Solid–solid synthesis, characterization, thermal decomposition and antibacterial activities of zinc(II) and nickel(II) complexes of glycine–vanillin Schiff base ligand

Figures & data

Table 1. Elemental analyses results and the melting point of the ligand and the complexes.

Schiff base and complex	Formula	m.p. (°C)	w(M) (%)	w(C) (%)	w(H) (%)	w(N) (%)	w(O) (%)
K(gly-van)	KC10H10O4N	81–82	–	48.69 (48.57)	4.23 (4.08)	5.76 (5.67)	25.69 (25.88)
[Zn(gly-van)(H2O)3]	ZnC10H15O7N	–	19.89 (20.02)	36.67 (36.77)	4.47 (4.63)	4.15 (4.29)	34.82 (34.29)
[Ni(gly-van)(H2O)3]·1.5H2O	NiC10H18O8.5N	–	17.25 (16.92)	35.26 (34.62)	5.38 (5.23)	3.85 (4.04)	38.26 (39.20)

Note: Calculated values are in brackets.

Figure 1. X-ray powder diffraction patterns of the complexes [Zn(C₁₀H₉O₄N)(H₂O)₃] (a) and [Ni(C₁₀H₉O₄N)(H₂O)₃]·1.5H₂O (b).

Table 2. Experimental data and calculated results for powder X-ray diffraction pattern of the complex [Zn(gly-van)(H₂O)₃] (monoclinic system: a = 0.6807 nm, b = 1.3818 nm, c = 1.2011 nm, and β = 95.80°).

Number	2θ (°)	h	k	l	dexp (nm)	dcal (nm)	I/I0	Number	2θ (°)	h	k	l	dexp (nm)	dcal (nm)	I/I0
1	13.061	1	0	0	0.6773	0.6772	100	22	42.417	2	5	−1	0.2129	0.2131	4.0
2	16.922	1	1	1	0.5235	0.5231	30.9	23	44.109	2	0	−5	0.2051	0.2053	1.5
3	18.382	1	2	0	0.4823	0.4836	5.1	24	45.284	2	4	3	0.2001	0.2004	1.7
4	18.799	1	0	−2	0.4716	0.4723	45.4	25	45.931	0	7	0	0.1974	0.1974	2.8
5	20.579	0	3	1	0.4312	0.4298	6.2	26	47.879	2	6	−1	0.1898	0.1897	4.8
6	23.197	0	1	3	0.3831	0.3827	4.7	27	48.763	2	0	5	0.1866	0.1866	2.1
7	24.080	1	3	−1	0.3693	0.3690	20.8	28	49.225	2	1	5	0.1850	0.1849	3.7
8	24.640	1	0	−3	0.3610	0.3596	8.0	29	50.437	0	5	−5	0.1808	0.1808	8.5
9	25.025	1	3	1	0.3555	0.3570	9.7	30	51.502	0	7	3	0.1773	0.1769	1.7
10	27.080	2	1	0	0.3290	0.3289	19.7	31	51.839	3	4	2	0.1762	0.1759	1.7
11	29.058	1	4	0	0.3070	0.3077	7.9	32	52.204	3	5	−1	0.1751	0.1750	2.2
12	30.863	2	2	1	0.2895	0.2885	2.7	33	53.283	3	1	−5	0.1718	0.1717	1.4
13	32.101	1	4	−2	0.2786	0.2788	7.5	34	54.938	3	2	4	0.1670	0.1668	1.3
14	33.157	0	5	1	0.2700	0.2693	5.8	35	55.754	0	7	−4	0.1647	0.1647	2.1
15	33.998	1	0	4	0.2635	0.2637	12.9	36	57.352	1	1	7	0.1605	0.1606	2.6
16	35.461	2	2	−3	0.2529	0.2530	7.4	37	59.732	2	5	5	0.1547	0.1546	1.2
17	38.737	1	5	2	0.2323	0.2320	9.0	38	61.282	2	7	−4	0.1511	0.1515	2.1
18	39.683	0	5	3	0.2269	0.2271	5.4	39	61.779	4	3	2	0.1500	0.1501	2.1
19	40.041	3	0	0	0.2250	0.2257	6.6	40	64.200	2	6	5	0.1450	0.1450	2.0
20	40.474	3	1	0	0.2227	0.2228	3.9	41	66.372	4	4	−4	0.1407	0.1408	1.0
21	41.856	1	6	−1	0.2157	0.2157	1.2	42	67.993	3	6	4	0.1378	0.1378	0.8

Table 3. Experimental data and calculated results for powder X-ray diffraction pattern of the complex [Ni(gly-van)(H₂O)₃]·1.5H₂O (monoclinic system: a = 0.7457 nm, b = 1.3331 nm, c = 1.2560 nm, and β = 91.89°).

Number	2θ (°)	h	k	l	dexp (nm)	dcal (nm)	I/I0	Number	2θ (°)	h	k	l	dexp (nm)	dcal (nm)	I/I0
1	11.881	1	0	0	0.7443	0.7453	100	21	40.198	0	5	3	0.2242	0.2249	1.2
2	18.118	1	0	−2	0.4892	0.4881	6.3	22	40.816	3	2	−2	0.2209	0.2205	3.0
3	19.338	1	2	1	0.4586	0.4585	30.7	23	41.414	0	3	5	0.2178	0.2186	9.4
4	21.259	0	0	3	0.4176	0.4184	6.5	24	42.178	3	1	−3	0.2141	0.2140	3.3
5	22.499	1	2	−2	0.3948	0.3938	48.5	25	43.753	0	1	−6	0.2067	0.2067	1.0
6	22.958	1	2	2	0.3871	0.3855	15.8	26	44.092	2	0	5	0.2052	0.2051	1.3
7	24.682	2	0	−1	0.3604	0.3605	3.9	27	45.177	0	4	−5	0.2005	0.2005	2.1
8	25.554	2	1	−1	0.3483	0.3480	2.1	38	46.777	2	5	−3	0.1940	0.1940	5.1
9	25.990	2	1	1	0.3426	0.3422	5.1	29	50.029	0	7	−2	0.1822	0.1822	1.8
10	29.357	1	4	0	0.3040	0.3042	15.7	30	51.223	2	1	6	0.1782	0.1783	1.8
11	30.299	1	4	1	0.2947	0.2948	16.1	31	53.185	3	1	5	0.1721	0.1723	2.9
12	30.761	2	2	−2	0.2904	0.2922	7.0	32	53.679	2	3	−6	0.1706	0.1708	1.8
13	31.193	1	1	−4	0.2865	0.2859	2.4	33	54.398	2	7	−1	0.1685	0.1684	1.4
14	34.176	2	3	−2	0.2621	0.2624	4.2	34	54.882	4	3	−2	0.1672	0.1670	2.9
15	35.101	0	3	4	0.2554	0.2563	13.3	35	55.837	0	5	−6	0.1645	0.1646	1.3
16	36.175	2	4	0	0.2481	0.2484	1.8	36	56.352	1	6	−5	0.1631	0.1631	1.8
17	37.609	2	3	−3	0.2390	0.2387	1.4	37	58.114	4	4	−2	0.1586	0.1585	1.4
18	38.457	1	5	−2	0.2339	0.2340	2.6	38	63.049	2	8	2	0.1473	0.1474	0.9
19	39.154	3	1	−2	0.2299	0.2301	5.9	39	63.960	5	2	0	0.1454	0.1455	1.2
20	39.923	3	1	2	0.2256	0.2252	2.4	40	64.345	4	5	−3	0.1447	0.1447	2.1

Figure 2. Infrared spectra of the complexes [Zn(C₁₀H₉O₄N)(H₂O)₃] (a) and [Ni(C₁₀H₉O₄N)(H₂O)₃]·1.5H₂O (b).

Figure 3. TG–DSC curves of the complexes [Zn(C₁₀H₉O₄N)(H₂O)₃] (a) and [Ni(C₁₀H₉O₄N)(H₂O)₃]·1.5H₂O (b).

Table 4. Thermal decomposition data of the Schiff base complexes.

		Mass loss (%)
Reaction	TDSC (°C)	Wexp.	Wtheor.
[Zn(C10H9O4N)(H2O)3]
↓ −3H2O	148 (endo.)	15.72	16.55
[Zn(C10H9O4N)]
↓ −CH3CN	296 (exo.)
↓ −CO2, −CH3OC6H3	367 (exo.)	59.78	58.53
ZnO		24.50^a	24.92^b
[Ni(C10H9O4N)(H2O)3]·1.5H2O
↓ −1.5H2O	100 (endo.)	8.31	7.79
[Ni(C10H9O4N)(H2O)3]
↓ −3H2O	293 (endo.)	15.28	15.58
[Ni(C10H9O4N)]
↓−CH3CN, −CO2, −CH3OC6H3	424 (exo.)	54.32	55.10
NiO		22.09^a	21.53^b

^a The experimental percentage mass of the residue in the sample.

^b The calculated percentage mass of the residue in the sample.

Scheme 1. Molecular structure of the complexes.

Table 5. Antibacterial activity of the Schiff base and the complexes.

		Inhibition zone (mm)
Compound	Concentration (mg/mL)	S. aureus	E. coli	B. subtilis	S. epidermidis
Gly-van Schiff base	1.0	12.1	14.9	14.1	12.3
[Zn(C10H9O4N)(H2O)3]	1.0	11.4	16.6	14.9	14.2
[Ni(C10H9O4N)(H2O)3]·1.5H2O	1.0	10.8	18.7	16.3	13.0
Moxifloxacin	1.0	21.3	24.8	33.6	30.2