Synthesis, analytical and spectral studies of novel schiff base complexes of Th(IV) and UO2(VI) along with their X-Ray diffraction data and toxic effects

Article abstract of DOI:10.1155/2010/198498

Schiff base was obtained using furfuraldehyde and 2-amino pyridine to prepare new complexes of thorium(IV) and dioxouranium(VI) metals by various anions. The synthesized ligands and complexes were analytically studied through spectral data, elemental analysis and conductance measurements along with x-ray diffraction pattern. The complexes showed various coordination number and their toxic effects to bacterial and fungal genus was studied by two different methods of measurement.

Full text of DOI:10.1155/2010/198498

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
http://www.e-journals.net
2010, 7(3), 799-806
Synthesis, Analytical and Spectral Studies of Novel
Schiff Base Complexes of Th(IV) and UO2(VI) Along
with their X-Ray Diffraction Data and Toxic Effects
SONAL AGNIHOTRI and KISHOR ARORA*
Govt. Auto. K.R.G. P.G. College, Kampoo, Lashkar,
Gwalior (M.P.) – 474001, India.
jain.abhishek4@gmail.com
Received 31 October 2009; Accepted 20 December 2009
Abstract: Schiff base was obtained using furfuraldehyde and 2-amino pyridine
to prepare new complexes of thorium(IV) and dioxouranium(VI) metals by
various anions. The synthesized ligands and complexes were analytically studied
through spectral data, elemental analysis and conductance measurements along
with x-ray diffraction pattern. The complexes showed various coordination
number and their toxic effects to bacterial and fungal genus was studied by two
different methods of measurement.
Keywords: Synthesis, Analytical studies, Thorium(IV) and dioxouranium complexes, Schiff base,
Toxicity.
Introduction
Thorium(IV) and dioxouranium(VI) metal ions have atomic radii 1.17Å and 1.90 Å
respectively and have high positive charge, so that these metals can easily achieve high
coordination number1.
According to the definition of Pearson2 these metals are hard acids and possess vacant
inner d-orbitals, hence can expand their co-valency with increase in their coordination number.
Their enormous complex forming tendency is attributed to the vacant inner 5f sub shell which
can expand greatly to accommodate a number of ligands. The greater spatial extension of 5f
orbitals of actinides along with the fact that these orbitals are diffused at the periphery of atom
make them suitable to form number of complexes because in such situation the orbitals are
disturbed by ligands3. Coordination number greater than four can be achieved by them through
donations of electrons from ligands into the d-orbitals of these metal atoms. The hybridization
may be predicted by assuming the contribution of atomic orbitals towards the combination of
hybridization orbitals. In this present work the Schiff base was derived from furfuraldehyde
and 2- amino pyridine to obtain 2N-(Furfuralidiene)amino pyridine {2-FAPy}.

800
KISHOR ARORA et al.
Experimental
All the chemicals used were of AR grade and were used without further purification.
Elemental analysis was carried on Elemental Vario EL III Carlo Erba 1108 CDRI Lucknow.
Conductivity measurements for the complexes have been carried out on Elico 01/01 cell type
conductivity bridge. Molecular weights were determined in freezing PhNO2 using Beckmann
Thermometer method cryoscopically in the laboratory. IR spectra were taken through
Schimadzu 8201 PC (4000-400 cm-1). Mass spectra were obtained through JEOL SX- 102
(FAB) PMR spectra of selected samples were recorded on τ scale through Bruker Avance IT
400 NMR spectrometer. Electronic spectral studies were done through Perkin Elmer Lambda
15 x-ray diffraction studies were conducted through powder pattern method at wavelength λ
1.54 A0. Biocidal studies of representative complexes were conducted on fungal and bacterial
species by paper disc method on PDA medium in our laboratory in DMF solvent.
Preparation of complexes
2+
Th4+ and UO2 complexes of Schiff base 2-FAPy were prepared by refluxing the nitrate,
iodide, isothiocynate, perchlorate salts of Th4+ and UO22+ in proper M:L ratio using ethanol
solvent. Uranyl acetate was also complexed with 2-FAPy in proper M:L ratio. The
complexes were left in petri dish to obtain crystalline product and were recrystallised with
solvent and washed with solvent and ether.
Synthesis of ligand
Solution of furfuraldehyde (1 mmole) in approx. 30 mL ethanol was mixed with solution of 2-
amino pyridine (1 mmole) in approx.30 mL ethanol. The resultant solution was refluxed in RB
flask fitted with water condenser for six hours. On cooling Schiff base crystallized out which was
filtered and re-crystallized with proper solvent. The structure of ligand is given in Figure 1.
2-FAPy
CH=N
NH
O
Figure 1. Structure of ligand.
Results and Discussion
The analytical data for the ligand metal complexes are listed in Table 1. It is observed that
most of the complexes are non- hygroscopic and anhydrous as is evident from molecular
weight and percentage of H values; which are nearly same for theoretical and experimentally
calculated data. It is evident from the results that ratio of molecular weights for ThX4.2L
-
(X= NO3 ), ThX4.4L (X=NCS-), for observed and calculated approaches unity (0.98);
suggestive of the fact that no change corresponding to ionization occurs in solution for these
-
complexes. This fact is found valid for UO2X2.2L (X= NO3 , NCS-, CH3COO-) also4.
For ThI4.4L, this ratio is approximately one-third ie., 0.53; 0.36 for UO2(ClO4)2 4L and
approximately one -fifth for Th(ClO4)4. 6L. This is suggestive of the fact that anions of the
complexes are ionisable, primary valencies of complex and that they ionize furnishing more
than one ion in solution5,6.
Mass spectral studies
Mass spectra of Schiff base was recorded. For 2-FAPy the parent ion peak is obtained at
173 m/z (M+1) peak. Base peak at 154 m/z is formed from parent ion through loss of H3O+.
Other significant peaks are recorded at 136 and 289 m/z values.

Analytical and Spectral Studies of Novel Schiff Base Complexes
801
Table 1. Analytical results of 2-FAPy and its complexes.
Elemental Analysis Data
Base/Complex
2-FAPy
60.07(57.8) 4.82(5.2) 17.90(16.18) 173(172) 168-175
236
374(1136) 184 111.1
-
1.6
[Th(2-FAPy)2(NO3)4] 25.2(28.36) 1.16(1.89) 10.08(13.23) 809(826)
[Th(2-FAPy)4I2]I2
[Th(2-
FAPy)4(NCS)4]
[Th(2-
FAPy)6](ClO4)4
[UO2(2-
FAPy)2(NO3)2]
[UO2(2-
FAPy)2(NCS)2]
[UO2(2-
50.70(48.9) 3.16(3.1)
44.6(48.5)
9.85(9.1)
2.46(2.7) 13.15(14.3) 1132(1156) 200 1.4
38.98(39.2) 2.34(2.6) 8.84(9.16) 244(1222) 212 200.9
30.02(32.6) 2.54(2.17) 13.09(15.2) 721(736)
65.9(63.1) 2.19(2.11) 15.3(13.4) 713(728)
179
201
1.9
1.1
19.74(20.7) 1.27(1.38) 4.71(4.8) 416.5(1157) 203 196.4
FAPy)4](ClO4)2
[UO2(2-
FAPy)2(CH3COO)2]
[UO2(2-FAPy)2I2]
65.1(66.20) 12.96(13.24) 6.81(7.72) 710.5(725) 164
2.8
31.86(33.42) 1.88(2.22) 6.54(7.79) 704(718) 224 1.64
IR spectral studies
IR spectra of Schiff base were recoded. For 2-FAPy the prominent peak at 1603 cm-1 shows
variation in its complexes. This peak is of aromatic aldehydic system involved in
azomethine linkage. When the IR spectra of ligands are compared with those of complexes
then shift in the azomethine (-C=N-) peaks are observed through which the metal atom is
believed to be bonded thus the azomethine bond is considered to be a part of coordination7,8. The
important peaks of Th(IV) and UO22+ (VI) are listed in Tables 2 & 3.
Table 2. Infra red absorpton frequencies (cm-1) for thorium(IV) complexes of 2-FAPy.
Th(NO3)4.
ThI4
Th(NCS)4 Th(ClO4)4
Assignment
2-FAPy
(2-FAPy)2 (2-FAPy)4 (2-FAPy)4 (2-FAPy)6
1603
1528
1382
1312
1151
1668
1626
1667
1624
1380
1326
1087
C=N stretching azomethine
1599
1593
Ring stretching N phenyl
stretching
Ring bending of benzene
Ring bending and
deformation
1383
1352
1151
1383
1166
1479
1384
1152
1479
1492
1490
996
768
670
510
1546
998
768
628
514
985
943
775
735
C-N-C bending
996
768
669
551
994
769
669
515
Out of plane ring
deformation
Out of plane for mono
substituted benzene
ν M-N metal ligand
vibration
669
-

802
KISHOR ARORA et al.
Table 3. Infra red absorption frequencies (cm-1) for dioxouranium(VI) complexes of 2-FAPy.
1603
1528
C=N stretching
azomethine
1605
1540
1665
1626
1601
1596
1651
1382
1312
1151
Ring stretching N-phenyl
stretching
1384
1352
1325
1152
1473
1383
1163
1478
1384
1151
1478
1376
1111
1428
Ring bending of benzene
Ring bending and
deformation
1152
1492
1476
985
943
775
735
C-N-C bending
930
770
677
519
996
768
624
515
994
768
901
765
699
510
970
760
671
509
Out of plane ring
deformation
Out of plane (mono
substituted benzene)
670
623
669
-
ν(M-N) metal ligand
vibration
514
PMR spectral studies
In the PMR spectra of 2-FAPy and its iodide complex with dioxouranium(VI) the furan
protons imparted their characteristic peaks between 7.38 ppm values9 on δ scale. Interaction
of αα’ and ββ’ as well as αβ protons of the heterocycle produced peak between 7.3 to
7.8 ppm values on δ scale. The azomethine proton also produce its significant peak in the
same scale proton of the pyridine ring produces multiplet in 4.9-5.7 cps range because of
α
-β interactions .Significant peaks of iodide complexes are in form of multiplet in the range
7.69-7.83 and a pentet in 6.72-6.75 ppm range.
X ray diffraction studies
In this present investigation two representatives samples were chosen for x-ray diffraction
studies through powder method viz [Th(2-FAPy)2(NO3)4], [Th(2-FAPy)4I2] (Figure 2 & 3).
The analysis was based on Bragg’s equation and a, b, c; angles and constants hkl along with
inter planar distance ‘d’ were obtained10-14.
The results were analyzed to obtain crystal system along with other parameters. The
results are tabulated in Tables 4 & 5. [Th(2-FAPy)2(NO3)4] belongs to orthorhombic
system with a = 15.393{8}Ao, b = 76.94{4}Ao, c = 7.479{9} Ao (Table 4). [Th(2-
FAPy)4I2], belongs to orthorhombic system with a = 16.757{2}Ao , b = 9.937{3}Ao, c =
4.068{2} Ao (Table 5).

2-Theta Scale
Figure 2. X-Ray diffraction for [Th(2-FAPy)2 (NO3)4].

2-Theta Scale
Figure 3. X-Ray diffraction for [Th(2-FAPy)4I2]

Analytical and Spectral Studies of Novel Schiff Base Complexes
805
Table 4. Crystallographic data for [Th(2-FAPy)2(NO3)4].
I
hkl
200
001
301
101
022
113
113
420
dobs
dcalcd.
7.7
7.47
4.610
4.074
3.756
3.452
3.221
3.181
2θ obs.
11.509
11.866
19.298
21.870
23.762
30
26
37
45
82
7.682
7.452
4.595
4.060
3.820
3.452
3.211
3.178
23.786 100
27.757
28.050
49
39
Table 5. Crystallographic data for [Th(2-FAPy)4I2]
I
hkl
200
200
001
101
020
301
220
101
-
dobs
dcalcd.
8.319
7.522
6.902
6.285
4.671
4.572
4.070
3.648
3.236
2θ obs.
10.625
11.755
12.814
14.079
18.983
19.398
21.819
22.529
53
37
38
48
39
65
64
83
8.369
7.549
6.936
6.311
4.695
4.583
4.074
3.948
3.235
27.538 100
Toxic effects on microorganisms
Three complexes of this series were chosen [UO2(2-FAPy)2(NCS)2] [UO2(2-
FAPy)4(ClO4)2], [Th(2-FAPy)4(ClO4)6] for toxic effects study. Thorium perchlorate
complex of this ligand was found to be least effective for E.coli and uranium perchlorate
was found to be most effective for bacterial toxicity. It was interesting to note that
moderate concentration of complex of uranium salt is found to be maximum toxic for
bacterial growth. For Aspergillus species maximum concentration of thorium and
dioxouranium complexes is 60%; it was found to be most potent fungal inhibitor. The
uranyl complexes showed maximum toxicity as the development of fungal colony was
farthest from this complex sample disc. The significant results are shown in Table 6.
Cause of toxicity might be accumulation of heavy metals in microbes affecting its
mobility and confirming its toxicity in further exposure of intracellular metal binding site
and increasing passive. Intracellular accumulation of these heavy metals occur through ion
pump and ion channel etc. Permeability of cell membrane to toxic metals can result
accumulations15-19
Table 6. Colony diameter/ radial distance of colony around sample disc (cm).
.
Study
Complex
Pure
Complex conc. in DMF
DMF
20%
40%
60%
↓
Antibacterial
E.coli
[UO2(2-FAPy)2)(NCS)2]
0.2/0.0
0.5/0.1
4.0/0.2
0.1/0.0
0.4/0.2
2.5/0.1
0.1/0.3
0.1/0.3
0.2/0.4
1.0/0.1
Antifungal
Aspergillus
Antifungal
Mucor
[UO2 (2-FAPy)2 (ClO4)2]
[UO2(2-FAPy)2 (ClO4)2]
0.3/0.3
1.0/0.1

806
KISHOR ARORA et al.
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