Synthesis, crystal structure determination and antimicrobial studies of copper(II) picrate complexes with N,N,N′,N″-tetrakis(2-hydroxyethyl/propyl) ethylenediamine and tris(2-hydroxyethyl)amine

The present work consist of synthesis, spectroscopic and crystal structure investigations of complexes [Cu(THEEN) (H2O)] (PIC)2 (1), [Cu(THPEN)] (PIC)2·C3H8O (2) and [Cu(TEAH3)(PIC)] (PIC)·(H2O) (3) and their application in antimicrobial activities. In these complexes, THEEN is N,N,N′,N″-tetrakis(2-hydroxyethyl) ethylenediamine and THPEN is N,N,N′,N″-tetrakis(2-hydroxypropyl) ethylenediamine, are tetrapodal ligands and TEAH3 is tris(2-hydroxyethyl)amine, a tripodal ligand. Crystal structure investigations have revealed that the coordination number of Cu(II) is five with square pyramidal geometry in complex (1) and THEEN is interacting with metal ion through both of its amine nitrogens and two of the four hydroxyl oxygens in a tetradentate manner. The metal ion in complex (2) is having a distorted octahedral geometry with coordination number six and THPEN is interacting with it through all ligating sites in a hexadentate way. The picrate anions are present outside the coordination sphere in both of these complexes and are involved in hydrogen bonding interactions resulting in the formation of charge-separated complexes (1) and (2). The coordination number of Cu(II) is five with square pyramidal geometry in complex (3) where the ligand tris(2-hydroxyethyl)amine (TEAH3) is interacting through all of its donor atoms in a tetradentate way. One of the two picrate anions is in coordination with metal ion whereas other is present outside the coordination sphere and is involved in hydrogen bonding interactions resulting in formation of partially charge-separated complex.

Graphical abstractThe synthesis and crystal structures of Cu(II) picrate complexes with N,N,N′,N″-tetrakis(2-hydroxyethyl)ethylenediamine and N,N,N′,N″-tetrakis(2-hydroxypropyl)ethylenediamine (THEEN & THPEN) and tripodand (TEAH3) are described. The interaction of tetrapodands and tripodand with Cu(II) picrate resulting in the formation of charge separated complexes (1), (2) and partially charge-separated complex (3) are formed. The antimicrobial studies of synthesized complexes indicate that these complexes can further be explored as specific antibacterial drugs.Figure optionsDownload full-size imageDownload as PowerPoint slide