Synthesis And Characterization Of Chiral Heteronuclear Complexes Of Schiff Base Containing Dipeptide

In recent years, much attention has been paid to chiral heteropolymetallic complexes. This kind of complexes have interesting structures as well as potential applications. They are also as models for the active sites of metalloproteins in the area of the bioinorganic chemistry. So the study into these chiral heteropolymetallic systems has become one of the aims of a good number of research groups working in chemistry and biochemistry.In this paper, a series of carboxylate-bridged heteronuclear compounds containing chiral dipepides and salicylaldehyde (its derivatives) has been synthesized and characterized by IR, UV-Vis, single crystal X-ray analysis and CD spectroscopic techniques.1,The chiral Schiff base ligand derived from the condensation of salicylaldehyde and glycyl-L-leucine, which is able to accommodate a copper (â…¡) ion at inner ONNO coordination site, leading to the mononuclear complex. It can act as potential'ligand'to bind other metal ions to give five chiral heterometallic complexes Cu(â…¡)-M(â…¡) (M=Ba,Sr,Cd,Mg,Ni). Complexes(1)-(2)formed a M-Cd-M trinuclear complex via carboxylate bridged. They are hold together via different hydrogen-bonding models , and formed 3-D network structures. Complexes(3)-(5) formed cation columns [M(H₂O)₆]²⁺ and anion columns [CuL]- arrangement and are hold together via different hydrogen-bondings, and from 3-D chiral network structures. The CD spectra of the complexes exhibits negative Cotton effect.2,The chiral mononuclear copper (â…¡) complex of Schiff base derived from the condensation of salicylaldehyde and glycyl-L-Valine , It can act as potential'ligand'to bind metal cations to give two chiral heterometallic complexes Cu(â…¡)-M(â…¡) (M=Ba, Ni). Complexe (6) formed the honeycombed hydrogen-bonded chiral network along the c-axis. In the complexe (7), complexe formed cation layers [M(H₂O)₆]²⁺ and anion layers [CuL]^- arrangement and are hold together via different hydrogen-bondings, and from 3-D network structures. These optically active compounds were confirmed by Circular dichroism measurements.3,Four complexes of Schiff base derived from 3-methoxysalicylaldehyde and three dipeptides have been synthesized and characterized. Complexes(8)-(10) have the similar crystal structures. Complexes formed a Cu-M dinuclear complex via carboxylate bridged. The crystal packing of complexs formed helical chains along the b-axes. The helical chains are hold together via different hydrogen-bonding models , and formed 3-D network structures. Complexe (11) formed cation columns [M(H₂O)₆]²⁺and anion columns [CuL³]^- arrangement and are hold together via different hydrogen-bonding models, and formed 3-D network structures.4,The Schiff base ligand derived from the condensation of 5-sulfonylsalicylaldehyde and DL-glycylalanine, which is able to accommodate a copper(â…¡) ion at inner ONNO coordination site , leading to the mononuclear complex . It can act as potential'ligand'to bind alkaline earth metal cations M²⁺(Ca²⁺,Sr²⁺,Ba²⁺) leading to 1D ladder-like polymer {[Ca(H₂O)₅(CuL)]·5H₂O}_n (12), 2D network polymer {[Sr(H₂O)₄(CuL)]·5H₂O}_n and {[Ba(H₂O)₅(CuL)]·5H₂O}_n (14). Complex (12) formed 1D chain-like polymer via carboxylate oxygen and one sulfonate oxygen atoms. In the complex (13), there are two sulfonate oxygen atoms coordinate to Sr²⁺and Cu²⁺, formed 2D network polymer. Compared to (13), complex (14) has the similar crystal structure.