Preparation, spectroscopic and thermal characterization of new La(III), Ce(III), Sm(III) and Y(III) complexes of enalapril maleate drug. In vitro antimicrobial assessment studies

• Enalapril maleate lanthanide complexes were synthesized.
• Enalapril acts as a bidentate chelate.
• Maleate moiety acts as a bidentate ligand.
• Kinetic and thermodynamic parameters were estimated.

The 1:1 M ratio metal complexes of enalapril maleate hypertensive drug with La(III), Ce(III), Sm(III) and Y(III) were synthesized. The suggested structures of the resulted complexes based on the results of elemental analyses, molar conductivity, (infrared, UV–visible and fluorescence) spectra, effective magnetic moment, thermal analysis (TG), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were discussed. The infrared spectral data were suggested that enalapril reacts with metal ions as an ionic bidentate ligand through its carboxylate oxygen and the amide carbonyl oxygen, but in case of the Sm(III) complex, it reacted as a monodentate through its amide carbonyl oxygen. Maleate moiety acts with all these metals as bidentate ligand through its carboxylate or carbonyl oxygen. The kinetic and thermodynamic parameters such as: Ea, ΔH*, ΔS* and ΔG* were estimated from the DTG curves. The antibacterial evaluation of the enalapril maleate and their complexes were also performed against some gram positive and negative bacteria as well as fungi.