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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. References: [1] Ammoumraoui IR, Braham AC, Roy LP and Kappenstein C (2011). Structural, Surface, Thermal and Catalytic Properties of Chitosan Supported Cu(II) Mixed Ligand Complex Materials. Bulletin of Material Science 34 1127–1135. [2]Antony R, David ST, Saravanan K, Karuppasamy K and Balakumar S (2013). 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[8]Schuchardt U, Cardoso D, Sercheli R, Pereira R, da Cruz RS, Guerreiro MC, Mandelli D, Spinace EV and Pires EL (2001). Cyclohexane oxidation continues to be a challenge. Applied Catalysis A: General 211 1–17. Sheldon RA, Arends [9] Imtiyaz R. parrey, athar adil hashmi Synthesis, characterization and catalytic activity of Schiff base Cu (II) metal complex 5(2)2015 1-6