In-vitro antibacterial, antifungal activity of some transition metal complexes of thiosemicarbazone Schiff base (HL) derived from N⁴-(7′-chloroquinolin-4′-ylamino) thiosemicarbazide

Figures & data

Figure 1 Scheme for the synthesis of the HL ligand.

Table I.  Physicochemical parameters of ligand and it's complexes.

				Elemental analysis, found/(Calcd) %
Compound^a (F. wt.)	Colour	Yield (%)	M.p. (^oC)	C	H	N	Cl	S	M	UM (Ohm cm^2 mol^-1)
HL C17H14N5ClOS (371.5)	Deep  orange-  yellow	85	265	55.21 (54.91)	4.32 (3.77)	19.11 (18.84)	9.83 (9.56)	8.831 (8.61)	—	—
(1)[(L)Cu(Cl)].H2O  C17H15N5Cl2O2  SCu (488.5)	Green	33	277	42.11 (41.76)	3.32 (3.07)	14.63 (14.33)	14.91 (14.53)	7.02 (6.55)	14.67 (13.20)	13.4
(2)[(L)Ni(Cl)(OH2)2].2H2O  C17H21N5  Cl2O5SNi (537)	Pale yellow	25	270	38.41 (38.01)	4.11 (3.91)	13.44 (13.04)	13.64 (13.23)	5.45 (5.96)	10.62 (10.94)	15.0
(3)[(L)Zn(Cl)(OH2)2].2H2O  C17H21N5  Cl2O5SZn (543)	Yellow	55	264	37.23 (37.54)	4.21 (3.86)	13.22 (12.88)	13.49 (13.07)	6.11 (5.89)	12.44 (12.04)	11
(4)[(L)Co(Cl)(OH2)2].H2O  C17H19N5  Cl2O4SCo (519)	Yellowish  green	47	250  (decomp)	39.75 (39.31)	4.00 (3.66)	13.81 (13.49)	14.01 (13.68)	6.54 (6.17)	11.68 (11.37)	12.6
(5)[(L)Mn(Cl)(OH2)2].H2O  C17H19N5  Cl2O4SMn (515)	Deep brown	34	260  (decomp)	39.22 (39.61)	3.45 (3.69)	13.82 (13.59)	14.10 (13.79)	6.51 (6.21)	10.93 (10.68)	18.4
(6)[(L)Fe(Cl)2(OH2)].2H2O  C17H19N5  Cl3O4SFe (551.5)	Reddish  brown	44	264  (decomp)	37.32 (36.99)	3.25 (3.45)	12.92 (12.69)	19.71 (19.31)	6.22 (5.80)	10.35 (10.15)	18.5
(7)[(L)Cr(Cl)2(OH2)].2H2O  C17H19N5  Cl3O4SCr (547.5)	Green	75	255  (decomp)	37.53 (37.26)	3.82 (3.47)	13.12 (12.79)	19.11 (19.45)	5.44 (5.84)	9.26 (9.50)	13.6

^a _{L =} [C₁₇H₁₃N₅ClOS]⁻

Table II.  Characteristic IR bands (cm⁻¹) of HL and its metal complexes.

Compound	ν(C = N)	ν(N–H)	ν(N–N)	ν(C = S)	ν(M–N)	ν(M–O)	ν(M–S)	ν(OH)	Other bands
HL C17H14N5ClOS (371.5)	1570 s	3270 m	1120 s	876 s	—	—	—	3530 m, br	δ(COH)ip, 1355
(1)[(L)Cu(Cl)].H2O C17H15N5Cl2O2SCu (488.5)	1520 s	3265 m	1136 s	820 s	450 w	560 m	360 w	—	ν (3436); δ (930, 770) (coordinated H2O)
(2)[(L)Ni(Cl)(OH2)2].2H2O C17H21N5 Cl2O5SNi  (537)	1525 m	3278 s	1137 w	825 s	460 w	555 m	365 w	—	ν (3440); δ (935, 770) (coordinated H2O)
(3)[(L)Zn(Cl)(OH2)2].2H2O C17H21N5Cl2O5SZn  (543)	1520 m	3270 s	1125 w	850 s	430 w	545	350 w	—	ν (3435); δ (930, 775) (coordinated H2O)
(4)[(L)Co(Cl)(OH2)2].H2O C17H19N5Cl2O4SCo  (519)	1530 m	3270 m	1125 w	845 m	445 w	555 m	355 w	—	ν (3435); δ (930, 775) (coordinated H2O)
(5)[(L)Mn(Cl)(OH2)2].H2O C17H19N5Cl2O4SMn  (515)	1527 m	3265 m	1136 s	820 m	445 w	545 w	360 w	—	ν (3440); δ (938, 770) (coordinated H2O)
(6)[(L)Fe(Cl)2(OH2)].2H2O C17H19N5Cl3O4SFe  (551.5)	1530 m	3278 s	1130 w	840 s	455 w	540 w	365 w	—	ν (3426); δ (930, 770) (coordinated H2O)
(7)[(L)Cr(Cl)2(OH2)].2H2O C17H19N5Cl3O4SCr  (547.5)	1520 m	3270 s	1137 s	825 m	450 w	555 m	355 w	—	ν (3435); δ (930, 775) (coordinated H2O)

s: strong, w: weak, m: medium, br.: broad

Table III.  Magnetic moment, electronic spectral data for HL and its metal complexes.

Compound	μeff.B.M.	π → π*, n → π* and charge transfer transitions (nm)	d → d transitions (nm)
HL C17H14N5ClOS (371.5)	—	279, 300, 353, 364, 382, 309	—
(1)[(L)Cu(Cl)].H2O C17H15N5Cl2O2SCu (488.5)	1.78	240, 311, 325, 348	665
(2)[(L)Ni(Cl)(OH2)2].2H2O C17H21N5 Cl2O5SNi (537)	2.85	240, 315, 327, 348, 355	768, 670(sh)
(3)[(L)Zn(Cl)(OH2)2].2H2O C17H21N5Cl2O5SZn (543)	—	279, 300, 353, 364, 385, 319	—
(4)[(L)Co(Cl)(OH2)2].H2O C17H19N5Cl2O4SCo (519)	5.2	239, 315, 327, 350, 359	656, 477
(5)[(L)Mn(Cl)(OH2)2].H2O C17H19N5Cl2O4SMn (515)	5.39	245, 315, 330, 352, 365	469–853
(6)[(L)Fe(Cl)2(OH2)].2H2O C17H19N5Cl3O4SFe (551.5)	5.8	233, 315, 327, 350, 355, 396	722
(7)[(L)Cr(Cl)2(OH2)].2H2O C17H19N5Cl3O4SCr (547.5)	3.8	233, 315, 327, 350, 355, 396	592, 396

Figure 2 Suggested structures for the metal complexes.

Table IV.  ¹H and ¹³C NMR spectral data (δ_ppm) of the ligand HL and its Zn(II) complex.

^1H NMR (δ)		^13C NMR (δ)						1H NMR (δ)		^13C NMR (δ)
[s, 1H] (a)	2.0	C1	118.0	C7	165.5	C13	145.7	[s, 1H] (a)	2.0	C1	118.0	C7	161.3	C13	145.7
[s, 1H] (b)	4.0	C2	132.5	C8	176.5	C14	120.5	[s, 1H] (b)	4.0	C2	132.5	C8	169.3	C14	120.5
[s, 1H] (c)	11.67	C3	123.5	C9	150.5	C15	127.3	[s, 1H] (c)	11.67	C3	123.5	C9	150.5	C15	127.3
[s, 1H] (d)	7.52	C4	129.6	C10	123.5	C16	130.9	[s, 1H] (d)	8.22	C4	129.6	C10	123.5	C16	130.9
[s, 1H] (e)	9.83	C5	116.5	C11	151.3	C17	129.4	(e) disappeared	—	C5	116.5	C11	151.3	C17	129.4
[m, 9H] (f & g)	7.7-8.48	C6	159.7	C12	117.7			[m, 9H] (f & g)	8.48-8.67	C6	162.6	C12	117.7

Table V.  Thermal analyses data for Zn(II) complex.

Compound M.F (M.wt.)	Dissociation stages	Temp range in TG°C	Weight loss found (Calcd.) %	Decomposition assignment
[(L)Zn(Cl)(OH2)2].2H2O C17H21N5Cl2O5SZn (543)	Stage I	120-150	7.26 (6.63)	2 mol outer sphere water
	Stage II	180-210	7.66. (6.63)	2 mol coordinated water
	Stage III	250-350	20.13 (19.61)	HCl, HCN, NHCNH2
	Stage IV	660-760	15.57 (15.00)	Formation of ZnO

Table VI.  Antimicrobial activity of the Schiff base HL and its metal complexes.

	Microbial species
Compound	(a)	(b)	(c)	(d)
HL C17H14N5ClOS (371.5)	+++	++	+++	+++
(1)[(L)Cu(Cl)].H2O C17H15N5Cl2O2SCu (488.5)	+++	+++	++	+++
(2)[(L)Ni(Cl)(OH2)2].2H2O C17H21N5 Cl2O5SNi (537)	+++	+++	++	++
(3)[(L)Zn(Cl)(OH2)2].2H2O C17H21N5Cl2O5SZn (543)	+++	++	++	+++
(4)[(L)Co(Cl)(OH2)2].H2O C17H19N5Cl2O4SCo (519)	+++	+++	+++	+++
(5)[(L)Mn(Cl)(OH2)2].H2O C17H19N5Cl2O4SMn (515)	++	+++	+++	+++
(6)[(L)Fe(Cl)2(OH2)].2H2O C17H19N5Cl3O4SFe (551.5)	+++	+++	++	++
(7)[(L)Cr(Cl)2(OH2)].2H2O C17H19N5Cl3O4SCr (547.5)	+++	+++	+++	++++
Cephalosporin ^a	+++	+++	+++	+++
Streptomycin^b	++++	+++	+++	++

(a) = S. aureus, (b) = E. coli, (c) = Candida. Albicans and (d) = Fusarium solani. Inhibition zone diameter in mm (% growth):+, 8-10 (36-45%);++, 10-16 (45-73%);+++, 16-19 (73-86);++++, 19-22 (86-100%). Percent growth values are relative to growth zone (22 mm) with 100% growth.

^aStandard antifungal and ^bantibacterial agents.