Crystal design, spectroscopic analyses and antibacterial study of new carbazate ligands and their Cu(II) complexes

The current work reports the synthesis and crystal structures of two carbazate ligands, 2-hydroxyacetophenone-methylcarbazate (HL1) and 2-hydroxyacetophenone-benzylcarbazate (HL2), and their Cu(II) complexes [Cu(L1) (CH3OH)]2 (1) and [Cu(L2)]n (2). All compounds were characterized by X-ray single-crystal analysis, spectro-scopic and physicochemical methods. Intermolecular interactions were analyzed quantitatively with the 3D Hirshfeld surface and the 2D fingerprint plots. The dimeric complex (1) exhibits a mu 2-oxo group located between the two metal ions, an ONO-donor system, and a coordinated methanol molecule with a square-pyramidal ge-ometry to the metal ions. The polymeric complex (2) shows the Cu(II) atom tetracoordinate, bonded to two anionic carbazate, through the ONO-donor system of one molecule, and to a deprotonated nitrogen atom from the second molecule of the ligand. This one-dimensional network shows the metal center with a square planar geometry. The antibacterial properties of the free ligands and metal complexes have been evaluated against periodontopathogenic bacterial strains and were observed to increase the activity after the complexation of the carbazates.