Synthesis, characterization and bioactivity of a novel 18-metallacrown-6: [Mn(pcshz)(CH 3OH)] 6 · 4CH 3OH · 4H 2O

Abstract

The reaction of N-propionyl-5-chlorosalicylhydrazide (H 3pcshz) with Mn(OAc) 2 · 4H 2O in methanol solution gives a novel 18-metallacrown-6 [Mn(pcshz)(CH 3OH)] 6 · 4CH 3OH · 4H 2O ( 1). The structure of 1 has been determined by X-ray diffraction and it crystallizes in the monoclinic system and space group P2(1)/ n. The ring of the metallacrown is consisted of six interlink [Mn–N–N] repeated units through hydrazide N–N group bridging the ring manganese ions. And the ligand enforces the metal ions to form the stereochemistry as a propeller configuration with alternation Λ/ Δ form. The largest diameters of the disc-shaped hexanuclear ring are about 8.82 Å at entrance, 9.83 Å at the central of the cavity, respectively. The solution integrity and stability of the metallacrown was studied by electrospray ionization (ESI)-MS and UV–Vis spectroscopy. The results show it is soluble and stable in methanol. Antibacterial screening data indicate the forming of the complex weakens dramatically the antibacterial activity of the ligand H 3pcshz except for Eschericha coli.