Journal of Chemical, Biological and Physical Sciences Synthesis ...

JCBPS; Section A; August 2015 – October 2015, Vol. 5, No. 4; 3629-3644.

E- ISSN: 2249 –1929

Journal of Chemical, Biological and Physical Sciences An International Peer Review E-3 Journal of Sciences Available online atwww.jcbsc.org Section A: Chemical Sciences

CODEN (USA): JCBPAT

Research Article

Synthesis, Characterization and Antimicrobial activity of New Binary Metal Complexes Derived from Amino SulfoNaphthalene Ligand. Abdou Saad El-Tabl*1, Moshira Mohamed Abd-El Wahed2, Mohammed Ahmed Wahba*3, Reham Wagdy Farid1, Shaimaa Mohammed Fahim Hashim1. 1

Department of Chemistry, Faculty of Science, El-Menoufia University, Shebin El -Kom, Egypt. Department of Pathology, Faculty of Medicine, El-Menoufia University, Shebin El-Kom, Egypt. 3 Inorganic Chemistry Department, National Research Centre, P.O. 12311, Dokki, Cairo, Egypt.

2

Received: 8 July 2015; Revised: 19 July 2015; Accepted: 7 August 2015

Abstract: New binary metal (II) complexes derived from amino sulfo-naphthalene ligand were prepared. The ligand and the metal complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility, IR, electronic, 1H-NMR, and mass spectral studies. Structural and spectroscopic properties revealed that the ligand adopted a tridentate fashion, while the metal complexes adopted a tetragonal distorted octahedral geometry around metal ions. All the complexes are non-electrolytic in nature as suggested by molar conductance measurements. Infrared spectral data indicate the coordination between ligand and central metal ion through a phenolic OH, one-imine nitrogen, one oxime-nitrogen atoms forming five-membered rings including the metal ions. The compounds were screened for their antimicrobial activities against Aspergillus funigatus, Streptococcs pneumoniae, Bacillis subtilis, Escherichia coli, Pseudomonas coli and candida albicans. Neither the ligand nor its metal complexes recorded antimicrobial activity against neither Pseudomonas coli nor Candida albicans. On the other hand all compounds including the ligand showed high activity against Aspergillus funigatus, Streptococcs pneumoniae, Bacillis subtilis, and Escherichia coli. Keyword: Naphthalene, Oxime, complexes, Antimicrobial. 3629

J. Chem. Bio. Phy. Sci. Sec. A, August 2015 – October 2015; Vol.5, No.4; 3629-3644.

Synthesis, Characterization…

Abdou Saad El-Tabl et al.

INTRODUCTION Schiff-base species of transition metal compounds and polydentate ligands has drawn extensive research due to their potential applications in medicine, materials science and environmental chemistry1-5. These compounds have a vital role in coordination chemistry because of their ability to bind to a wide range of metal ions forming stable complexes having a wide scope of applications. One interesting application in the field of coordination chemistry has been to investigate Schiff-base metal complexes in the biomedical filed3,6,7, biomimetic and catalytic systems6,8,9. Significant publications concerning with the development of coordination chemistry are related to the preparation and characterization of oximes and their metal complexes. These include the investigation of new synthetic methods and coordination modes of oxime species upon complexation10. Some oxime Schiff bases and their metal complexes exhibit antibiotic, antiviral and antitumor activities11-14. It has been suggested that the azomethine linkage is responsible for the biological activities of Schiff bases such as, antitumour, antibacterial, antifungal and herbicidal activities 15-18. Oximes ligands are capable to produce stable biological and toxicological metal complexes with a wide variety of metals. Our group and others has a growing interest in synthesis and characterization of biologically active transition metal complexes of a wide variety19-25. Since many transition metal complexes of oxime derivatives have been reported to display antifungal, antibacterial and antitumor activity11-14,22,26. Herein, we report synthesis and characterization of new binary oxime complexes derived from amino sulfonaphthalene ligand. These compounds were characterized by elemental and thermal analyses, spectral, magnetic and conductivity studies as well as thermal analysis (TGA/DTA). The work was extended to study the antimicrobial activity of the ligand as well as its metal complexes. EXPERIMENTAL Instrumentation and measurement: The ligand and its metal complexes were analyzed for C, H and N at the Microanalytical center, Cairo University, Egypt. Standard analytical methods were used to determine the metal ion content27-29.Mass 1H-NMR spectra were obtained on BRUKER 400 MHz spectrometers. Chemical shifts (ppm) are reported relative to TMS. FT-IR spectra of the ligand and its metal complexes were measured using KBr discs by a Jasco FT/IR 300E Fourier transform infrared spectrophotometer covering the range 400-4000 cm-1. Electronic spectra in the 200-900 nm regions were recorded on a Perkin-Elmer 550 spectrophotometer. The thermal analysis (TG) was carried out on a Shimadzu DT-30 thermal analyzer from room temperature to 800 ºC at a heating rate of 10 ºC/min. Magnetic susceptibilities were measured at 25oC by the Gouy method using mercuric tetrathiocyanatocobaltate(II) as the magnetic susceptibility standard. Diamagnetic corrections were estimated from Pascal’s constant 30. The magnetic moments were calculated from the equation:

 eff .  2.84  corr M .T . The molar conductance of 10-3 M solution of the complexes in DMSO was measured at 25ºC with a Bibbyconductometer type MCl. The resistance measured in ohms and the molar conductivities were calculated according to the equation:

3630




Where: M = molar conductivity / -1cm2mol-1, V = volume of the complex solution/ mL, K = cell constant (0.92/ cm-1), Mw = molecular weight of the complex, g = weight of the complex/g, = resistance/ . Synthesis of ligand: The ligand, (H2L) was prepared by dropwise addition of (20 g, 0.08 mol) 4-amino-3hydroxy naphthalene-1-sulphonic acid dissolved in 20 mL of absolute methanol solution in presence of sodium bicarbonate to a methanolic solution of (hydroxyimino)pentane-2,4-dione oxime (11.75g, 0.08 mol). The mixture was stirred and refluxed for three hours at 80 oC, then left to cool to room temperature. The solid product was filtered off then dried under vacuum over anhydrous CaCl2. Synthesis of metal complexes Preparation of complexes (2-14): Synthesis of complexes (2-14) as (1L:1M) were carried out by refluxing a hot methanolic solution of ligand (1g, 0.002 mol) with a hot methanolic solution of the metal salts of (1 g, 0.002mol) complex (2), (1 g, 0.002 mol) complex (3), (0.65 g, 0.002 mol) complex (4), (0.53 g, 0.002 mol) complex (5), (0.74g , 0.002 mol ) complex (6), (0.66 g,0.002 mol) complex (7), (0.4 g,0.002 mol) complex (8), (0.63g 0.002 mol ) complex (9), (0.66 g, 0.002 mol) complex (10), (0.47 g, 0.002 mol) complex (11), , (0.73 g, 0.002 mol) complex (12), (0.88 g, 0002 mol) complex (13), (1.1 g,0.002 mol) complex (14) for 1 hour under continuous stirring at 800 c . The obtained precipitate were filtered off and dried in a desiccator over CaCl2. RESULTS AND DISCUSSION All metal complexes are colored, crystalline solids, non-hygroscopic, and are very air stable solids at room temperature without decomposition for a long time. The complexes are insoluble in water, ethanol, methanol, benzene, toluene, acetonitrile and chloroform, but appreciably soluble in both dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The analytical and physical data (table 1) and spectral data, (tables 2-4) agree well with the proposed structures (Figure 1). The elemental analyses indicated that, all complexes were found to be composed in 1L: 1M molar ratio.

3631



3632





Fig. 1: Proposed structures of the ligand and its metal complexes Conductance measurements: The molar conductivities measurements of H2L divalent complexes were measured in DMSO solvent with 1.0×10-3 mol concentration. The low magnitudes of molar conductivities 1 cm2mol-1 (listed in Table 1) indicated that all of complexes possess non-electrolytic nature31-33. These values agree well with the analytical data assigned to the involvement of the anions groups in the metal coordination. Mass spectra: Mass spectrometry was used to confirm the molecular ion peaks of H 2L Schiff base and investigate the fragment species. The recorded mass spectrum of H2L ligand revealed molecular ion peak confirms strongly the proposed formula. It showed a molecular ion peak at m/e 372.33 amu, conﬁrming its formula weight (F.W. 372) and the purity of the ligand prepared. The prominent mass fragmentation peaks observed at m/z = 55, 65, 91, 128, 175,246, 307, 351 and 372 amu corresponding to C3H4O, C6H4O, C6H6O3, C10H8O6Na, C10H8O6Na, C15H9O6Na, C15H9N2O7Na, and C15H13N2NaO6S moieties respectively supported the suggested structure of the ligand. 1

H-NMR Spectra: The 1H-NMR spectrum of the 1igand was recorded in DMSO-d6. The 1H-NMR spectrum of the ligand showed two broad peaks at 10.1[s, 1H] and 9.8[s, 1H] assigned for protons of (OH)oxime and υ(OH)phenolic respectively. Protons signals of acetyl and methyl groups appeared around 5.82[3H] and 3.30[3H] ppm respectively22, 34, these signals are disappeared upon adding D2O. Finally two sets of multiplets were observed in the ranges (7.48-7.82) and (8.69-8.89) ppm assignable to the α-protons and the β-protons naphthalene ring respectively35. I.R spectra: The bonding of the ligand to the metal ions has been judged by a careful comparison of the infrared spectra of the metal complexes with those of the free ligand. A few significant bands have been selected to observe the effect on vibrations of the ligand’s groups upon complexation. The ligand showed broad bands centered at 3452 and 3410 cm-1 which could be assigned to υ(OH)phenolic and υ(OH)oxime, respectively. The two strong bands at 980 and 1100 cm-1 are assigned to υ(N-O). The splitting of the υ(N-O) vibration into two bands confirms the presence of two non-equivalent intramolecular hydrogen bonding which are stronger than the inter-molecular type36. The ligand spectrum also displayed three peaks at 1714, 1645 and 1631 cm-1 assignable to υ(C=O), υ(C=N) imine and υ(C=N)oxime respectively37-41. A medium band was observed at 1402 cm-1 which is related to stretching vibration of SO3 group. This band is slightly broadened on coordination but not shifted, i.e. the sulfonate group does not participate in the complexation process.

3633




Table 1:-Analytical and Physical Data of the Ligand [ H2L] (1) and its Metal Complexes. No.

Ligand/Complexes

(1)

[H2L] C15H13N2NaO6S

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)

[(HL)Cr(SO4)(H2O)2].H2O C16H21N2O13NaS2Cd [(HL)Cr(NO3)2(H2O)].3H2O C15H20N4O16NaSCr [(H2L)Mn(OAc)2(H2O)].2H2O C19H25N2O13NaSMn [(H2L)Mn (Cl)2(H2O)].H2O C15H17N2O8NaSCl2Mn [(HL)Fe(SO4)(H2O)2].3H2O C15H23N2O15NaS2 Fe [(H2L)Co(OAc)2(H2O)].4H2O C19H29N2O15NaSCo [(H2L)Co (SO4)(H2O)2].2H2O C15H21N2O14NaS2Co [(H2L)Co(Cl)2(H2O)].H2O C15H17N2O8 NaSCl2CO [(H2L)Ni(OAc)2(H2O)].2H2O C19H25N2O13NaSNi [(H2L)Ni(CO3)(H2O)2].3H2O C16H22N2O14NaSNi [H2L (Hg)(Cl)2] C15H13 N2 O6NaS Cl2Hg [(H2L)Pb(NO3)2(H2O)2] C15H17N4O14NaSPb [(H2L)UO2(NO3)2(H2O)].3H2O C15H21N4O18NaSU

* m(

3634

-1

Anal. /Found (Calc.) (%) H N

Color

FW

M.P(OC)

Yield(%)

Reddish brown

372.33

>300

75

48.33(48.39)

3.50(3.52)

Pale brown

588.46

>300

60

32.21(32.66)

3.23(3.60)

Gray

619.39

>300

56

29.28(29.09)

3.22(3.25)

599.4

>300

70

37.75(38.07)

4.61(4.20)

534.2

>300

40

33.43(33.73)

Brown

614.31

>300

45

Rose

567.36

>300

Gray

599.39

C

7.44 (7.52) 4.53 (4.76) 9.23 (9.05)

M

Cl

-

-

Molar Conductance*

8.87(8.84)

-

4.52

8.21(8.39)

-

1.24

4.32(4.67)

9.42(9.17)

-

1.09

3.0(3.21)

5.0( 5.24)

9.98(10.28)

13.07(13.30)

2.64

28.96(29.33)

3.48(3.77)

4.32(4.56)

8.87(9.09)

-

4.77

58

40.45(40.22)

3.97 (3.73)

5.15(4.94)

10.63(10.39)

-

2.15

>300

50

30.37(30.06)

3.51(3.53)

4.22(4.67)

9.53(9.83)

-

4.45

538.2

>300

56

33.30(33.47)

3.28(3.18)

4.96(5.21)

10.65(10.95)

12.94(13.17)

4.97

603.16

>300

68

37.69(37.83)

4.48(4.18)

4.45(4.64)

9.33(9.73)

-

1.11

Green

580.1

>300

58

33.54(33.13)

3.56 (3.82)

4.53)4.83)

9.87 (10.12)

-

1.49

Purple gray

643.82

>300

59

27.80(27.98)

2.58(2.04)

4.75 (4.35)

30.8(31.16)

10.85(11.01)

4.08

Gray

638.79

>300

68

27.98(28.20)

2.32(2.68)

8.62(8.77)

16.32(16.66)

-

2.97

Orange

838.43

>300

68

21.83(21.49)

2.32(2.52)

6.42(6.68)

28.0(28.39)

-

1.81

Yellowish brown Dark brown

Greenish yellow Greenish brown

cm2 mol-1)




In complexes (2, 3, 6, 15), the absence of υ (OH)oxime bands in metal complexes indicates its deprotonation during complexation (C=NO). This is further confirmed by simultaneous increasing in (NO) bands in theses complexes which are appearing in the 1000-1195 cm-1 range42, 43. The υ (OH) phenolic was considerably shifted to lower frequency by 30-32 cm-1 indicating the participation of this group in metal coordination. Furthermore the υ(C=N)imine and υ(C=N)oxime bands observed at 1645 and 1631 cm-1 in the ligand spectra, respectively, were shifted to lower frequency by 28-33 and 16–31 cm-1 suggesting the participation of two azomethine groups in the coordination process. Ir spectral data of complexes (3-5, 7-12, 18-20, 23, 25-27) revealed the presence of the υ (OH)oxime, however it subjected to a negative shift to higher or lower wavenumber comparing to the ligand referring to its participation in the metal coordination. Furthermore, υ(OH)oxime, υ(C=N)imine and υ(C=N)oxime were also shifted to lower wave numbers suggestion their participation in the metal bonding44, 45. These finding suggest that the ligand coordinate to the metal via ONNO donor sites. The appearance of two characteristic bands in the (14471425) and (1342-1320) cm-1 in the spectrum of complexes (4), (7), (10) were attributed to asym.(COO-) and sym.(COO-) respectively, indicating the participation of the acetate oxygen in the complex formation46. The mode of coordination of acetate group has often been deduced from the magnitude of the observed separation between the asym.(COO-) and sym.(COO-). The separation value (Δ) between asym(COO-) and sym.(COO-) for these complexes were in the (102-110) cm-1 range suggesting the coordination of acetate group in a monodentate fashion47, 48. The spectra of nitrato complexes (3), (13) and (14) showed three non-degenerated modes of the vibrations in the ranges (1384-1339), (1283-1275) and (835) assigned to unidentate nitrate groups49-52. The νs(NO3- ) appearing in (1384-1339) range is markedly shifted to lower frequencies compared to that of the free nitrate (1700-1800 cm-1), due to transfer of electron density from NO3- to metal ion [50]. The chloro complexes (5), (9) and (12) showed new bands at 435, 413 and 430 cm-1 respectively, this band was assigned to (M–Cl), whereas sulfate complexes (2, 6 and 8) exhibited new bands in the (1290-1220), (1175-1125) and (675-660) cm-1 ranges, these values indicate that the sulphate ion is coordinated to the metal ion in a unidentate chelating fashion45, 53. The mode of coordination is supported by presence of additional bands in 615-457 cm-1 and 638-604 regions corresponding to (M-N) and (M-O) bands respectively54, 55. Electronic transition: The electronic absorption data of the ligand and its complexes in dimethylformamide (DMF) are given in Table 3. The ligand and its complexes show three high energy bands in the range 295–280, 315–280 and 335–300 nm due to * transitions within the aromatic moieties, n* transition of chromophore moieties present in the ligand, and CT transitions, respectively52, 56, 57. The electronic absorption spectra chromium(III) complex (2, 3) displayed bands at 610, 570 and 462 nm attributable to 4A2g→4T1g(F), 4A2g→4T2g and 4A2g→2T2g transitions respectively. These transitions is suggesting with an octahedral structure around the Cr(III) ion 55. The µeff values 3.33 and 3.11 B.M. observed for chromium(III) (2, 3) complexes respectively, correspond to three unpaired electrons in an octahedral environment58, 59. The spectra of cobalt(II) complex (7-9), showed signals in the range 605-630, 530-550 and 469-440 nm assignable to 4Tlg(F)→4T2g(F)(ν1), 4Tlg(F)→4A2g(F)(ν2) and 4 Tlg(F)→4T2g(P)(ν3) transitions respectively, suggesting octahedral cobalt(II) geometries. The lower ratio of υ2/υ1= 1.1 than that reported for octahedral cobalt(II) complexes (1.95–2.48), may be due to distortion of the octahedral structure31

3635




Table 2:- IR Frequencies of the Bands (cm-1) of Ligand [H2L], (1) and its Metal Complexes

No.

ν(H2O)

ν(OH)

(1)

3530-3350

3452, 3410

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)

3553-3340 3330-3160 3520-3343 3330-3150 3530-3330 3280-3150 3560-3385 3320-3185 3560-3350 3300,3180 3550-3350 3320-3165 3659-3350 3340,3110 3520-3280 3560-3315 3300,3150 3550-3310 3300-3180 -

3420 3422 3418,3405 3410,3375 3420,3405 3415,3405 3400,3425 3270,3450 3420,3402 3420,3405 3415,3350

(13)

3300-3170

3425

(14)

3530-3310 3320-3170

3417,3406

3636

υ(Hbonding) 3650-3350, 3340-2850 3619-3325, 2315-2950 3655-3275, 3265-2760 3650-3150, 3100-2650 3610-3190, 3180-2680 3650-3280, 3270-2450 3650-3350, 3340-2920 3845-2850, 2800-2250 3600-3320, 3319-2930 3650-3325, 3320-2850 3650-3320, 3310-2650 3620-3285, 3275-2880 3650-3250, 3240-2760 3630-3550, 3540-2680

ν(C=O ))

ν(C=N)imine

ν(C=N)oxime

ν(N-O)

ν(Ar)

ν(SO3Na)

ν(OAc)/SO4/ NO3/CO3)

υ(M-O)

υ(M-N)

1714

1645

1631

1100,980

1605

1402

-

-

-

1677

1617

1585

1195, 1025

1568,870

1402

1175,1220, 660

612

510

-

1672

1612

1605

1190, 1028

1563,770

1400

1339,1280,850

604

543

-

1560,766

1403

1447,1342

616

531

-

1545,870

1405

-

625

575

435

1560,890

1402

1280,1125, 660

614

505

-

1575,785

1405

1425,1320

618

477

-

1560,862

1403

1290,1167, 675

638

457

-

1555,890

1404

-

637

615

413

1584,785

1405

1438,1335

616

528

-

1670,842

1402

1587,1360,1070, 750

616

520

-

1545,870

1401

-

616

473

624

520

-

614

520

-

1667

1610

1590

1670

1628

1590

1680

1628

1615

1679

1620

1590

1687

1616

1605

1679

1618

1597

1679

1617

1602

1620

1607

1585

1690

1616

1600

1687

1617

1588

1677

1617

1590

1165,1019, 980 1170, 1015,985 1190, 1000 1165, 1035,990 1150,1014, 980 1160,1025, 952 1165,1027, 880 1170,1030, 995 1164,1031, 985 1166,10245 ,990 1170,1220, 990

1560,760

1404

1565,765

1404


1383,1275,835, 722 1384,1283,835, 713

υ(MCl) -

430



The magnetic moment values of cobalt complex were in the 4.27-4.35 B.M. range which are corresponding to three unpaired electrons and close to a high spin cobalt(II) (d7)57, 60. The electronic absorption spectra of Ni(II) complexes (10, 11) displayed three d–d transition bands at 735, 740; 610, 610 and 570, 575 nm, attributable to the 3A2g(F)→3T2g(F)(ν1), 3A2g(F)→3T1g(v2) and 3A2g(F)→3T1g(P)(ν3) transitions respectively, which is consistent with its octahedral stereochemistry31, 61. This observation is further confirmed by their µeff values (2.89 and 3.25 B.M., respectively) corresponding to two unpaired electrons61. The ν2/ν1 ratio is 1.2 which is less than the usual range of octahedral nickel complex (1.5– 1.75), indicating that, the nickel complex has distorted octahedral geometry60, 62. The µeff values 6.32 and 6.21 B.M for manganese (II) complex (4, 5 respectively), corresponds to five unpaired electrons in a high spin manganese (II) (d5) system. The electronic absorption spectrum of manganese (II) complex (4, 5) displayed weak absorption bands at 623,622; 565,562 and 470 nm. These bands could be assigned to 6 A1g→4T1g(4G) (υ1), 6A1g→4Eg(4G)(υ2), 6A1g→4Eg(4D)(υ3) transitions respectively and compatible with an octahedral geometry around Mn(II) ion (Fig 1)63, 64. The electronic absorption spectrum of iron (III) complex (6) showed bands at 628, and 565 nm assignable to 6A1g4A1g (G), and 6A1g 4T2g (G) transitions respectively. However the magnetic moment value of iron(III) complex is 5.82 BM which confirmed a high spin octahedral structure around iron(III) ion60, 62. Copper (II) complexes showed µeff values in the range (1.67-174) B.M. corresponding to one unpaired electron, spin-only value and absence of metal–metal interaction. The copper (II) complexes showed three bands at 610-618, 565-590 and 445495 respectively. These bands correspond to 2B1g (dx2-y2) →2A1gdz2 (ν1) 2B1g (dx2-y2) →2B2g (dxy) (ν2) and 2 B1g (dx2-y2) →2Eg (dzy,dxz) (ν3) transitions. The position as well as the broadness of these bands suggest that these complexes have a tetragonal distorted octahedral geometry65, 66. This could be due to the Jahn teller effect that operates on the d9 electronic ground state of six coordinate system, elongating one trans pair of coordinate bonds and shortening the remaining four ones67-70. The diamagnetic mercury (II) (12), lead (II) (13) and uranium (V) (14) complexes did not show d-d transitions. The bands observed are due to intra-ligand transitions. Table 3: The electronic absorption spectral bands (nm) and magnetic moments (B.M.) for the ligand [H2L] (1), and its complexes Compound No. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)

3637

λmax (nm) 295nm (log  =3.98), 315 nm ( log  =4.25) 335(log  292,302,315,462,570,610 290,300,312,475,565,605 290,305,316,470,565,623 280,300,470,565,622 290,302,315,455,565,628 285,300,320,440,550,630 290,300,320,460,530,605 280,290,469,550,610 285,300,312,465,570,610,735 290,300,312,455,575,610,740 290,312,325 292,305,318 292,302,315

eff (B.M.)

2/1

-

-

2.33 2.11 6.32 6.21 Diamag 4.27 4.35 4.2 2.89 3.25 Diamag. Diamag. Diamag.

1.1 1.1 1.1 1.2 1.2 -




Thermal analyses: The thermal data of the complexes are given in Table 4. Such data corroborate the stoichiometric formula, number of water molecules, and end products. TG-DTA curves of complexes (3, 10, (14) were introduced as representative examples. Thermogram of complex (3)[(HL)Cr (NO3)2(H2O)].3H2O exhibited seven-step decomposition, the first step involving breaking of H-bonding accompanied with endothermic peak at 45 oC. In the second step, three molecules of hydrate water were lost endothermically with peak at 65 accompanied by 8.5% (calcd 8.7%) weight loss. Such a low temperature endothermic dehydrations indicated that the water molecules were not coordinated to the metal. Loss of one coordinated water molecule was recorded in the third step as an endothermic peak at 130 oC with 3.1 (calc. 3.2) weight loss. The weight loss 23.4 (calcd 23.6%) accompanied by an endothermic peak at 260 oC was assigned to loss of two nitrate groups (2NO3). The endothermic peak at 300 oC with weight loss 23.25 (calc. 24.34) loss of SO3Na group, whereas the endothermic peak observed at 410 oC refers to the melting point of the complex. The final step observed in 450-650 0C range with 21.7% weight loss (calcd 21.2%), refers to complete decomposition of the complex which ended up with the formation CrO. Complex (10) [(H2L) Ni (OAc)2(H2O)].2H2O exhibited multiple decomposition steps, the first step involving breaking of H-bonding accompanied with endothermic peak at 45 oC. In the second step, two molecules of hydrate water were lost endothermically with a peak at 90 oC accompanied by 5.6% (calcd 5.97%) weight loss. Loss of one coordinated water molecule was recorded in the third step as an endothermic peak at 200 oC with 3.16 (calc. 3.17) weight loss. 21.10% (calcd 21.49%) weight loss accompanied by an endothermic peak at 410 oC was assigned to loss of coordinated two acetate groups (2OAc), whereas the endothermic peak observed at 420 oC accompanied by 24.13 (calc. 23.89) weight loss was attributed to loss of SO3Na group. The endothermic peak at 490 oC refers to the melting point of the complex. The final step observed at 450-650 0C with 22.85% weight loss (calcd 22.80%), refers to complete decomposition of the complex which ended up with the formation NiO. Complex (14) [(H2L) UO2 (NO3)2(H2O)].3H2O exhibited multiple decomposition steps, the first step involving breaking of H-bonding accompanied with endothermic peak at 50 oC. In the second step, three molecules of hydrate water were lost endothermically with a peak at 80 oC accompanied by 6.3% (calcd 6.4%) weight loss. Loss of one coordinated water molecule was recorded in the third step as an endothermic peak at 160 oC with 2.33% (calc. 2.29%) weight loss. 16.66% (calcd 16.18%) weight loss accompanied by an endothermic peak at 230 oC was assigned to loss of two coordinated nitrate groups (2NO3), whereas the endothermic peak observed at 360 oC accompanied by 16.01% (calc. 16.04%) weight loss was attributed to loss of SO3Na group. The endothermic peak at 390 oC refers to the melting point of the complex. The final step observed at 490-600 0C with 47.2% weight loss (calcd 47.12%), refers to complete decomposition of the complex which ended up with the formation UO. Antimicrobial activity: The antimicrobial activity of some compounds was examined against Aspergillus funigatus, Streptococcs pneumoniae, Bacillis subtilis, Escherichia coli, pseudomonas coli and candida albicans, the results are depicted in figure 2. All the tests were performed in triplicate and the diameters of the inhibition zones were measured in millimeters. The drug Tetracycline is taken as standard to compare the effectiveness of the test compounds. The effectiveness of the compound can be predicated by knowing the zone of inhibition value in mm. The antibacterial activity was then interpreted as followed: The diameter of inhibition zone > 15.0 mm was considered as strong; 10.0 to 14.5 mm as moderate and