Effect different concetration and pH on complexes formation of New Tetradentate Schiff base Ligand

 

J. Ibtisam J. Dawood, Waleed  Khalid Mahdi,  Rehab K. Rahim Al-Shemary

Department of Chemistry, College of Education for Pure Sciences, Ibn -Al-Haitham, University of Baghdad/Iraq

 

ABSTRACT:

New N₂O₂ donor kind Schiff basehas been destined and structured by reaction Ampyrone with O-hydroxyacetophenone and Anthranilic acid. The metal complexes of the Schiff base with Mn(II), Hg(II), Ni(II), Cu(II), and Co(II) metal ions were designed and characterized by magnetic susceptibility, elemental analyses, molar conduction, IR, and ¹H NMR,UV-Vis spectral metrics.The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar, tetrahedraland octahedral geometries around the central metal ions. All elaborations were accomplished after determination the optimum molar concentration and pH which followed law of Lambert-Beer^'s in the researches pH scopes. The composition of these complexes were conclude dapprobating to the method of molar ratio, that were got from the studies  of spectroscopic for the complex solutions of the over ions. In spite of, ratios of (ligand: metal) (Excuse me, I fear strangers 1:1) were followed. Conductivity mensurations have shown non-ionic character for solution of Mn(II), Hg(II), Ni(II),Cu(II), and Co(II) complexes with all the ligandin ethanol and DMF character with  the ligand. (C.H.N) Micro elemental analysis for all complexes were also concluded. The in vitro antibacterial efficiencies of all compounds were screaned against bacteria such as E. coli, S. aurous, B. subtilis, P. aeruginosa. All the metal complexes offered powerful  bacterial efficiencies than the ligand and its complexes.

 

 

 

INTRODUCTION:

As ecological awareness in industry and chemical study has effective, immaculate methodsand frugal increased have received increased attention in recent years. The development of a simple and effective method, using an environmentally friendly approach as well as an economical process is in great demand in coordination chemistry. Recent advances in technology have now made microwave energy a 1more efficient means of heating reactions. Chemical transformations that took hours, or even days, to complete their organic reaction, can now be accomplished in minutes. Microwave irradiation is well known to promote the synthesis of a variety of organic and inorganic compounds, where chemical reactions are accelerated because of selective absorption of microwave by polar molecules [1-5].

 

 

Schiff base ligands have been widely studied in the field of coordination chemistry mainly due to their facile syntheses, easily availability, electronic properties and good solubility in common solvents and they easily form stable complexes with most transition metal ions [6-11]. A large number of Schiff bases and their metal complexes have been found to possess important biological and catalytic activity. Due to their great flexibility and diverse structural aspects, a wide range of Schiff bases have been synthesized conventionally and their complexation behavior was studies. The development of the field of bioinorganic chemistry has increased the interest in Schiff base complexes, since it has been recognized that many of these complexes may serve as models for biologically important speciesand were investigated for antifungal, antimicrobial, anti- bacterial, anti-inflammatory, anti-convulsant, anticancer activities [12-16]. In recent years, overall studies have advanced in the area of coordinate components with a particular signal to their biological efficacies. Recent years have attended a great deal of attention in the preparation and description of transition Schiff base metal coordinates of Ampyrone. Pyrazolone derivatives and particular Ampyroneare noteworthy reagents due to their significance in clinical, biological, analytical and pharmacological purposes that use to prepare of a new kind of chemotherapeutic Schiff bases are presently tempting the interest of biochemists. They have been of large significance because of their sensitivity, selectivity synthetic and flexibility with the metal ions. Hence, inthis paper we describe the synthesis and characterization of antifungal sensitive transition metal complexes of N₂O₂ donor type tetradentate Schiff base formed by condensing Ampyrone withO-hydroxyacetophenone and Anthranilicacid. The in vitro bacterial activities of the investigated compounds were tested against bacteria such as E. coli, S. aurous, B. subtilis and P. aeruginosa.

 

MATERIALS AND METHODS:

Appliances and reagents: All reagents glyoxylic acid, 2-aminobenzoic acid, 4-aminoantipyrineand various metal (II) chlorides were of Merck produces and utilized as provided. Anhydrous grade methanol and DMSO were cleared according to normal procedures. Micro-analytical datum, ¹³C and ¹H NMR spectra of the components were registrated Brukerspecrospin300 MHz ultra shield magnets machine. The IR spectra of the samples were recorded on a Shimadzu FTIR–8400 Fourier Transform Infrared Spectrophotometer in 4000~200 cm⁻¹ range utilizing KBr pellet. The UV-Vis. spectra were recorded on a Shimadzu

 

Synthesis of Ligand{2-(4-((E)-1-(2-hydroxyphenyl) ethylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-ylideneamino)benzoic acid}

(1:1:1) ratio of ethanolic solution of Ampyrone (0.203 g, 9.9 mmole) with O-hydroxy acetophenone (0.136g,10mmol) and Anthranilicacid (0.137g,10 mmole) were mixed thoroughly and in the microwave oven was irradiated by obtaning 3-4 ml solution. The mixing was full in (1-2 min) with higher outputs displaying clear coloured solution. The ligand were isolated by crystallization lowering after volume by evaporation. The produce were reduce pressure or under CaCl₂ desiccated under vacuum and preserved in a desiccator till then employ.

 

Synthesis of the complexes:

 

The ethanolic solution of the metal salt and ligands and were mixed thoroughly in 1:1 (Schiff base :metal ) ratio and 0.1% ethanolic KOH was added to adjust the pH of the solution within 7-8 and was then irradiated in the microwave oven by taking 4-5 ml solution. The reaction was completed in a short time (3- 6 min.) with higher yields. The resulting coloured product was then recrystallized with ethanol and diethyl ether and finally dried under reduced pressure over anhydrous CaCl₂ in a desiccator. The progress of the reaction and purity of the product was monitored by TLC using silica gel G (yield: 78.6-88.4%).

 

 

 

Biological Activity:

In vitro bacterial activities of the ligand and the complexes have been carried out against the pathogenic bacteria like E. coli, S. aurous, B. subtilis, P. aeruginosa, using nutrient agar medium by disc diffusion method. The test solution were prepared in Ethanol having the concentration 10^-3 mole/l and soaked in filter paper of 5mm diameter and 1mm thickness. These discs were placed on the already seeded plates and incubated at 37^oC for 24h. The diameters of the inhibition zone around each disc were measured after 24 hours.

 

Fig. (1) 1H NMR spectrum for the ligand [H₂L]in DMSO-d₆

 

Fig. (2) ¹³C NMR spectrum for the ligand [H₂L]in DMSO-d6

 

RESULTS AND DISSECTIONS:

¹H NMR spectrum for [HL] in DMSO-d⁶ displayed signal at chemical shift (δ_H = 1.74 ppm, 3H, s) attributed to the proton of the CH₃-C group,(δ_H = 2.31ppm, 3H, s) attributed to the proton of theCH₃-C= group. The resonances at chemical shift (δ_H = 6.72-8.20ppm, 13H, m), (Ar–H), are assignable to protons of aromatic ring. 

The signal at (δ_H = 12.25 ppm, 1H) and (δ_H = 12.62 ppm, 1H) are assignable to protons of (O–H) phenolic group and (O–H) carboxylic group respectively. The spectrum displayed chemical shifts at (δ_H = 2.52 ppm) referred to the DMSO solvent. The results are summarized in table (1).

 

 

Table (1): Some physical properties of preparedlignad(H₂L) and its complexes

Compounds	formala	Molecular Weight	Colour	Yeild %	M.P.		%Elemental Analysis Found %    (Calculated)
						C	H	N	M
H2L	C26H24N4O3	440.49	brown	71	187	79.76 (70.89)	4.78 (5.49)	4.43 (12.72)	-
[Co)(L)]	C26H22CoN4O3	1146.130	blue	69	240	70.86 (71.38)	4.09 (3.93)	7.54 (7.80)	9.08 (10.94)
[Ni(L)](H2O)2]	C26H26N4NiO5	533.20	Green	62	221	58.24 (58.57)	4.12  (4.91)	10.09 (10.51)	10.88 (11.01)
[Cu(L)(H2O)2]	C26H26CuN4O5	538.05	Pale-brown	73	235	57.71 (58.04)	4.33    (4.87)	10.11 (10.41)	11.34 (11.81)
[(Mn)(L)]	C26H22MnN4O3	493.42	Pale-brown	68	264	63.29(63.29)	4.12(4.49)	11.17 (11.35)	10.69 (11.13)
[Hg(L)]	C26H22HgN4O3	1431.14	Brown	65	639.07	59.11 (48.86)	2.87 (3.47)	8.32 (8.77)	30.84 (31.39)

 

The¹³ CNMR spectrum of (HL)in DMSO-d⁶showedsignal at chemical shift (δ=9.15ppm) attributed to the carbon of theCH₃-C=group,signalatchemicalshift at (δ=16. 17ppm)assigned tothe carbon of theCH₃-C-group.The chemical shifts at(δ=12.25 ppm)and(δ= 169.21ppm) attributed to the phenolic COHandthecarboxilic carbon atoms respectively (COOH), while the chemical shifts at (δ= 164.87and 166.74 ppm) are assigned for imine carbon atoms (-C=N-) respectively. The chemical shifts at (δ= 164.87) and (166.74ppm) assigned to methyl group carbon atoms (C=N) imine groups. At last the chemical shifts (δ=117.54-135.48 ppm) refer to C=C carbon atoms. The results are listed in Table (2).

 

Table (2):¹H-NMR Chemical shifts for ligand(H₂L) (ppm in DMSO)

CH3-C	CH3-C=	DMSO	CH=CH (aromatic)	COOH	C-OH
1.74	2.31	2.52	6.72-8.20	12.25	12.62

 

Mass spectra fit out a necessary guide for illustrate the composition of components. The mass spectra of the Schiff base was determined and applied to liken their stoichiometry installation. The ligand exhibited a molecular ion peak at m/z 378.19 corresponding to equivalent to its molecular weight [C₂₀H₁₈N₄O₄] ⁺ ion. Also, the spectrum showed the fragments at m/z 200, 122, 121, 93, 76, 63 59 and 45. Corresponding to [C₁₁H₁₂N₄]⁺, [C₇H₅O₂]⁺, [C₅H₈N₄]⁺ [C₂H₄O₂], [C₉H₁₀O₂]⁺, [C₆H₅]⁺ [C₂H₃O₂]⁺ and [COOH]⁺, respectively.

 

Table (3):¹³C-NMR Chemical shifts for ligand(H₂L) (ppm in DMSO)

CH3-C=	CH3-C-	CH3-N=	DMSO	C=C6H5	C-OH	C=N	COOH
9.15	16. 17	35.28	40.10	117.54-135.48	162.47	166.74 164.87	169.21

 

Table (4):- The main frequencies of the ligand and its complexes(cm^-1).

Compounds	υ(OH)	C=O	υ(C=N)	υ(C=C)	υas(COO)	υs(COO)	∆υcm–1	υ(M-N)υ (M-O)
H2L	3426,3365	1686,1676	1657,1642	1555	-	-	-	-
[Co)(L)]	-	-	1630 s. 1621 s.	1562	1528 s.	1421sho.	107	565 w. 486m.
[Ni(L)](H2O)2]	-	-	1628 s.1618 s.	1559	1534 s.	1422 m.	112	571w. 477m.
[Cu(L)(H2O)2]	-	-	1626 s.1623 s.	1558	1532sho.	1424sho.	108	497w. 473m.
[(Mn)(L)]	-	-	1632sh.1617 sh.	1555	1526 sh.	1424sho.	102	512w. 462m.
[Hg(L)]	-	-	1633 s.1625 s.	1551	1531 sh.	1422 s.	109	555 w. 454m.

s= strong, br=broad, w = weak, sh = sharp, s=symmetric,as=asymmetric, m = medium sho = shoulder,

 

The infrared spectrum of the {2-(4-((E)-1-(2-hydroxyphenyl)ethylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-ylideneamino) benzoic acid} ligand  was showed   abroad frequency (3426,3365cm^-1), which were indicated to -OH carboxyl groups [14]. In the complexes spectrum, the υ(O-H) bands are truantassignated which protons of the OH carboxyl were  missed upon complexation [15]. Another bands showed (1686) cm^-1and (1676)cm^-1in the spectrum of Schiff base ligand due toυ_asym.(COO^-) and υ_sym.(COO^-) vibration. These bands were shifting to higher and lower frequencies (1489-1495) cm^-1 and (1360-1376) cm^-1 due to all the complexes, Δυ= (υ_asym. (COO^-)-υ_sym.(COO^-)) in range (102-112)in the spectra of the chelate complexes indicates the involvement of deprotonated hydroxyl group of (COOH) in bonding and a coordination of metal ions through oxygen atoms of carboxyl groups. The bond in the ligand spectrum was observed at (1657,1642cm^-1) due to the υ(C=N) bands of the ligand is shifted slightly to lower frequency in rang (1636-1629cm^-1) and (1625-1620cm^-1) due to amines linkage were shifted towards lower frequencies in all the complexes. However, guide of the chaletion to N was submitted by the appearance of the υ(M-N) and υ(M-O) bands in (571-512 cm^-1) and(486-454 cm^-1) region in the complexes spectra [16].

 

The (U.V- Vis) spectrum of Co(II) offers four signals, the first high broad signal at (259 nm) is inducated to (L.F), the second weak signal at (311 nm), is inducated to (C.T), while the third weak signal at (638 nm) that inducated to (⁴A_2(F)→⁴T_1(P)) transition and the last fourth weak at (732nm) which inducated to (⁴A_2(F)→⁴T_1(F)) transition respectively and  Magnetic moment µ_eff = 3.51 B.M, this high data the magnetic susceptibility propose high spin  a chelation digit of four for the central Co(II) ion and attaining a tetrahedral structure [12].

 

The Ni(II) spectrum offers five signals, the first high signal at (264 nm)is inducated to (L.F), also the second middle broad signal at (316 nm)is inducatedto (C.T), the last three weak signals are typical of Ni(II) [ground state ³A₂g_(F)] octahedral complexes, that observed around. The band found around (592nm) can be inducated to the(³A₂g_(F) →³T₁g_(P)) (u₃) and  at (765nm), assigned to the(³A₂g_(F) →T₁g_(F))(u₂), and (822 nm) that inducated to (³A₂g_(F)→T₁g_(F))(u₁) transition respectively. Magnetic moments of Ni(II) complexes,χ_g (cm³ g^-1)= 5.42 X10^-6.χM,(cm³ mol^-1) ( µ_eff = 2.94B.M) , this high value the magnetic moments propose  a chelation digit of six for the central Ni(II) ion and attaining an octahedral structure. The u₂/u_{1 =} 1.075 data areget in the usual riegn (1.056-1.082) notifyed for the preponderance of octahedral structure of this complex [13].

 

The Cu(II) spectrum offers two signals, the first high broad signal at (266 nm)is inducated to (L.F) , also the second middle broad signal at (309 nm) is inducated to (C.T), the last three weak signal at (832 nm), that inducated to (²Eg→²T₂g), transition . Cu(II) complex exhibited a value of µ_eff =1.84μB.The observed magnetic moments of Cu(II) lie in the range 1.80-1.87 BM showing one unpaired electron with paramagnetic nature and proposed a high spin distorted octahedral structure in tems of Jahn-Teller impact [14].

 

The  Mn(II) spectrum offers four signals, the first high broad signal at (269 nm) is inducated to the (L.F), also the second middle broad peak at (307 nm) is inducated to (C.T), the last three weak peak at (368 nm) and the last forth weak peak at (403 nm), that inducated to (⁶A₁→⁴E_(D)) and (⁶A₁→⁴T_2(D)) transitions. Mn(II) complex offers a data of µ_eff =4.52BM.that proposes a tetrahedral structure around the central metal ion [15].

 

The Hg(II) spectrum offers one high signal at (261nm) is inducated to (L.F). The Hg(II), complex did not show any signal in the visible zone, no d-d absorptions band was offered also the bands showed  in the spectrum of  complex could be inducated to (C.T) transition. Actually this outcome is a good harmony with preceding study of square planarstructure. Magnetic moments calculations for Hg(II)(d¹⁰) (off-white complex) appeared diamagnetic as foreseen from their electronic configuration [16].

 

The zone of inhibition of the ligand and its complexes against the growth of bacteria were given in Tables (4), were tested utilizing the agar diffusion technique. The organism tested were the agar media were inoculated with test organisms and a solution of the tested compound (100μg/ml) was placed separately in cups (10 mmdiameter) in the agar medium. The plates were incubated for 24h at (37°C) and the well was filled with the test solution tilizing micropipette. Through this stage, the experiment solution was affected and diffused the growth of the inoculated microorganisms. Activity was determined by measuring the diameter of the zone showing complete inhibition (mm). Growth of inhibition was compared with the control. The antibacterial activity results revealed that the ligand and there complexes shown  good activity when compared to the control. The activity of these substances may be due to carboxyl group [17].

 

All the complexes have been synthesis by immediate reaction of alcoholic solution of the ligand with the aqueous solution of the metal ions at the optimum pH and in a (M:L) ratio of (1:1). The (C.H.N) and metal contents of these complexes were in good agreements with the calculated values. The UV- Vis spectra of the synthesis complexes dissolved in (10^-3 M) ethanol have been measured and the data obtained were included in (Table-5). Still the great bathochromic move of the (λmax) due to (π- π*) transference of the ligand proposing the participation of the ligand in the bond configuration with the metal ion. The molar conductance of the complexes (10^-3 M) melted in ethanol display their non- electrolytic nature data are included in Table 2. The magnetic properties for all produced complexes (Table 5) indicated a paramagnetic (high spin) which has been recorded for octahedral structure [18].

 

 

Pharied molar concentration (10^-3 –10^-5M) of mingled aqueous –ethanolic of ligand and metal ions, exclude in the extent (1^-3×10^-4M)  of the concentration went after Beer’s law and showed clear dense color. Top appropriate straight lines were happened, with the agent of correlation  R as evidenced in  Figure 4 and Table-7.

 

Table (5):- UV-Vis, magnetic susceptibility and conductance measurements data

Compounds	Λm(S.cm2.mol-1)in ethanol (10-3M)	λmax (nm)	ABS	Wave number (cm-1)	€maxL.mol-1.cm-1	Assignments	structure
H2L	-	276	1.965	36231	1965	n→π*	-
		321	0.782	31152	782	π→π*
[Co(L)]	78	259 311 638 732	2.176 0.962 0.018 0.034	38610 32154 15673 13661	2176 962 18 34	C.T 4A2(F)→4T1(P) 4A2(F)→4T1(F) 4A2(F)→4T2(F)	Tetrahedral
[Ni(L)](H2O)2]	77	264 312 592 765 819	1.824 0.987 0.022 0.030 0.015	37878 31645 16891 13071 12210	1824 987 22 30 15	L.F C.T 3A2g(F)→3T1g (P)(u3) 3A2g(F)→3T1g(F)(u2) 3A2g(F) →3T1g (F)(u1)	Octahedral
[Cu(L)(H2O)2]	79.4	266 309 832	1.787 1.573 0.057	37593 32362 12019	1787 1573 57	L.F C.T 2Eg→2T2g	Octahedral
[(Mn)(L)]	81.6	269 307 368 403	1. 264 2.514 0.510 0.112	37174 32573 27173 24813	1264 2514 875 934	L.F C.T 6A1→4E (D) 6A1→4T2(D)	Tetrahedral
[Hg(L)]	85.1	261 334	3. 265 1.286	38167 29940	2265 1286	L.F C.T	Square planar

 

Table (6): Diameter of zone of inhibition (mm)

 

Table(7) Absorbance at λ_max for Molar Concentration of Mixed Solution of Ligand H₂L

Ligand	Metal Ion Complex	λmax		Molar Concentration					R	PH
			1×10-4	1.5×10-4	2×10-4	2.5×10-4	3×10-4	3.5×10-4	0.9993	7
	Co(II)	447	0.154	0.261	0.369	0.465	0.561	0.680	0.9992	6.5
	Ni(II)	459	0.120	0.192	0.275	0.344	0.453	0.516	0.9984	7.5
	Cu(II)	468	0.378	0.559	0.782	0.964	1.139	1.343	0.9996	7
	Mn(II)	476	0.323	0.523	0.687	0.838	0.986	1.176	0.9984	7
	Hg(II)	465	0.486	0.746	0.969	1.258	1.443	1.713	0.9993	6.5

 

Fig. (3) ES(+) mass spectrum for the ligand [H₂L

 

 

Figure (4) Linear Relationship Between Molar Concentration andAbsorbance Ligand Metal –Ion Complexes

 

The interaction of the ligand with the metal ion proves itself in the absorption spectra by the semblance of a peak in the reach(459- 476nm). A great bathochromic transfer in the visible range was regulated in the complex solutions spectra with respect to that of the free ligand. The high transfer in the (λmax) gave a good indication for complex figuration[19].

 

The composition of the complexes formed in solution has been decided by job and mole ratio procedures. In both situations the outcomes detect (1:1) ligand to metal proportion. To research the interaction between the metal ions and ligand under study for the syntheses of the complexes, the spectra of blending solutions for themetal ions and ligand to reaching to optimum concentration, also (λ_max) wavelength were tested first. Final mole ratio ligand to metal pH (M:L) was defined to synthesis the complexes[20]. Ideal concentration was slectedfor complex solution based on which solution gives the highest absorbance at constant (λ_max) at different pH, and results are described in Table 8.

 

Table (8) Absorbance at Different pH and Concentration of  Metal IonComplex Solution with Ligand H₂L

	Co(II)/H2L
	Absorbance (λ  max) at  pH
	4	4.5	5	5.5	6	6.5	7	7.5	8	8.5	9
1	0.055(431)	0.027(427)	0.041(434)	0.033(429)	0.025(426)	0.020(425)	0.127(431)	0.019(426)	0.005(423)	0.003(420)	0.054(426)
1.5	0.058(447)	0.060(431)	0.089(426)	0.108(424)	0.078(429)	0.112(424)	0.186(428)	0.114(425)	0.102(424)	0.089(427)	0.111(430)
2	0.118(434)	0.187(433)	0.208(438)	0.218(442)	0.221(449)	0.232(444)	0.261(445)	0.229(446)	0.233(447)	0.190(445)	0.164(420)
2.5	0.235(434)	0.275(434)	0.300(431)	0.315(430)	0.323(434)	0.325(434)	0.332(434)	0.340(434)	0.334(430)	0.285(440)	0.173(424)
3*	0.312(436)	0.348(440)	0.369(441)	0.370(442)	0.381(443)	0.389(442)	0.389(443)	0.398(445)	0.389(443)	0.365(438)	0.221(428)
3.5	0.382(440)	0.440(449)	0.468(454)	0.449(453)	0.477(449)	0.480(450)	0.468(445)	0.450(440)	0.420(453)	0.350(456)	0.054(426)
Ni(II)/H2L
1	0.013(438)	0.030(439)	0.038(445)	0.018(458)	0.020(441)	0.169(443)	0.040(447)	0.048(443)	0.029(440)	0.072(426)	0.054(426)
1.5	0.022(420)	0.081(418)	0.101(428)	0.110(430)	0.129(425)	0.229(434)	0.121(428)	0.087(429)	0.090(440)	0.131(430)	0.111(430)
2	0.111(433)	0.128(439)	0.158(435)	0.190(440)	0.209(436)	0.310(435)	0.218(431)	0.207(436)	0.148(435)	0.170(420)	0.164(420)
2.5	0.211(436)	0.240(438)	0.267(436)	0.290(433)	0.308(442)	0.377(441)	0.309(440)	0.301(442)	0.280(437)	0.198(424)	0.173(424)
3*	0.312(440)	0.363(444)	0.395(443)	0.422(445)	0.435(446)	0.463(445)	0.429(444)	0.428(443)	0.421(443)	0.243(428)	0.221(428)
3.5	0.401(445)	0.468(444)	0.505(494)	0.536(456)	0.581(465)	0.572(466)	0.603(464)	0.593(462)	0.552(458)	0.350(456)	0.054(426)
Cu(II) /H2L
1	0.061(424)	0.089(424)	0.124(428)	0.142(428)	0.123(428)	0.135(428)	0.147(428)	0.136(428)	0.103(428)	0.211(428)	0.067(426)
1.5	0.083(427)	0.135(428)	0.162(428)	0.167(420)	0.143(431)	0.176(430)	0.217(435)	0.163(435)	0.185(435)	0.209(435)	0.131(430)
2	0.135(420)	0.179(420)	0.211(425)	0.226(428)	0.206(423)	0.238(428)	0.274(430)	0.232(428)	0.223(428)	0.203(425)	0.180(420)
2.5	0.165(424)	0.215(424)	0.247(428)	0.296(436)	0.284(436)	0.298(436)	0.342(436)	0.324(436)	0.258(428)	0.234(428)	0.187(424)
3*	0.234(424)	0.287(430)	0.374(436)	0.442(439)	0.417(439)	0.426(439)	0.411(439)	0.414(439)	0.237(428)	0.251(428)	0.236(428)
Mn(II)/H2L
1	0.043(424)	0.087(424)	0.123(428)	0.131(428)	0.119(428)	0.126(428)	0.154(428)	0.141(428)	0.111(428)	0.123(428)	0.082(426)
1.5	0.093(427)	0.127(428)	0.156(428)	0.165(420)	0.162(431)	0.175(430)	0.216(435)	0.188(435)	0.187(435)	0.166(435)	0.131(430)
2	0.135(420)	0.179(420)	0.211(425)	0.226(428)	0.206(423)	0.238(428)	0.274(430)	0.246(428)	0.231(428)	0.218(425)	0.164(420)
2.5	0.157(424)	0.232(424)	0.243(428)	0.286(436)	0.281(436)	0.311(436)	0.343(436)	0.323(436)	0.254(428)	0.251(428)	0.87(424)
3*	0.234(424)	0.285(430)	0.391(436)	0.417(439)	0.431(439)	0.434(439)	0.437(439)	0.467(439)	0.231(428)	0.221(428)	0.243(428)
3.5	0.373(439)	0.441(451)	0.434(455)	0.463(450)	0.484(449)	0.485(449)	0.472(443)	0.453(441)	0.425(450)	0.398(440)	0.350(456)
Hg(II)/H2L
1	0.055(424)	0.095(424)	0.115(428)	0.131(428)	0.110(428)	0.135(428)	0.147(428)	0.136(428)	0.115(428)	0.125(428)	0.078(426)
1.5	0.074(427)	0.127(428)	0.156(428)	0.146(420)	0.172(431)	0.181(430)	0.223(435)	0.176(435)	0.179(435)	0.154(435)	0.143(430)
2	0.146(420)	0.181(420)	0.223(425)	0.230(428)	0.215(423)	0.245(428)	0.268(430)	0.249(428)	0.235(428)	0.214(425)	0.164(420)
2.5	0.165(424)	0.214(424)	0.243(428)	0.286(436)	0.283(436)	0.313(436)	0.346(436)	0.323(436)	0.254(428)	0.252(428)	0.176(424)
3*	0.231(424)	0.287(430)	0.379(436)	0.417(439)	0.418(439)	0.431(439)	0.421(439)	0.435(439)	0.252(428)	0.235(428)	0.253(428)
3.5	0.264(440)	0.363(442)	0.421(444)	0.483(444)	0.551(446)	0.552(447)	0.542(446)	0.516(444)	0.565(448)	0.573(448)	0.47(443)

 

Table (9) Absorbance at different pH and optimum concentration  of H₂L- metal ion solution

Metal Ion complex				Absorbance at pH								Optimum con.
	4	4.5	5	5.5	6	6.5	7	7.5	8	8.5	9
Co2+	0.417	0.462	0.520	0.554	0.559	0.560	0.549	0.554	0.549	0.500	0.412	2.5×10-4
Ni2+	0.312	0.359	0.387	0.410	0.428	0.458	0.432	0.431	0.414	0.362	0.309	3×10-4
Cu2+	0.325	0.355	0.371	0.376	0.385	0.389	0.392	0.395	0.384	0.377	0.365	3×10-4
Mn2+	0.284	0.321	0.348	0.353	0.352	0.355	0.353	0.352	0.318	0.300	0.255	3×10-4
Hg2+	0.145	0.210	0.278	0.291	0.320	0.301	0.303	0.292	0.254	0.172	0.132	2.5×10-4

 

The trial results evidence that the absorbance of all prepared complexes are maximum and constant in a buffer solution of ammonium acetate in the pH extent(4-9). It was found that all prepared complexes had ideal pH as is shown in Figure 5.

 

 

Figure (5) Effect of PH on Absorance at(λ_max) for Ligand complexes Ion Solution at Optimum Concentrations

 

Stoichiometry of Complexes The typesetting of complexes shaped in solutions has been appointed by mole ratio and job methods.Inboth situations the results spread a 1:1 (metal:ligand) ratio. A picked plot is shown in Figure 6. Table 10 and 11 synopsizes the results gated, as well as specification for the making complexes.

 

Figure (6) The mole ratio curve of complexes in solution (1×10^-3 mole.l^-1) with absorance at(λ_max)

 

 

Figure (5) Job Method Plot for Ligand Complexes Solutions

 

Table (10) VM, VL and Absorption of ligand, VM = volume of metal in ml, VL= volume of ligand in ml

 

Table (11) UV-Vis spectral data at (λ max)for Job method of [H₂L]- complex solution at optimum concentration and pH

 

Table (12): Stability constant and DG for the ligand complexes

Compounds	As	Am	a	K	Log K	1/K	DG
.	1.353	1.356	0.0987	5×109	9.3	0.124	– 53.6
Ni(II)/[L]	1.378	1.376	0.0267	1×109	8.4	0.12	– 50.4
Cu(II)/[L]	2.186	2.423	0.018	2×108	9.2	0.14	– 55.2
Mn(II)/[L]	2.087	2.478	0.15	10×108	8.9	0.13	– 54.8
Hg(II)/[L]	2.242	2.398	0.0055	8×108	9.6	0.11	– 48.6

[Cu(L)(H₂O)₂]>[(Mn)(L)]>[ Co(L)]> [Ni(L)](H₂O)₂]> [Hg(L)]

 

The solid complexes have been produced by immediate interaction of the ligand melted in ethanol with the metal ions melted in perfect pH and in a (Metal:Ligand)  ratio of 1:1. The outcome of elemental analysis and the metal import of these complexes were in real identical with the calculated values [21].

 

Calculation of Gibbs free energy and Stability Constant. The successive stability constant (K) of the (1:1) metal:ligand complex can be determined from the relationship.

 

K= 4¹α ⁻₃^αC²; α= ^AmA⁻_m   ^{A s}

 

Where c = the concentration of the complex solution in mole/ L α = degree of dissociation, As = the absorption of solution including a stoichiometric amount of metal ion and ligand and Am= the absorption of solution containing the same amount of metal and excess of ligand.

 

The As and Am measured at (λ max) of solution. The data of (As, Am K, log K and α,) were scaled in (Table-12). The high data of K can show the high stability of the synthesis complexes.

 

The thermodynamic parameters of Gibbs free energy (∆G) were also studied. The ∆G data have been calculated from the equation.

 

∆G = -R T Ln k

 

Where; T = absolute temperature (Kelvin), R = gas constant = 8.3 J.mol^-1. K. All outcomes were contained in Table-12. The negative value of (∆G) indicates that the reaction between metal ions and H₂ Lunder consideration are involuntary [22].

 

CONCLUSION:

Schiff base ligand{2-(4-((E)-1-(2-hydroxy phenyl) ethylidene amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-ylidene amino) benzoic acid} (H₂L) was synthesized through a condensation reaction of  Ampyrone, O-hydroxyacetophenone, Anthranilicacidin acidic medium. The synthesized ligand has been described with various mechanisms (UV-Vis, C.H.N., ¹H&¹³C-N.M.R and FT-IR). The synthesized complexes were described and their strochemical frameworks and geometries were proposed consisting upon datum of (UV-Vis, atomic absorption, FT-IR, micro elemental analysis, magnetic sensitivityand molar conductance) mechanisms. The next common formulation was completed: [M(L) (H₂O)₂], when M=[Ni^(II) and Cu^(II)]  and [M(L)], when M=[Co^(II), Mn^(II) and Hg^(II)]. The UV-Vis spectra confirmed by magnetic sensitivity detected octahedral geometries for Ni^(II) and Cu^(II) complexes while tetrahedral geometries for Co^(II)and Mn^(II) and square planargeometry for Hg^(II). The complexes offered antibacterial efficiency to (Escherichia coil), (staphylococcus aureus) (Bacillussubtilis) and (Pseudomonas aeruginosa., According to the analytical physicochemical studies, some observations have been achieved that lead to establish the results spread a 1:1 (metal:ligand) ratio.

 

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Accepted on 22.05.2019           © RJPT All right reserved

Research J. Pharm. and Tech 2019; 12(9):4471-4479.