Metal-based Schiff base polymers: preparation, spectral, thermal and their in vitro biological investigation

Figures & data

Scheme 3 Synthetic routes to polymer metal complexes of APOFB.

Table 1. Analytical data of polymeric Schiff base APOFB and its polymer metal complexes.

Abbreviation	Yield %	Calculated (found) (%)
		C	H	N	M
APOFB	75	67.73	4.87	11.28	–
		(68.10)	(4.89)	(11.37)	–
APOFB-Mn(II)	70	57.44	4.48	9.57	9.38
		(57.93)	(4.50)	(9.62)	(9.26)
APOFB- Co(II)	77	60.77	4.01	10.12	10.65
		(61.20)	(4.32)	(10.05)	(10.77)
APOFB-Ni(II)	80	60.79	4.01	10.13	10.61
		(60.91)	(4.12)	(10.15)	(10.70)
APOFB-Cu(II)	78	60.26	3.97	10.04	11.39
		(60.37)	(4.00)	(9.98)	(11.45)
APOFB-Zn(II)	71	60.06	3.96	10.01	11.68
		(59.83)	(4.02)	(9.96)	(11.80)

Scheme 1 Synthetic route of the monomeric Schiff base.

Scheme 2 Synthetic route to the polymeric Schiff base APOFB.

Table 2. IR spectral bands and their assignments for polymeric Schiff base APOFB and its polymer metal complexes.

Compounds	Assignments
	Ar-OH	νCH (asym-sym)	νC=N	νC–O	νM–O	νM–N
APOFB	3380	2917–2825	1612	1211	…...	…...
APOFB-Mn(II)	…...	2917–2825	1603	1251	550	445
APOFB-Co(II)	…...	2917–2825	1597	1246	544	433
APOFB-Ni(II)	…...	2917–2825	1590	1271	560	458
APOFB-Cu(II)	…...	2917–2825	1602	1280	535	450
APOFB-Zn(II)	…...	2917–2825	1599	1266	565	468

Table 3. Magnetic susceptibility and electronic spectra of polymeric Schiff base APOFB and its polymer metal complexes.

Abbreviation	Magnetic moment (B.M.)	Electronic spectral data		10Dq	B	β	β%	Geometry
		Electronic transition (cm^−1)	Assignment
APOFB-Mn(II)	5.49	21,600	^4A1g(G)←^6A1g(F)	4046	809	0.84	16	Octahedral
		18,450	^4T2g(G)←^6A1g(F)
		15,900	^4T1g(G)←^6A1g(F)
APOFB-Co(II)	4.58	17,650	^4T1(F)←^4A2	8238	741	0.66	34	Tetrahedral
		9340	^4T1(P)←^4A2
APOFB-Ni(II)	2.58	15,980	^3T1(P)←^3T1	5593	799	0.74	26	Tetrahedral
		9744	^3A2←^3T1
		4600	^3T2←^3T1
APOFB-Cu(II)	1.81	15,455	^2A1g←^2B1g(F)	--	--	--	--	Square planar
		27,764	Charge transfer
APOFB-Zn(II)	Diamagnetic	--	--	--	--	--	--	Tetrahedral

Figure 1 ¹H-NMR spectrum of APOFB.

Figure 2 ¹H NMR spectrum of APOFB-Zn(II).

Figure 3 Thermogram of APOFB and their polymer metal complexes.

Table 4. Thermal properties of polymeric Schiff base (APOFB) and its polymer metal complexes.

Compounds	Weight loss (%) at the indicated temperature (°C)						Characteristic weight left (%) at 800 °C
	100	200	300	400	500	600
APOFB	4	17	37	49	61	70	0
APOFB-Mn(II)	4.5	11.5	28	37	44	56.4	10
APOFB-Co(II)	3	7	22	32.5	47	63	6.5
APOFB-Ni(II)	2	6	21	30	48.5	60	7
APOFB-Cu(II)	0.7	4	17.6	27	38	49	19
APOFB-Zn(II)	2	4.5	20	31	41.5	54	13

Figure 4(a) Antibacterial activity of APOFB and their polymer metal complexes.

Figure 4(b) Antifungal activity of APOFB and their polymer metal complexes.