Antimicrobial activity and molecular reactivity of phenylthiosemicarbazones containing the Thiophenyl Nucleus and their Cu(ii) complexes

Abstract

The antimicrobial activity and molecular reactivity of two phenylthiosemicarbazone ligands containing the thiophenyl nuclues (L & L )  with their Cu(II) complexes have been investigated. The thiosemicarbazone ligands 1 2 were obtained by condensing 4- phenylthiosemicarbazone with 2-thiophene carboxaldehyde and 3-methyl-2- thiophene carboxaldehyde respectively. The antimicrobial  activity of the ligands and the metal complexes were evaluated using gram-positive and gram-negative bacterial strains. In addition the  compounds were further characterised with various global molecular reactivity descriptors using DFT calculations. The compounds exhibited mild inhibition against the bacterial strains, especially Staphylococus aureus and Escherichiia coli. In addition, the activity of the  uncomplexed thiosemicarbazones became enhanced upon chelation with Cu(II) ions. The DFT studies showed that ligand L is more  reactive than L and the energy gaps for the complexes were 1 2 0.936 eV and 1.103 eV for [CuL ] and [CuL ] respectively. Furthermore, the  results showed that the copper(II) 1 2 complexes are soft molecules having higher molecular reactivity, high electro-optic responses and  low kinetic stability than their respective ligands.