all chemicals were commercial reagent grade purchased
from Fluka and Merck and utilized as soon as possible after receiving
them without any further purifications. A Unicam Maston 1000 FT-IR
spectrophotometer (400–4000 cm–1 in KBr pellets
and at room temperature) was utilized for recording the FT-IR spectra.
A Bruker FT-NMR 500 MHz spectrometer (the chemical shift of protons
is reported in parts per million (ppm) in CDCl3 and DMSO-d6) was used for obtaining the 1H
NMR spectra of L, AgL2, and PdL2. A Cary 100
Bio Varian spectrophotometer (10 mm path length, quartz cell) was
used for UV–Vis analysis. The carboxamide-based ligand was
synthesized and was characterized by different methods. The palladium
metal ion solution was obtained from its acetate salt, and the silver
metal ion was synthesized from its chloride salt.