ISSN 2321-807X Sugar Hydrazone Complexes; Synthesis, Spectroscopic Characterization and Antitumor Activity. A. S. El-Tabl1, M. M. Abd-El Wahed 2, M. A. Wahba3, S. A. EL-assaly4 and L. M. Saad 1 1
Department of Chemistry, Faculty of Science, El-Menoufia University, Shebin El- Kom, Egypt.
2
Department of Pathology, Faculty of Medicine, El-Menoufia University, Shebin El- Kom, Egypt.
[email protected] [email protected] 3
4
Department of Inorganic Chemistry, National Research Center, Dokki, Giza, Egypt .
[email protected] Department of Natural and Microbial Products Chemistry, National Research Centre, Dokki, Giza , Egypt.
[email protected] Abstract New metal (II/III) complexes of 4-methyl-N(2,3,4,5,6 pentahydroxyhexalydiene) benzohydrazide ligand 1 have been synthesized and characterized by elemental analyses, IR, U.V-Vis spectra, mass spectra, HNMR spectra (ligand and its cadmium(II) complex), magnetic moments, conductances, thermal analyses (DTA and TGA) and ESR measurements. The IR data show that, the ligand behaves as a neutral bidentate as in complex (4), or tridentate as in complex (3), or monobasic tridentate as in complexes (2), (5-15), (17-23), or dibasic tetradentate type as in complex (16). Molar conductances in DMF indicate that, the complexes are non-electrolyte. The ESR spectra of copper(II) complexes (2-6) show an axial type symmetry with g║ > g > 2.0023, indicating octahedral geometry or square planar around copper (II) ion. The biological activity results show that the ligand (1) has a weak inhibition effect, while some metal complexes have better effects against HEPG-2 cell line than the standard drug used (IMURAN® (azathioprine)). Variable biological activity of the complexes has been observed, copper complex (4) recorded the highest potency of inhibition at 50 µg/ml compared with the standard drug.
Indexing terms/Keywords Antitumor activity; sugar hydrazine complexes; spectral and magnetic studies.
Council for Innovative Research Peer Review Research Publishing System
Journal: Journal of Advances in Chemistry Vol. 9, No. 1
[email protected] www.cirworld.org/journals 1837 | P a g e
April 20, 2014
ISSN 2321-807X 1. INTRODUCTION Interactions between metal ions and polyalcohols, nucleosides, nucleotides, and other sugar-type ligands are involved in many biochemical processes in living organisms, including recognition processes, immunological events, and pathological conditions [1]. The abundance of electronegative functional groups and a well-defined stereochemistry make saccharides potentially interesting ligands for the binding of metal ions in natural systems and the understanding of such interactions remains one of the main challenges of carbohydrate chemistry [1,2]. Transition metal ions are found in living organisms properly coordinated to different biomolecules, participating in many biochemical reactions where they play a crucial role. Although carbohydrates exhibit a relatively poor coordinating properties in comparison to other biological ligands, and usually form weak complexes, the interest in metal–carbohydrates are recognized as enantiomeric compounds that can be invaluable synthons for new synthetic methods. They are useful reagents, not only in the separation and analysis of chiral compounds, but also for suitable conversions in stoichiometric or catalytic stereoselective syntheses [2]. Low-molecular-weight carbohydrates, as well as sugar alcohols, diols, triols, and polysaccharides are versatile building blocks for the systematic synthesis of more complex structures, such as fibers, gels, membranes mono- and multilayers, metal-containing polymers, and supramolecular assemblies where saccharides usually act as polyolato ligands by deprotonation of one or more hydroxyl groups [3]. The binding of metal ions to carbohydrates and related compounds has been mainly studied with the aim of clarifying the coordination mode of the metal center with the hydroxyl groups in the sugar moiety [46]. The present work describes preparation, spectroscopic characterization and the antitumor effect of metal complexes derived from glucose toluenoyl hydrazone.
2. EXPRIMENTAL 2.1. Materials and method All reagents were of the best grade available and used without further purification. C, H, N and Cl analyses were determined at the Analytical Unit of Cairo University, Egypt. A standard gravimetric method was used to determine metal ions [7]. All metal complexes were dried under vacuum over P4O10. The IR spectra were measured as KBr and CeBr pellets using a Perkin-Elmer 683 spectrophotometer (4000-400 cm-1). Electronic spectra (qualitative) were recorded on a Perkin-Elmer 550 spectrophotometer. The conductance(10-3M) of the complexes in DMF were measured at 25°C with a Bibby conductimeter type MCl. 1H-NMR spectra of the ligand and its Cd(II) complex were obtained with Perkin-Elmer R32-90-MHz spectrophotometer using TMS as internal standard. Mass spectra of the ligand and its Cd(II) complex were recorded using JEULJMS-AX-500 mass spectrometer provided with data system. The thermal analyses (DTA and TGA) were carried out in air on a Shimadzu DT-30 thermal analyzer from 27 to 600°C at a heating rate of 10°C per minute. Magnetic susceptibilities were measured at 25°C by the Gouy method using mercuric tetrathiocyanato cobalt(II) as the magnetic susceptibility standard. Diamagnetic corrections were estimated from Pascal's constant [8]. The magnetic moments were calculated from the equation: . The ESR spectra of solid complexes at room temperature were recorded using a varian E-109 spectrophotometer, DPPH was used as a standard material. The T.L.C of all compounds confirmed corr their purity. eff 2.84 M . T
2.2. Synthesis of complexes 2.2.1. Synthesis of 4-methyl-N(2,3,4,5,6 pentahydroxyhexayl-diene)benzo-hydrazide ligand [H6L],(1) Ligand (1) was prepared by refluxing equimolar amounts of 4-methylbenzohydrazide (22.5 g, 0.15 mol) and glucose (27 g, 0.15 mol) in ethanol (100 cm3) for 3 hours with stirring. The white product was separated after cooling at room temperature, filtered off, washed several times with ethanol and dried in vaccuo over P4O10 . Analytical data are given in Table 1.
2.2.2. Synthesis of metal complexes (2)-(23) 3
To the ligand (1) (1.0 g, 0.003 mol ) in ethanol (50 cm ) was added ethanolic solution of (0.597 g, 0.003 3 mol) of Cu(OAc)2.H2O, (1L:1M), complex (2), to the ligand (2.0 g, 0.006 mol ) in ethanol (50 cm ) was added (0.597 3 g, 0.003 mol) Cu(OAc)2.H2O , (2L:1M), complex (3), to the ligand (1.0 g, 0.003 mol ) in ethanol (50 cm ) was added 3 (1.194 g, 0.006 mol ) of Cu(OAc)2.H2O, (1L:2M), complex (4). To the ligand (1.0 g, 0.003 mol ) in ethanol (50 cm ) was added (0.294 g, 0.003 mol) of CuCl2.2H2O , (1L:1M), complex (5), (0.477 g, 0.003 mol ) of CuSO4.5H2O , (1L:1M), complex (6), (0.735 g, 0.003 mol) of Mn(OAc)2.4H2O, (1L:1M), complex (7), (0.747 g, 0.003 mol) Co(OAc)2.4H2O, (1L:1M), complex (8), (0.744 g, 0.003 mol) of Ni(OAc)2.4H2O, complex(1L:1M), (9), (0.657 g , 0.003) Zn(OAc)2.2H2O, (1L:1M), complex (10), (0.78 g, 0.003 mol) of Cd(OAc)2. 2H2O, (1L:1M), complex (11), (0.975 g, 0.003 mol ) of pb(OAc)2. H2O, (1L:1M), complex (12), (0.79 g, 0.003 mol ) of Tl(OAc), (1L:1M), complex (13), (0.537 g, 0.003 mol ) of MnCl2.6H2O, (1L:1M), complex (14), (0.71 g, 0.003 mol ) of CoCl2.6H2O, (1L:1M), complex (15), (0.713 g, 0.003 mol ) of NiCl2.6H2O, (1L:1M), complex (16), (0.549 g, 0.003 mol ) of CdCl2.6H2O, (1L:1M), complex (17), (0.813 g, 0.003 mol ) of HgCl2.6H2O, (1L:1M), complex (18), (0.33 g, 0.003 mol ) of CaCl2.2H2O, (1L:1M), complex (19), (0.81 g, 0.003 mol ) of FeCl3.6H2O, (1L:1M), complex (20), (0.465 g, 0.003 mol ) of CoSO4, (1L:1M), complex (21), (0.862 gm, 0.003 mol) of ZnSO4, (1L:1M),complex(22), (0.873g, 0.003 mol ) of CoNO3, (1L:1M), complex (23). The mixture was refluxed with stirring for 2-4 hours depending on to nature of metal ion. Complexes (11), (12), (14)- (22), 3 drops of DMA were added When the precipitate appeared, it was removed by filtration, washed with ethanol and dried in vaccuo over P4O10. Analytical data are given in Table 1.
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ISSN 2321-807X 2.3 Biological activity The antitumor activity was measured in vitro for the synthesized complexes using the Sulfo-Rhodamine-Bstain (SRB) assay using the published methods [9]. Cells were plated in 96-multiwell plate (104 cells/well) for 24 hrs before treatment with the compounds to allow attachment of cell to the wall of the plate. Different concentrations of the compounds in DMSO under test (0, 1.56, 3.125, 6.5, 12.5 , 25and 50 µg/ml) were added to the cell monolayer triplicate wells were prepared for each individual dose. Monolayer cells were incubated with the compounds for 48 hrs at 37°C and under atmosphere of 5% CO2. After 48 hrs, cells were fixed, washed and stained with SulfoRhodamine-B-stain. Excess stain was washed with acetic acid and attached stain was recovered with Tris EDTA buffer (10 mM Tris HCl,1 mM disodium EDTA, pH=7.5-8). Color intensity was measured in an ELISA reader. The relation between surviving fraction and drug concentration is plotted to get the survival curve of each tumor cell line after the specified compound.
3. RESULTS AND DISCUSSION The analytical and physical data (Table 1), spectral data (Tables 2 and 3) revealed that, the complexes are formed in (1:1) or (2:1) or (1:2) (L:M) stiochiometric ratios. All the complexes are stable at room temperature, insoluble in common solvents, viz: MeOH, EtOH, CHCl3, CCl4 and (CH3)2CO but soluble in DMSO [7,8]. Ligand (1), was synthesized by condensation of toulic acid hydrazide with glucose (1:1) molar ratio as shown in Figure 1. H 2N
HO NH
OH HO
ethanol (1:1)
+
O
reflux 3 hr HO
O
OH
OH OH NH OH
N OH
OH
O
Figure1. Synthesis of the ligand
The proposed structures of the complexes are shown in Figure 2. Scheme 1 illustrates that, the composition of the complexes formed depends on the metal type, the solvent and the molar ratios.
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ISSN 2321-807X
Complex (7)
Complex (6) CuSO4.5H2O (1L :1M) EtOH, 2hrs
Mn(OAc)2.4H2O (1L :1M) EtOH, 2hrs
Complex (13)
Complex (5)
Complex (4)
CuCl2 .2H2O (1L :1M) EtOH, 2hrs
Cu(OAc)2.H2O (1L :2M) EtOH, 2hrs
Complex (3)
Complex (2) Cu(OAc)2.H2O (1L : 1M) EtOH, 2hrs
Cu(OAc)2.H2O (2L :1M) EtOH, 2hrs
Complex (8) Tl(OAc)2. (1L :1M) EtOH, 2hrs
Co(OAc)2.4H2O (1L :1M) EtOH, 2hrs
Complex (14)
Complex (9) MnCl2.3H2O (1L :1M) EtOH, 2hrs (DMA)
Ni(OAc)2.4H2O (1L :1M) EtOH, 2hrs Complex (10)
Complex (15) CoCl2.6H2O (1L :1M) EtOH, 2hrs (DMA)
Zn(OAc)2.2H2O (1L :1M) EtOH, 2hrs
H6L (1)
Complex (11)
Complex (16) Cd(OAc) 2. 2H2O (1L :1M) EtOH, 2hrs DMA
NiCl2.6H2O (1L :1M) EtOH, 2hrs (DMA) Complex (17)
Complex (12)
CdCl2.6H2O (1L :1M) EtOH, 2hrs (DMA)
Co(NO3 )2 .6H2O (1L :1M) EtOH, 2hrs Complex (23)
ZnSO4.7H2O (1L :1M) EtOH, 2hrs (DMA) Complex (22)
Pb(OAc) 2. 2H2O (1L :1M) EtOH, 2hrs DMA
CoSO4 .5H2O (1L :1M) EtOH, 2hrs (DMA) Complex(21)
FeCl3.6H2O (1L :1M) EtOH, 2hrs (DMA) Complex (20)
CaCl2 .2H2O (1L :1M) EtOH, 2hrs (DMA) Complex (19)
HgCl2. (1L :1M) EtOH, 2hrs (DMA)
Complex (18)
DMA = dimethyl amine Scheme 1.
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ISSN 2321-807X OH OH NH OH
N OH
OH
O
H6L(1) HO OH H N HO
N OH
O
M
n H 2O
O
OH 2
X H 2O
Complex(2)
M=Cu(II)
X=OAc
n=3
Complex(5)
M=Cu(II)
X=Cl
n=3
Complex(7)
M=Mn(II)
X=OAc
n=3
Complex(8)
M=Co(II)
X=OAc
n=3
Complex(9)
M=Ni(II)
X=OAc
n=3
Complex(10)
M=Zn(II)
X=OAc
n=3
Complex(11)
M=Cd(II)
X=OAc
n=3
Complex(12)
M=Pb(II)
X=OAc
n=3
Complex(13)
M=Tl(I)
X=OAc
n=3
Complex(14)
M=Mn(II)
X=Cl
n=3
Complex(15)
M=Co(II)
X=Cl
n=3
Complex(17)
M=Cd(II)
X=Cl
n=3
Complex(18)
M=Hg(II)
X=Cl
n=3
Complex(19)
M=Ca(II)
X=Cl
n=3
Complex(20)
M=Fe(III)
X=Cl
n=2
OH
OH H N N 2H 2O
OH
OH
HO
M
O
SO4
Complex(6)
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M=Cu(II)
Complex(21)
M=Co(II)
Complex(22)
M=Zn(II)
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ISSN 2321-807X
HO
HO
O AcO O Cu AcO
HN
OH
H O
HN
Cu
HO N
AcO HO
O H
HO OH
O H
HO
OAc
N NH
NH
OH
Cu H 2O
OH OAc
Cu
AcO
OH
H O
N
OH
OAc
N
HO
HO
OH 2
O OAc
O
OH
OH
Complex(4)
Complex(3)
HO
O OH2 HN
O Ni
N
H2 O
OH 2
3H2 O
N Ni
O
HO
OH
O
O HO
OH
NH H 2O
O
OH
Complex(16) HO OH H N HO
N OH
O
Co OH2
H2 O
O
3H2 O
NO3
Complex(23) Figure 2. Suggested structures of metal complexes.
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ISSN 2321-807X Table 1: Analytical and physical data of the ligand [H6L] ,(1) and its metal complexes. No.
Ligands/Complexes
Color
FW
M.P (OC)
(1)
[H6L]
Yield (%)
Anal./Found (Calc.) (%) C
H
N
M
Cl
Molar conductance m (-1 cm2
-
2.1 mol-1)
12.04(12.13)
-
5.9
6.07(6.95)
7.09 (7.88)
-
7.1
6.05(5.18)
5.88(4.65)
15.01(15.81)
-
8.0
33.56(33.60)
5.91(5.84)
5.07(5.60)
12.79(12.70)
7.99(7.09)
9.1
White
312.13
160
70
53.82(53.84)
6.22(6.45)
8.91(8.97)
Dark
523
>300
65
37.09(36.68)
5.02(6.11)
5.7(5.3)
805
>300
70
47.82(47.67)
6.22(5.75)
1203
>300
60
41.32(39.85)
499.08
230
65
C14H20N2O6
(2)Cu(OAc) (H2O) 2].3H2O [(H5L)
(3)
C16H32N2O13Cu
green
[(H6L) 2Cu(OAc) 2 ]
Greenish white
C32H46N4O16 Cu (4)
[(H6L)2Cu3(OAc)6 (H2O) 2]green C40H62N4O26 Cu3
(5)
[(H5L) Cu(Cl) (H2O)2] .3 brown H2O C14H29N2O11Cu Cl
(6)
[(H6L)Cu(OOSO2)].2H2O Dark green C14H24N2O12 S Cu
507
>300
65
33.01(33.10)
4.56(4.76)
5.85(5.51)
12.99(12.51)
-
10.2
(7)
[(H5L) Mn (OAc) (H2O)2]. Pale 3H2O brown
515
>300
60
37.71(37.29)
6.26(6.21)
5.84(5.44)
10.72(10.66)
-
9.1
519.12
>300
65
37.41(37.00)
6.27(6.21)
5.62(5.39)
11.83(11.35)
-
10.2
518.13
295
70
37.56(37.2)
6.44(6.21)
5.43(5.39)
11.37(11.31)
-
11.1
524.12
290
55
36.05(36.55)
6.36(6.13)
5.36(5.33)
12.47(12.44)
-
7.2
C16H32N2O13 Mn (8)
[(H5L) Co (OAc)(H2O)2]. Redish 3H2O brown C16H32N2O13 Co
(9)
[(H5L)Ni(OAc) (H2O)2].3 Yellow H2O C16H32N2O13 Ni
(10)
[(H5L) Zn(OAc) (H2O)2]. Yellow 3H2O C16H32N2O13 Zn
(11)
[(H5L) Cd(OAc)(H2O)2]. Yellowish 3H2O green C16H32N2O13 Cd
574.09
295
70
33.83(33.55)
5.84(5.63)
4.92(4.89)
19.73(19.62)
-
7.6
(12)
[(H5L) Pb(OAc)(H2O)2]. Gray 3H2O
668.16
210
70
28.72(28.78)
4.83(4.79)
4.21(4.19)
31.17(31,04)
-
8.3
666.16
244
75
30.61(28.86)
4.82(5.00)
3.06(4.21)
28.65(30.70)
-
10.1
7.27(7.21)
12.0
C16H32N2O13Pb (13)
[(H6L) Tl(OAc)(H2O) 2]. Yellowish 3H2O white C16H33N2O13Tl
(14)
[(H5L) Mn(Cl) (H2O)2].3H2Pale O orange C14H29N2O11Mn Cl
491.09
270
50
34.99(34.19)
5.95(5.94)
5.17(5.70)
10.99(11.17)
(15)
[(H5L)Co(Cl) (H2O)2]. 3H2Pale O brown C14H29N2O11CoCl
495.08
290
55
33.89(33.92)
5.94(5.90)
5.98(5.65)
11.11(11.89)
(16)
[(H4L) 2 Ni2(H2O)4].3H2O Pale brown C28H50N4 O19Ni2
862.18
>300
55
38.69(38.92)
6.27(5.83)
5.13(6.48)
13.75(13.58)
-
10.3
(17)
[(H5L) Cd(Cl) (H2O)2].5H2White O
585.28
298
50
28.73(31.65)
5.68(5.21)
4.79(5.27)
19.2(21.16)
6.06(6.45)
9.1
7.19(7.15)
12.0
C14H33N2O13CdCl
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[(H5L)Hg(Cl)( H2O)2].3H2O Gray
638.12
280
45
26.88(26.38)
4.69(4.55)
4.07(4.39)
31.99(31.49)
5.76(5.56)
7.3
C14H29N2O11HgCl (19)
[(H5L)Ca(Cl)(H2O)2].3 H2O Pale brown C14H29N2O11Ca Cl
476.11
250
60
35.57(35.26)
6.89(6.13)
5.46(5.87)
8.81(8.4)
7.81(7.43)
7.9
(20)
[(H5L)Fe(Cl )2 (H2O)].2H2O Dark brown C!4H25N2O9FeCl2
491.08
230
60
34.17(34.13)
5.94(5.12)
5.16(5.69)
11.28(11.33)
14.05(14.41)
11.6
(21)
[(H6L)Co (OOSO2)].2H2OPink
>300
60
33.53(33.41)
4.64(4.81)
5.90(5.57)
11.31(11.71)
9.8
>300
60
33.37(32.98)
4.95(4.74)
5.86(5.49)
12.35(12.83)
8.6
>300
55
32.96(35.91)
5.82(4.95)
8.09(8.97)
11.28(11.99)
503.03
C14H24N2O12S Co (22)
[(H6L)Zn (OOSO2)].2H2OYellowish green C14H24N2O12S Zn
(23)
[(H5L)Co(NO3)( H2O)2]. 3H2O
507.03
Brown
-
10.3
522.07
C14H29N3O14Co
Table 2 : IR frequencies of the bands (cm-1) of ligand [H6L] and its metal complexes and their assignments. No.
(1)
ν(H2O/OH)
3380-3314 3471,3348 3520-3325
(2)
33203000, 3500-3300 3380
(3)
3335-3200 3469,3312 3560-3360
(4)
(5)
(6)
34203100, 3550-3320 3423 33853100, 3480-3300 3384 3470,3406 3550-3325
(7)
3260-3100 3463,3385 3600-3425
(8)
34003020, 3650-3425 3407
(9)
34203000, 3389
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ν(Hbond.) 36003080 356030603010 2520
ν(NH)
ν(C=O)acetyle
3280
1653
3310
1720
ν(C=N)imine
ν(Ar)
υ (OAc) /[NO3] / SO4
υ(MO)
υ (MN) -
1631
1595,837720
-
-
1600
1685,827
1528,1415
628
υ(MCl) -
-
30002500 35503240
3312
1667
1629
1612,715
1506,1372
520
433
-
32003000 36003220
3280
1640
1620
1568,749
1566,1410
635
494
-
31002900 35703110
3258
1640
1609
1568,749
-
551
448
440
31002880 35603220
3260
1640
1614
1595,750
1126,1076,867,702,476
515
495
-
320036502650 3250
3264
1650
1620
1546,751
1512,1416
567
465
-
3030
3280
1611
1622
1555,770
1530,1405
518
417
-
30202775 36603100
3234
1667
1616
1540,746
1550,1417
556
32002700 3610-
466
30002200
April 20, 2014
-
ISSN 2321-807X 3638-3277 (10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
32603000, 3580-2700 3377 34003100, 3650-3320 3360 33103200, 3600-3350 3467 33303000, 3525-3325 3423 33203225, 3500-3300 3403 32953000, 3650-3225 3378 34003030, 3500-3153 3405 33003100, 3660-3140 3313 31122910, 3530-3325 3451 33203010, 3550-3330 3415
(20)
(21)
33253000, 3325-3220 3421 ,3177
(22)
3490-3300 3407 3390-3150
(23)
31003000, 3381
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36503050
3244
1650
1618
1575,753
1560,1360
558
434
-
300036002600 3120
3320
1690
1615
1590,750
1560,1409
504
420
-
310037002524 3320
3467
1650
1620
1565,749
1507
566
465
-
331036403000 3110
3234
1643
1608
1591,743
1556,1380
569
458
310035502600 3230
3248
1665
1617
1596,750
-
579
493
440
322535403000 3025
3240
1667
1609
1580,746
-
548
440
450
300035502665 3020
3267
1649
1615
1580,753
-
520
456
30302500 36003050
3226
1686
1651
1590,750
-
569.
474
430
3012
3380
1644
1620
1565,784
562
502
450
300036102660 3000
3294
1645
1610
1576,720
-
600
507
440
31752765 35903050
3231
1637
1619
1568,735
-
560
471
429
30002600 33753030
3053
1649
1609
1561,794
1151,1018,888,702,472
567
449
3304
1656
1622
1558,751
1130,1072,879,702,472
616
544
3293
1648
1608
1576,772
`1325,1280,820, 735
516
440
-
31002600 3650-
322036602650 3220 339532003010 2650 30002200
April 20, 2014
-
ISSN 2321-807X Table 3 : The electronic absorption spectral bands (nm) and magnetic moments (B.M) for the ligand [H6L] and its complexes.
*
eff (BM)
λmax (nm)
No.
-3
-1
-1
270 nm (є = 6.51×10 mol cm ) (1)
-3
-1
-1
298 nm (є = 7.2×10 mol cm ) -3
-1
-
-1
320 nm (є = 7.72×10 mol cm )
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(2)
630, 585, 495 ,395, 310, 290, 265
1.72
(3)
619, 568, 527, 460, 320, 284, 262
1.70
(4)
619, 568, 510, 320, 270, 260
1.51
(5)
614, 609, 522, 320, 290, 265
1.68
(6)
530, 495, 469, 310, 290, 265
2.12
(7)
610, 590, 450, 315, 285, 260
4.32
(8)
618, 595, 425, 305, 290, 265
4.15
(9)
616, 570, 425, 305, 280, 265
3.1
(10)
318, 285, 270
Diamag.
(11)
317, 292, 265
Diamag.
(12)
320, 292, 270
Diamag.
(13)
318, 290, 270
2.1
(14)
620, 569, 523, 316, 290, 265
4.1
(15)
620, 580, 435, 305, 290, 260
4.3
(16)
622, 585, 430, 310, 285, 265
2.68
(17)
320, 290, 265
Diamag.
(18)
320, 290, 268
Diamag.
(19)
320, 292, 270
Diamag.
(20)
616,570, 424, 321, 296, 260
5.16
(21)
600, 560, 480, 310, 287, 260
3.78
(22)
320, 290, 268
Diamag.
(23)
619, 568,5 27, 410, 305, 285, 260
3.87
April 20, 2014
ISSN 2321-807X 3.1. General characterization 3.1.1 Mass spectra The mass spectra of the ligand and its Cd(II) complex (17) confirmed their proposed formulations. The mass spectrum of the ligand (1), Figure (1) revealing a molecular ion peak m/z at 312 a.m.u., coincident with the molecular weight of the ligand. Moreover, the fragmentation pattern splits a parent ion peak at m/z = 150 a.m.u. corresponding to C8H10N2O while the fragments at m/z =285, 275, 236, 212, 161, 135, 119, 91, 65 and 55 a.m.u. are corresponding to C12H17N2O6, C13H11N2O5, C8H16N2O6, C10H16N2O3, C9H9N2O, C8H9NO, C4H7O4 ,C3H7O3, C5H5 and C4H7 moieties respectively. The mass spectrum of Cd(II) complex (17) , revealing a molecular ion peak m/z at 585 a.m.u which is compatible with the molecular weight of the complex (585.28). Additionally, the fragmentation pattern splits a parent ion peak at m/z = 256 a.m.u. corresponding to C8H18NOCd while the fragments at m/z =583, 386, 236, 213, 185, 119, 81, 69 and 55 a.m.u. are assigned to C14H32N2O13CdCl, C10H27N2O4CdCl, C7H10NOCd, C10H17N2O3, C9H17N2O2, C4H7O4, C5H5O, C5H9 and C4H7 moieties respectively. The fragments of the ligand (1) and Cd(II) complex (17) are represented in Table 4. Table 4: Mass spectra of [H6L] (1) and its Cd(II) complex (17) i. Mass spectrum of [H6L] (1) m/z
Rel. Int.
Fragment
55
23
C4H7
65
25
C5H5
91
56
C3H7O3
119
100
C4H7O4
135
100
C8H9NO
150
100
C8H10N2O
161
100
C9H9N2O
212
65
C10H16N2O3
236
40
C8H16N2O6
275
50
C13H11N2O5
285
33
C12H17N2O6
312
70
HL [C14H20N2O6]
ii. Mass spectrum of Cd(II) complex (17)
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m/z
Rel. Int.
Fragment
55
70
C4H7
69
100
C5H9
81
45
C5H5O
119
20
C4H7O4
185
100
C9H17N2O2
213
100
C10H17N2O3
236
100
C7H10NOCd
256
100
C8H18NOCd
386
35
C10H27N2O4CdCl
585
25
C14H32N2O13CdCl
April 20, 2014
ISSN 2321-807X 3.1.2. 1H–NMR spectra The 1H–NMR spectra of (1) and its Cd(II) complex(17) in deuterated DMSO show signals consistent with the proposed structures. The ligand shows peak at 9.8-10 p.p.m relating to proton of OH group [10, 11, 12]. The signal observed at 11.5 p.p.m is assigned to the proton of CONH group [11]. The signal observed at 5.8 p.p.m is due to N=CH proton. The spectrum shows peaks observed as multiplet in the 7.25 – 7.9 p.p.m range which are assigned to aromatic protons [11]. The signals observed at 2.5 and 2.3 p.p.m, are due to the protons of CH2 and CH3 groups respectively. The spectrum of Cd(II) complex (17) shows the protons of NH at 11.5. The peaks observed as multiple ones in the 9.8-10 p.p.m range are assigned to protons of OH group [11,12,13] .The aromatic protons appear in the 7.27.7 p.p.m range [14,15]. The signal observed at 5.8 p.p.m is due to N=CH proton.
3.1.3. Conductivity The molar conductance values of the complexes in DMF (10-3 M) lie in the 12 –2.1 Ω mol-1cm2 range (Table 1), indicate that, all complexes are not electrolytes [10,16]. This confirms that, the anion is coordinated to the metal ion.
3.1.4. IR spectra The modes of bonding between the ligand and the metal ion can be revealed by comparing the IR spectra of the solid complexes with that of the ligand as shown in Table 2. The IR spectrum of the ligand shows broad medium bands in the 3600-3080 and 3060- 2520 cm-1 ranges, attributed to intra- and intermolecular hydrogen bonds between OH and NH with C=N and C=O groups [17,18] . The spectrum also shows bands at 3471, 3348 and 3280 cm-1, assigned to the stretching vibrations of the hydroxyl ν(OH) and ν(NH) groups [11,19, 20]. The relatively strong bands located at 1653, 1631, 1595 and 837-720 cm-1 range are assigned to the ν(C=O), ν(C=N), ν(C=C)Ar respectively [9]. A broad band appears in 3380-3314 cm-1 range corresponding to hydrated water [21]. In all complexes, the band due to azomethine ν(C=N) was shifted with a decreasing its intensity indicating its coordination to the central metal ion [11, 22]. The ν(NH) and ν(OH) bands appear in the 3380 – 3053 and 3470 - 3177 cm-1 ranges [23,24]. The ν(C=C)Ar appears in the 1685-1540 and 837- 715 cm-1 ranges [23,24]. The complexes show broad bands in the 3660 – 2700 and 3385 – 2910 cm-1 ranges except (3) assigned to the presence of hydrated or coordinated water molecules [23, 24]. While, the bands appearing in the 3700 – 3010 and 3310 – 2200 cm-1 ranges, are due to intra- and intermolecular hydrogen bondings [11,19,20]. New bands in the 635–504 and 544– 417 cm-1 ranges were taken as indication of coordination between the metal ions with oxygen and nitrogen atoms [22, 23, 24]. Complexes (6), (21) and (22) show bands at 1126, 1076, 867, 702 and 476, 1151, 1018, 888, 702 and 472 and 1130, 1072, 879, 702 and 472 cm-1 respectively which is assigned to the coordinated monodentate sulphate group [26]. IR spectral studies reported on metal acetate complexes [26] indicate that, the acetate ligand coordinates [22] in either a monodentate, bidentate or bridging manner, the νa (CO2) and νs(CO2) of the free acetate group appeared at 1550 and 1410 cm-1 respectively. In monodentate, coordination ν(C=O) is observed at higher energy than νa(CO2) and ν(C-O) appeared at lower value than νs(CO2). As a result, the separation between ν(CO) bands is much large in monodentate complexes. In complexes (2– 13), the band assigned to νa(CO2) appeared in the 1551 – 1518 cm-1 range and the νs(CO2) band observed in the 1414 – 1385 cm-1 ranges. The difference between these two bands is in the 140 – 103 cm-1 range, suggesting that, the acetate group coordinates in unidentate manner with the metal ions [11]. However, bridging acetate group with both oxygen atoms coordinated (as in copper(II) acetate) have ν(CO) bands close to the free ion values [11, 27] as found for complex (4), νa(CO2) = 1566 and νs(CO2) = 1410 cm-1. A new band observed in the 450 – 429 cm-1, may be assigned to ν(M-Cl) in the chloro complexes (5), (14), (15), (17), (18), (19) and (20) [28-31]. Complex (23) shows bands at 1325, 1280, 820 and 735, assigned to coordinated nitrate group [17, 21].
3.1.5. Magnetic moments The room temperature magnetic moments for the complexes (2)-(23), are shown in Table 3. Copper(II) complexes (2), (3), (4) and (5) show values 1.72, 1.70 , 1.51 and 1.68 B.M. These values correspond to one unpaired electron in an octahedral structure [15, 31] .The lower values of magntism may be due to spin-spin interactions present through acetate bridge in complex (4) and hydrogen bondings in complex (2), (3) and (5). On the other hand complex (6) shows a value 2.12 B.M, corresponding to one unpaired electron in square planar structure. Manganese (II) complexes (7) and (14) give 4.32 and 4.1 B.M indicating presence of a high spin octahedral structure [17, 31]. Cobalt (II) complexes (8), (15), (21) and (23) show values 4.15, 4.3, 3.78 and 3.87 B.M., indicating high spin octahedral structure [17, 31]. Nickel (II) complex (9) and (16) give 3.1 and 2.68 B.M., confirmed t2g6 eg2 electronic configuration with two unpaired electrons in an octahedral Ni(II) complex [17,33]. Thallium (I) complex (13) gives 2.1 B.M., indicating an octahedral structure. Iron(III) complex (20) shows value 5.16 B.M., which is an indication for a high spin octahedral structure [17, 34]. Zinc(II) complexes (10) and (22), cadmium(II) complexes (11) and (17), lead(II) complex (12), mercury(II) (18), calcium(II) complex (19), show diamagnetic values.
3.1.6. Electronic spectra The electronic spectral data for the ligand (1) and its metal complexes in DMF solution are summarized in Table 3. Ligand (1) in DMF solution shows three bands at 320 nm (є = 7.72×10-3 mol-1cm-1), 298 nm (є =7.2×10-3 mol-1cm-1) and 270 nm (є = 6.51×10-3 mol-1cm-1), which may be assigned to n→* and →* transitions
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April 20, 2014
ISSN 2321-807X respectively [35]. Copper(II) complexes (2), (3), (4) and (5) show bands in the 260–290 and 310 –395 nm ranges, these bands are due to intraligand transitions, whereas, the bands appearing in the 420 – 522 and 527 –630 nm 2 2 2 2 ranges are assigned to O→Cu charge transfer, B1→ E and B1→ B2 transitions, indicating a distorted tetragonal octahedral structure [10,36,37]. Complex (6) shows bands at 265, 290 and 310 nm, these bands are within the 2 2 2 2 2 2 ligand and bands appear at 469,495 and 530 nm are corresponding to B1g→ B2g, B1g→ Eg and B1g→ A1g respectively, suggesting a square planar geometry [38,39]. Manganese(II) complexes (7) and (14) show bands at 610, 590, 450, 315, 285,260 and 620, 569, 523, 316, 290, 265 nm, respectively, the last three bands are within the 6 4 6 4 6 4 ligand, however, the other bands are corresponding to A1g→ Eg, A1g→ T2g and A1g→ T1g transitions which are compatible to an octahedral geometry around the Mn(II) ion [40]. Cobalt(II) complexes (8), (15) and (23) show bands at 618, 595, 425, 305, 290, 265 and 620, 580, 435, 305, 290, 260 and 619, 568, 527, 410, 305, 285, 260 nm 4 4 respectively. The last three bands are within the ligand and the other bands are assigned to T1g(F) → A2g and 4 4 T1g(F) → T2g(F) transitions respectively, corresponding to high spin Co(II) octahedral complexes [41]. Complex (21) shows bands at 600, 560, 480, 310, 287 and 260 nm. The last three bands are within the ligands and the other 2 2 2 2 2 2 bands are corresponding to B1g→ B2g, B1g→ Eg and B1g→ A1g transition respectively, suggesting a square planar geometry [41]. Nickel(II) complexes (9) and (16) show bands at 616, 570, 425, 305, 280, 265 and 622, 585, 430, 3 310, 285, 265 nm, the last three bands are within the ligand and the other three bands are attributable to A2g(F) 3 3 3 3 3 → T1g(P)(3), A2g(F) → T1g(F)( 2) and A2g(F) → T2g(F)( 1) transitions respectively, indicating an octahedral Ni(II) geometry [10,42]. The 2/1 ratio for (9) and (16) are 1.34 and 1.36, which is less than the usual range of 1.5 – 1.75, indicating a distorted octahedral Ni(II) complex [10,43]. Iron(III) complex (20) shows bands at 616, 570, 424, 321, 296 and 260 nm respectively, the last bands are within the ligand while the other bands are due to charge transfer and 6A1→4T1 transitions, suggesting distorted octahedral geometry around the iron(III) ion [44,45]. Zinc(II) complexes (10) and (22), Cadmium(II) complexes (11) and (17), Mercury(II) complexes (18), Calcium(II) complexes (19), Lead(II) complexes (12) and Thallium (I) complex (13) show three bands in the 270-265 ,292-290 and 320-317 nm ranges, which are assigned to intraligand transition.
3.1.7. Electron Spin Resonance The ESR spectral data for complexes (2-8) are presented in Table 5. The spectra of copper(II) complexes (2), (3) (4), (5) and (6) are characteristic of d9 configuration species having axial type of a d(x2-y2) ground state which is the most common for copper(II) complexes [46,47]. The complexes show g║ > g┴> 2.0023, indicating octahedral geometry or square planar around copper(II) ion [48, 49].The g- values are related by the expression G = (g║-2)/( g┴ -2) [48,50], where (G) exchange coupling interaction parameter (G). If G < 4.0, a significant exchange coupling is present, whereas if G value > 4.0, local tetragonal axes are aligned parallel or only slightly misaligned. Complexes (3), (4) and (5) show 3.8, 3.0 and 3.7 values indicating spin-exchange interactions take place between copper(II) ions through acetate group in complex (4) or hydrogen bonding in complex (5). This phenomen is further confirmed by the magnetic moments values (1.7, 1.51 and 1.68 B.M.). On the other hand, complexes (2) and (6) show 4.3 and 4.5 B.M. values respectively indicating tetragonal axes are present in these complexes. The g║/A║ value is also -1 considered as a diagnostic term for stereochemistry [51], The g║/A║ values in the (105-135) cm range are expected -1 for copper complexes within perfectly square planar geometry and those higher than 150 cm is expected for tetrahedrally distorted complexes. The g║/A║ values for the copper complexes lie just within the range expected for the complexes (Table 5). The g-value of the copper(II) complexes with a 2B1g ground state (g║>g g┴) may be expressed by [52] 2 ║
g║ = 2.002 – (8K g┴ = 2.002 –
2 (2K ┴
°/ΔExy) ...………………………………….. ……… (1) °/ΔExz) ………………………………………...... (2)
Where k║ and k┴ are the parallel and perpendicular components respectively of the orbital reduction factor (K), ° is the spin – orbit coupling constant for the free copper, ΔExy and ΔExz are the electron transition energies of 2 2 2 2 B1g→ B2g and B1g→ Eg. From the above relations, the orbital reduction factors (K║, K┴, K), which are measure terms for covalency [55], can be calculated. For an ionic environment, K=1; while for a covalent environment, K
