Available Online through www.ijptonline.com

3.4. IR-spectra
R. Rajavel* et al. /International Journal Of Pharmacy&Technology
The IR spectra of the reported compounds were measured as KBr disk and the important IR-spectral feature along
with their tentative assignments are given in Table-II. In the spectrum of the complexes the absence of band in the
region ∼3400cm -1 corresponding to free primary amine suggests that complete condensation of amino group with
diketone group. The disappearance of these band and the appearance of a new strong absorption band near 1586-
1600cm -1 confirms the formation of the Schiff base, as this band assigned to ν(C=N) stretching vibration[19]. The
data in Table.2. display that frequency value of the ν(C=N) is lower value of ν(C=N) stretching energy may
explained on the basis of a drift of the lone pair density of the azomethine nitrogen towards the central metal
atoms[20, 21], indicating that the coordination takes place through the nitrogen atom of the (C=N) group. Thus, it
appears that each diketone molecule has reacted with the amino groups of the 3,3’-diaminobenzidine with
phthalaldehyde forming the Schiff base and the diaminonaphthalene is used for ring closure and giving rise to
macrocyclic metal complex molecule. The presence of acetate in complexes 1&2 is evidenced by two medium
absorption features centered at 1610 cm −1 for ν as (COO) and 1450 cm −1 for ν sy (COO). The difference between (ν as -
ν sy ) is around 160 cm −1 agrees with the coordination mode for the acetate ion with the central metal ion[22, 23, 24].
All of the perchlorate salts show a medium band near 1145-1190 cm −1 and a strong band at 1085-1109 cm −1 and
sharp band at 621-626 cm −1 , indicative of uncoordinated perchlorate anions[25- 28]. For vanadyl complexes, a strong
band observed at 980 cm −1
is assigned to ν(V=O) which rules out the possibility of a dimeric structure[29].
Conclusive evidence of the bonding is also shown by the observation that new bands in the IR- spectra of the metal
complexes appear at 460-501 cm −1 assigned to ν(M-N) stretching vibrations[30]. Thus from the IR- spectra it is clear
that the compounds may be bonded to the metal ions through the imine nitrogen.
3.5. Cyclic Voltammetry studies
The electrochemical behavior of the complexes was examined by employing a platinum electrode as working
electrode, Ag/AgCl as a reference electrode and platinum wire as auxiliary electrode. The working media consisted of
IJPT | April-2012 | Vol. 4 | Issue No.1 | 4018-4031 Page 4024