JOSEPH ET AL.
3
incubation at 37°C and of fungi after 48 h incubation at 37°C
was taken as the MIC. The concentration of DMSO in the
medium did not affect the growth of any of the microorga-
nisms tested.
Ligand L4. Molecular formula C27H21N7; molecular
weight 443 g mol−1. Yield 74%. Anal. Calcd (%): C,
73.13; H, 4.97; N, 22.10. Found (%): C, 72.92; H, 4.68;
N, 21.96. UV (nm): 340, 264. FT‐IR (KBr disc, cm−1):
3051–3298 (ArꢁH); 2931, 1637 (C¼N); 1274 (ꢁNH,
benzimidazole moiety). 1H NMR (CDCl3, δ, ppm):
7.32–8.5 (m, ArꢁH, 12H), 2.51 (1H, s, ꢁCH3, 6H), 8.7
(ꢁCH¼Cꢁ, s, 1H), 6.5 (ꢁNH(imidazole), 2H, s). FAB‐
MS (m/z): 444.
2.6 | Synthesis of knoevenagel condensate β‐diketones
A series of Knoevenagel condensate β‐diketones with diffe-
rent substituted aromatic aldehydes (3‐bromobenzaldehyde,
L1; 3‐fluorobenzaldehyde, L2; 3‐chlorobenzaldehyde, L3;
3‐cyanobenzaldehyde, L4) were refluxed in the presence of
potassium carbonate as a catalyst in ethanolic medium. The
product was formed with loss of water to afford substituted
β‐diketone. The progress of the reaction was monitored by
TLC. After completion of reaction, the reaction mixture was
poured on crushed ice. The yellow‐coloured Knoevenagel
condensate β‐diketone was obtained. The separated product
was filtered, washed with ice‐cold water and dried in vacuo.
2.8 | Synthesis of copper complexes
Ethanolic solutions of 2‐aminobenzoimidozole derivatives
(2 M) and copper acetate (1 M) were refluxed for about 6 h
at 40°C. The progress of the reaction was monitored by
TLC until the product was formed. Then, it was poured on
crushed ice. The solid material was removed by filtration
and recrystallized from ethanol.
Copper complex of L1. Molecular formula
C30H27N6O4BrCu; molecular weight 679 g mol−1. Yield
60%. Anal. Calcd (%): C, 53.07; H, 4.01; N, 12.37; Cu,
9.36. Found (%): C, 52.92; H, 3.86; N, 12.16; Cu, 9.14. UV
(nm): 336, 246, 468. FT‐IR (KBr disc, cm−1): 3068–3223
(ArꢁH); 2899, 1637 (C¼N); 1244 (ꢁNH, benzimidazole
moiety); 458 (MꢁO); 551 (MꢁN); 1413 νasy(COO−); 1156
2.7 | Synthesis of schiff base ligands
A hot ethanolic solution of 2‐aminobenzimidazole (2 M) was
added dropwise to 1 mol of Knoevenagel condensate β‐
diketone in the presence of 40 ml of ethanol and refluxed at
42°C with anhydrous potassium carbonate used as a
catalyst. The obtained product was set aside in a refrigerator
for 12 h. The progress of reaction was monitored by TLC.
After completion of reaction the solid material was removed
by filtration and recrystallized from ethanol.
νsy(COO−). FAB‐MS (m/z): 680. Λm = 11 Ω−1 cm2 mol−1
μeff = 1.83 BM.
;
Copper complex of L2. Molecular formula
C30H27N6O4FCu; molecular weight 618 g mol−1. Yield
64%. Anal. Calcd (%): C, 58.30; H, 4.40; N, 13.59; Cu,
10.28. Found (%): C, 58.05; H, 4.26; N, 13.44; Cu, 10.16.
UV (nm): 336, 246, 482. FT‐IR (KBr disc, cm−1): 3183–
3317 (ArꢁH); 2775, 1647 (C¼N); 1224 (ꢁNH, benzimid-
azole moiety); 489 (MꢁO); 530 (MꢁN); 1340 νasy(COO−);
Ligand L1. Molecular formula C26H21N6Br; molecular
weight 497 g mol−1. Yield 68%. Anal. Calcd (%): C, 62.79;
H, 4.26; N, 16.89. Found (%): C, 62.54; H, 4.02; N, 16.76.
UV (nm): 344, 252. FT‐IR (KBr disc, cm−1): 3048–3147
(ArꢁH); 2709, 1663 (C¼N); 1255 (ꢁNH, benzimidazole
1274 νsy(COO−). FAB‐MS (m/z): 619. Λm
Ω−1 cm2 mol−1; μeff = 1.80 BM.
=
9
1
moiety). H NMR (CDCl3, δ, ppm): 7.56–8.56 (m, ArꢁH,
12H), 2.51 (1H, s, ꢁCH3, 6H), 8.6 (ꢁCH¼Cꢁ, s, 1H), 6.5
(ꢁNH(imidazole), 2H, s). FAB‐MS (m/z): 498.
Copper complex of L3. Molecular formula
C30H27N6O4ClCu; molecular weight 635 g mol−1. Yield
60%. Anal. Calcd (%): C, 56.79; H, 4.29; N, 13.24; Cu,
10.01. Found (%): C, 56.58; H, 4.14; N, 13.10; Cu, 9.86.
UV (nm): 344, 252, 490. FT‐IR (KBr disc, cm−1):
3059–3215 (ArꢁH); 2316, 1633 (C¼N); 1274 (ꢁNH,
benzimidazole moiety); 472 (MꢁO); 621 (MꢁN); 1334 νasy
(COO−); 1166 νsy(COO−). FAB‐MS (m/z): 636. Λm = 7
Ω−1 cm2 mol−1; μeff = 1.85 BM.
Ligand L2. Molecular formula C26H21N6F; molecular
weight 436 g mol−1. Yield 72%. Anal. Calcd (%): C,
71.55; H, 4.85; N, 19.25. Found (%): C, 71.32; H, 4.72;
N, 19.08. UV (nm): 336, 244. FT‐IR (KBr disc, cm−1):
3064–3134 (ArꢁH); 2927, 1612 (C¼N); 1251 (ꢁNH,
benzimidazole moiety). 1H NMR (CDCl3, δ, ppm):
7.56–7.84 (m, ArꢁH, 12H), 3.51 (1H, s, ꢁCH3, 6H), 8.2
(ꢁCH¼Cꢁ, s, 1H), 5.2 (ꢁNH(imidazole), 2H, s). FAB‐
MS (m/z): 437.
Copper complex of L4. Molecular formula
C31H27N7O4Cu; molecular weight 625 g mol−1. Yield 74%.
Anal. Calcd (%): C, 59.57; H, 4.35; N, 15.68; Cu, 10.17.
Found (%): C, 59.34; H, 4.18; N, 15.52; Cu, 10.04. UV
(nm): 340, 266, 480. FT‐IR (KBr disc, cm−1): 3102–3160
(ArꢁH); 2860, 1760 (C¼N); 1264 (ꢁNH, benzimidazole
moiety); 462 (MꢁO); 560 (MꢁN); 1278 νasy(COO−); 1192
Ligand L3. Molecular formula C26H21N6Cl; molecular
weight 453 g mol−1. Yield 60%. Anal. Calcd (%): C, 68.95;
H, 4.67; N, 18.55. Found (%): C, 68.72; H, 4.46; N, 18.38.
UV (nm): 326, 248. FT‐IR (KBr disc, cm−1): 3047–3138
(ArꢁH); 2931, 1637 (C¼N); 1251 (ꢁNH, benzimidazole
moiety). 1H NMR (CDCl3, δ, ppm): 7.3–8.5 (m, ArꢁH,
12H), 2.5 (1H, s, ꢁCH3, 6H), 8.7 (ꢁCH¼Cꢁ, s, 1H), 6.4
(ꢁNH(imidazole), 2H, s). FAB‐MS (m/z): 454.
νsy(COO−). FAB‐MS (m/z): 626. Λm = 6 Ω−1 cm2 mol−1
μeff = 1.84 BM.
;