This document summarizes the synthesis and characterization of new Schiff base ligands and their metal complexes. It describes the synthesis of five Schiff base ligands derived from substituted benzaldehydes and anilines using the reflux method. Copper and nickel complexes were formed from two of the ligands. The ligands and complexes were characterized using infrared spectroscopy, which showed shifts in the C=N and C-O peaks upon complexation. The research aims to synthesize new Schiff bases and their Cu2+ and Ni2+ complexes and characterize them using IR spectroscopy to determine the coordination sites.

1. HAMED, Sulaimon Adekunle
MATRIC NO:139073005
SUPERVISOR: DR. I. A. OLASUPO
BY
1
Synthesis and Characterization of New
Schiff base Ligands derived from
substituted and benzylated benzaldehyde
and their Metal Complexes

2. Presentation Outline
Introduction
Review of literature
Aim and Objectives
Methodology
Results and Discussion
Conclusion
2

3. Introduction
A Schiff base is a compound having a carbon-
nitrogen double bond (C=N).
They are products obtained from the
condensation of primary amines and carbonyl
compounds (Ashraf et al., 2011).
R1, R2, and/or R3 = Alkyl or Aryl
Ashraf M., Wajid A., Mahmood K., Maah M., and Yusuff I. (2011). Spectra investigation of
the Activities of Amino Substituted Bases. Oriental Journal of Chemistry. 27(2): 363-372. 3

4. 4
Mechanisms of Schiff base formation
The mechanism of Schiff base synthetic reaction
involves a nucleophilic attack of the primary
amine through its lone pair of electrons on the
electrophilic carbonyl carbon.

5. 5
Schiff base Synthesis
Four common methods that vary in
reaction time, product, and percentage yield
have been reported for the synthesis of Schiff
bases. These methods include:
• Microwave method
• Room temperature method
• Grindstone method
• Reflux method

6. Applications of Schiff bases
Schiff bases derived from aromatic and
aliphatic amines and aldehydes show a lot of
biological importance as well as wide range of
applications (Kumar et al., 2009). These
includes:
Application in medicine and pharmacy
Application in synthesis and chemical analysis
Agricultural applications
Application in coordination chemistry
Kumar, S., Dhar, D. N., and Saxena, P. N. (2009). Applications of metal complexes of
Schiff bases-a review. Journal of scientific and industrial research. 68(3): 181 - 187. 6

7. Schiff base metal complexes
• Transition metals are known to form Schiff base
complexes.
• It is known that the existence of metal ions
bonded to biologically active compounds may
enhance their activities (Song et al., 2005).
• A typical example of a salicylaldehyde diimine
Schiff base complex is shown below:
7
Song, X.Z., Wang,Y., Wang, Z., Zhang, Chen, C. (2005). Chemistry Abstract. 143: 367252.

8. Review of Literature
Fasina et al., (2012) synthesized and characterized a
Schiff base derived from o-phenylenediamine and 5-
bromosalicylaldehyde and of its metal complexes
The IR spectrum absorption bands of the ligand at
1602(C=N) and 1270cm-1
(C-O) appeared at lower
frequency.
8
Fasina, T. M., Ogundele, F. N., Ejiah, and Dueke-Eze, C. U. (2012). Biological Activity of copper(II), cobalt(II), and nickel(II) complexes
of Schiff base derived from o-phenylenediamine and 5-bromosalicylaldehyde. International Journal of Biological Chemistry. 6(1): 24-30.

9. 9
• Sobola et al., (2014) synthesized and
characterized copper(II) complexes of some ortho-
substituted aniline Schiff bases.
• The imine (C=N) functional group shifted from
1612-1615cm-1
to 1602-1606cm-1
• C-O functional group shifted from 1280–1273cm-1
to 1336–1325cm-1
.
Sobola, A. O., Watkins, G. M., & Van Brecht, B. (2014). Synthesis, characterization and antimicrobial activity of copper
(II) complexes of some ortho-substituted aniline Schiff bases; crystal structure of bis (2-methoxy-6-imino) methylphenol
copper (II) complex. South African Journal of Chemistry. 67: 45-51.

10. 10
• Mounika et al., (2010) reported the synthesis and
characterization of a Schiff base derived from 3-Ethoxy
Salicylaldehyde with 2-Amino Benzoic acid and their
complexes
•The imine (C=N) functional group shifted from
1622cm-1
to 1592-1556cm-1
)
• C=O functional group shifted from 1692cm-1
to 1654–
1586cm-1
.
Mounika, K., Pragathi, A., and Gyanakumari, C. (2010). Synthesis characterization and biological activity of a Schiff
base derived from 3-ethoxy salicylaldehyde and 2-amino benzoic acid and its transition metal complexes. Journal of
Scientific Research. 2(3): 513 -528.

11. Aim and Objectives
The aim of this research work is to synthesize and carry
out physico-chemical characterization of new Schiff
base ligands and their complexes.
Specifically, the research objectives are:
To synthesize new Schiff base ligands derived from
substituted and benzylated benzaldehyde and aniline.
To form Cu2+
and Ni2+
complexes of 2-(benzyloxy)-5-
bromobenzaladehyde and 3-chlorodimethyl-4-
((phenylimino)methyl)aniline
To characterize the synthesized Schiff bases and their
respective metal complexes using Infrared (IR)
technique 11

12. Methodology
The reflux method was adopted in the synthesis of the
Schiff bases and the formation of the metal complexes
Synthesis of the Schiff base ligands (L1, L2 &L3)
L1-L3
L1: X = H, Y = OEt
L2: X = H, Y = OMe
L3: X= Br, Y= H
12

13. Synthesis of Schiff base Ligand, L4
Synthesis of Schiff base Ligand, L5
13

14. 14
Formation of Cu(II) and Ni(II) complexes of
L3 and L4
• All the metal-ligand complexes (ML) were
formed by reaction of hydrated metal
salts(CuCl2.2H2O, NiCl2.6H2O) and the Schiff
base ligands in a molar ratio of (1:1) under
reflux for 4 hours.

15. Result and Discussion
Physical properties of the Schiff base
15
Ligand Molecular
weight (g)
Texture Colour Melting
point(0
C)
Yield
(%)
L1 331 Oil Deep
orange
_ 92.2
L2 317 Oil Deep
orange
_ 95.7
L3 366 Crystal Yellow 88-89 56.8
L4 258 Crystal Yellow 140-142 91.08
L5 276 Crystal Orange 103-104 80.0

16. 16
ComplexColour Texture Melting
point
Yield
(g)
CuL3 Black Powdery 156-157 0.22
NiL3 Light
Yellow
Crystalline 131-132 0.19
CuL4 Black Powdery 188-189 0.08
NiL4 Brown Powdery >300 0.33
• Physical properties of Cu and Ni complexes of L3 and L4

17. 17
Compoundv(C=N)cm-1
vsp3
(C-H) cm-1
vsp2
(C-H)cm-1
v(C-O)cm-1
L1 1617 2978 - 1060
L2 1618 2934 3028 1068
L3 1616 2967 - 1068
L4 1577 2895 3054 -
L5 1611 - - 1273
FTIR spectroscopy of synthesized Schiff bases

18. 18
Compound v(C=N)cm-1
v(C-O)cm-1
v(C-N)cm-1
L3 1616 1068 -
CuL3 1589 1065 -
NiL3 1573 1068 -
L4 1577 - 1277
CuL4 1587 - 1254
NiL4 1583 - 1217
FTIR spectroscopy of L3, L4, CuL3, NiL3, CuL4 and NiL4

19. Conclusion
The synthesis of five Schiff base ligands(L1-L5)
was achieved
The synthesis of Ni2+
and Cu2+
of L3 and L4 was
also achieved
The IR spectra of L3 shows the coordination was
via the imine nitrogen (C=N) and the ether oxygen
(C-O) to the Cu2+
whereas, in Ni2+
coordination was
via the C=N only.
In L4, the coordination site for both the Cu2+
and
Ni2+
ions was via the imine and amine nitrogen i.e.
(C=N) and (C-N) 19

20. 20
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