Synthesis, structures and antimicrobial activity of chloro- And fluoro-substituted thiocarboxyhydrazones

Article abstract of DOI:10.4067/S0717-97072015000200002

A series of chloro- And fluoro-substituted thiocarboxyhydrazones, 2-(2-chlorobenzylidene)-N-methylhydrazinecarbothioamide (1), 2-(4-fluorobenzylidene)- N-methylhydrazinecarbothioamide (2), and 2-(2-chloro-4-fluorobenzylidene)-N-methylhydrazinecarbothioami

Full text of DOI:10.4067/S0717-97072015000200002

J. Chil. Chem. Soc., 60, Nº 2 (2015)
SYNTHESIS, STRUCTURES AND ANTIMICROBIAL ACTIVITY OF CHLORO- AND FLUORO-SUBSTITUTED
THIOCARBOXYHYDRAZONES
ZENG-XIN LIU*
School of Chemistry and Chemical Engineering, Linyi University, Linyi Shandong 276005, P. R. China
ABSTRACT
A series of chloro- and fluoro-substituted thiocarboxyhydrazones, 2-(2-chlorobenzylidene)-N-methylhydrazinecarbothioamide (1), 2-(4-fluorobenzylidene)-
N-methylhydrazinecarbothioamide (2), and 2-(2-chloro-4-fluorobenzylidene)-N-methylhydrazinecarbothioamide (3), were synthesized and characterized by
elemental analysis, IR and UV-vis spectra, and single crystal X-ray diffraction. Structures of the three compounds are similar, but with slight modification by
chloro- and fluoro-substitute groups. The crystal structures of the compounds are stabilized by hydrogen bonds and π···π interactions. The antimicrobial activity
of the compounds shows that they are effective against some bacteria.
Keywords: thiocarboxyhydrazones; antimicrobial activity; crystal structure; hydrogen bonding.
6
INTRODUCTION
NMR (d -DMSO, ppm): 2.99 (s, 3H), 7.33 (d, 2H), 7.80 (d, 2H), 8.59 (s, 1H),
1
1.32 (s, 1H).
2-(2-Chloro-4-fluorobenzylidene)-N-methylhydrazinecarbothioamide (3):
Yield, 90%. Anal. Calc. for C H ClFN S: C, 44.0; H, 3.7; N, 17.1%. Found: C,
44.1; H, 3.6; N, 17.3%. IR data (KBr, cm ): 3296m, 3141w, 2986w, 2930w,
1598m, 1555s, 1518m, 1481m, 1425w, 1394w, 1245s, 1090m, 1040m, 910w,
The widespread excessive use of antibacterial agents lead to development
of more resistant bacteria to commonly used antibiotics. This has led to
intense research for new types of antibiotics. Hydrazones are a kind of
interesting biological active compounds. In recent years, a number of
9
9
3
-1
1
-6
-1
-1
hydrazones have been reported to have various antimicrobial activities.
855m, 669w, 619w, 445w. UV-Vis in methanol [λ , nm (ε, L mol cm )]: 318
max
1 6
Thiocarboxyhydrazones are a special kind of hydrazone compounds, with the
C=O groups replaced by C=S groups. The slight modification of the structures
(22525), 233 (10220). H NMR (d -DMSO, ppm): 2.99 (s, 3H), 7.19 (s, 1H),
7.26 (d, 1H), 7.78 (d, 1H), 8.93 (s, 1H), 12.05 (s, 1H), 11.55 (s, 1H).
7
-10
leads to more potent antimicrobial activities. In addition, such compounds
X-ray data collection and structure refinement: Suitable single crystals of
the compounds were selected and mounted in air onto thin glass fibers. Accurate
unit cell parameters were determined by a least-squares fit of 2θ values, and
intensity data sets were measured on a Bruker Smart 1000 CCD diffractometer
with Mo Kα radiation (λ = 0.71073 Å) at room temperature. The intensities
were corrected for Lorentz and polarization effects, but no corrections for
extinction were made. The structures of the compounds were solved by direct
methods using the SHELXL 97 program. The non-hydrogen atoms were
located in successive difference Fourier syntheses. The final refinement was
performed by full matrix least-squares methods with anisotropic thermal
1
1-13
have potential antitumor and cytotoxic properties.
Recent research
indicated that halido-substituted hydrazones have more potent activities than
1
4,15
those without such substitute groups.
In order to explore more effective
antimicrobial materials, in the present work, a serious of three chloro-
and fluoro-substituted thiocarboxyhydrazones, 2-(2-chlorobenzylidene)-
N-methylhydrazinecarbothioamide
(1),
2-(4-fluorobenzylidene)-N-
1
6
methylhydrazinecarbothioamide (2), and 2-(2-chloro-4-fluorobenzylidene)-N-
methylhydrazinecarbothioamide (3), have been prepared, characterized, and
studied on their antimicrobial activities.
2
parameters for non-hydrogen atoms on F . The amino hydrogen atoms were
EXPERIMENTAL
located from difference Fourier maps and refined isotropically, with N‒H
distances restrained to 0.90(1) Å. The remaining hydrogen atoms were located
at the calculated positions. Crystallographic data and experimental details for
structure analyses are summarized in Table 1. Selected bond lengths and angles
of the complexes are listed in Table 2.
General: All chemicals and solvents used during the synthesis were of
AR grade and used as received. 2-Chlorobenzaldehyde, 4-fluorobenzaldehyde,
-chloro-4-fluorobenzaldehyde and 4-methyl-3-thiosemicarbazide with
2
AR grade were purchased from Aldrich. Elemental analyses (CHN) were
performed using a Perkin-Elmer 240 elemental analyzer. Infrared spectrum
was recorded on a Nicolate Magna IR 750 series II FT-IR spectrophotometer
as KBr pellet. UV-Vis spectra from 200 to 600 nm were recorded on a Perkin-
Elmer Lambda-25 spectrophotometer. H NMR spectra were recorded on 300
MHz Brucker Advance.
Preparation of the compounds: The compounds were prepared according
to the same method. Equimolar quantities of 4-methyl-3-thiosemicarbazide
were reacted with 2-chlorobenzaldhyde, 4-fluorobenzaldehyde, and 2-chloro-
Fungal assay: C. albicans (ATCC 10231) was grown on Sabouraud
dextrose agar (SDA) plates at 37 ºC and maintained at 4 ºC for short-term
storage. Cultures were routinely sub-cultured every 4–6 weeks. Cultures were
8
-3
grown to the stationary phase (approximately 1 × 10 cells cm ) overnight at
37 ºC in minimal medium (2% w/v glucose, 0.5% w/v yeast nitrogen base,
0.5% w/v ammonium sulphate), again at 37 ºC. The complex (200 mg) were
dissolved in DMSO (1.0 mL) and diluted by water (9.0 mL) to give a stock
1
3
-1
solution with concentration of 2.0 × 10 μg mL . Doubling dilutions of the
solution were made to yield a series of test solutions. Minimum inhibitory
concentrations MIC100 values (minimum concentration required to inhibit 100%
of cell growth) were then determined using the broth microdilution method.
Bacterial screening: Bacteria were maintained on Nutrient Agar plates at
4 ºC and cultured in liquid broth when required. Liquid broth was used for the
antibacterial testing. Liquid broth (13 g) was dissolved in water (1000 mL)
in a Duran bottle, and then dispensed into 250 mL conical flasks, autoclaved
and allowed to cool. Solutions of the complex were prepared by dissolving
the complex (20 mg) in DMSO (0.5 mL). To the solution was added sterilised
4
-fluorobenzaldehyde, respectively, in methanol for 3 h, and the reaction
progress was monitored by TLC. Then, the solvent was removed by distillation
to give colorless solid. The precipitate formed was filtered and washed with
methanol and recrystallized from methanol. Single crystals suitable for X-ray
diffraction, were obtained by slow evaporation of the methanol solution of the
compounds.
2
-(2-Chlorobenzylidene)-N-methylhydrazinecarbothioamide (1): Yield,
9
3%. Anal. Calc. for C H ClN S: C, 47.5; H, 4.4; N, 18.5%. Found: C, 47.3;
9
10
3
-1
-3
H, 4.5; N, 18.4%. IR data (KBr, cm ): 3296m, 3123m, 2986w, 1654w, 1543s,
Millipore water (9.5 mL) to produce a stock solution of concentration 2.0 × 10
-1
1
4
523s, 1437m, 1239s, 1158w, 1090m, 1034m, 947w, 845m, 755m, 657m,
μg mL . Stock solution (0.5 mL) was added to sterile water (9 mL) to produce
a drug solution with concentration of 100 μg mL , and with the concentration
-1
-1
-1
51w. UV-Vis in methanol [λmax, nm (ε, L mol cm )]: 320 (20520), 230
1
6
(10360). H NMR (d -DMSO, ppm): 2.99 (s, 3H), 7.40-7.55 (m, 3H), 7.79 (d,
of DMSO being 0.5%. This solution (100 μL) was added to a microtiter plate.
1:1 serial dilutions were made so as to produce a test concentration range of
1
H), 9.00 (s, 1H), 11.73 (s, 1H).
-(4-Fluorobenzylidene)-N-methylhydrazinecarbothioamide (2): Yield,
7%. Anal. Calc. for C H FN S: C, 51.2; H, 4.8; N, 19.9%. Found: C, 51.1;
-1
2
50–0.1 μg mL . Both E. coli and MRSA were grown in liquid broth at 37 ºC
and 200 rpm to an OD600 of 1.0. The microtiter plate was inoculated with 100
μL of bacterial cells (OD600 = 1.0). The plates were incubated at 37 ºC for 24
h and OD600 values were read using an RMX plate reader to give MIC50 values
(minimum concentration required to inhibit 50% of cell growth).
8
9
10
3
-1
H, 4.8; N, 19.7%. IR data (KBr, cm ): 3339w, 3160m, 2995w, 2931w, 1609m,
1
5
555s, 1505s, 1400m, 1233s, 1152w, 1085m, 1034m, 929w, 830w, 582w,
26w, 477w. UV-Vis in methanol [λmax, nm (ε, L mol cm )]: 315 (18315). H
-1 -1 1
2
872

J. Chil. Chem. Soc., 60, Nº 2 (2015)
Table 1. Crystallographic data for the compounds.
1
2
3
Empirical formula
Formula weight
Crystal system
Space group
Unit cell dimensions
a (Å)
C H ClN S
C H FN S
C H ClFN S
9
10
3
9
10
3
9
9
3
227.7
211.3
245.7
Monoclinic
Monoclinic
Monoclinic
C2/c
P2 /c
C2/c
1
14.3289(8)
8.0603(5)
7.4960(6)
14.8095(10)
9.3833(6)
97.590(2)
1032.5(1)
4
13.850(2)
8.9415(11)
18.167(3)
b (Å)
c (Å)
18.7173(11)
90.892(2)
β (º)
92.963(2)
3
Cell volume (Å )
2161.5(2)
2246.7(5)
Number of formula units/cell (Z)
8
8
-3
Dcalc (g cm )
F(000)
1.399
1.359
1.453
944
440
1008
-1
Absorption coefficient (mm )
Temperature (K)
0.510
0.291
0.509
298(2)
298(2)
298(2)
Wavelength (Å)
0.71073
0.71073
0.71073
Crystal size (mm)
0.23×0.21×0.20
2.18-26.42
-17, 17; -10, 10; -23, 19
26.42 (98.7%)
0.8917, 0.9048
10522
0.23×0.23×0.22
2.59-25.50
-9, 9; -16, 17; -11, 11
25.50 (99.6%)
0.9360, 0.9387
8784
0.17×0.15×0.15
2.71-25.50
-16, 14; -10, 9; -21, 20
25.50 (99.7%)
0.9185, 0.9276
9040
θ Range for data collection (º)
Index ranges (h, k, l)
Completeness to theta
Maximum and minimum transmission
Total number of reflections measured
Totle number of unique reflections (Rint)
Number of observed reflections [I > 2σ(I)]
Data/restraints/parameters
2195 (0.0269)
1885
1915 (0.0368)
1519
2077 (0.0305)
1644
2195/2/134
1.053
1915/2/134
1.050
2077/2/143
1.037
2
Goodness-of-fit on F
Final R indices [I > 2σ(I)]
R indices (all data)
R = 0.0319, wR = 0.0847
R = 0.0414, wR = 0.1021
R = 0.0359, wR = 0.0882
1
2
1
2
1
2
R = 0.0397, wR = 0.0917
R = 0.0549, wR = 0.1113
R = 0.0513, wR = 0.0969
1
2
1
2
1
2
-3
Largest diff. peak and hole (e Å )
0.203, -0.176
0.217, -0.182
0.274, -0.226
Table 2. Selected bond lengths (Å) and bond angles (°) for the compounds.
RESULTS AND DISCUSSION
1
Chemistry: 4-Methyl-3-thiosemicarbazide treated with appropriate
aldehydes to produce the desired products (Scheme 1). The purity of all
products was determined by TLC using several solvent systems of different
polarities. The synthesized compounds were characterized by elemental
C7-N1
C8-N2
1.275(2)
1.351(2)
1.319(2)
116.1(1)
119.1(1)
N1-N2
C8-S1
1.373(2)
1.692(2)
C8-N3
1
analysis, IR and UV-vis spectra, and H NMR spectra.
C7-N1-N2
N2-C8-S1
2
N1-N2-C8
N2-C8-N3
119.3(1)
116.8(1)
C7-N1
1.272(2)
1.352(3)
1.325(2)
117.1(2)
123.8(2)
N1-N2
C8-S1
1.369(2)
1.682(2)
N2-C8
C8-N3
Scheme 1. Synthesis of the compounds. 1: X = Cl, Y = H; 2: X = H, Y =
F; 3: X = Cl, Y = F.
C7-N1-N2
N2-C8-S1
3
N1-N2-C8
N2-C8-N3
120.2(2)
117.1(2)
1
Spectra analysis: The H NMR spectra of the compounds show signals
at about 11-12 ppm, which are related to the protons of the NH groups. The
signals of the protons on the CH=N double bonds appear at about 8.5-9.0 ppm,
and the aromatic protons occur in the range 7.2-7.8 ppm. The signals indicative
C7-N1
1.281(2)
1.355(2)
1.315(3)
115.8(2)
119.0(2)
N1-N2
C8-S1
1.368(2)
1.687(2)
N2-C8
of the protons of the CH groups are located at 2.99 ppm.
3
The IR and UV-vis spectra (Fig. 1) of the compounds are very similar.
C8-N3
-1
The medium and sharp bands at about 3300 cm are assigned to the νN-H. The
C7-N1-N2
N2-C8-S1
N1-N2-C8
N2-C8-N3
120.5(2)
116.2(2)
-1
bands observed at slight over and below 3000 cm are assigned to the aromatic
-1
and aliphatic C-H vibrations. The intense bands at about 1550 cm are due to
1
7
the absorption of the C=N bonds. The medium bands in the region 830-860
2
873

J. Chil. Chem. Soc., 60, Nº 2 (2015)
-1
cm are attributed to the νC-S. The absorptions of the electronic spectra may be
assigned to the n→π* transitions.
Figure 4. ORTEP view of the molecular structure of 3, showing the atom
numbering scheme for non-hydrogen atoms.
In the crystal packing diagram of the compounds (Figure 5 for 1, Figure
6
for 2, Figure 7 for 3), molecules are linked through intermolecular N‒H···S
hydrogen bonds (Table 3) and π···π interactions (Table 4), to form 1D chains.
Figure 1. UV-vis spectra of the compounds.
Crystal structure description: The molecular structures of the compounds
1
, 2, and 3 are shown in Figures 2, 3, and 4, respectively. In each of the
compounds, the sulphur atom and the azomethine nitrogen atom are in trans
position with respect to the N2-C8 bond. The molecules of the compounds
are not coplanar, as evidenced by the dihedral angles [14.0(4)º for 1, 16.7(3)
º for 2, and 5.2(3)º for 3] between the N1N2C8S1 thiourea groups and the
benzene rings. The bond distances in the thiosemicarbazone side chains agree
well with the values observed for similar compounds where the C=S groups
1
7
are present in the thionic form. There is no obvious charge delocalization in
the molecules, as evidenced by the typical C-N single bonds between atoms
C8 and N3.
Figure 5. Molecular packing diagram of 1. Hydrogen bonds are drawn as
dashed lines.
Table 3. Hydrogen-bond geometry (Å, °) for the compounds.
D–H···A
1
D–H
H···A
D···A
D–H···A
Figure 2. ORTEP view of the molecular structure of 1, showing the atom
numbering scheme for non-hydrogen atoms.
i
N3–H3A···S1
0.90(1)
0.90(1)
2.83(2)
3.497(2)
3.414(1)
133(2)
171(2)
ii
N2–H2···S1
2.526(10)
2
iii
N3–H3···S1
0.90(1)
0.90(1)
2.86(2)
2.58(1)
3.499(2)
3.445(2)
130(2)
165(2)
3
ii
N2–H2···S1
Symmetry codes: (i) 1/2 – x, 1/2 + y, 3/2 – z; (ii) 1 – x, y, 3/2 – z; (iii) x,
/2 – y, –1/2 + z.
3
Figure 3. ORTEP view of the molecular structure of 2, showing the atom
numbering scheme for non-hydrogen atoms.
2
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J. Chil. Chem. Soc., 60, Nº 2 (2015)
Table 4. Parameters between the planes for the compounds.
Distance
between ring
centroids (Å)
Perpendicular
distance of Cg(I)
on Cg(J) (Å)
Beta
angle
(º)
Perpendicular
distance of Cg(J)
on Cg(I) (Å)
Dihedral
angle (º)
Gamma
angle (º)
Cg
Slippage
1
iv
v
Cg(1)-Cg(1)
4.2739
4.6898
0
0
-3.5826
3.4799
33.0
42.1
33.0
42.1
2.331
3.144
-3.5826
3.4799
Cg(1)-Cg(1)
3
vi
Cg(2)-Cg(2)
3.7558
4.8459
0
0
3.4979
21.4
46.6
21.4
46.6
1.368
3.521
3.4979
vii
Cg(2)-Cg(2)
-3.3297
-3.3297
Symmetry codes: (iv): – x, – y, – z; (v): 1/2 – x, 1/2 – y, – z; (vi): 1 – x, 1 – y, – z; (vii): 1/2 – x, 1/2 – y, – z. Cg(1) and Cg(2) are the
centroids of C1-C2-C3-C4-C5-C6 (1) and C1-C2-C3-C4-C5-C6 (3), respectively.
Biological assay results: The biological assay results are summarized in
Table 5. Compound 1 has medium activity against C. albicans and E. coli, but
no activity against MRSA. Compounds 2 and 3 have similar activities against
C. albicans and E. coli. As for the activity on MRSA, compound 3 is better
than compound 2. From the results, it is not difficult to see that the 4-fluoro
containing compound 2 has stronger activities than the 2-chloro containing
compound 1. When the chloro and fluoro groups are combined together to one
new compound 3, the activities are not improved obviously, except for MRSA.
CONCLUSION
In summary, three new similar chloro- and fluoro-substituted
thiocarboxyhydrazones have been prepared and characterized. Single crystal
structures of the compounds are presented. The antimicrobial activity of the
compounds shows that they are effective against some bacteria.
Supplementary data
Crystallographic data for structural analyses have been deposited with the
Cambridge Crystallographic Data Centre, CCDC Nos. 981995 (1), 981996 (2),
and 981997 (3). Copies of this information may be obtained free of charge
from The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax:
+44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.
ac.uk).
-1
Table 5. Antimicrobial assay results (μmol L ).
C. albicans
MIC100
MRSA
MIC50
E. coli
MIC50
Compound
1
2
3
12.5
3.12
3.12
>50
25
ACKNOWLEDGMENTS
The author acknowledges the Linyi University for supporting this work.
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2
875