522 Yousaf et al.
Asian J. Chem.
Crystallization of the metal complex was done by employing
a combination of three solvents i.e. toluene, ethanol, ethyl
acetate. Finally a product was obtained with fine crystals.
Washing of product was done by mixing different solvents
and then the product was dried.
Different spectroscopic techniques were used to get the
spectroscopic data of compounds. Mass spectra of ligand was
taken at 70 ev by electron ionization technique on Perkin-
Elmer Clarus 680 GC-MS instrument in the R and D section
of Zeta Chemical Co. Pvt. Ltd., Lahore, Pakistan. Fourier
transform infrared spectra were taken on a Perkin Elmer FTIR
and Thermo FTIR Nicolet IS 10. 1H NMR and 13C NMR were
recorded via 60 MHz JNM-ECX60 FT-NMR system. Crystal
data (X-ray crystallography) of titled complex was taken on
the single crystal X-ray diffraction.
Characterization of ligand
Fourier transform infrared spectroscopic analysis:
FTIR was used to confirm the ligand's functional groups. The
range used for the FTIR spectra was 4000-400 cm-1 as KBr
pallets. On the basis of previously work this assignment was
made16. The bending vibrations for imine group were observed
at 1625-1608.9 cm-1 and for phenolic-OH group bending
vibrations were observed at 1370 and 1198 cm-1 for ligand.
Data shown in Tables 1 and 2.
TABLE-1
BENDING VIBRATIONAL IR FREQUENCIES
IN cm-1 FOR IMINE GROUP
Compound
Ligand
Complex
Observed value
1625-1609 cm-1
1625-1597 cm-1
Standard value
1630-1575 cm-1
1630-1575 cm-1
Antibacterial activity: To check antibacterial activity
various strains were used. Strains used were Staphylococcus
aureus, Escheria coli and Bacillus subbtilis10. The metal
complex and ligand were employed for antimicrobial activity
by using Disc diffusion method CLSI, 2007. The main proce-
dure used to check the antibacterial activity includes mixing
of agar in water i.e. distilled water was taken in which nutrient
agar was dissolved, which was uniformly dispersed. Then the
material set aside in autoclave for sterilization for 20 min at
121 ºC. The medium then transferred to Petri plates but before
Petri plates it was treated with inoculums. Henceforth, parallel
discs of filter papers containing 100 µL (10 %) of ligand and
metal complex were employed on the medium. The medium
in the Petri plates was left at 37 ºC for 24 h for the growth of
bacteria. Clear zones were formed by ligand and metal complex,
which inhibited the bacterial growth. Inhibition zones were
measured in millimeters by employing zone reader11. The
standard drug employed was rifamipicin.
Antifungal activity: To check antifungal activity different
strains were employed. A. alternate, A. flavus and A. niger10 were
the used strains. Synthesis of growth medium was done and
then engaged to Petri dishes after sterilization. Incubation for
growth of fungus was carried at 28 ºC for 48 h. Growth medium
was employed to filter paper discs for fungus growth. Ligand
and its metal complexes were applied up to 100 µL (10 %) on
each disc and incubation started. Clear zones were formed by
the ligand and metal complex, which showed antifungal
activity11. Fluconazol was the standard drug used for antifungal
activity of complex and ligand12.
TABLE-2
BENDING VIBRATIONAL IR FREQUENCIES
IN cm-1 FOR PHENOLIC GROUP
Compound
Observed value (cm-1)
1370 and 1198
Standard value (cm-1)
Ligand
Complex
1410-1310 s and ca. 1200
1410-1310 s and ca. 1200
1386 and 1190
1H NMR: NMR spectra were recorded by using ECX60
FT NMR (60 MHz) and solvent used was CDCl3. Reference
standard used was TMS. The singlet peak at 3.95 ppm showed
by protons of ethylene. Each aryl group has four protons in
the molecule. Different environment of these protons was
found and data of these shown in the Table-3 with lableling
from C1, C4, C1, C2, C3 and C4 protons showed doublet, triplet,
triplet and doublet at 7.02, 7.52, 7.08 and 7.66 correspon-
dingly. Imines protons showed singlet at 8.54 ppm. Imine
group have π electrons, which were deshielded and showed
high value.A singlet at 11.26 ppm showed by phenolic protons
which was probably due to the strong effect of deshielded
oxygen atom.
TABLE-3
1H NMR DATA OF LIGAND
Position of protons
Type of peak
Doublet
Triplet
Triplet
Doublet
Value (ppm)
7.02
C1
C2
C3
C4
7.08
7.52
7.66
13C NMR: The simple and same environment of the ligand
molecule containing different atoms permit it easy 13C NMR
spectrum. The data shown in the Table-4, two carbon atoms
corresponds to each peak in the molecule. First peak at 61.9
ppm is due to the CH2-CH2 group. The signals of sp3 hybridized
carbon atom present in the middle of the molecule mostly
appears at about 30 ppm but due to the presence of electrone-
gative atom (N) and the presence of π bonds adjacent to CH2-
CH2 group caused such downfield from 30 ppm (base value)
to the 61.9 ppm (found value). The CH carbon exhibit sp2
hybridization, which is not terminal commonly found at 140
ppm with found value 157.5. The presence of electronegative
nitrogen (N) was correlated with the observed value of carbon
which showed some deviation. Also the aryl group contains
RESULTS AND DISCUSSION
Crystallization in triple solvent system: Three indepen-
dent solvents were checked for crystallization of the obtained
complex. Even so, the dissolution of the titled complex in single
solvent was not successfully done and hinder the proper
crystal formation. Solubility of the titled complex by using
0.5 g in three separate solvents i.e. in ethyl acetate, toluene
and ethanol was 1.2, 0.5 and 0.1 % correspondingly. On the
basis of previously reported results4,13-15, the solubility of the
metal complex was increased successfully by employing a
combination of three solvents and the results showed that
solubility of the metal complex was up to 11 % for 0.5 g of the
complex dissolved. This was due to the intermolecular bonding
and bridging of the used solvents.