Some biologically active oxovanadium(IV) complexes of triazole derived Schiff bases: their synthesis, characterization and biological properties

Figures & data

Scheme 1.  Preparation of proposed ligands.

Figure 1.  Proposed structure of the oxovanadium(IV) complexes.

Table 1.  Micronalytical data of the oxovanadium(IV) complexes.

No.	Complex	M.P. (dec.) (°C)	Yield (%)	Calc. (Found) (%)
				C	H	N
(1)	[VO(L1)2]SO4 [673.15]	239–241	90	42.80 (42.76)	2.69 (2.67)	20.80 (20.77)
	C24H18N10O9SV
(2)	[VO(L2)2]SO4 [729.19]	260–262	85	46.10 (46.07)	3.59 (3.56)	19.20 (19.16)
	C28H26N10O9SV
(3)	[VO(L3)2]SO4 [729.19]	254–256	89	46.10 (46.05)	3.59 (3.57)	19.20 (19.17)
	C28H26N10O9SV
(4)	[VO(L4)2]SO4 [810.18]	246–248	83	35.53 (35.49)	1.74 (1.71)	17.27 (17.25)
	C24H14Cl4N10O9SV
(5)	[VO(L5)2]SO4 [853.39]	220–222	87	33.78 (33.74)	1.65 (1.63)	22.98 (22.95)
	C24H14N14O17SV

Table 2.  Physical, spectral, and IR data of oxovanadium(IV) complexes.

No.	ΩM (Ω^−1 cm^2 mol^−1)	BM (μeff)	λmax (cm^−1)	IR (cm^−1)
(1)	80	1.78	13,339, 18,805, 29,860	1616 (HC=N), 490 (V-O), 455 (V-N), 978 (V=O), 1088 (SO4)
(2)	82	1.75	13,298, 18,826, 29,875	1619 (HC=N), 485 (V-O), 461(V-N), 980 (V=O), 1086 (SO4)
(3)	87	1.73	13,258, 18,845, 29,903	1618 (HC=N), 491 (V-O), 458(V-N), 982 (V=O), 1087 (SO4)
(4)	85	1.70	13,376, 18,870, 29,944	1621 (HC=N), 495 (V-O), 466(V-N), 981 (V=O), 1085 (SO4)
(5)	89	1.76	13,402, 18,889, 29,965	1623 (HC=N), 496 (V-O), 463(V-N), 979 (V=O), 1087 (SO4)

Table 3.  Antibacterial activity (concentration used 1 mg/mL of DMSO) of triazole derived Schiff bases and oxovanadium(IV) complexes.

Bacteria	Zone of inhibition (mm)
	L1	L2	L3	L4	L5	1	2	3	4	5	SD
Gram-negative
(a)	12	09	13	19	15	21	24	18	22	25	35
(b)	20	10	16	10	08	28	18	23	15	19	35
(c)	17	11	15	18	12	19	15	23	30	26	40
(d)	15	08	13	17	18	20	30	15	21	19	50
Gram-positive
(e)	10	07	13	14	09	11	17	15	19	12	20
(f)	12	13	20	13	21	18	23	25	16	25	30
SA	3.7237	2.1602	2.7568	3.4302	5.1153	5.4681	5.5647	4.4007	5.3944	5.4037	10

Note. (a), E. coli; (b), S. flexneri; (c), P. aeruginosa; (d), S. typhi; (e), S. aureus; (f), B. subtilis; <10, weak; >10, moderate; >16, significant; SD, standard drug (imipenem); SA, statistical analysis.

Figure 2.  Comparison of antibacterial activity.

Figure 3.  Average antibacterial activity of triazole derived Schiff bases versus oxovanadium(IV) complexes.

Table 4.  Antifungal activity (concentration used 200 µg/mL) of triazole derived Schiff bases and oxovanadium(IV) complexes.

Organism	%age Inhibition
	L1	L2	L3	L4	L5	1	2	3	4	5	SD
(a)	20	15	24	21	19	28	24	30	27	25	A
(b)	21	18	12	15	30	35	60	40	21	35	B
(c)	30	16	20	2	40	55	28	35	40	45	C
(d)	43	32	24	29	20	45	3	29	50	27	D
(e)	15	23	17	33	25	19	40	26	42	36	E
(f)	23	22	10	28	10	32	28	14	39	20	F
SA	9.9331	6.2609	5.9469	6.4627	10.2956	12.7383	13.1706	8.8543	10.5971	9.080

Note. (a), T. longifusus; (b), C. albicans; (c), A. flavus; (d), M. canis; (e), F. solani; (f), C. glabrata; SD, standard drugs, MIC: A, miconazole (70 µg/mL, 1.6822 × 10⁻⁷ M/mL); B, miconazole (110.8 µg/mL, 2.6626 × 10⁻⁷ M/mL); C, amphotericin B (20 µg/mL, 2.1642 × 10⁻⁸ M/mL); D, miconazole (98.4 µg/mL, 2.3647 × 10⁻⁷ M/mL); E, miconazole (73.25 µg/mL, 1.7603 × 10⁻⁷ M/mL); F, miconazole (110.8 µg/mL, 2.66266 × 10⁻⁷ M/mL); SA, statistical analysis.

Figure 4.  Comparison of antifungal activity.

Figure 5.  Average antifungal activity of triazole derived Schiff bases versus oxovanadium(IV) complexes.

Table 5.  Minimum inhibitory concentration (M/mL) of selected compounds (2), (3), and (4) against selected bacteria.

No.	2	3	4
Gram-negative
E. coli	—	—	1.628 × 10^−6
S. flexneri	—	—	—
P. aeruginosa	3.432 × 10^−7	—	—
S. typhi	—	—	—
Gram-positive
S. aureus	1.213 × 10^−6	—	5.476 × 10^−7
B. subtilis	—	2.303 × 10^−5	—

Table 6.  Brine shrimp bioassay data of triazole derived Schiff bases L₁–L₅ and oxovanadium(IV) complexes (1)–(5).

Ligand/complex	LD50 (M/mL)
L1	2.506 × 10^−3
L2	3.752 × 10^−3
L3	4.936 × 10^−3
L4	3.342 × 10^−3
L5	5.893 × 10^−3
(1)	1.781 × 10^−3
(2)	5.358 × 10^−3
(3)	2.325 × 10^−3
(4)	8.213 × 10^−4
(5)	6.819 × 10^−3