF3), 90.6 (q, 2J = 33, C-5), 47.9 (C-4), 15.1 (Me).

H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
311
Anal. Calc. for C11H11F3N4O3 (304.22): C, 43.43; H, 3.64; N,
18.42%.
(12 C, Ar), 123.4 (q, 1J = 285, CF3), 91.2 (q, 2J = 33, C-5), 44.4 (C-4),
21.0 (Me).
Found: C, 43.41; H, 3.39; N, 18.39%.
Anal. Calc. for C19H16ClF3N4O2 (424.80): C, 53.72; H, 3.80; N,
13.19%.
(E)-N0-[(1-Phenyl)ethyliden-1-yl]-(5-trifluoromethyl-5-hydroxy-
3-methyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4ak). White
solid; yield 62%; mp 130–132 8C.
Found: C, 53.73; H, 3.75; N, 13.26%.
(E)-N0-(4-Methylbenzylidene)-[5-trifluoromethyl-3-(2-furyl)-5-
hydroxy-4,5-dihydro-1H-pyrazol-1-yl]carbohydrazide (4df). Yellow
solid; yield 70%; mp 180–181 8C.
1H NMR (200.13 MHz, DMSO-d6):
d = 9.39 (s, 1H, NH), 7.81–
7.78 (m, 2H, Ar), 7.77 (s, 1H, OH), 7.40 (s, 3H, Ar), 3.48 (d, 1H, H-4,
J = 19), 3.09 (d, 1H, H-4, J = 19), 2.23 (s, 3H, Me), 2.05 (s, 3H, Me).
1H NMR (400.13 MHz, DMSO-d6):
d = 10.69 (s, 1H, NH), 8.41 (s,
13C NMR (100.6 MHz, DMSO-d6):
d
= 152.7 (C55O), 149.8 (C-3),
1H, CH), 7.95 (s, 1H, OH), 7.93 (q, 1H, Fur, J = 2), 7.54 (d, 2H, Ar, J = 8),
7.25 (d, 2H, Ar, J = 8), 7.08 (dd, 1H, Fur, J = 1), 6.70 (q, 1H, Fur, J = 2),
3.79 (d, 1H, H-4, J = 19), 3.45 (d, 1H, H-4, J = 19), 2.34 (s, 3H, Me).
149.4 (C55N), 137.9, 128.8, 128.1, 125.9 (6C, Ar), 123.1 (q, 1J = 285,
CF3), 90.8 (q, 2J = 34, C-5); 47.8 (C-4); 14.7 (Me); 12.8 (Me).
Anal. Calc. for C14H15F3N4O2 (328.29): C, 51.22; H, 4.61; N,
17.07%.
13C NMR (100.61 MHz, DMSO-d6):
d = 149.5 (C55O), 146.0 (C-3),
145.5 (C55N), 145.3, 131.9, 114.1, 112.2 (4 C, Fur), 141.7, 139.2,
129.3, 126.6 (6C, Ar), 123.2 (q, 1J = 285, CF3), 90.65 (q, 2J = 33, C-5),
44.2 (C-4), 20.9 (Me).
Anal. Calc. for C17H15F3N4O3 (380.32): C, 53.69; H, 3.98; N,
14.73%.
Found: C, 51.20; H, 4.62; N, 17.01%.
(E)-N0-(4-Methylbenzylidene)-(5-trifluoromethyl-5-hydroxy-3-
phenyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4bf). Yellow
solid; yield 52%; mp 173–175 8C.
1H NMR (200.13 MHz, DMSO-d6):
d
= 10.80 (s, 1H, NH), 8.43 (s,
Found: C, 53.61; H, 3.34; N, 14.90%.
1H, CH), 7.95 (s, 1H, OH), 7.97–7.92 (m, 2H, Ar), 7.57 (d, 2H, 3J = 8,
Ar), 7.52–7.49 (m, 3H, Ar), 7.26 (d, 2H, Ar, J = 8), 3.89 (d, 1H, H-4,
J = 19), 3.56 (d, 1H, H-4, J = 19), 2.34 (s, 3H, Me).
(E)-N0-(1,3-Dioxobenzyliden-5-yl)-[5-trifluoromethyl-3-(2-furyl)-
5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl]carbohydrazide (4dh). Yel-
low solid; yield 65%; mp 177–178 8C.
13C NMR (100.61 MHz, DMSO-d6):
d
= 150.1 (C55O), 149.5 (C-3),
1H NMR (200.13 MHz, DMSO-d6):
d = 10.71 (s, 1H, NH), 8.36 (s,
145.9 (C55N), 139.3, 132.0, 130.5, 130.2, 128.6, 126.9, 126.6 (12 C,
Ar), 123.3 (q, 1J = 285, CF3), 91.4 (q, 2J = 34, C-5), 44.4 (C-4), 20.9
(Me).
Anal. Calc. for C19H17F3N4O2 (390.36): C, 58.46; H, 4.39; N,
14.35%.
1H, CH), 8.00 (s, 1H, Ar), 7.94 (d, 1H, Fur, J = 1), 7.23 (s, 1H, OH), 7.09
(d, 1H, Fur, J = 3), 7.05 (s, 1H, Ar), 7.00 (s, 1H, Ar), 6.71 (q, 1H, Fur,
J = 2), 6.09 (s, 2H, dioxol), 3.80 (d, 1H, H-4, J = 19), 3.49 (d, 1H, H-4,
J = 19).
13C NMR (100.61 MHz, DMSO-d6):
d = 149.5 (C55O), 148.6 (C-3),
Found: C, 58.61; H, 4.38; N, 14.19%.
147.9 (C55N), 145.8, 145.5, 145.3, 141.7, 129.1, 122.7, 114.1, 112.2,
108.3, 104.7, 101.4 (11C, Fur, Ar), 123.2 (q, 1J = 285, CF3), 90.9 (q,
2J = 33, C-5), 44.2 (C-4).
Anal. Calc. for C17H13F3N4O5 (410.30): C, 49.76; H, 3.19; N,
13.65%.
(E)-N0-(4-Methoxybenzylidene)-(5-trifluoromethyl-5-hydroxy-3-
phenyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4bg). Yellow
solid; yield 53%; mp 185–186 8C.
1H NMR (400.13 MHz, DMSO-d6):
d = 10.71 (s, 1H, NH), 8.40 (s,
1H, CH), 7.96–7.93 (m, 2H, Ar), 7.91 (s, 1H, OH), 7.62 (d, 2H, Ar,
J = 8), 7.51–7.49 (m, 3H, Ar), 7.02 (d, 2H, Ar, J = 8), 3.87 (d, 1H, H-4,
J = 19), 3.81 (s, 3H, OMe), 3.56 (d, 1H, H-4, J = 19).
Found: C, 49.71; H, 3.18; N, 13.73%.
(E)-N0-(Benzylidene)-[5-trifluoromethyl-5-hydroxy-3-(2-thienyl)-
4,5-dihydro-1H-pyrazol-1-yl]carbohydrazide (4ea). White solid; yield
62%; mp 113–115 8C.
13C NMR (100.61 MHz, DMSO-d6):
d = 151.7 (C55O), 149.9 (C-3),
149.4 (C55N), 160.2, 130.4, 130.1, 128.6, 128.2, 127.2, 126.2, 114.0
(12 C, Ar), 123.2 (q, 1J = 285, CF3), 92.1 (q, 2J = 33, C-5), 55.1 (OMe),
43.7 (C-4).
Anal. Calc. for C19H17F3N4O3ꢁH2O (424.37): C, 53.77; H, 4.51; N,
13.20%.
1H NMR (400.13 MHz, DMSO-d6):
d = 10.60 (s, 1H, NH), 8.46 (s,
1H, CH), 7.87 (s, 1H, OH), 7.77 (d, 1H, Thienyl, J = 5), 7.44–7.39 (m,
3H, Ar), 7.67 (d, 2H, Ar, J = 7), 7.57 (d, 1H, Thienyl, J = 3), 7.19–7.17
(m, 1H, Thienyl), 3.88 (d, 1H, H-4, J = 19), 3.57 (d, 1H, H-4, J = 19).
13C NMR (100.61 MHz, DMSO-d6):
d = 149.3 (C55O), 146.1 (C-3),
Found: C, 53.56; H, 4.54; N, 13.11%.
145.9 (C55N), 134.5, 130.3, 128.5, 126.5 (6C, Ar), 132.9, 129.6,
129.3, 127.7 (4C, Thienyl), 123.0 (q, 1J = 284, CF3), 91.2 (q, 2J = 33, C-
5), 44.9 (C-4).
Anal. Calc. for C16H13F3N4O2S (382.36): C, 50.26; H, 3.43; N,
14.65%.
(E)-N0-(Furan-2-ylmethylene)-(5-trifluoromethyl-5-hydroxy-3-
phenyl-4,5-dihydro-1H-pyrazol-1-yl)carbohydrazide (4bj). White
solid; yield 67%; mp 142–143 8C.
1H NMR (200.13 MHz, DMSO-d6):
d = 11.39 (s, 1H, NH), 8.18 (s,
1H, CH), 8.13 (d, 1H, Fur, J = 2), 7.88–7.83 (m, 2H, Ar), 7.60–7.56 (m,
3H, Ar), 7.46 (s, 1H, OH), 7.06 (d, 1H, Fur, J = 3), 6.83 (q, 1H, Fur,
J = 2), 3.98 (d, 1H, H-4, J = 19), 3.64 (d, 1H, H-4, J = 19).
Found: C, 50.28; H, 3.01; N, 14.56%.
(E)-N0-(4-Methylbenzylidene)-[5-trifluoromethyl-5-hydroxy-3-
(2-thienyl)-4,5-dihydro-1H-pyrazol-1-yl]carbohydrazide
(4ef).
13C NMR (50.32 MHz, DMSO-d6):
d
= 150.9 (C55O), 148.9 (C-3),
White solid; yield 73%; mp 182–183 8C.
148.2 (C55N), 145.2, 130.7, 116.0, 112.5, (4C, Fur), 129.8, 129.4,
129.1, 126.4 (6C, Ar), 123.1 (q, 1J = 285, CF3), 91.2 (q, 2J = 34, C-5),
44.7 (C-4).
Anal. Calc. for C16H13F3N4O3 (366.29): C, 52.46; H, 3.58; N,
15.30%.
1H NMR (400.13 MHz, DMSO-d6):
d = 10.63 (s, 1H, NH), 8.41 (s,
1H, CH), 7.95 (s, 1H, OH), 7.93 (dd, 1H, Thienyl, J = 1), 7.54 (d, 2H, Ar,
J = 8), 7.25 (d, 2H, Ar, J = 8), 7.09 (d, 1H, Thienyl, J = 3,4), 6.71 (q, 1H,
Thienyl, J = 1), 3.88 (d, 1H, H-4, J = 19), 3.56 (d, 1H, H-4, J = 19), 2.34
(s, 3H, Me).
Found: C, 52.24; H, 3.31; N, 15.73%.
13C NMR (100.61 MHz, DMSO-d6):
d = 149.4 (C55O), 146.2 (C-3),
(E)-N0-(4-Chlorobenzylidene)-[5-trifluoromethyl-5-hydroxy-3-
(methylphenyl)-4,5-dihydro-1H-pyrazol-1-yl]carbohydrazide (4ce).
White solid; yield 61%; mp 185–186 8C.
145.9 (C55N), 139.2, 131.9, 130.6, 126.6 (6 C, Ar), 133.0, 129.9,
129.3, 127.9, (4 C, Thienyl), 123.2 (q, 1J = 286, CF3), 91.3 (q, 2J = 33,
C-5), 45.1 (C-4), 20.9 (Me).
Anal. Calc. for C17H15F3N4O2S (396.39): C, 51.51; H, 3.81; N,
14.13%.
1H NMR (200.13 MHz, DMSO-d6):
d
= 10.93 (s, 1H, NH), 8.48 (s,
1H, CH), 7.98 (s, 1H, OH), 7.85 (d, 2H, Ar, J = 8), 7.71 (d, 2H, Ar, J = 8),
7.52 (d, 2H, Ar, J = 8), 7.32 (d, 2H, Ar, J = 8), 3.87 (d, 1H, H-4, J = 19),
3.56 (d, 1H, H-4, J = 19), 2.38 (s, 3H, Me).
Found: C, 51.42; H, 3.74; N, 14.09%.
(E)-N0-(3-Nitrobenzylidene)-[5-trifluoromethyl-5-hydroxy-3-(1-
naphthyl)-4,5-dihydro-1H-pyrazol-1-yl]carbohydrazide (4fb). Yellow
solid; yield 96%; mp 194–196 8C.
13C NMR (100.61 MHz, DMSO-d6):
d
= 151.9 (C55O), 150.2 (C-3),
149.4 (C55N), 144.4, 140.4, 133.9, 129.2, 128.8, 128.7, 127.5, 126.8,

312
H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
1H NMR (200.13 MHz, DMSO-d6):
d
= 11.15 (s, 1H, NH), 9.03 (d,
˚
Mo Ka radiation with l = 0.71073 A. The crystallographic struc-
1H, Ar, J = 8), 8.59 (s, 1H, CH), 8.52 (s, 1H, Ar), 8.27–8.22 (m, 2H, Ar),
8.12 (s, 1H, Ar), 8.08 (s, 1H, OH), 7.91 (d, 1H, Ar, J = 7), 7.79 (s, 1H,
Ar), 7.75 (s, 1H, Ar), 7.71–7.59 (m, 3H, Ar), 4.15 (d, 1H, H-4, J = 19),
3.78 (d, 1H, H-4, J = 19).
tures of the 4,5-dihydropyrazoles (4aa, 4ae, 4af, 4df) were solved
by direct methods (SHELXS-97) [20]. Refinements were carried out
with the SHELXL97 package [21]. The absorption correction was
performed by Gaussian methods [22]. All refinements were made
by full-matrix least-squares on F2 with anisotropic displacement
parameters for all non-hydrogen atoms. Hydrogen atoms were
included in the refinement in calculated positions with C–H
13C NMR (100.61 MHz, DMSO-d6):
d = 151.2 (C55O), 149.5 (C-3),
148.1 (C55N), 143.6, 136.4, 133.3, 132.7, 130.7, 130.2, 129.7, 128.5,
127.5, 126.7, 126.1, 124.8, 123.5, 120.3 (16C, Ar), 122.9 (q, 1J = 285,
CF3), 90.4 (q, 2J = 33, C-5), 47.0 (C-4).
˚
˚
˚
distances of 0.93 A (aromatic CH), 0.97 A (methylene CH2), 0.98 A
˚
Anal. Calc. for C22H16F3N5O2 (471.39): C, 56.05; H, 3.42; N,
14.86%.
(methine CH), 0.86 (NH) and 0.82 A (OH) using a riding model. The
hydrogen isotropic thermal parameters were kept equal to Uiso(H)
c 1.5 Ueq for Csp3, and 1.2 for Csp2. Molecular graphics were
prepared using ORTEP3 for Windows [23]. The crystal data and
details concerning data collection and structure refinement are
given in Table 6. Crystallographic data for the structure of 4aa, 4ae,
4af and 4df reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre and allocated the
deposition number CCDC 762876, 787517, 762875 and 762877,
respectively. Copies of the data can be obtained free of charge, on
application to CCDC 12 Union Road, Cambridge CB2 1EZ, UK (Fax:
+44 1223 336033 or deposit@ccdc.com.ac.uk).
Found: C, 56.01; H, 3.41; N, 14.94%.
(E)-N0-(4-Chlorobenzylidene)-[5-trifluoromethyl-5-hydroxy-3-(1-
naphthyl)-4,5-dihydro-1H-pyrazol-1-yl]carbohydrazide (4fe). Yellow
solid; yield 75%; mp 171–173 8C.
1H NMR (200.13 MHz, DMSO-d6):
d = 11.30 (s, 1H, NH), 8.98 (d,
1H, Ar, J = 8), 8.88 (s, 1H, CH), 8.08 (s, 1H, OH), 8.04–7.99 (m, 2H,
Ar), 7.88 (s, 1H, Ar), 7.73–7.62 (m, 3H, Ar), 7.54–7.40 (m, 4H, Ar),
4.13 (d, 1H, H-4, J = 19), 3.76 (d, 1H, H-4, J = 19).
13C NMR (100.61 MHz, DMSO-d6):
d = 151.0 (C55O), 149.7 (C-3),
142.0 (C55N), 133.3, 132.6, 131.9, 130.6, 129.7, 129.5, 128.3, 128.2,
127.4, 127.2, 126.9, 126.5, 126.1, 124.8 (16C, Ar), 123.1 (q, 1J = 285,
CF3), 90.4 (q, 2J = 33, C-5), 47.1 (C-4).
3.3. Antioxidant activity
Anal. Calc. for C22H16ClF3N4O2 (460.83): C, 57.34; H, 3.50; N,
12.16%.
3.3.1. DPPH assay on TLC (screening)
Found: C, 57.31; H, 3.48; N, 12.07%.
The compound was measured from the bleaching of the purple-
colored methanol solution of 2,2-diphenylpicrylhydrazyl (DPPH).
3.2. X-ray crystallography/X-ray diffraction data
Samples at the concentrations of 10, 25, 50, 100 and 200 mg/mL
were applied to the TLC plates (aluminum sheets covered with
silica gel 60 F254, Merck). The plate was sprayed with a 0.2% DPPH
reagent in methanol and left at room temperature for 30 min using
X-ray data were collected on a Bruker SMART CCD diffractom-
eter [19]. Data were collected using graphite-monochromatized
Table 6
General and crystal data and summary of intensity data collection and structure refinement for compounds.
Compound
4aa
4af
4df
4ae
Formula
C26H26F6N8O4
628.55
C14H15F3N4O2
328.30
C17H15F3N4O3
380.33
C13H14ClF3N4O3
366.73
Mr
CCDC
Temperature (K)
293(2)
293(2)
293(2)
296(2)
˚
Wavelength (A)
0.71073
Monoclinic
P21/n
0.71073
Monoclinic
P21/c
0.71073
Monoclinic
P2(1)
0.71073
Monoclinic
P21/c
Crystal system
Space group
Unit cell parameters
˚
a (A)
8.1603(2)
15.1323(5)
23.7584(9)
90
13.6533(4)
14.1863(5)
8.1226(2)
90
6.057(5)
9.272(5)
15.708(5)
90
9.6176(15)
8.2904(13)
19.471(3)
90
˚
b (A)
˚
c (A)
a
b
g
(8)
(8)
(8)
90
95.623(2)
90
99.941(5)
90
94.365(9)
90
90
3
˚
V (A )
2933.65(16)
4
1565.69(8)
4
868.9(9)
2
1548.0(4)
4
Z
Density (calculated) (g cmꢀ3
Absorption coefficient (mmꢀ1
F(0 0 0)
)
1.423
1.393
1.454
1.574
)
0.124
0.120
0.123
0.301
1296
680
392
752
Crystal size (mm)
0.585 ꢃ 0.190 ꢃ 0.088
1.60–28.33
ꢀ10 ꢄ h ꢄ 10
ꢀ20 ꢄ k ꢄ 20
ꢀ31 ꢄ l ꢄ 31
30,226
0.331 ꢃ 0.156 ꢃ 0.061
1.50–26.08
ꢀ16 ꢄ h ꢄ 16
ꢀ17 ꢄ k ꢄ 17
ꢀ10 ꢄ l ꢄ 10
13,349
0.220 ꢃ 0.210 ꢃ 0.034
3.41–27.18
ꢀ7 ꢄ h ꢄ 7
ꢀ11 ꢄ k ꢄ 11
ꢀ20 ꢄ l ꢄ 20
7820
0.20 ꢃ 0.16 ꢃ 0.15
2.10–26.82
ꢀ12 ꢄ h ꢄ 12
ꢀ8 ꢄ k ꢄ 10
ꢀ22 ꢄ l ꢄ 24
12,912
u
range for data collection (8)
h, k, l range
Reflections collected
Independent reflections
Data/restraints/parameters
Absorption correction
Refinement method
7294 [R(int) = 0.0515]
7294/0/405
Gaussian
3089 [R(int) = 0.0539]
3089/0/217
Gaussian
3798 [R(int) = 0.0369]
3798/1/246
Gaussian
3302 [R(int) = 0.0303]
3302/1/217
Gaussian
Full-matrix least-squares on F2 Full-matrix least-squares on F2 Full-matrix least-squares on F2 Full-matrix least-squares on F2
Final R indices [I > 2
s
(I)]
R1 = 0.0486, wR2 = 0.1222
R1 = 0.1017, wR2 = 0.1567
1.007
R1 = 0.0556, wR2 = 0.1425
R1 = 0.1071, wR2 = 0.1826
0.976
R1 = 0.0513, wR2 =0.1097
R1 = 0.1151, wR2 = 0.1352
0.963
R1 = 0.0394, wR2 = 0.1050
R1 = 0.0478, wR2 = 0.1115
1.036
R indices (all data)
Goodness of fit on F2
ꢀ3
˚
Largest diff. peak and hole (eA
)
0.379 and ꢀ0.420
0.366 and ꢀ0.317
0.163 and ꢀ0.173
0.436 and ꢀ0.492

H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
313
as standard antioxidant, quercetin, at the concentration of 2
m
g/
4. Conclusions
mL. Yellow spots formed from bleaching of the purple color of
DPPH reagent were evaluated as positive antioxidant activity [24].
In summary, we have demonstrated the facile and convenient
synthesis and a crystal structure study of a new series of
twenty-one trifluoromethyl-containing (E)-N0-arylidene-1H-
pyrazole-1-carbohydrazides (4) by the cyclocondensation reac-
tions of carbohydrazides (2) with aryl/heteroaryl aldehydes and
acetophenone in 52–97% yields. The carbohydrazides 2 were
easily obtained from the reaction of 1,1,1-trifluoro-4-alkyl(aryl/
heteroaryl)-4-methoxy-3-alken-2-ones (1) with carbohydrazide.
Subsequently, the twenty-seven pyrazolyl-carbohydrazides 2
and 4 were screened for their antioxidant and antimicrobial
proprieties and evaluated by DPPH and MIC methods. Both
series 2 and 4 showed ability to capture DPPH free radical for
3.3.2. Spectrophotometric DPPH assay
The DPPH radical scavenging model is extensively used to
evaluate antioxidant activities faster than other methods. Radical
scavenging activity of solutions at several concentrations of the
compounds 2 and 4 were evaluated against stable DPPH (2,2-
diphenyl-2-picrylhydrazyl
hydrate)
spectrophotometrically
according to Yen and Chen [6,25], with some modifications. The
absorbance decrease was measured at 517 nm on a UV-Visible
spectrophotometer.
For the quantitative evaluation of antioxidant capacity, samples
and standard BHT (Butylatedhydroxytoluene) were dissolved in
ethanol (3 mg/mL). To the 2 mL of ethanol was added 1 mL of
diluted sample. A serial dilution was performed resulting in
IC50 from 47.57 to 487
mg/mL but presented weak fungistatic
and bacteriostatic activity for high MIC levels ranging from
0.25 mg/mL to 0.5 mg/mL.
concentrations ranging from 250
mg/mL to 7.81 mg/mL. An
amount of 0.5 mL of methanol solution of DPPH 0.004% was
added to each sample. After 30 min of incubation at room
temperature away from light, the reduction of the DPPH free
radical was obtained by reading the absorbance against a blank in
each specific assess met, including samples in their respective
dilutions. As a control (0% inhibition), a solution of 2 mL of ethanol
and 0.5 mL of methanol of DPPH 0.004% solution was used.
BHT was used as a positive control. The experiment was carried
out in duplicate. Radical scavenging activity was calculated as
follows:
Acknowledgements
The authors thank the financial support from Conselho Nacional
de Desenvolvimento Cientıfico – CNPq (Proc. 303.296/2008-9) and
the Fundac¸a˜o de Amparo a Pesquisa do Estado do Rio Grande do Sul
(FAPERGS). Fellowships from Coordenac¸a˜o de Aperfeic¸oamento de
´
`
´
Pessoal de Nıvel Superior – CAPES and CNPq are also acknowl-
edged.
References
ꢀ
ꢁ
Absorbance of control ꢀ absorbance of sample
[1] J.C. Sloopa, C.L. Bumgardnerb, W.D. Loehlea, J. Fluorine Chem. 118 (2002) 135.
[2] H.G. Bonacorso, A.P. Wentz, R.V. Lourega, C.A. Cechinel, T.S. Moraes, H.S. Coellho,
N. Zanatta, M.A.P. Martins, M. Ho¨erner, S.H. Alves, J. Fluorine Chem. 127 (2006)
1006.
%Inhibition ¼
ꢃ 100
absorbance of control
The determination of the IC50 or concentration of sample or
pattern that causes 50% inhibition of DPPH was obtained by linear
regression from the points plotted by the average percentages
obtained.
[3] H.G. Bonacorso, A.D. Wastowski, N. Zanatta, M.A.P. Martins, J.A. Naue, J. Fluorine
Chem. 92 (1998) 23.
[4] R.B. Oliveira, E.M.S. Fagundes, R.P.P. Soares, A.A. Andrade, A.U. Krettli, C.L. Zani,
Eur. J. Med. Chem. 43 (2008) 1983.
[5] (a) L.T.S. Rocha, K.A. Costa, C.P. Oliveira, E.B. Nascimento Jr., C.M. Bertollo, F.
Arau´ jo, L.R. Teixeira, S.P. Andrade, H. Beraldo, M.M. Coelho, Life Sci. 79 (2006) 499;
(b) T. Hemalatha, P.K.M. Imran, A. Gnanamani, S. Nagarajan, Nitric Oxide 19
(2008) 303.
3.3.3. Antimicrobial testing (MIC)
The in vitro antimicrobial activity of the compounds 2
and 4 was assessed against a collection of microrganisms
including two yeasts C. albicans ATCC 10231 and Saccharomyces
cerevisiae ATCC 2601 and six bacteria Escherichia coli ATCC 25922,
Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis
ATCC 12228, Bacillus subtilis ATCC 6633, Klebsiellapneumoniae
ATCC 13883 and Streptococcus pyogenes ATCC 19615. Standard
microorganism strains were obtained from American Type
Culture Collection (ATCC), and standard antibiotics chloram-
phenicol and nistatine were used in order to control microbial
test sensitivity [26,27]. MIC as well as minimal fungicidal and
bactericidal concentrations were determined by broth micro-
dilution methods according to modified Hammer et al. [26] and
NCCLS standards [28–30].
Compounds from the series 2 and 4 were dissolved in DMSO/
EtOH (2.5 mg/mL) and the solutions were diluted with medium. By
further progressive dilutions with test medium the required
concentrations (0.5, 0.25, 0.125, 0.062, 0.031, 0.015 mg/mL) were
obtained.
The MIC was determined on 96 well culture plates by a micro
dilution method using a microorganism suspension with a density
of 105 CFU/mL in Casein Soy Broth (CSB) incubated for 24 h at
35 8C ꢂ 1 8C for bacteria, and Sabouraud Broth (SB) incubated for 48 h
at 25 8C ꢂ 1 8C for yeasts. The cultures that did not present growth
were used to inoculate solid medium plates (Muller Hinton Agar and
Sabouraud Agar) in order to determine the Minimal Lethal
Concentration (MLC). Proper blanks were assayed simultaneously
and samples were tested in duplicate.
[6] V. Gressler, S. Moura, A.F.C. Flores, D.C. Flores, P. Colepicolo, E. Pinto, J. Braz. Chem.
Soc. 21 (2010) 1477.
[7] X. Du, G. Chum, E. Hansell, P.S. Doyle, C.R. Caffrey, T.P. Holler, J.H. McKerrow, F.
Cohen, Eur. J. Med. Chem. 45 (2002) 2695.
[8] A. Shafiee, A. Rineh, A. Kebriaeezadeh, A. Foroumadi, V. Sheibani, M.R. Afarinesh,
Med. Chem. Res. 18 (2009) 758.
[9] H.G. Bonacorso, C.A. Cechinel, E.D. Deon, R.C. Sehnem, F.M. Luz, M.A.P. Martins, N.
Zanatta, N. ARKIVOC ii, 2009, p. 174.
[10] (a) F. Effenberger, R. Maier, K.H. Schonwalder, T. Ziegler, Chem. Ber. 115 (1982)
2766;
(b) F. Effenberger, K.H. Schonwalder, Chem. Ber. 117 (1984) 3270;
(c) M. Hojo, R. Masuda, E. Okada, Synthesis (1986) 1013;
(d) M. Hojo, R. Masuda, S. Sakaguchi, M. Takagawa, Synthesis (1986) 1016;
(e) G.M. Siqueira, A.F.C. Flores, G. Clar, N. Zanatta, M.A.P. Martins, Quim. Nova 17
(1994) 24;
(f) A.F.C. Flores, S. Brondani, N. Zanatta, A. Rosa, A.M.P. Martins, Tetrahedron Lett.
43 (2002) 8701;
(g) H.G. Bonacorso, M.B. Costa, S. Moura, L. Pizzuti, M.A.P. Martins, N. Zanatta,
A.F.C. Flores, J. Fluorine Chem. 126 (2005) 1396;
(h) H.G. Bonacorso, C.A. Cechinel, M.B. Costa, M.R. Oliveira, M.A.P. Martins, N.
Zanatta, A.F.C. Flores, J. Heterocycl. Chem. 42 (2005) 1055;
(i) M.A.P. Martins, E. Guarda, C.P. Frizzo, E. Scapin, P. Beck, A.C. Costa, N. Zanatta,
H.G. Bonacorso, J. Mol. Catal. A: Chem. 266 (2007) 100.
[11] M.A.P. Martins, D.N. Moreira, C.P. Frizzo, P.T. Campos, K. Longhi, M.R.B. Marzari, N.
Zanatta, H.G. Bonacorso, J. Mol. Struct. 969 (2010) 111.
[12] S.M.S.V. Wardell, M.V.N. de Souza, J.L. Wardell, J.N. Low, C. Glidewell, Acta
Crystallogr., Sect. B: Struct. Sci. 63 (2007) 879.
[13] P. Machado, P.T. Campos, G.R. Lima, F.A. Rosa, A.F.C. Flores, H.G. Bonacorso, N.
Zanatta, M.A.P. Martins, J. Mol. Struct. 917 (2009) 176.
[14] (a) G.R. Desiraju, Acc. Chem. Res. 35 (2002) 565;
(b) T. Steiner, Angew. Chem. Int. Ed. 41 (2002) 48.
[15] P. Pyykko, Chem. Rev. 97 (1997) 597.
[16] I.A. Vladimirov, Vestn. Ross. Akad. Med. Nauk. 7 (1998) 43.
[17] (a) H.W. Boucher, G.H. Talbot, J.S. Bradley, J.E. Edwards, D. Gilbert, L.B. Rice, M.
Sched, B. Spellberg, J. Bartlett, Clin. Infect. Dis. 48 (2009) 1;
(b) R.C. Moellering, Int. J. Antimicrob. Agents 37 (2011) 2.

314
H.G. Bonacorso et al. / Journal of Fluorine Chemistry 135 (2012) 303–314
[18] T. Kelesidis, I. Kelesidis, P.I. Rafailidis, M.E. Falagas, Antimicrob. J. Chemother. 60
(2007) 214.
[19] Bruker, APEX2 (Version 2.1), COSMO (Version 1.56), BIS (Version 2.0.1.9), SAINT
(Version 7.3A), SADABS (Version 2004/1) and XPREP (Version 2005/4), Bruker AXS
Inc., Madison, WI, USA, 2006.
[20] (a) G.M. Sheldrick, SHELXS-97, Program for Crystal Structure Solution, University
of Go¨ttingen, Germany, 1997.
(b) M. Ozgen, R.N. Reese, A.Z. Tulio Jr., J.C. Scheerens, A.R. Miller, Agric. J. Food.
Chem. 54 (2006) 1151.
[21] G.M. Sheldrick, SHELXL-97, Program for Crystal Structure Refinement, University
of Go¨ttingen, Germany, 1997.
[24] (a) C. Bicchi, A. D’Amato, P. Rubiolo, J. Chromatogr. 99 (1999) 843;
(b) E. Simionatto, Z.C. Stu¨ ker, J. Braz. Chem. Soc. 18 (2007) 879.
[25] G.C. Yen, H.Y. Chen, J. Agric. Food Chem. 43 (1995) 27.
[26] K.A. Hammer, C.F. Carson, T.V. Riley, J. Appl. Microbiol. 86 (1999) 985.
[27] E. Simionatto, C. Porto, Z.C. Stu¨ker, Quim. Nova 30 (2007) 1923.
[28] NCCLS, Reference Method for Broth Dilution Antifungal Susceptibility Testing of
Yeasts, Approved Standard, NCCLS Document M27-A2, National Committee for
Clinical Laboratory Standards, Wayne, PA, USA, 2002.
[29] NCCLS, Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria
that Grow Aerobically, Approved Standard, 5th ed., NCCLS Document M7-
A5, National Committee for Clinical Laboratory Standards, Wayne, PA, USA,
2002.
[22] P. Coppens, L. Leiserowitz, D. Rabinovich, Acta Crystallogr. 18 (1965) 1035.
[23] L.J. Farrugia, J. Appl. Crystallogr. 30 (1997) 565.
[30] S. Burt, Int. J. Food Microbiol. 94 (2004) 223.