TABLE OF CONTENTS

i.          Title page

ii.         Certification

iii.        Dedication

iv.        Acknowledgement

v.         Abstracts 

vi.        Table of contents

vii.       List of tables  

viii.      List of figures

CHAPTER ONE; INTRODUCTION

1.1       Schiff base

1.2       Schiff base metal complexes

1.3       Application of Schiff bases

1.3.1    Biological importance of Schiff bases

1.3.2    Antibacterial activities

1.3.3    Antifungal activities

1.3.4    Enzymatic Activities

1.4       Stoichiometry

1.4.1    Uses of stoichiometry

1.4.2     Stoichiometry complexation reactions

1.5        Aim and objective of the research

  CHAPTER TWO

Literature review

CHAPTER THREE; EXPERIMENTAL, MATERIALS & METHOD

3.1       Materials /Apparatus

3.2       Reagents

3.3       Methods

3.3.1    Preparation of a Schiff base ligand

3.3.1a  Synthesis ofN,N^/Bis (2-hydroxylbenzylidene- 1,4-phenylenediimine and)-  M

3.3.1b  Synthesis of N,N^/Bis(4-dimethylbenzylidene-1,4-phenylenediimine) -N

3.3.2    Preparation of complexes

3.3.2a Synthesis ofN,N^/Bis (2-hydroxylbenzylidene-1,4-phenylenediimine)- Co(II)complexes

3.3.2b  Synthesis ofN,N^/Bis (2-hydroxylbenzylidene- 1,4-phenylenediimine )- Mn(VII)  complexes 

3.3.2c  Synthesis ofN,N^/Bis (2-hydroxylbenzylidene- 1,4-phenylenediimine )- Mo(VII)  complexes 

3.3.2.dSynthesis of N,N^/Bis (4-dimethylbenzylidene-1,4-phenylenediimine)-Co(II) complexes

3.3.2e Synthesis of N,N^/Bis (4-dimethylbenzylidene-1,4-phenylenediimine)-Mn(VII) complexes

3.3.2f  Synthesis of N,N^/Bis (4-dimethylbenzadehyde-1,4-phenylenediamine)Mo(VII) complexes

3.4       Stoichiometry of the complexes

3.5       Characterization of the Schiff base ligands and their complexes

3.5.1    Melting/decomposition point

3.5.2    Electronic Spectra

3.5.3    Infrared spectroscopy

3.5.4    Antimicrobial Analysis

CHAPTER FOUR; RESULT AND DISCUSSION

4.1         Physical properties

4.2        Solubility assay of the ligands and their complexes                       

4.3        Stoichiometry of the complex

4.4        Reaction Scheme

4.4.1 The reaction scheme between 1,4-phenylenediamine and 2-hydroxylbenzadehyde (M)

4.4.2   The reaction scheme between 1,4-phenylenediamine and 4-Dimethylaminobenzadehyde (N)

4.5    Electronic Spectra

4.5.1    N,N^/Bis(2-hydroxylbenzylidene-1,4-phenylenediimine)-M and their CoM, MnM, Mo₂M complexes

4.5.2    N,N^/Bis(4-dimethylaminobenzylidene- 1,4-phenylenediimine)-N and their  CoN, MnN, Mo₂N complexes

4.6Infrared Spectra

4.8  Proposed Structures

4.9   Antimicrobial properties

CHAPTER FIVE

Conclusions and Recommendations

REFERENCE

APPENDIX

LIST OF TABLES

Table 3.4 Volume of the Stoichiometry of the each metal and ligand complexes

Table4.1. The physical properties of the ligand

Table 4.2 Solubility Assessment

Table 4.3 Summary of Stoichiometry results

Table 4.5   Electronic spectra Data showing wavelength (nm), Wave number (cm^-1) and Infrared absorption frequencies (cm^-1) molar absorptivity €,Lmol^-1cm^-1)

Table 4.6.N,N^/Bis(2-hydroxylbenzylidene-1,4-phenylenediimine)-M and their CoM, MnM, Mo₂M complexes Table: 4.7 Infrared absorption frequencies (cm^-1) of N,N^/Bis (4-dimethylaminobenzylidene -1, 4-phenylenediimine)-N

Table 4.9 Theinhibition zone Diameter(nm) of the Antimicrobial activity of ligand and complexes samples against E.coli, S.typhi, S.aureus, E. feacalis, C.albicans

LIST OF FIQURES

Fig 1: General structure of Schiff bases

Fig 2: Formation of Schiff Base upon heating

Fig 3: Some classes of Schiff base ligands

Fig 4: Structure of Co(II), Cd(II) tetrahedral geometry and Ni(II) complexes

Fig 5: structure of metal complexes 

Fig 6:  Schiff base 2-{(E)-[(8-aminonaphthalen-1- yl)imino]methyl}phenol

Fig7: The geometries of metal complexes

Fig 8: Job’s curve for CoM

Fig 9: Job’s curve for MnM

Fig 10: Job’s curve for Mo₂M

Fig 11: job’s Curve for CoN

Fig 12: Job’s curve for MnN

Fig 13: Job’s curve for Mo₂N

Fig: 14:The reaction scheme between 1,4-phenylenediamine and 2-hydroxylbenzadehyde(M)

Fig 15: The reaction scheme between 1,4-phenylenediamine and 4-Dimethylaminobenzadehyde (N)

Fig 16 :N,N^/Bis(2-hydroxylbenzylidene,  1,4-phenylenediimine) -(M)

Fig 17:N,N^/Bis(2-hydroxylbenzylidene,  1,4-phenylenediimine) –Co(II) complex, CoM

Fig 18: N,N^/Bis (2-hydroxylbenzylidene,  1,4-phenylenediimine)-Mn(VIII) complex, MnM

Fig 19: N,N^/Bis (2-hydroxylbenzylidene,  1,4-phenylenediimine)-Mo(VIII) complex, Mo₂M

Fig 20; N,N^/Bis (4-dimethylaminobenzylidene,  1,4-phenylenediimine) (N)

Fig 21: N,N^/Bis( 4-dimethylaminobenzylidene,  1,4-phenylenediimine)-Co(II) complexes, CoN

Fig 22: N,N^/Bis(4-dimethylaminobenzylidene,  1,4-phenylenediimine)-Mn(VII) complexes, MnN

Fig 23: N,N^/Bis (4-dimethylaminobenzylidene,  1,4-phenylenediimine-Mo(VII) complexes, Mo₂N

CHAPTER ONE

INTRODUCTION

1.1 SCHIFF BASES

Schiff bases are condensation products of primary amines with carbonyl compounds and they were first reported by Schiff (Cimerman et. al., 2000). 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. 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 (Singh et. al., 1975, Perry et. al., 1988, Elmali et. al., 2000, Patel et. al., 1999, Valcarcel et. al., 1994, Spichiger et. al., 1998,Lawrence et. al., 1976)showed that the presence of a lone pair of electrons in an sp2 hybridized orbital of nitrogen atom of the azomethine group is of considerable chemical and biological importance.

A Schiff base is a nitrogen analog of an aldehyde or ketone in which the C=O group is replaced by C=N-R group. It is usually formed by condensation of an aldehyde or ketone with a primary amine.The formation of a schiff base from an aldehydes or ketone is a reversible reaction and generally takes place under acid or base catalysis, or upon heating.

Schiff bases are generally bidentate (1), tridentate (2), tetradentate (3) or polydentate (4) ligands capable of forming very stable complexes with transition metals. They can only act as coordinating ligands if they bear a functional group, usually the hydroxyl, sufficiently near the site of condensation in such a way that a five or six membered ring can be formed when reacting with a metal ion.

Schiff bases derived from aromatic amines and aromatic aldehydes have a wide variety of applications in many fields, eg., biological, inorganic and analytical chemistry (Cimerman et. al.,2000 and Elmali et. al.,2000). Applications of many new analytical devices require the presence of organic reagents as essential compounds of the measuring system.

1.2 SCHIFF BASE METAL COMPLEXES

Transition metal complexes with Schiff bases have expanded enormously and embraced wide and diversified subjects comprising vast areas of organometallic compounds and various aspects of bio-coordination chemistry (Anacona  et. al., 1999). The design and synthesis of symmetrical Schiff bases derived from the 1:2 step wise condensation of carbonyl compounds, with alkyl or aryl diamines and a wide range of aldehyde or ketone functionalities, as well as their metal(II) complexes have been of interest due to their preparative accessibility, structural variability and tunable electronic properties allowing to carry out systematic reactivity studies based ancillary ligand modifications. In recent years much effort has been put in synthesis and characterization of mono- and bi-nuclear transition metal complexes (Trujillo et. al., 2008).Schiff bases are used in optical and electrochemical sensors, as well as in various chromatographic methods to enable detection of enhanced selectivity and sensitivity (Valcared et. al., 1994, spichiger et. al., 1998,Lawerence et. al., 1998). Among the organic reagents actually used, Schiff bases possess excellent characteristics, structural similarities with natural biological substances, relatively simple preparation procedures and the synthetic flexibility that enables design of suitable structural properties (Patai 1970).