Synthesis, Spectral Characterization and Antimicrobial Studies of Co(II) Complexes with Tetradentate Schiff bases Derived from Ortho-Phthalaldehyde

A series of cobalt (II) complexes have been synthesized with Schiff bases derived from ortho-phthalaldehyde and various amines in aqueous methanol solution. The newly synthesized Schiff bases and their Co (II) complexes have been characterized  by elemental analysis, magnetic susceptibility, thermal, conductance measurements, mass, IR, electronic, 1H,13C-NMR spectral techniques. These ligands act as tetradentate species and coordinate to the metal center through the different potential donor atoms such as N, O and S. The probable octahedral structures have been assigned to these complexes. All the synthesized Schiff base ligands and Co(II) metal complexes have also been screened for their antimicrobial activities and metal complexes found to be more active than respective Schiff-base ligands

Synthesis, Spectral and Antibacterial Studies of Copper(II) Tetraaza Macrocyclic Complexes

A novel family of tetraaza macrocyclic Cu(II) complexes [CuLX2] (where L = N4 donor macrocyclic ligands) and (X = Cl−, NO3 −) have been synthesized and characterized by elemental analysis, magnetic moments, IR, EPR, mass, electronic spectra and thermal studies. The magnetic moments and electronic spectral studies suggest square planar geometry for [Cu(DBACDT)]Cl2 and [Cu(DBACDT)](NO3)2 complexes and distorted octahedral geometry to the rest of the ten complexes. The biological activity of all these complexes against gram-positive and gram-negative bacteria was compared with the activity of existing commercial antibacterial compounds like Linezolid and Cefaclor. Six complexes out of twelve were found to be most potent against both gram-positive as well as gram-negative bacteria due to the presence of thio group in the coordinated ligands

Substrate-Directed C-H Functionalization of 2-Aryl Pyridines by Transition Metal Complexes

International audienceTransition metal mediated C-H activation is a powerful synthetic tool for the total synthesis of complex natural products and biologically active molecules. The strategy involves mainly C-H activation, nucleophilic addition and regeneration of the catalyst. It proceeds through a C-H bond cleavage by ligand coordination to transition metal. Transition metals like Pd, Rh, Ru, Co, and Ir are the most often used catalysts, which form a complex with 2-aryl pyridine and facilitates the functionalization of various C-H bonds to generate diverse C-C and C-X bonds under typically mild reaction conditions with low catalyst loading. In particular, the chelation-assisted cleavage of C-H bonds at ortho-position of the pyridine directing group has been recognized as one of the most powerful strategies for the functionalization of unreactive C-H bonds. Recently, transition metal catalyzed C-H bond activation has received significant interest because it does not require the prefunctionalization of the substrate. Therefore, the metal-catalyzed C-H activation and functionalization is currently considered as atom economy and simplified procedure in comparison with the traditional strategies