Synthesis, characterization and bioactivity of a new Fe(III) 18-metallacrown-6 and a new trinuclear linear Ni(II) complexes

Abstract

A new trinuclear linear Ni(II) compound [Ni 3(H 2O) 2(DMA) 2(acshz) 2] · 2DMF (DMA = dimethylamine) ( 1) and a new Fe(III) 18-metallacrown-6 [Fe 6(acbshz) 6(DMF)(H 2O) 5] · 5DMF ( 2), with two similar pentadentate ligands, N-acryloyl-salicylhydrazide (H 3acshz) and N-acryloyl-5-bromosalicylhydrazide (H 3acbshz) have been synthesized and characterized by X-ray crystallography. In compound 1, three nickel ions arrange in a strictly linear structure, adjacent molecules are linked by intermolecular H bonds to form a 2D infinite wave-like structure. In compound 2, the ring of the metallacrown is consisted of six interlink [Fe–N–N] repeated units through hydrazide N–N group bridging. It is the first metallacrown that the coordination environments of metal ions in the cycle ring are different, and these differences make the two faces of the disc-shaped hexanuclear ring do not have opposite chiralities. The studies in solution integrity and stability of the metallacrown 2 show it is soluble and stable in DMF. UV–Vis titrations demonstrate the metallacrown 2 is stable in DMF even in the presence of excess metal ions. Antibacterial screening data indicate the two compounds all have antimicrobial activities against the tested microorganisms. The activities of metallacrown 2 are stronger than trinuclear compound 1.