Metal based isatin-derived sulfonamides: Their synthesis, characterization, coordination behavior and biological activity

Figures & data

Scheme 1.  Preparation of ligands (L₁)-(L₄).

Table I.  Analytical conductivity, magnetic and spectral data of metal (II) complexes.

No.	ΩM (Ω^− 1 cm^2 mol^− 1)	B.M (μeff)	λmax (cm^− 1)	IR (cm^− 1)
1.	14.2	4.87	7355, 17365, 20375, 29210	1570(C = N), 1700(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 435(M-N), 529(M-O), 315(M-Cl)
2.	86.0	1.41	14825, 19250, 30240	1565(C = N), 1695(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 433(M-N), 535(M-O)
3.	11.0	3.23	10395, 15835, 26395, 30105	1560(C = N), 1696(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 430(M-N), 529(M-O), 315(M-Cl)
4.	15.5	Dia	28955	1568(C = N), 1698(C = O), 1325, 1140(SO2), 960
				(S-N), 845 (C-S), 432(M-N), 527(M-O), 315(M-Cl)
5.	16.0	4.90	7210, 17285, 20525, 29225	1565(C = N), 1690(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 438(M-N), 535(M-O), 315(M-Cl)
6.	89.0	1.44	15210, 19235, 30155	1567(C = N), 1699(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 439(M-N), 520(M-O)
7.	15.3	3.28	10440, 15825, 26425, 30235	1560(C = N), 1692(C = O), 1345, 1110(SO2), 960
				(S-N), 845(C-S), 433(M-N), 530(M-O), 315(M-Cl)
8.	14.7	Dia	29125	1564(C = N), 1694(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 430(M-N), 534(M-O), 315(M-Cl)
9.	11.9	4.88	7325, 17390, 20505, 29245	1565(C = N), 1696(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 434(M-N), 535(M-O), 315(M-Cl)
10.	87.0	1.53	14985, 19325, 30225	1563(C = N), 1693 (C = O), 1325, 1140 (SO2), 960
				(S-N), 845 (C-S), 435(M-N), 522 (M-O)
11.	14.8	3.24	10445, 15690, 26510, 30230	1562 (C = N), 1698(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 430(M-N), 525(M-O), 315(M-Cl)
12.	15.9	Dia	28880	1561(C = N), 1691(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 440(M-N), 520(M-O), 315(M-Cl)
13.	16.0	4.90	7305, 17295, 20465, 29195	1560(C = N), 1690(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 425(M-N), 526(M-O), 315(M-Cl)
14.	87.2	1.37	15220, 19300, 30185	1563(C = N), 1693(C = O), 1325, 1140(SO2), 960
				(S-N), 845 (C-S), 433(M-N), 533 (M-O)
15.	15.8	3.20	10380, 15740, 26355, 30155	1560(C = N), 1695(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 435(M-N), 535(M-O), 315(M-Cl)
16.	14.6	Dia	28765	1565(C = N), 1698(C = O), 1325, 1140(SO2), 960
				(S-N), 845(C-S), 431(M-N), 528(M-O), 315(M-Cl)

Figure 1.  Comparison of antibacterial activity.

Figure 2.  Average antibacterial activity of ligands versus metal (II) complexes.

Table II.  Antibacterial bioassay (concentration used 1 mg/mL of DMSO) of ligands and metal (II) complexes.

	Bacterial Strains
	Gram-negative				Gram-positive
Compd.	E. colii (a)	S..flexeneri (b)	P. aeruginosa (c)	S. typhi (d)	S. aureous (e)	B. subtilis (f)
L1	15	13	7	11	13	12
L2	13	15	6	11	12	13
L3	14	15	8	13	14	14
L4	14	14	9	12	16	15
1	18	17	11	17	17	16
2	17	16	14	16	17	18
3	18	18	13	18	19	18
4	24	23	15	22	24	23
5	17	17	10	19	19	18
6	21	18	12	18	19	18
7	20	19	11	18	21	19
8	26	22	14	23	25	23
9	17	19	10	17	18	17
10	18	17	12	18	18	21
11	16	20	13	19	20	21
12	25	22	15	24	20	21
13	20	19	12	16	20	19
14	19	18	11	16	18	22
15	18	19	12	18	20	19
16	24	22	14	23	26	25
SD	30	27	26	27	30	28
M1	5	4	5	4	4	5
M2	4	4	4	5	5	4
M3	4	3	4	4	4	4
M4	5	4	5	5	5	5

(a) = E. coli (b) = S. flexenari (c) = P. aeruginosa (d) = S. typhi (e) = S. aureus (f) = B. subtilis < 10:weak; >10:moderate;>16:Significant SD = Standard Drug (Imipenum), M₁ = CoCl₂.6H₂O, M₂ = CuCl₂, M₃ = NiCl₂, M₄ = ZnCl₂

Figure 3.  Comparison of antifungal activity.

Table III.  Antifungal bioassay (concentration used 200 μg/mL) of ligands and metal (II) complexes.

	Fungal Strains
Compd.	T. longifucus (a)	C. albicans (b)	A. flavus (c)	M. canis (d)	F. solani (e)	C. glaberata (f)
L1	30	0	40	35	0	0
L2	35	0	40	30	0	0
L3	0	45	50	0	0	35
L4	35	40	0	50	30	0
1	65	35	55	0	65	0
2	20	60	50	0	70	70
3	65	40	35	70	0	40
4	65	0	80	65	70	30
5	50	0	40	45	60	35
6	0	75	40	75	45	0
7	78	35	45	70	0	70
8	70	60	55	60	40	80
9	45	0	60	35	50	30
10	0	60	50	55	0	85
11	70	55	0	85	40	60
12	80	60	45	70	60	75
13	45	0	60	0	80	80
14	25	60	50	0	75	55
15	70	55	0	75	30	60
16	80	65	55	75	55	85
SD	A	B	C	D	E	F

SD = Standard Drugs MIC μg/mL; 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).

Figure 4.  Average antifungal activity in ligands versus metal (II) complexes.

Figure 5.  Proposed structures of the metal (II) complexes.

Table IV.  Minimum inhibitory concentration (μg/mL) of the selected compounds (4), (8), (12) and (16) against selected bacteria.

	Gram-negative			Gram-positive
Compd.	E. coli	S. flexenari	S. typhi	S. aureus	B. subtilis
4	1.051 × 10^− 7	5.256 × 10^− 8	1.051 × 10^− 7	5.256 × 10^− 8	2.628 × 10^− 8
8	5.381 × 10^− 8	2.691 × 10^− 8	5.381 × 10^− 8	1.076 × 10^− 7	1.076 × 10^− 8
12	5.549 × 10^− 8	1.110 × 10^− 7	2.750 × 10^− 8	5.549 × 10^− 8	1.110 × 10^− 8
16	1.105 × 10^− 7	5.524 × 10^− 8	2.762 × 10^− 8	5.524 × 10^− 8	1.105 × 10^− 7

Table V.  Brine shrimp bioassay data of the ligands (L₁)-(L₄) and their metal (II) complexes (1)-(16).

Compound	LD50 (μg/mL)	Compound	LD50 (μg/mL)
L1	> 2.454 × 10^− 3	7	>1.084 × 10^− 3
L2	> 2.523 × 10^− 3	8	>1.076 × 10^− 3
L3	>2.615 × 10^− 3	9	>1.118 × 10^− 3
L4	>2.601 × 10^− 3	10	6.372 × 10^− 4
1	>1.058 × 10^− 3	11	>1.118 × 10^− 3
2	4.529 × 10^− 4	12	>1.110 × 10^− 3
3	>1.059 × 10^− 3	13	>1.113 × 10^− 3
4	>1.051 × 10^− 3	14	5.513 × 10^− 4
5	>1.084 × 10^− 3	15	>1.113 × 10^− 3
6	5.683 × 10^− 4	16	>1.105 × 10^− 3