Silver(I) and copper(I) complexes with a Schiff base derived from 2-aminofluorene with promising antibacterial activity

Abstract

By reaction of 2-aminofluorene with 2-pyridinecarboxaldehyde a new Schiff base (L) is obtained. The reaction of this ligand with Ag(I) and Cu(I) salts in different stoichiometry leads to the complexes [Ag(CF3SO3)(L)PPh3] (1) or [ML2]A (M = Ag, Cu; A = CF3SO3, ClO4 or BF4). Structural characterization by X-ray crystallography has been carried out for complexes [AgL2]ClO4 (4) and [Ag(L)(PPh3)2](CF3SO3) (6), which confirms the chelate nature of L and the presence of Ag⋯H interactions between two molecules. The biological studies show that Schiff base L presents antibacterial activity in Gram-positive bacteria and E. coli. The coordination to silver increases this activity, but the formation of the copper complex does not generate significant changes.