Synthesis, structure, fluorescent property, and antibacterial activity of new Cd(II) metal complex based on multidentate Schiff base ligand N,N′-Bis(3-methoxysalicylidenimino)-1,3-diaminopropane

Abstract

The sequential reaction of a multisite coordinating compartmental ligand N,N′-Bis(3-methoxysalicylidenimino)-1,3-diaminopropane (H2L1) with Cd(OAc)2 followed by the addition of NaCl in a 2:3:2 stoichiometric ratio affords homometallic trinuclear Cd(II) coordination compound [Cd3(L1)2(Cl)2] (1). The complex 1 has been thoroughly characterized by common elemental analysis (CHN), FT-IR and UV–Vis spectroscopy. Single crystal X-ray diffraction was also performed to determine the complete structure of complex 1. X-ray diffraction studies reveal that the molecular complex comprises a linear tri-nuclear ensemble of cadmium metal ions, which is further supported by the concerted coordination action of two dianionic [L1]2– ligands along with two monodentate Cl− ligands. The central Cd(II) ion is attached to the terminal Cd(II) ions through two phenoxide bridging groups of the fully deprotonated ligands [L1]2–. This arrangement leads to two neighbouring four membered Cd2O2 rings. The terminal Cd(II) ions are penta-coordinated (2 N, 2O, Cl) in a distorted square pyramidal geometry and central Cd(II) ion attained distorted trigonal prismatic geometry through six oxygen atoms coordination from ligands. Tri-nuclear Cd(II) complex 1 display intraligand (π—π∗) fluorescence in DMSO solution at room temperature. The fluorescence properties of complex 1 as well as the respective di-compartmental Schiff base ligand (H2L1) have been investigated in DMSO solvent at room temperature with a comparative approach. Result confirmed that complex 1 is highly fluorescence active mediated due to “chelation enhanced fluorescence” [CHEF] but Schiff base ligand (H2L1) is fluorescence silent. The antibacterial efficacy of complex 1 was further investigated against some important Gram-positive and Gram-negative bacteria.