Heteroleptic cobalt(II) complex with nitrogen-rich macrocycles - Structure, bioactivity and DFT modelling

We herein discuss the synthesis and characterization of a novel mononuclear cobalt(II) complex CoII(TPBP)(HTMA)2 with the N-donor ligands; hexamethylenetetramine HTMA and meso-tetrakis[4-(benzoyloxy) phenylporphyrin H2TPBP. Firstly, molecular structure and supramolecular assembly have been thoroughly described. The basic core (porphyrin macrocycle) is nearly planar and the cobalt coordination centre sits in slightly distorted octahedral environment occupied by four pyrrolic nitrogen atoms (NPy) and two HTMA nitrogens (NHTMA). On the basis of quantum chemical density-functional theory calculations, metal—ligand charge-transfer interaction (MLCTI), spin density distribution and chemical reactivity character have been also highlighted. Finally, the bio-activity of free porphyrin and their cobalt complexes was evaluated in vitro, by examining their inhibitory effect against some yeasts and fungal strains, and their ability to scavenge 1,1-diphenyl-picrylhydrazyl DPPH radical. This research could provide rich insights into the structural, electronic and (bio)chemical features of analogues macrocyclic metal complexes.