Synthesis and characterization of amino acid (phenylalanine) schiff bases and their metal complexes

Faliah Hassan, Ali Al-Jeboori, Thaera Abdulridha, Mussa Al-Shimiesawi, Mithal Abdulkareem, Abd Oun, Ahmed Abd-Ul-Ridha, Amer Abdulla
2014 Journal of Chemical and Pharmaceutical Research   unpublished
Schiff bases derived from the condensation of benzaldehyde or acetone and the amino acid phenylalanine in basic media using sodium hydroxide as a catalyst have been synthesized and their Co (II), Ni (II) and Cu (II) complexes have been prepared. The Schiff bases and their complexes that been prepared, were analyzed and characterized by using different techniques, such as elemental analysis, infrared and electronic spectra. The IR spectra, UV bands and atomic absorption analysis show that the
more » ... is show that the Schiff base ligand forming chelates with 2 : 1 (ligand : Metal) stoichiometry. Some of prepared metal complexes were evaluated for in-vitro antibacterial activity against Negative and Positive Bacteria. The complexes showed significant anti bacterial activity. INTRODCTION Amino acids are molecules containing an amine group, a carboxylic acid group and aside chain that varies between different amino acids. These molecules are particularly important in biochemistry (VOET D., 1993), where this term refers to amino acids with the general formula H NCHRCOOH, where R is an organic substituent. Amino acids containing uncharged amino groups, at physiological PH values, ay also undergo Schiff base formation, which presents another potential mechanism for metal complexes. Schiff bases are condensation products of primary amines with carbonyl compounds and they were first reported by Schiff in 1864. The common structural feature of these compounds is the azomethine group with a general formula RHC=N-R1, where R and R1 are alkyl, aryl, cyclo alkyl or heterocyclic groups which may be variously substituted. These compounds are also known as anils, imines or azomethines. Several studies (Kumar N., 2013 ,Gupta V. , 2013 ,Kumar L., 2011 , , ünve H., 2002) showed that the presence of alone pair of electrons in an SP 2 hybridized orbital of Nitrogen atom of the azomethine group is of considerable chemical and biological importance. Because of the relative easiness of preparation, synthetic flexibility and the special property of C=N group, Schiff bases are generally excellent chelating agents especially when functional group like-OH or-SH is present close to the azomethine group so as to form a five or six membered-ring with the metal ion. Schiff bases have been used extensively as ligands in the field of coordination chemistry, some of the reasons are that the intramolecular hydrogen bonds between the (O) and the (N) atoms which play an important role in the formation of metal complexes and that Schiff base compounds show, photochromosim and thermochromism in the solid state by proton transfer from the hydroxyl (O) to the imine (N) atoms (Elerman Y.,2002).Schiff bases have appeared to be an important intermediate in a number of enzymatic, reactions involving interaction of enzyme with amino or carbonyl group of the substrate (Lehlinger L., , 1975).
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