3.5. Thermal Analyses (TG and DTG) Studies
The Schiff base ligand exhibits a first estimated mass
loss of 13.33% (calcd. 12.93%) at 25˚C - 140˚C, which
may be attributed to the liberation of 2NH3and 2H2
molecules as gases. In the following stages within the
temperature range from 140˚C - 750˚C, the organic part
C17H8with CO2gas are lost with an estimated mass loss
of 86.67% (calcd. 87.07%). The thermogram of Fe(III)-L
chelate show three decomposition steps within the
temperature range from 50˚C - 790˚C. The first step of decomposition within the temperature range from 50˚C - 245˚C corresponds to the loss of 2HCl gases with an
estimated mass loss of 16.18% (calcd. 16.00%). While
the second step occurs withinthe temperature range from
245˚C - 520˚C and corresponds to the removal of HCl,CO and 2NH3as gases with a mass loss of 21.91% (calcd.
21.58%). The final step (520˚C - 790˚C) corresponds to
the removal of the organic part of the ligand leaving metal
oxide as a residue. The overall weight loss amounts to
84.37% (calcd. 84.27%). The TG curve of the cobalt
complex shows five stages of decomposition within the
temperature range of 25˚C - 705˚C. The first three stages
at 25˚C - 270˚C correspond to the loss of 2HCl as gases
in the first step and NO and NH3as gases in the next
steps, while the final stages involve the loss of organic
molecule leaving the metal oxide as residue. The overall
weight loss amounts to 82.90% (calcd. 82.33%). The
Cu(II) complex decomposed infour steps. The overall
weight loss amounts to 82.22% (calcd. 81.45%), Table 4
and Figure 3.