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Synthesis, Characterization and Catalytic activity of water Soluble
Cysteine Cu (II) and Ni(II) metal complexes
Aarpita Shrivastav Imtiyaz Rasool Parrey and Athar Adil Hashmi*
Department of Chemistry, Jamia Millia Islamia (Central University),
New Delhi-110025 (India)
*Corresponds author E-mail:[email protected]
ABSTRACT:
The Complexes of Cu(II) and Co(II) with amino acid cysteine were synthesized and Characterized by elemental
analysis, Uv-Visible, IR, NMR,SEM ,TGA,DSC,XRD. In these complexes the amino acid coordinated to 1:2 with
metal and they exhibits octahedral geometry. The catalytic activity of these complexes was studied in olefins using
eco-friendly nontoxic molecular oxygen as oxidant.
KEYWORDS: Amino acid, Metal complexes, cysteine, Molecular Oxygen
1. Introduction:
Amino acids are molecules containing an amine group, a carboxylic acid group and a side
chain that varies between different amino acids. These molecules are particularly important in
biochemistry, where this term refers to α-amino acids with the general formula
H2NCHRCOOH, where R is an organic substituent. Amino acids containing uncharged amino
groups, at physiological pH values, may also undergo Schiff base formation (i.e. condensation
with aldehydes), which presents another potential mechanism for metal complexes. Lysine is
an α-amino acid with the chemical formula HO2CCH(NH2)(CH2)4NH2.This amino acid is an
essential amino acid, which means that humans cannot synthesize it Lysine is a base, as are
arginine and histidine. DL-2,3-Diaminopropionic acid (DAP) is acommon plant metabolite,
which may occurs free but also as the β-acetyl- or β-N-oxalylderivatives in some plants[1-5].
Condensation Reactions of amino acids
Copper:
Copper plays an important role in bone formation in skin pigment synthesis, eyes, hair, wound
healing, participates in the synthesis of red blood cells, is important for psycho-emotional
balance and influence the function of glands with internal secretion. The body that represents
more accurately the concentration of copper in the body is the liver; as a result, some authors
give greater importance than other methods dosage hepatitis to assess the state of deficiency, or
toxicity sufficient. Stored mainly in parenchymal cells, copper may occur in greater quantity
and Kupffer cells in case of poisoning.
Biological role of Copper amino acid
In biological systems, copper is found in the form of Cu (II), rarely Cu (I) in deoxihemocianine,
and rarely Cu (III). Function of copper in biological systems can be found in redox reactions
associated with reducing. O2 to water, O2 transfer to the substrate, respectively mono oxigen
insert oxygenase to transform phenol to diphenols and insertion dioxigen - dioxygenase, the
transformation of catechol to a quinone. Copper ion complexation with various α-amino acids
is similar, except that histidine formation of connections to the nitrogen atoms and oxygen
atoms aminic group of carboxylate moiety, respectively glicin-NNOO coordination type [6].
Cobalt
Cobalt metal is relatively less common in nature plays a very important technical importance is
due to its value as a component of hard alloys (cermets) and steliţior type casting alloys and
special alloys with specific properties, magnetic, refractory and antacids Cobalt is a transition
metal of Group IB, is the 27th element of the periodic table, atomic mass 58.933 amu, Density:
8.90 g/cm3 Melting point: 14950C 29270C boiling point has electronic configuration
Biological role of Copper
Cobalt is an essential trace mineral whose biological activity is manifested through its role in
the series of coenzymes and vitamin B12. Vitamin B12 is important in the hematopoetic
indispensable in the synthesis of hemoglobin, is also anemic and antipernicios factor. Cobalt
absence of living organisms might result in severe nervous system dysfunction, anemia and
unnatural developments in cell growth. To treat these symptoms, it takes the whole molecule
and not just the Cobalt.
Biological role of Copper amino acid
Recent studies on the formation of complexes of cobalt (II) with different ratio amino acids
such as cysteine and methionine, due to their bacteriostatic action [7]. Also, the literature
presents a series of studies on the action of divalent cobalt complexes with lysine, arginine,
histidine and serine on HSV-1 virus [8]. Complexes with arginine and histidine had no effect on
virus replication but inhibits virus replication complex with lysine and serine at the very best
inhibitory effect (90%)
1.1 Experimental:
Amino acid Cysteine 5gm were treated with 2.5gm of transition metal in presence of ethanol at
temperature 500C at 24 hr. greenish and a light yellow color indicates the formation of copper
and nickel amino acid complex is formed. The power crystals were cooled filtered a then dried.
Yield 1.2gm
O
2
O
N
OH
Ethanol
MX2.XH2O
NH2
50oC,5hr
SH
OH
HS
M
HO
O
N
SH
2. discussion Result and discussion
2.1 FT-IR Spectrum of Cysteine and its Complexes:
The vibrational for cysteine modes due to carboxylate and amino groups was found to exist at
1680-1540 cm-l (COO¯), 3150–3000 cm-l (–NH2). Further to this 1410 cm-l (weak) for
symmetric stretching of COO¯ and 660 cm-l for COO¯ (deformation). The peak at 1660–1610
cm-l and 1550–1480 cm-1 were also assigned for (–NH2) vibrations for bending. Changes were
observed in the IR bands of (–NH2) and (COO¯). The new bands were exhibited in the range of
400–660 cm-1, which are tentatively assigned for the M–N coordination and M–O coordination
was also observed in the range of 940–1210 cm-1. Thus we can say that the metal complexes
shifts in M–C=O and M–NH2 bands as well as the widening of the bands were clearly reveals
the formation of metal complexes with a bi dentate mode. Fig1a b c is the respective IR
spectrums of complexes.
Fig.1 (a). FT-IR spectrum of Cysteine and Cysteine copper metal complex
Fig.1 (b) FT-IR Spectrum of cysteine cobalt and cysteine nickel metal complexes
2.2 Thermo gravimetry analysis
The TGA curves of cyctein metal complexes as shown in Fig.2a,b and c showed the absence of
water molecules, as sudden weight loss was observed at 300°C. The total weight loss was 50%.
The weight loss at 447°C was 47×9%, which corresponds to a weight loss of molecular
weight160 units. Similarly, the TGA curve of 2 complex showed absence of water molecules
and the total % weight loss is 60×73%, and the weight loss at 891°C was 54×24%, which
corresponds to a weight loss of molecular weight of 179 units. The thermo gravimetric analysis
(TGA) provides authentic information regarding the absence of water molecules in the
coordination sphere of the complex. Further, the electronic, magnetic, IR and NMR spectral
data confirm tetrahedral geometry for all the complexes studied. Based on these conclusions,
Fig2 (a). TGA of Cys-Cu metal complexes
Fig.2 (b). TGA Cys-Co metal complex
Fig2(c).
TGA of cys-Ni complex
Catalytic Oxidation Reactions
Preliminary Studies
Oxidation experiments were carried out by taking a definite amount of the catalyst and the
substrate, the rate of oxidation was calculated from the slope of the plot between the volume of
oxygen uptake (ml) vs time (min).
It is clear from the figure that up to a certain point, the plots are linear and the departure from
linearity occurs after some time [9]. The rates were calculated from the slope of the linear
portion. For calculating the actual rate of reaction in mols.litre-1minute-1, the vapour pressure
of the solvent (1:1 methanol-toluene mixture by volume) is subtracted from 760 mm of Hg (1
atmospheric pressure) to get the partial pressure of oxygen (pO2).
Po2 x 273 x slope x 1000
Rate =
308 x 760 x V x 22400
Slope = rate in ml/ minute obtained from the curve of O2 uptake Vs time and V = Volume
of the reaction mixture (20 ml)
The vapour pressure of methanol-toluene (1:1 mixture by volume) is 159 of Hg at 350C.
So pO2
is
601 mm of Hg. Therefore 1ml / minute of oxygen uptake is equivalent to a rate of
1.56x10-3 moles litre-1 min-1 under the experimental conditions and the values are given in table
3.
Rate of Oxidation for the Substrates
[Catalyst] X 103 M= 0.12
Substrate (0.2 M)
Rate X 103 (M min-1)
2-Butanol
0.47
2-proponol
0.42
Benzyl alcohol
0.58
Rates of oxidation of the three different alcohols were compared under the same experimental
conditions. The rate of oxidation is found to be higher for benzyl alcohol > 2- butanol >
2-proponol
CONCLUSIONS
Two complexes of Cu (II), Ni(II) with amino acid cysteine were prepared by refluxing the
amino acid and metals. The complexes were characterized by elemental analysis, FT-IR
spectrum, Thermo gravimeter analysis and Uv visible spectra. In these complexes the amino
acid coordinated 1:2 ratios with metals and they exhibited different geometries. All the
complexes were found to be active for the oxidation of some alcoholic substrates under mild
conditions of temperature and pressure using molecular oxygen as the oxidant. The influence
of concentration of the catalyst and the substrate on the rate of reaction has been carried out. In
the case of benzyl alcohol as the substrate, the formation of benzaldehyde as the oxidation
product was confirmed by GC – MS technique.
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[9] Imtiyaz R. parrey, athar adil hashmi Synthesis, characterization and catalytic activity of
Schiff base Cu (II) metal complex 5(2)2015 1-6