Synthesis, characterization, and antibacterial activity of the ligands including thiophene/furan ring systems and their Cu(II), Zn(II) complexes

Carboxamide complexes having general formula as [ML]Cl₂·nH₂O (where M?=?Cu(II), Zn(II); n?=?0, 1/2) were synthesized using heterocyclic carboxamide ligands: 1,4-bis[3-(2-thiophenecarboxamido)propyl]piperazine (L¹) and 1,4-bis[3-(2-furancarboxamido) propyl]piperazine (L²). Their structures were characterized with elemental analysis, molar conductivity, magnetic susceptibility, and spectral methods (¹H-NMR, ¹³C-NMR, FT-IR, LC-MS). TGA and DTA curves were also performed. The structure–activity relationship for the ligands was investigated using PM3 semi-empirical method. The antibacterial activities of the carboxamides and their complexes were investigated against bacteria; Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 11230, Bacillus magaterium RSKK 5117, B. cereus RSKK 863, Salmonella enteritidis ATCC 13076, B. subtilis RSKK 244 using microdilution method.