THE ANALYTICAL SIGNIFICANCE OF COPPER SCHIFF BASE COMPLEXES

THE ANALYTICAL SIGNIFICANCE OF COPPER SCHIFF BASE COMPLEXES

CHAPTER ONE

INTRODUCTION

1.1   Meaning of Schiff Base

        Schiff bases are condensation products of primary amines and carbonyl compounds, such as aldehyde or ketone. Schiff base was discovered by a German chemist Hugo Schiff in 1864. Schiff bases are considered as one of the most popular families of organic compounds which are used as synthetic intermediates as well as quite helpful in the establishment of coordination chemistry (Gemi, 2004).

        Schiff bases are considsed as a very important class of organic compounds, having wide applications in many biological aspects, proteins, visual pigments, enzymic aldolization and delarboxylation reactions. More over some Schiff bases and their metal complexes exhibits antibiotic, antiviral and antitumor agents. They are used as catelysts in polymer and dye industries, beside some uses as antifertility and enzymatic agents. An interesting application of Schiff base is their use as an effective corrosion  inhibitor, which is based  on their ability to spontaneously form a monolarger on the surface to be protected, Schiff  bases are also

R1 called imines, and they contain carbon nitrogen R double  bond ( C=N-R) (Ozaslen et al, 2011). Due to the physico chemical properties of Schiff bases, they have played a very important role as chelating ligands for transition metal and for the development of coordination chemistry. Since they have flexible nature and easily proton donating property, the study of Schiff bases and their complexes with transition metals, lathanides and radioactive metals has flourished since few decides. Schiff base ligand shows a number of sites for binding that lead to higher coordination polyhedral and cause greater kinetor and thermodynamic stability (A Shral et al, 2001).

1.2   Meaning of Copper Schiff Base Complex

        Schiff bases are varstatile Ligants and when they undergo coordinate covalent bonding with a transition metal such as copper a copper –Schiff base complexes are formed.

        The Schiff bases has ability to donate core  pair of electron  to the central  metal which is copper, in other to form a complex or coordination compound. Some of the Schiff base has the ability to donate pairs of electron to the copper hence they are called tridentate ligand, those that can donate four pairs of electron are called tetradentate ligand and vice versa. Copper Schiff bases have wide applications in food industry, dye industry, analytical chemistry, catelysis, agrochemical, fungicidal, anti-inflammable activity, anti radical activity and biological activities (Barboin, 2006).

        Schiff base complexes are considered to be among the most important sterer chemical models in main group and transition metal coordination chemistry due to their preparative accessibility and structural variety. Copper (11) Complexes shows distorted octahedral and tetrahedral symmetries due to d9 configuration. The distortion is usually seen as axil elongation consistent with the liability and geometric flexibility of the complex (Gemi, 2004).

        Therefore typical copper (II) complexes have square planer or square pyramidal geometries with weakly associated ligand in the axial position, but some copper (II) complexes possess regional bipyramidal geometry. The fundamental role of copper and the recognition of its complexes as important bioactivities compounds in vitro and in vivo aroused an ever-increasing interest in these agents as potential drugs for therapeutic intervention in various diseases (Jesmi and Ali, 2010).

        A considerable number of Schiff bases copper complexes have potential biological interest, being used as more or less successful models of biological compounds. Not only they have played a seminal role in the development of modern coordination chemistry, but also they can be found at key points in the development of inorganic biochemistry, Catalysis and optical materials (Kumer et al, 2009).

1.3   Uses of Schiff Bases and their Metal Complexes

        The Schiff base ligands and their metal complexes have special importance in the field of coordination chemistry. A survey of the literature shows that, in recent times, increasing number of studies has been devoted to the synthesis and structural studies. However, the utility aspects of the Schiff bases and their metal complexes have received their share of attention with an all round progress in the field of coordination chemistry. The importance of Schiff bases and their metal complexes with transition metals have been well emphasized by several researchers.

1.4   Analytical Applications

        The Schiff bases have remarkable property of forming complexes and serve as excellent chelating ligands. Due to their ligational property they have been extensively used as analytical reagents. Schiff bases formed from salicylaldehyde are used in gravimetric analysis and spectrophotometric determination. For example, the Schiff bases derived from ethylenediamine forms an insoluble complex with Ni (II), which has been used for its gravimetric determination. Also, the same reagent has been used recently for the spectrophotometric determination of Ni (II) at trace level.

Biological Importance

        The active functional group of Schiff bases is azomethine (-HC=N-) and its importance has been studied in bio-chemistry. Its biological importance has been studied in the fields of fungicides and insecticides21. Also, the intermediate of the azomethine group shows biological importance in large number of enzymatic reactions. These compounds exhibit many physiological activities. They are found to be useful as plant growth regulants and as an anti-coagulating materials.

1.5   Objective of the Study

        The main objective of this study is to analyse Schiff base and its complexes have a variety of application including biological, chemical and analytical. Earlier work has shown that some drugs showed increase activity when administrated as metal chalets rather than as organic compounds.

1.6   Materials and Methodology

        Chemicals used for this work like substituted hydroxyl benzaldehyde , hydrazine hydrate, diethyl malonate , metal salts , Ethanol, chloroform, methanol, distilled water, Acetone cobalt standard, Nickel standard etc were of analytical grade.

1.7   Apparatus and Instruments

        The apparatus used in this project are melting point apparatus, condenser, heating mantle, round bottom flask, rotary evaporator, beakers, measuring cylinder, ice bath, desiccators, suction pump, funnel, filter paper, stirrer etc.