Experimental
Materials and methodologies
All the chemicals used were of AR grade, procured from Alfa/Aesar and Aldrich. Solvents used were of analytical grade. IR spectra (KBr pellets) were recorded in the region 4000–400 cm−1 on a FT-IR spectrum BX-II spectrophotometer. 1H NMR spectrum was recorded with a model Bruker Advance DPX-300 spectrometer operating at 300 MHz using DMSO-d6 as a solvent and TMS as an internal standard. EPR spectra of Cu(II) complexes were recorded as polycrystalline sample and in the DMSO solution, at room temperature (RT) on E4-EPR spectrometer using the DPPH as the g-marker. Electronic spectra were recorded in DMSO solution on a Shimadzu UV mini-1240 spectrophotometer. Magnetic moment measurements (Gouy balance) were made at room temperature using CuSO4⋅5H2O as a calibrant.
Synthesis and characterization of ligand (L)
A solution of thiosemicarbazide (1.822 g, 0.02 mol) in 15 mL absolute ethanol was heated for 10 min in the presence of a few drops of acetic acid to make a clear solution. To this a hot solution of 2-carboxybenzaldehyde (3.00 g, 0.02 mol) in absolute ethanol (15 mL) was added drop wise with constant stirring. The resulting mixture was refluxed for 30 min and cooled overnight at 0 °C. The off white product (Scheme 1) so formed was filtered, washed with cold ethanol, and dried under vacuum over P4O10, Yield was 65.0%. Melting Point observed was 188 °C.