5,5-Diethylbarbiturate complexes of silver with 2,2′-bipyridine and 3-(2-pyridyl)propanol: Syntheses, crystal structures, spectroscopic, thermal and antimicrobial activity studies

Abstract

Two silver 5,5-diethylbarbiturate (barb) complexes with 2,2′-bipyridine (bpy) and 3-(2-pyridyl) propanol (pypr), [Ag(barb)(bpy)] (1) and [Ag(barb)(pypr)] (2), have been prepared and characterized by elemental analysis, IR spectroscopy, thermal analysis, and single crystal X-ray diffraction. Both complexes crystallize in the triclinic space group P1̄ with Z = 2. The barb ligand in 1 is N-coordinated and the bpy ligand acts as a bichelating ligand leading to an AgN3 tricoordination. Crystals of 1 feature a three-dimensional network based on N-H⋯O hydrogen bonding, π(bpy)⋯π(bpy), C-H⋯π(bpy) and π(bpy)-Ag interactions. In 2, the pypr and barb ligands behave as monodentate ligands through their N atoms, forming a distorted linear AgN2 coordination. Molecules of 2 are doubly bridged by N-H⋯O hydrogen bonds and further connected via O-H⋯O hydrogen bonds and aromatic π(pypr)⋯π(pypr) stacking interactions into a supramolecular network. Both complexes exhibit similar thermal decomposition behavior in air. The first stage corresponds to removal of the co-ligands such as bpy or pypr while the degradation of the barb moiety occurs at higher temperatures to give Ag2O. Like the barb, bpy and pypr ligands, 2 does not show any significant antimicrobial activity, but 1 is active against bacteria and fungi. © 2008 Verlag der Zeitschrift für Naturforschung.