HAMED, Sulaimon Adekunle

MATRIC NO:139073005

SUPERVISOR: DR. I. A. OLASUPO

BY

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Synthesis and Characterization of New Schiff base Ligands derived from

substituted and benzylated benzaldehyde and their Metal Complexes

Presentation Outline

IntroductionReview of literatureAim and ObjectivesMethodologyResults and DiscussionConclusion

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IntroductionA 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

C N

R3R1

R2

4

Mechanisms of Schiff base formationThe 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.

R NH2R' C

O

R'' R N C R''

R'

..

O

H

H

R N C R''

R'

OH

H

CarbinolaminePrimary amine Carbonyl

R'' C

OH

R'

N

H+R'' C

OH2

R'

N

R N C

R'

R''

HRHR

H2O

Schiff base

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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

Applications of Schiff basesSchiff 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 pharmacyApplication in synthesis and chemical analysisAgricultural applicationsApplication 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

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:

7Song, X.Z., Wang,Y., Wang, Z., Zhang, Chen, C. (2005). Chemistry Abstract. 143: 367252.

N N

OO

M

Review of LiteratureFasina 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.

8Fasina, 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.

Br

OH

O+ NH2

NH2

-H2 O

Ref lux, 700C, 4hrs

Br

OH

N

N

Br

OH

2,2'-(1,2-phenylenebis(azanylylidene))bis(methanylylidene))bis(4-bromophenol)

5-bromosalicylaldehyde

o-phenylenediamine

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• 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.

R1

OH

H

O

+

NH2

R

R1

OH

N

R

EtOH

Reflux

R=CH3 or H

R= Cl; Br; CH3 or OCH3

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• 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.

C2H5O OH

O

H+

NH2

COOH

Ethanol

Reflux

C2H5O

OH

N

OH

O

3-ethoxy salicylaldehyde 2-aminobenzoic acid Ligand

Aim and ObjectivesThe 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

MethodologyThe reflux method was adopted in the synthesis of the Schiff bases and the formation of the metal complexesSynthesis of the Schiff base ligands (L1, L2 &L3)

L1-L3

L1: X = H, Y = OEtL2: X = H, Y = OMeL3: X= Br, Y= H

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CHO

Y

O +

NH2

O

Y

HC N

Ethanol

Ref lux, 700C

X X

Synthesis of Schiff base Ligand, L4

Synthesis of Schiff base Ligand, L5

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H2NCHO

N

Cl

EtOH

Reflux, 700C

Cl

CH=N

N

2-chloro-4-(dimethylamino)benzaldehyde

aniline

3-chloro-N ,N-dimethyl-4-((phenylimino)methyl)aniline

Br CHO

OH

+

H2N BrHC

OH

N

ethanol

ref lux, 700C

5-bromosalicylaldehyde Aniline 4-bromo-2-(phenylimino)methyl phenol

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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.

Result and DiscussionPhysical properties of the Schiff base

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Ligand Molecular

weight (g)

Texture Colour Melting

point(0C)

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

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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

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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

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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

ConclusionThe synthesis of five Schiff base ligands(L1-L5)

was achievedThe synthesis of Ni2+ and Cu2+ of L3 and L4 was

also achievedThe 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

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THANKS FOR LISTENING