Synthesis, spectral characterization and in vitro biological studies of Co(II), Ni(II) and Cu(II) complexes with 1,2,4-triazole Schiff bases

Figures & data

Figure 1.  Structure of Schiff bases.

Table I.  Elemental analysis of Co(II), Ni(II) and Cu(II) complexes and their magnetic and molar conductance data.

Comp. Empirical formula		M%		C%		H%		N%		Molar conductance Ohm-1 cm-2 mole^− 1	Mag. Moments (μeff BM)
No.		Obsd	Calcd	Obsd.	Calcd	Obsd.	Calcd	Obsd.	Calcd
I	C24H18N6O6	–	–	59.17	59.25	3.67	3.70	17.22	17.28	–	–
II	C25H20N6O6	–	–	59.91	60.00	3.94	4.00	16.77	16.80	–	–
III	C26H22N6O6	–	–	60.62	60.70	4.21	4.28	16.31	16.34	–	–
IV	C27H24N6O6	–	–	61.31	61.36	4.49	4.54	15.88	15.90	–	–
1	Co(C24H16N6O6).2H2O	10.16	10.18	49.72	49.74	2.73	2.76	14.48	14.51	22	4.62
2	Co(C25H18N6O6).2H2O	9.91	9.94	50.57	50.59	3.02	3.04	14.15	14.17	24	4.90
3	Co(C26H20N6O6).2H2O	9.69	9.71	51.38	51.41	3.27	3.29	13.81	13.84	20	4.52
4	Co(C27H22N6O6).2H2O	9.45	9.49	52.15	52.18	3.53	3.54	13.51	13.53	27	4.63
5	Ni(C24H16N6O6).2H2O	10.11	10.14	49.75	49.76	2.75	2.76	14.50	14.52	23	3.35
6	Ni(C25H18N6O6).2H2O	9.88	9.90	50.61	50.62	3.01	3.03	14.14	14.17	27	3.22
7	Ni(C26H20N6O6).2H2O	9.65	9.67	51.41	51.43	2.27	3.29	13.82	13.85	26	3.15
8	Ni(C27H22N6O6).2H2O	9.42	9.45	52.16	52.19	3.51	3.54	13.50	13.53	23	3.23
9	Cu(C24H16N6O6).2H2O	10.87	10.89	49.33	49.35	2.71	2.74	14.37	14.39	28	1.68
10	Cu(C25H18N6O6).2H2O	10.61	10.63	50.19	50.21	3.00	3.01	14.03	14.06	18	1.80
11	Cu(C26H20N6O6).2H2O	10.37	10.39	51.01	51.02	3.26	3.27	13.71	13.74	26	1.72
12	Cu(C27H22N6O6).2H2O	10.14	10.16	51.78	51.79	3.50	3.52	13.41	13.43	19	1.65

Table II.  The important infrared frequencies (cm⁻¹) of 3-substituted-4-amino (8-formyl-7-hydroxy-4-methylcoumarin)-5-hydrazino-1,2,4-triazole Schiff bases.

Ligand No.	v (NH)	Lactone v (C = O)	V (C = N)	H-bonded –OH Stretching	v (C = C)	Phenolic v (C–O)
I	3130 brm 3071 m	1700	1625	2758	1590	1279
II	3125 brm 3068 m	1707	1630	2750	1600	1285
III	3115 brm 3058 m	1705	1615	2755	1595	1292
IV	3120 brm 3065 m	1710	1620	2752	1597	1294

Table III.  The important infrared frequencies (in cm−1) of Co(II), Ni(II) and Cu(II) complexes of 3-substituted-4-amino (8-formyl-7-hydroxy-4-methylcoumarin)-5- hydrazino-1,2,4-triazole Schiff bases.

Complex No.	v (OH)	v (C = O)	V(C = N)	Phenolic v (C–O)	v (M-N)	v(NH)	v (M-O)
1	3440	1615	1380	1704	535	3010	376
2	3435	1707	1620	1377	540	3003	378
3	3430	1700	1605	1372	475	3006	375
4	3434	1705	1610	1379	480	2995	379
5	3429	1700	1614	1375	520	2998	380
6	3431	1707	1624	1374	510	3001	381
7	3430	1705	1607	1377	495	3000	379
8	3429	1710	1609	1373	485	3005	384
9	3427	1712	1613	1371	532	2995	382
10	3437	1707	1619	1370	515	2990	385
11	3432	1705	1604	1376	474	3008	381
12	3438	1704	1602	1372	460	3007	378

Figure 2.  FAB-mass spectrum of Schiff base (II).

Figure 3.  FAB-mass spectrum of Ni(II) (6) complex.

Table IV.  Ligand field parameters of Ni(II) complexes with 3-substituted-4-amino (8-formyl-7-hydroxy-4-methycoumarin)-5- hydrazino-1,2,4-triazole Schiff bases (I-IV)

	Transitions (cm)
Complex No.	V1	V2	V3	V2 Cald. cm^−1	Dq (cm^−1)	B^−1(cm^−1)	% Distortion	V1/V2	LSFE	eff Cald. (BM)		Do P%
5	9810	15835	26256	15867	981.00	846.21	0.203	1.614	33.63	3.193	0.801	19.86
6	9855	15785	26320	15928	985.50	845.54	0.898	1.602	33.78	3.192	0.801	19.93
7	9832	15766	26325	15904	983.20	948.92	0.873	1.604	33.71	3.193	0.804	19.61
8	9822	15844	26675	15963	982.20	878.18	0.784	1.613	33.65	3.193	0.832	16.83

Table V.  Emission spectral data of Schiff base (II)

Solvents	Schiff base (II) (EX)	(EM)
DMSO	438.0 (438)	503.0 (472.0)
DMF	440.0 (440)	504.0 (480.4)
MeCN	446.0 (446)	494.8 (464.0)
Dioxan	442.0 (442)	468.0 (471.4)

The values in the parenthesis are these observed after the addition of 2% NaOH solution.

Table VI.  Emission spectral data of Co(II) (2), Ni(II) (6) and Cu(II) (10) complexes

Solvents	Complexes	(EX)	(EM)
	Co(II)	353.0 (410.2)	475.0 (465.2)
DMSO	Ni(II)	461.0 (488.4)	487.6 (469.2)
	Cu(II)	389.2 (432.0)	444.6 (455.6)
	Co(II)	445.0 (410.2)	470.8 (464.8)
DMF	Ni(II)	460.0 (488.4)	487.6 (467.4)
	Cu(II)	412.0 (432.0)	440.2 (460.0)
	Co(II)	353.6 (410.2)	304.4 (462.0)
MeCN	Ni(II)	470.0 (488.4)	580.6 (470.5)
	Cu(II)	373.2 (432.0)	429.0 (462.4)
	Co(II)	243.2 (410.2)	285.6 (466.2)
Dioxan	Ni(II)	244.0 (488.4)	286.2 (471.2)
	Cu(II)	244.0 (432.0)	285.2 (464.8)

Table VII.  Anti bacterial and anti fungal results of Schiff bases (I-IV)

Compd.	Conc.(ug ml-1)	Antibacterial activity (Zone of inhibition in %)				Antifungal activity (Zone of inhibition in %)
		E. coli	S. aureus	S. pyogenes	P.aeruginosa	A. f lavus	Cladosporium	A. niger
I	100	50	45	48	74	75
	50	40	–	–	58	74	66	61
	25	35	–	–	55	68	50	52
II	100	58	59	52	60	88	82	78
	50	50	47	43	52	71	67	40
	25	43	36	38	47	45	52	–
III	100	55	57	59	69	70	76	131
	50	48	46	50	57	100	88	120
	25	40	39	41	50	90	71	54
IV	100	61	60	57	63	74	72	80
	50	53	52	46	56	79	67	74
	25	47	46	38	48	77	54	71
Standard	100	100	100	100	100	100	100	100
	50	100	100	100	100	100	100	100
	25	100	100	100	100	100	100	100

Table VIII.  Anti bacterial and anti fungal results of Co(II), Ni(II) and Cu(II) complexes (1–12) and standard

Compd.	Conc (μg ml ^− 1)	Antibacterial activity (Zone of inhibition in %)				Antifungal activity (Zone of inhibition in %)
		E.coli	S.aureus	S.pyogenes	P.aeruginosa	A.flavus	Cladosporium	A. niger
1	100	45	55	62	70	86	69	49
	50	–	48	54	64	81	58	69
	25	–	–	42	52	80	50	60
2	100	68	62	70	68	91	71	52
	50	54	0	59	61	80	63	79
	25	41	55	54	52	77	51	78
3	100	79	75	68	76	89	82	80
	50	67	68	59	71	78	71	82
	25	53	59	51	64	71	58	83
4	100	72	76	70	79	94	85	85
	50	55	70	60	72	84	77	86
	25	40	61	53	67	79	66	80
5	100	75	79	69	78	84	76	82
	50	58	70	61	70	77	62	87
	25	40	65	52	64	70	59	79
6	100	78	82	72	81	89	83	70
	50	62	74	68	75	81	72	84
	25	52	67	60	70	72	58	70
7	100	70	71	68	80	79	78	62
	50	62	64	57	72	71	67	88
	25	48	52	60	66	64	60	82
8	100	80	73	71	73	76	82	88
	50	72	61	64	62	69	70	82
	25	69	50	59	54	62	61	70
9	100	52	66	65	82	88	77	80
	50	42	59	52	72	79	69	72
	25	38	52	48	69	78	58	67
10	100	68	73	69	85	94	83	89
	50	54	64	50	76	90	72	73
	25	50	60	42	70	91	64	67
11	100	72	78	77	80	89	78	90
	50	63	70	70	71	80	64	81
	25	58	67	61	62	80	59	74
12	100	75	79	73	76	90	84	85
	50	66	63	62	64	82	75	72
	25	60	57	57	56	85	65	67
Standard	100	100	100	100	100	100	100	100
	50	100	100	100	100	100	100	100
	25	100	100	100	100	100	100	100

Figure 4.  In vitro antibacterial spectrum of compounds III, 4, 6, 8, 10, 12, Gentamycine (Std.) at 100 μgml concentration.

Figure 5.  In vitro antifungal spectrum of compounds III, 4, 6, 8, 10, 12, Flucanazole (Std.) at 100 μgml concentration.

Table IX.  Minimum inhibitory concentration MIC (ug/mL) results for some compounds.

Compd.	Antibacterial activity (Zone of inhibition in %)				Antifungal activity (Zone of inhibition in %)
	E. coli	S. aureus	S. pyogenes	P.aeruginosa	A. flavus	Cladosporium	A. niger
III	15	15	20	10	10	15	20
4	20	10	25	25	15	25	10
6	25	15	25	15	15	25	15
8	15	25	25	25	20	25	20
10	25	20	25	20	10	20	20
12	15	25	20	20	15	15	20

Table X.  Brine shrimp bioassay data of the ligands (I–IV) and their metal (II) complexes 1–12.

Compound	LD50 (moles/mL)
I	4.517 × 10^− 3
II	6.324 × 10^− 3
III	5.842 × 10^− 3
IV	6.247 × 10^− 3
1	2.430 × 10^− 3
2	2.459 × 10^− 3
3	1.742 × 10^− 3
4	8.945 × 10^− 4
5	2.750 × 10^− 3
6	8.839 × 10^− 4
7	1.764 × 10^− 3
8	7.135 × 10^− 4
9	1.751 × 10^− 3
10	7.022 × 10^− 4
11	2.299 × 10^− 3
12	8.759 × 10^− 4

Figure 6.  Proposed structure of Metal(II) complexes.

Table S1.  Thermogravimetric data of Co(II) (2), Ni(II) (6) and Cu(II) (10) complexes of 3-substituted-4-amino (8-formyl-7-hydroxy-4-methylcoumarin)-5-hydrazino-1,2,4-triazole Schiff base (II)

	Decomposition temperature	%Weight loss.		Metal Oxide %	Inference
Empirical Formula	oC	Obsd	Calcd.	Obsd.	Calcd.
Co(C25H18N6O6).2H2O	105–135	6.05	12.62	6.07	12.64	Loss of coordinated water molecules
	330–365	20.90	20.91			Loss of triazole moieties
	440–480	63.05	63.08			Loss of coumarin moieties
Ni(C25H18N6O6).2H2O	110–140	6.04	6.07	12.57	12.60	Loss of coordinated water molecules
	325–355	20.89	20.92			Loss of triazole moieties
	435–472	63.09	63.10			Loss of coumarin moieties
Cu(C25H18N6O6).2H2O	220–230	6.00	6.02	13.30	13.31	Loss of coordinated water molecules
	300–330	20.73	20.75			Loss of triazole moieties
	455–473	62.57	62.59			Loss of coumarin moieties

Figure S1.  Cyclicvoltammogram of Cu(II) (10) complex.

Figure S2.  Cyclicvoltammogram of Co(II) (2) complex.

Figure S3.  Emission spectrum of Schiff base (II) in DMF (a), DMSO (b), MeCN (c) and Dioxan (d).

Figure S4.  (a) Emission spectra of Schiff base in DMF. (b) Emission spectra (red shift) of Schiff base in DMF with 2% NaOH.

Figure S5.  (a) Emission spectra of Schiff base in Dioxan. (b) Emission spectra (blue shift) of Schiff base in Dioxan with 2% NaOH.

Figure S6.  (a) Emission spectra of Schiff base in DMSO. (b) Emission spectra of Cu(II) complex in DMSO.

Figure S7.  Emission spectra of Cu(II) (a), Co(II) (b) and Ni(II) (c)complexes in Dioxan.