Synthesis, spectral characterization, in vitro microbial and cytotoxic studies of lanthanum(III) and thorium(IV) complexes with 1,2,4-triazole Schiff bases

Figures & data

Figure 1.  Synthesized Schiff bases.

Table I.  Elemental analysis and molar conductance data of Schiff bases (I-IV) and their La(III) and Th(IV) complexes (1-8).

		M%		C%		H%		N%
No.	Empirical formula	Obsd.	Calcd.	Obsd.	Calcd.	Obsd.	Calcd.	Obsd.	Calcd.	Molar conductance Ohm^− 1 cm^− 2 mole^− 1
I	C24H18N6O6 (L^I)	–	–	59.20	59.26	3.66	3.70	17.24	17.28	–
II	C25H20N6O6 (L^II)	–	–	59.93	60.00	3.95	4.00	16.77	16.80	–
III	C26H22N6O6 (L^III)	–	–	60.64	60.70	4.21	4.28	16.30	16.34	–
IV	C27H24N6O6 (L^IV)	–	–	61.31	61.36	4.52	4.55	15.88	15.91	–
1	[La(L^I)·3H2O]·2H2O	19.47	19.51	40.40	40.45	2.08	2.11	11.75	11.79	28
2	[La(L^II)·3H2O]·2H2O	19.11	19.14	41.28	41.33	2.31	2.34	11.52	11.57	25
3	[La(L^III)·3H2O]·2H2O	18.71	18.77	42.13	42.17	2.52	2.57	11.31	11.36	22
4	[La(L^IV)·3H2O]·2H2O	18.39	18.43	42.95	42.98	2.76	2.79	11.10	11.14	20
5	[Th(L^I)(NO3)·2H2O]·2H2O	27.30	27.33	33.89	33.92	1.72	1.76	11.49	11.54	19
6	[Th(L^II)(NO3)·2H2O]·2H2O	26.95	26.99	34.73	34.76	1.92	1.96	11.30	11.36	18
7	[Th(L^III)(NO3)·2H2O]·2H2O	26.40	26.45	35.52	35.57	2.11	2.16	11.11	11.17	20
8	[Th(L^IV)(NO3)·2H2O]·2H2O	26.00	26.04	36.31	36.36	2.31	2.36	10.94	10.99	24

Table II.  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.	ν (NH)	Lactone ν (C = O)	ν (C = N)	H-bonded –OH Stretching	ν (C = C)	Phenolic ν (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.  Important infrared frequencies (cm-1) of La(III) and Th(IV) complexes (1-8).

Complex No.	ν(OH)	ν(C = N)	νCH3	Phenolic C-O	ν(M-N)	ν(M-O)
1	3435	1604	2930	1385	485	542
2	3422	1600	2928	1392	491	537
3	3440	1603	2922	1380	489	548
4	3438	1610	2940	1386	480	539
5	3425	1609	2915	1390	490	555
6	3437	1607	2930	1384	483	543
7	3439	1600	2928	1386	492	542
8	3442	1611	2927	1389	485	550

Table IV.  Antibacterial and antifungal activities of Schiff bases (I-IV).

		Antibacterial activity (Zone of inhibition in %)				Antifungal activity (Zone of inhibition in %)
Compd.	Conc. (μg mL^− 1)	E. coli	S. aureus	S. pyogenes	P. aeruginosa	A. flavus	Cladosporium	A. niger
L^I	100	50	45	48	67	85	74	75
L^II	100	58	59	52	60	88	82	78
L^III	100	55	57	59	69	70	76	131
L^IV	100	61	60	57	63	74	72	80
Standard	100	100	100	100	100	100	100	100

Standard = Gentamycine (antibacterial) and fluconozole (antifungal).

Table V.  Antibacterial and antifungal activities of La(III) and Th(IV) complexes (1-8) and standards.

		Antibacterial activity (Zone of inhibition in %)				Antifungal activity (Zone of inhibition in %)
Compd.	Conc. (μg mL^− 1)	E. coli	S. aureus	S. pyogenes	P. aeruginosa	A. flavus	Cladosporium	A. niger
1	100	72	64	73	76	80	77	79
2	100	68	62	–	72	73	70	74
3	100	74	69	72	74	75	71	–
4	100	70	57	70	75	70	67	68
5	100	70	60	64	69	68	–	75
6	100	67	52	63	66	61	60	69
7	100	–	59	–	60	60	63	71
8	100	71	58	60	61	64	67	70
Standard	100	100	100	100	100	100	100	100

Standard = Gentamycine (antibacterial) and Fluconozole (antifungal).

Figure 2.  Antibacterial activity of Schiff base and its La(III) and Th(IV) complexes (100 μg/mL).

Figure 3.  Antifungal study of Schiff base and its La(III) and Th(IV) complexes(100 μg/mL).

Table VI.  Minimum inhibitory concentration (μg/mL⁻¹) for La(III) and Th(IV) complexes.

	Antibacterial activity				Antifungal activity
Compd.	E. coli	S. aureus	S. pyogenes	P.aeruginosa	A. flavus	Cladosporium	A. niger
1	10	20	15	10	15	20	20
2	15	20	–	15	20	20	15
3	10	20	15	15	15	15	–
4	15	25	15	10	10	15	20
5	10	15	25	25	25	–	15
6	20	25	25	25	30	30	25
7	–	20	–	30	30	25	20
8	15	20	30	30	30	25	25

Table VII.  Brine shrimp bioassay data for the ligands (L^I-L^IV) and their metal (II) complexes 1-8.

Compound	LD50 (moles/mL)
L^I	4.517 × 10^− 3
L^II	6.324 × 10^− 3
L^III	5.842 × 10^− 3
L^IV	6.247 × 10^− 3
1	7.623 × 10^− 4
2	6.459 × 10^− 3
3	5.682 × 10^− 3
4	8.945 × 10^− 4
5	4.750 × 10^− 3
6	7.839 × 10^− 3
7	8.241 × 10^− 4
8	5.135 × 10^− 3

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