J. da Silva Santos et al. / Journal of Fluorine Chemistry 195 (2017) 31–36
35
3
4
5
3J4,5 = 9.5 Hz, J5,6 = 10 Hz, 1H, H-5); 8.11 (q, J2,6 = 8 Hz, J3,6 = 4 Hz,
4.2.9. 3,4-Difluoro-benzaldehyde thiosemicarbazone (3i)
Yield: 95%; m.p.198 ꢁC. IR (KBr) nmax in cmꢀ1: 3421, 3390 (NH2);
4J4,6 = 6 Hz, 1H, H-6). 13C NMR (500 MHz, DMSO-d6):
d 178.8 (s, C-
2
3
40); 151.2 (dddd, JC-F = 249.5 Hz, J3,4 = 9 Hz, J2,4 = 3 Hz, 1C, C-4);
148.5 (dddd, JC-F = 253.0 Hz, 2J2,3 = 11 Hz, 3J2,4 = 3 Hz, 1C, C-2); 139.4
(dt, JC-F = 247.5 Hz, 2J2,3 = 15–16 Hz,1C, C-3); 133.2 (s,1C, C-10); 121.8
(t, 3J2,6 = 3–4 Hz,1C, C-6); 120.6 (q, 2J1,2 = 6.5 Hz, 3J1,3 = 3 Hz,1C, C-1);
3159 (NH); 1508 (C
¼
N); 1280 (CꢀꢀF); 1093 (C
¼
S). 1H NMR
(500 MHz, DMSO-d6):
d
11.53 (s, 1H, H-30); and 8.21 (bs, 1H, H-60);
8.00 (s, 1H, H-10); 7.27 (bs, 1H, H-50); 7.55 (m, 1H, H-2); 7.45 (q,
3
3
4J3,5 = 8 Hz, J4,5 = 12 Hz, J5,6 = 10 Hz, 1H, H-5); 8.12 (dddd,
113.6 (dd, J4,5 = 18 Hz, J3,5 = 3 Hz, 1C, C-5). 19F NMR (500 MHz,
5J3,6 = 2 Hz, J4,6 = 4 Hz, 1H, H-6). 13C NMR (500 MHz, DMSO-d6):
d
2
3
4
DMSO-d6):
d
ꢀ133.3 (1F, FC-4); ꢀ142.9 (1F, FC-2); ꢀ161.7 (1F, FC-3).
178.7 (s, C-40); 151.9 (dd, JC-F = 248.5 Hz, 2J3,4 = 13 Hz, 1C, C-3); 149.1
(d, JC-F = 245.5 Hz, 2J3,4 = 13 Hz, 1C, C-4); 140.2 (s, 1C, C-10); 132.7 (d,
3J1,3 = 6 Hz, 4J1,4 = 3 Hz, 1C, C-1); 125.6 (t, 4J6,3 = 3 Hz, 1C, C-6); 118.1
Anal. Calcd for C8H5F3N3S: C, 41.20; H, 2.59; N; 18.02; S, 13.75;
Found: C, 41.08; H, 2.67; N, 18.32; S, 13.64.
2
2
(d, J4,5 = 18 Hz, 1C, C-5); 115.5 (d, J2,3 = 18 Hz, 1C, C-2). 19F NMR
4.2.5. 2,3,5,6-Tetrafluoro-benzaldehyde thiosemicarbazone (3e)
Yield: 93%; m.p. 227 ꢁC. IR (KBr) nmax in cmꢀ1: 3410, 3238 (NH2);
3140 (NH); 1523 (C
(500 MHz, DMSO-d6):
d
ꢀ136.5 (d, 3J3,4 = 25 Hz, 1F, FC-3); ꢀ138.2 (d,
3J3,4 = 25 Hz, 1F, FC-4). Anal. Calcd for C9H9F2N3S: C, 44.65; H, 3.28;
¼
N); 1296 (CꢀꢀF); 1076 (C
¼
S). 1H NMR
N, 19.52; S, 14.90; Found: C, 44.57; H, 3.36; N, 19.71; S, 14.83.
(500 MHz, DMSO-d6):
d
11.83 (s, 1H, H-30); 8.54 (bs, 1H, H-50); 8.16
(s, 1H, H-10); 7.89 (m, 1H, H-4); 7.42 (bs, 1H, H-60). 13C NMR
4.2.10. 4-Trifluoromethyl-benzaldehyde thiosemicarbazone (3j)
Yield: 95%; m.p. 170 ꢁC. IR (KBr) nmax in cmꢀ1: 3417, 3244 (NH2);
(500 MHz, DMSO-d6):
d
178.9 (s, C-40); 146.1 (ddd, JC-F = 244.5 Hz,
3
2J2,3 = 13 Hz, J2,4 = 4 Hz, 2C, C-2, C-6); 144.4 (ddd, JC-F = 253.0 Hz,
3143 (NH); 1517 (C
(500 MHz, DMSO-d6):
¼
N); 1294 (CꢀꢀF); 1089 (C
¼
S). 1H NMR
J2,3 = 14 Hz, 3J3,5 = 5 Hz, 2C, C-3, C-5); 131.5 (t, 3J1 ,2 = 3 Hz, 1C, C-10);
d
11.63 (s, 1H, H-30); 8.36 (bs, 1H, H-50);
2
0
114.7 (t, 2J1,2 = 11–12 Hz, 1C, C-1); 107.6 (t, 2J3,4 = 23 Hz, 1C, C-4). 19
F
8.20 (bs,1H, H-60); 8.11 (s, 1H, H-10); 8.03 (d, 4J2,6 = 2 Hz, 2H, H-2, H-
6); 7.74 (d, 4J3,5 = 2 Hz, 2H, H-3, H-5).13C NMR (500 MHz, DMSO-d6):
3
4
NMR (500 MHz, DMSO-d6):
d
ꢀ139.6 (q, J5,6 = 20 Hz, J3,5 = 15 Hz,
3
4
2F, FC-3, FC-5); ꢀ142.5 (q, J2,3 = 25 Hz, J2,6 = 15 Hz, 2F, C-2, C-6).
Anal. Calcd for C8H4F4N3S: C, 38.25; H 2.01; N, 16.73; S,12.76;
Found: C, 38.07; H, 2.32; N, 16.86; S, 12.65.
d
178.8 (s, C-40); 140.7 (s, 1C, C-10); 138.7 (s, 1C, C-1); 129.9 (d, 2J4C-
F = 32 Hz, 1C, C-4); 128.3 (s, 2C, C-2, C-6); 125.9 (d, 3J3C-F = 3 Hz, 2C,
C-3, C-5); 123.9 (d, JC-F = 544.3 Hz, 1C, FCF3). 19F NMR (500 MHz,
DMSO-d6):
d
ꢀ61.0 (3F, CF3). Anal. Calcd for C9H7F3N3S: C, 43.72; H,
4.2.6. 2,3,4,5,6-Pentafluoro-benzaldehyde thiosemicarbazone (3f)
Yield: 95%; m.p. 245 ꢁC. IR (KBr) nmax in cmꢀ1: 3417, 3244 (NH2);
3.26; N, 17.00; S, 12.97; Found: C, 43.61; H, 3.41; N, 17.23; S, 12.73.
3143 (NH); 1517 (C
(500 MHz, DMSO-d6):
8.12 (s,1H, H-10); 7.43 (bs,1H, H-60). 13C NMR (500 MHz, DMSO-d6):
179.0 (s, C-40); 146.3 (m, JC-F = 253.5 Hz, 2C, C-2, C-6); 141.5 (m, JC-
F = 257.5 Hz, 1C, C-4); 137.9 (m, JC-F = 246.5 Hz, 2C, C-3, C-5); 130.8
¼
N); 1292 (CꢀꢀF); 1072 (C
¼
S). 1H NMR
4.3. Biological activity assays
d
11.79 (s, 1H, H-30); 8.52 (bs, 1H, H-50);
4.3.1. Parasites
d
T. cruzi epimastigotes from Y strain [30], were cultivates at 26 ꢁC
in liver infusion LIT (Liver Infusion Triptose) medium supple-
mented with 10% heat inactivated fetal calf serum, 100 U/mL
penicillin, and 100 mg/mL streptomycin. The epimastigotes were
collected in the log phase of cell culture growth. The parasites were
centrifuged (2500 rpm) by 15 min at 4 ꢁC and, resuspended with
PBS (Phosphate Buffered Saline) buffer and the pellet were counted
in Neubauer chamber to final concentration of 4 ꢅ106 parasites/mL
of the cell suspension.
3
2
3
(d, J1 ,2 = 2 Hz, 1C, C-10); 110.1 (dt, J1,2 = 12.3 Hz, J1,3 = 4 Hz,
0
4J1,4 = 3 Hz, 1C, C-1). 19F NMR (500 MHz, DMSO-d6):
d
ꢀ162.7 (td,
3J3,4 = 25 Hz, J3,6 = 10 Hz, 2F, FC-3, FC-5); ꢀ153.4 (t, J4,5 = 25 Hz,
4J4,6 = 22.5 Hz, 2F, FC-3, FC-5); ꢀ142.1 (dd, 3J2,3 = 25 Hz, 4J2,4 = 22.5 Hz,
5J2,5 = 10 Hz, 4J2,6 = 15 Hz, 2F, C-2, C-6). Anal. Calcd for C8H3F5N3S: C,
35.69; H, 1.50; N, 15.61; S, 11.91; Found: C, 35.48; H, 1.72; N, 5.79; S,
11.76.
5
3
4.2.7. 3,5-Difluoro-benzaldehyde thiosemicarbazone (3g)
4.3.2. Assays
Yield: 92%; m.p. 205 ꢁC. IR (KBr) nmax in cmꢀ1: 3446, 3394
T. cruzi epimastigotes at 5.106/mL were incubated in LIT
medium with fluorinated thiosemicarbazones (3a–j), and in the
absence (negative control), and in the presence of benzinidazol as
positive control. The compounds were solubilized in DMSO (1.5% v/
(NH2); 3159 (NH); 1508 (C
(500 MHz, DMSO-d6):
¼
N); 1315 (CꢀꢀF); 1097 (C
¼
S). 1H NMR
d
11.63 (s, 1H, H-30); 8.33 (bs, 1H, H-50); 8.28
3
4
(bs, 1H, H-60); 7.98 (s, 1H, H-10); 7.62 (dd, J2,3 = 8 Hz, J2,4 = 4 Hz,
5J2,5 = 1.6 Hz, 4J2,6 = 4 Hz, 2H, H-2 e H-6); 7.22 (tt, 3J3,4 = 8 Hz, 1H, H-
v) in the range concentration of 100–3.125 mg/mL. The parasite
4). 13C NMR (500 MHz, DMSO-d6):
d
178.8 (s, C-40); 162.0 (dd, JC-
cultures were incubated at 26 ꢁC by 24 h in 96-well plates. The
living epimastigotes were counted using a Neubauer chamber, and
the EC50 values, corresponding to effective dose that kills 50% of the
parasites were calculated using a perceptual of live parasites versus
log dose and, after applied linear regression to resulting curve. The
untreated parasites were used as controls. Pentamidine isothio-
3
F = 245.0 Hz, J3,5 = 13–14 Hz, 2C, C-3 e C-5); 139.8 (m, 1C, C-10);
138.7 (t, 3J1,3 = 9–11 Hz, 1C, C-1); 110.6 (dd, 2J2,3 = 22 Hz, 2C, C-2, C-
6); 104.7 (t, 2J3,4 = 26 Hz, 1C, C-4). 19F NMR (500 MHz, DMSO-d6):
d
ꢀ109.7 (2F, C-3, C-5). Anal. Calcd for C9H9F2N3S: 44.65; H, 3.28; N,
19.52; S, 14.90; Found: C, 44.59; H, 3.52; N, 19.74; S, 14.98.
nate was used as reference drug (IC50 = 10 ug/mL, 16.90
tests were carried out in triplicate.
mM). All
4.2.8. 4-Fluoro-benzaldehyde thiosemicarbazone (3h)
Yield: 96%; m.p.193 ꢁC. IR (KBr) nmax in cmꢀ1: 3433, 3253 (NH2);
3151 (NH);1521 (C
¼
N); 1286 (CꢀꢀF); 1085 (C
¼
S). 1H NMR
4.4. Descriptors calculation and 2D-QSAR
(500 MHz, DMSO-d6):
d
11.47 (s, 1H, H-30); 8.31 (bs, 1H, H-50);
8.10 (bs, 1H, H-60); 8.04 (s, 1H, H-10); 7.84 (t, 4J2,6 = 6 Hz, 2H, H-2, H-
The molecular structures were drawn by ACD/ChemSketch
software (ACDLabs software package, version 12.0), and the values
of physical-chemistry descriptors, such as, log P, molar refractivity
(MR) and, molar volume (MV) were calculated for each compound.
The 2d-QSAR models were derived by multiple regression
analysis that were performed using the BuildQSAR program [29] to
determine the equations and the statistic parameters. In equations
the numbers in parentheses represent the 95% of confidence
intervals of the coefficients, n is number of data points, r is the
6); 7.19 (t, 3J3,4 = 8 Hz, 4J3,5 = 4 Hz, 2H, H-3, H-5). 13C NMR (500 MHz,
DMSO-d6):
d
178.4 (s, C-40); 164.4 (d, JC-F = 247.5 Hz, 1C, C-4); 141.6
(s,1C, C-10); 131.2 (d, 4J1,4 = 2 Hz,1C, C-1); 129.9 (d, 3J2,4 = 8 Hz, 2C, C-
2, C-6); 116.1 (d, J3C-F = 22 Hz, 2C, C-3, C-5). 19F NMR (500 MHz,
2
DMSO-d6):
d
ꢀ110.9 (s, 1F, FC-4). Anal. Calcd for C8H7FN3S: C, 48.72;
H, 4.09; N, 21.31; S, 16.26; Found: C, 48,68; H, 4.17; N, 21.46; S,
16.05.