1048
KISHOR ARORA et al.
IR spectral studies
IR spectra were taken through Schimadzu 8201 PC for range 4000-400 cm-1 using KBr pellets.
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 coordination4,5. For 2-TBAPy
the significant peaks include one at 781-740 cm-1 belonging to 2- substituted pyridine system
and other at 1275-1200 cm-1 peculiar to C-O-C stretching mode of aryl alkyl ether6. In the
spectra of 2-HBAPy the typical peak of 1,4 di-substituted benzene ring around 800 cm-1 and
aromatic aldehydic system involved in conjugation around 1600 cm–1 are clearly distinct. The
–C=N- stretching frequency for 2-TBAPy is around 1593 cm-1 while for its thorium iodide,
thorium isothiocynate and thorium perchlorate the absorption is around 1507 cm-1, 1593 cm-1
and 1590 cm-1 respectively. For 2-HBAPy the same is around 1596 cm-1 and for thorium
iodide, thorium isothiocynate and thorium perchlorate these are around 1593 cm-1, 1514 cm-1
and 1504 cm-1 respectively. The dioxouranium complexes also show such type of shifts in their
IR absorption frequencies. The details are discussed in Tables 4-7.
PMR spectra
PMR spectra of 2-TBAPy and its complex with uranyl acetate were recorded. The azomethine
proton produces a multiplet around 6.5 ppm which remain persisted in the uranyl acetate
complex as well. For methoxy protons singlet is observed around 9.8 ppm also found in the
complex. The signal of amino pyridine protons is observed in the 6-8 ppm range. Other signal
obtained for these complexes are at 7.1489-7.3980 and around 7.97 ppm value.
Antibacterial and antifungal studies
Antibacterial and antifungal activities of some of the representative complexes were done through
paper disc method in our own laboratory. The bacterial strain E.coli and fungal strain Aspergillus
and Mucor were grown on PDA medium. Paper disc of approx. 1.5 cm diameter were cut and
dipped in different concentration of complexes (w/v) in DMF. Paper disc dipped in pure DMF
solution was chosen as control. Later these plates were inocculated by bacteria or fungi and
incubated in oven for 2-3 days in inverted position. Culture medium was chosen as NA solution.
The results were analyzed on two bases viz the radial distance of colony developed from
the periphery of paper disc7-9 and diameter of largest colony developed around the paper disc.
Toxic effects of complexes with 2-TBAPy
Three representatives complexes were chosen for this purpose viz. [UO2(2TBAPy)2(CH3COO)2],
[UO2(2TBAPy)4(NO3)2], [UO2(2TBAPy)2 I2]. The significant results are discussed in Table 8.
For bacterial species the uranyl acetate complex showed negligible toxicity at minimum
concentration while uranyl iodide was found to be maximum efficient amongst the
complexes at moderate concentrations. Uranyl acetate proved to be potent antifungal agent
in this series.
Toxic effects of complexes with 2-HBAPy
Two representative complexes of uranyl salts were chosen in this series of hydroxy
benzalidene ligands viz [UO2(2HBAPy)2 I2], [UO2(2HBAPy)2(NCS)2]. For bacterial toxicity
the thiocyanate complex came out to be effective as bacterial colony developed far away
from its sample disc and that too of small diameter; whereas for Aspergillus sp, iodide
complex was more potent antifungal than thiocyanate and the same was proved for Mucor sp
as well. The significant results are tabulated in Table 8.
Agnihotri, Sonal
