Prepared by Tesfaye Tebeka 1 APPLIED SCIENCE FACULTY APPLIED CHEMISTRY DEPARTMENT STUDENT PROJECT ON:- SYNTHESIS AND CHARACTERIZATION OF SCHIFF BASE METAL COMPLEX DERIVED FROM AMINO ACID AND NINHYDRIN ADVISOR: ATO BELETE YILMA(M.Sc) BY TESFAYE TEBEKA in Partial Fulfillment of the Requirements for the of Bachelor of Degree in applied chemistry. JUNE, 2009
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SYNTHESIS AND CHARACTERIZATION OF SCHIFF BASE METAL COMPLEX
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Prepared by Tesfaye Tebeka 1
APPLIED SCIENCE FACULTY APPLIED CHEMISTRY DEPARTMENT
STUDENT PROJECT ON:-
SYNTHESIS AND CHARACTERIZATION OF SCHIFF BASE META L
COMPLEX DERIVED FROM AMINO ACID AND NINHYDRIN
ADVISOR: ATO BELETE YILMA(M.Sc)
BY TESFAYE TEBEKA in Partial Fulfillment of the Requirements for the of Bachelor of Degree in applied chemistry. JUNE, 2009
Prepared by Tesfaye Tebeka 2
TABLE OF CONTENT CONTENT PAGE Abbreviation i Acknowledgement ii Abstract iii CHAPTER ONE ............................................................................................................... 8 1 INTRODUCTION .......................................................................................................... 8
1.1 Synthesis of Schiff base metal complexes.............................................................. 8 CHAPTER TWO ............................................................................................................ 11 Literature review ............................................................................................................ 11 2. Schiff bases components under investigation........................................................... 11
2.2 1 REACTIVITY ................................................................................................ 15 2.2.2 The ninhydrin reaction with amino acids and their mechanism............... 15 2.2.3 Mechanism reaction of ninhydrin and amino acids ................................... 17
2.3 Schiff Bases............................................................................................................ 18 2.3.1 Biological Important Of Schiff Base............................................................ 19 2.3.2 Catalytic applications of Schiff bases........................................................... 20
2.4 The chemistry of metal ions................................................................................. 21 2. 4.1 Cobalt II) complexes..................................................................................... 22 2.4.2 Nickel (11) complexes.................................................................................... 23
2.5 Objectives and the scope of the present studies................................................. 24 2.5.1General objective............................................................................................ 24 2.5.2 Specific objectives.......................................................................................... 24
CHAPTER THREE .......................................................................................................... 25 3 Materials and methodology....................................................................................... 25
3.1 Apparatus and instruments............................................................................... 25 3.2 General procedures............................................................................................... 25
3.2.1 Synthesis of Schiff base derived from cystein with Ninhydrin ............... 25 3.2.2 Synthesis of Ruhmann’s purple.................................................................... 25 3.2.3 Synthesis of Schiff base metal complex........................................................ 26 3.2.4 Synthesis of Ruhmann’spurple metal complexes...................................... 26 3.2.5 Ruhmann’s purple metal complex of lysine and ninhydrin ....................... 26
are intense than those of the octahedral ones[11].
In octahedral cobalt (II) complexes 4T1g and 2A1g are the spin free and spin paired
ground state respectively. For high octahedral geometry, a band near 8000-1000 Cm-1 can
be assigned to 4T1g 4T2g transition A multiple band observe around 2000 cm -1 is
attributed . 4T1g 4T2g transition
The 4T1g 2Eg transition is interesting in that it represents configurationally t2g5
eg2 t2g6eg1 and should be brood and it maximum should shift to lower frequencies
Prepared by Tesfaye Tebeka 23
with decreasing temperature, since its energy curve plotted against of has a larger
negative slope than the curve for the ground tern [12]
Some other transitions of CO (II) are 4T1g (F) 4T1g 4T2g, 4T1g 2Eg, 4T1g 4A2g (F) and 4T1g 4T1g (P) which are observed at 8000-9000cm-1 11 000cm-1,1600-
18000cm -1 And 2000 -21000cm-1 respectively.
Tetrahedral complexes of Co (II) with 4A2 ground state are expected to have three
transitions. 4A2 4T2,
4T2 4T1 (F) and 4A2
4T2 (P) low spin square planar
complexes exhibit a narrow band near 8500cm-1 and a stronger bounder band near
20000cm -1.
2.4.2 Nickel (11) complexes
Octahedral Ni (II) complexes with 3A2g ground state are expected to have three spin
The completeness of the reaction was tested using thin layer chromatography precoated
with silica gel plates were used for stationary phase and ethanol was used as a mobile
phase. The completeness of the reaction was determined by the appearance of single spot
(blue or violet –blue color that of the reaction between amino acid and ninhydrin.)
3.3.2 Solubility
The Solubility of the complexes was cheeked by various organic solvents: Diethyl ether,
acetone, and methanol, chloroform (CHCl3) Benzene, ethanol by stirring a small amount
of the complex a test tubes
3.3.3 Melting (decomposition points)
The melting point (decomposition points) was determined by placing a finely powdered
sample in a capillary tube and heating by melting point apparatus.
3.3.4 Conductivity measurements
The conductivity measurements were performed using conductometres in acetone, aprotic
solvent having 10-3 M at room temperature (Philip Harris Conductometres)
3.3.5 Electronic absorption spectra
Electronic absorption spectra in the UV- Visible range were recorded in 200-1100nm
using acetone as solvent (SPECTRONIC GENESEYC 2PC)
3.3.6 Flame atomic absorption spectroscopy
Metal complex was pre pared by heating the complex in 5ml of HNO3 and 10ml of
perchloric acid. For sample analysis four series of working standard metal solution were
prepared by dilution of the metal stocks solution with water and reading the absorbance
(Buck Scientific)
Prepared by Tesfaye Tebeka 28
CHAPTER FOUR
4 RESULTS
The composition of the complexes are indicated in each case by metal and (R1, R2, R3) or
s or a combination in which R1= Ruhmann’s purple derived from Iso-leucine and
ninhydrin, S = Schiff base of cystein and ninhydrin
R2 = Ruhmann’s purple of ninhydrin and glutamine, R3 = Ruhmann’s purple of Ninhydrin
and lysine .The compositions are judged from the analytical and spectral data which will
be presented and discussed in the following sections
Table-1 melting point of complexes
Complex Color Appearance Yield (%) Mp (dec.t )0c
CoS Shiny white crystalline 50.13 330
NiS Shiny white crystalline 20.9 330
CoR1 red powder 63.4 236
NiR1 Brick read powder 72.4 220
CoR2 red powder 45.5 229
NniR2 Brick read powder 54.3 241
CoR3 Grey powder 79.24 235-244
NiR3 Grey powder 77.6 238-243
Where S is Schiff base
R1=Ruhmann’s purple derived from Iso-leucine and ninhydrin
R2= Ruhmann’s purple of glutamine and ninhydrin
R3=Ruhmann’s purple of lysine and ninhydrin
Solubility test of metal complex Solubility of complexes was checked in acetone, chloroform, ethanol solvents by shaking small amount of the complex in test tube.
Prepared by Tesfaye Tebeka 29
Table- 2 Soluble test of complex indifferent solvent Complex Acetone CHCL3 CH3OH COS X X X NIS X X X CoR1 X R2Ni COR2 X NiR2 X COR3 X NiR3 X Where s- Schiff derived form cystein ninhydrin
R1= Ruhmann’s purple of Iso-leucine and ninhydrin
R2= Ruhmann’s purple of glutamine and ninhydrin
R3=Ruhmann’s purple lysine and Ninhydrin
- Soluble
X – Insoluble
Table -3 – molar conductance values Ruhmann’s purple metal complex.
The metal complexes isolation from different amino acids namely: Iso-leucine,lysine
,cystein and glutamine are all distinctly colored , stable to atmospheric condition and are
soluble in organic solvent like methanol and ethanol but only partially soluble in solvents
like chloroform and insoluble in petroleum ether
From table 1 the Schiff base metal complexes of Ni (II) Co (II) that is derived from
cystein and ninhydrin neither melt nor decompose up to 330 oc, while the ruhmann’s
purple metal complexes of Ni (II) and Co (II) that are derived from lysine and Ninhydrin
start melting at a temperature around 236 degree centigrade and also complex of Ni (II)
derived from iso-lecine and ninhydrin which melts at lower temperature around 220 oc
Generally the two ligands prepared are Schiff base ligand which is synthesized from
cystein and ninhydrin and Ruhmann’s purple ligands those synthesized from ninhydrin
and iso-lecine sine and glutamine amino acids .
4.2.1 Molar conductance studies
The molar conductance values were calculated from conductivity measurements in
acetone( aprotic non-polar solvent ).The molar conductance values of the products
obtained from all complexes are very small in the range of 17.6 – 120 Ω-1 cm2mol -1
this shows that they are non_electrolyte nature.
From the above table 3 the conductivity of the metal complexes of ruhmann’s purple is
very low indicates that, these complexes are non- electrolyte and this support,
their neutral nature of the complex and the obtained value suggests that in the
coordination sphere their is no anions present outside
4.2.2 UV-Visible spectroscopic analysis The spectra of transition metal complexes depends on the transition of unpaired electrons
from the ground state to an excited state most of the transition metal complexes are
colored ,a color is observed due to d-d transition in the visible region
The ninhydrin and the amino acid ( Iso-leucin, glutamine , lysine ) from a deep blue
purple colored compound which maximally absorbs at 2469.36 and 17543.36cm-1
The compounds formed via four steps condensation, decarboxylation, hydrolysis and
further condensation.
Prepared by Tesfaye Tebeka 33
The electronic specter data of the metal complexes are given in table 4. For CoR3 and
NiR3 complex, the spectral data displays two bands at 17543.38, 20408.16 and 1785.14,
20202.02cm-1. The first band is due to charge transfer.
Avery strong at 2000cm-1Is assigned of π to π* is due to a molecule π bonds with C= O
group and n to π* transition is due to a compound containing an azomethine group (-
CH=N-) which absorbs between 17391.5 -24691.34cm-1
The band between 24691.34 17391.5cm-1Is also associated with the transition of n to π*
this is due to d-d transition of the complex in the region
The literature data reveals that the band around 32000cm-1 and are assigned to the n to π *
transition of the carbonyl group
The electronic spectrum of the metal complexes of Co (II) and Ni (II) complexes show
common bands at 18518.5cm-1 And 20833.34cm-1 which are the characteristics band of
exocyclic azomethine chromophore in the coordination, which in the free state absorbs at
24691.36cm-1 In Ruhmann’s.
The complex prefers a low spin configuration, which is exhibited due to the presence
strong field ligands; such as the azomethine and carbon groups. The Ni (II) complex
exhibited an octahedral geometry with two unpaired electrons.
The valve of magnetic moment obtained corresponds to the literature valve, indicating
the coordination of the metal in an octahedral geometry and the complexes of Co (II) of
the metal in an octahedral geometry with a low spin configuration.
In octahedral cobalt (II) complexes 4T1g and 2A1g are the spin free and spin paired
ground state respectively. For high octahedral geometry, a band near 8000-1000 Cm-1 can
be assigned to 4T1g 4T2g transition A multiple band observe around 2000 cm -1 is
attributed . 4T1g 4T2g transition
4.2.3 Atomic absorption spectroscopy
The determination of Ni (II) and CO (II) concentration.
0.04gram of metal complex of CO (II) and Ni (O) were digesting in 5ml nitric acid and
10ml of perchloricacid. Four serious of Working standard having 0.5,1,2 and 4 ppm were
prepared by appropriate dilution of metal stock solution with distilled water. The
calibration graph (concentration Vs absorbance) was drown in the appendix part.
Prepared by Tesfaye Tebeka 34
From this calibration curve, the concentration of the metal ions in the complex are
determined having 93.12% Ni (II) and 90.36% Co (II) were found by composition
Prepared by Tesfaye Tebeka 35
5 Conclusions
Metal complexes such as Co(II) and N (II) were synthesized by using the Schiff base and
Ruhmann’s purple formed from by the condensation of ninhydrin with cystein and
ninhydrin with three amino acids like; Iso-Leucine, Glutamine and lysine respectively.
Even if there is an absence of spectrometer instruments such as; IR, NMR,MS that can
provide substantial evidence for determination of structure of the complexes which is
formed from Ninhydrin - amino acids reactions with transition metals such as Co(II)
Ni(II) will be proposed. The following structure will be drawn based on the central view
of the nature of the ligand_metal complex
I) The proposed structure of Ruhmann’s purple with Ni(II) and Co(II)
Prepared by Tesfaye Tebeka 36
II The proposed structure for Schiff base with Ni (II) and Co(II).
The complexes formed with Co (II) and Ni (II) is powders in nature and obtained in good
yield. As can be seen from the result data the complexes are distinctly colored; they have
different percentage yields and appearances. The elemental analysis data of the
complexes are given in tables. The analytical data matches with 1:2 metals to Ruhmann’s
purple and1:1schiff base complexes in an octahedral geometry for the complexes of Ni
(II) and Co (II). The molar conductance (Λ m) values were calculated from conductivity measurements of
the solvent (Acetone) and a metal complex in acetone. The molar conductance values of
the products obtained from all the complexes are very small, in the range of 17.6-120Ω-1
cm-2 mol-1. These show their non-electrolyte nature.
Ninhydrin and Iso-Leucine, glutamine or lysine form a deep blue purple colored
compound known as the Ruhmann’s purple, which maximally absorbs at 20833.34 cm-1
The compound is formed via four steps; condensation, decarboxylation, hydrolysis and
further condensation. The electronic spectral data of the metal complexes are given in
table 4. The bands observed at 2000cm-1 and 21691.34 cm-1 in the complexes are
assigned to the π→π * transition of the benzene moiety. The electronic spectrum of the Co (II) & Ni (II) complexes show common bands around 18518.5cm-1 and 20833.34cm-1
which are characteristics bands of the exocyclic azomethine chromopher.
Prepared by Tesfaye Tebeka 37
6 Recommendations Our project work concerned with preparation, structural determination & characterization
of Schiff base & Ruhmann’s purple which are the condensed from the reaction of
ninhydrin & amino acids and then complexing this residue with transition metals such
as cobalt & nickel complexes. While we doing our experimental analysis we had been
faced the problem such as lack of IR, H-NMR and C-NMR to know the complete
structure of ligands and complexes. And we were also faced lack of chemicals like
DMSO & DMF to dissolve our complexes. So the structure of the complexes & ligands
was proposed using only UV-VIS spectroscopy & from the theoretical back ground. By
taking into consideration these mentioned and other related problems the concerned
body shall give and provide solution.
Prepared by Tesfaye Tebeka 38
7 REFERENCES 1 FAlbert cotton Advanced Inorganic chemistry, 6th edition. 2. Belete Yilma June 2004 , synthesize and characterization of metal complexes, Office
Research and graduate programs, Addis Ababa University.
3. Skoog Holler BIEMAN, principles of instrumental Analysis, 5th edition.
4 Namsun Wang1996, Amino acid Assay by Ninhydrin colorimetric method,
7. Marry, R, KHarpers1996, Biochemisteary, 24th edition; John wiler New York. 8. J. Lewis and R.G Wilk, 1967, Modern coordination chemistry, principles and methods,
New York.
9 J. Lewis and R.G Wilk, 1967, Modern coordination chemistry, principles and methods,
New York.
10. J. Chemsol Dalton, 2001 Trans, 2850-2857.
11 .Bodie Douglas, Darla mc Daniel, John Alexander, 1995 concept and models of
inorganic chemistry, 3rd edition, USA.
12. J.E. Huheer, EA keiter and R.L Keiter, inorganic chemistry, principle of structure
and Reactivity, 4th edition Harper Collins college publisher USA.
Prepared by Tesfaye Tebeka 39
8 Appendixes Calculation of the Results Results obtained from Ruhmann’s purple (R1) and ninhydrin with cobalt (II) taken for simplicity 1.Determination of molar conductivity having 10-3M preparation of 10-3M
mole = mass ⁄molecular weight = 193.666
033.0−glmo
=4.95*10-5mol
Conc. = mol ⁄Vol. of soln , where Volume of Solvent (acetone) =50ml
C=λ3
5
10*50
10*95.4−
−
= 0.99*10-3Mol≈*10-3 mollit
M(Ω-1cm2mol-1)=C
k1000
Where M -Molar conductivity K -specific conductance C - Concentration
K= bRR acetone
− 11
where b -call constant=∆λ
R- Resistance
K= 534.8008.0*0075.0
0075.0008.0
008.0
1
0075.0
1 ∩=−=−
M (Ω-1Cm2Mol-1) = 1000*imol
s
λΙ
/10
34.83− ,
=1000*333
9
/10*/10
10*34.8−−−
−
cmititmol λλ where S-Siemens ands=
Ω1
= 10*33
9
/10*
10*34.8
CmlitMol −
−
= CmMol
CmSS 333 10*10*34.8 −
M( )12 01−−Ω ηCm =8.34SCm2η01-1 Determination of concentration of standard sample from Absorbance Measurements 2. Determination concentration of Ruhmann’s (R1) Ni Complex First From the calibration curve the equation must be calculated Y= mx+ b m=Slope x=conc. b- Intercept y =Absorbance of sample
Prepared by Tesfaye Tebeka 40
Slope (m) 24
11.022.0
−−=
∆∆
x
Y =0.055
The equation of calibration curve become Y=0.055x (The graph pass through origin) Then from the equation, the concentration of R1 Ni calculated as: 0.041=0.055x
X=055.0
041.0
x=0.745ppm, Determination of concentration of Ruhmann’s (R1) Co (II) complex First From the calibration the equation obtained is Y=Mx+b
Slope =24
184.035.0
−−=
∆∆
x
Y=0.083
The equation of calibration curve become, Y=0.083x (pass through the origin) is the equation calibration curve of R1 Co complex calculated as follow. Y=0.083x, where Y-is the absorbance of R1 Co complex 0.086= 0.083x
X=083.0
060.0=0.722ppm Concentration of R1Co
3. Determine the percentage of the metals in the complexes. From the calibration graph (concentration versus absorbance), the percentage of metals calculated as follow.
M (II) % =Absorbance (A1ppm)* 1000
100*
sampleoftheMass
toedVolumedist
Known Data Concentration of Ni Ri= 0.745ppm Volume diluted to =50ml Mass of the sample (R1Ni) =0.049m
Ni (II) %= 0.745ppm*1000
100*
04.0
50
gm
mλ
Ni (II) % =93.125% • Similarly the percentage of Co(II) in Ruhmann’s (R1) Co Complex Was
calculated as
Co (II) % = Absorbance (∆ppm) *1000
100*
sampletheofmass
todillutedVolume
Prepared by Tesfaye Tebeka 41
Known data : Concentration of R1 Co Calculated from absorbance = 0.722ppm Volume diluted to=50ml Mass of the sample (R1Co) = 0.04 gm
Co (II) %= 0.722ppm=1000
100*
04.0
50
gm
ml
Co (II) %=90.36% 4. Percentage yield on of the complexes. The percentage yield of the complexes are determined as
% yield =yieldltheoretica
yieldCtual∆*100
For example the percentage of Ni Ruhmann’s purple complex A Y of complex=0.49M
Prepared by Tesfaye Tebeka 42
T.Y of R1Ni can obtained from the limiting Reaction
C
O
O
N
O
O-
+M(II)
O
O-
O-
O
-O
N
2
M
O-
O
N
-O
O
0.5g
0.8g
From this reaction 2:1moleratio of Ruhmann's purple metal complexthe following result was obtained
Prepared by Tesfaye Tebeka 43
From this rxn 2:1 mol ration
Ruhmann’s purple with the metal
gm
m
η60
59.0
//71.182
88.0
mog
0.82mmol 4.3mmol The limiting reactant is the Ruhmann’s purple
mol
X
mol
m
/719.6666059
59.0 =
X= m559.0604
)73.666(5.0 =
%Yield= %72100*559.0
49.0100*
/
. ==m
m
YT
YA
Prepared by Tesfaye Tebeka 44
Graph of calibration curve
Calibration curve of Ni
y = 0.0553x
R2 = 0.9986
0
0.05
0.1
0.15
0.2
0.25
0 2 4 6
Concentration
Abs
orba
nce
Where; concentration in ppm Absorbance in nm Fig 1; calibration curve of Ni
Prepared by Tesfaye Tebeka 45
Calibration curve of Co
y = 0.0553x
R2 = 0.9986
0
0.05
0.1
0.15
0.2
0.25
0 2 4 6
Concentration
Abs
orba
nce
Where ; Concentration in ppm and Absorbance in nm Fig 2; calibration curve of Co