Organic Amino Acids Chelates ; Preparation , Spectroscopic Characterization and Applications as Foliar Fertilizers

Cu(II) complexes of amino acid hydrolyzate soya protein isolate have been prepared. In order to study the mode of coordination in the above chelates and their effect as foliar fertilizers, Mn(II), Co(II), Nil(II), Cu(II), Zn(II) and Cd(II) complexes of L-mino acids have been prepared and characterized by elemental, spectral analyses,( IR, UV-VIS, mass spectra and ESR), electrical conductance, magnetic moments and thermal analyses (DTA and TGA). ESR spectra of copper (II) complexes show isotropic and anisotropic types d(x 2 -y 2 ) with a covalent bond character. The amino acids chelates were evaluated as foliar fertilizers by treating plants with micronutrient, amino acid solutions and varying concentrations of micronutrient amino acids chelates. It was found that spraying plant with 2.5% micronutrient amino acids chelates gives the best results regarding: plant height, stem diameter, leaves area, number of flowers, number of branches per plants and total yield per plant.


INTRODUCTION
Plant supplying with mineral nutrients effectively is a crucial factor for healthy leaf area on the trees and consequently effective photosynthesis. Deficiency of essential mineral nutrients especially micronutrients is of general occurrence during the past few decades, due to intensive cropping, extensive use of chemical fertilizers, loss of micronutrients by leaching, and decreased use of farm yard manure. Large area of agricultural land has been found to be deficient in one or other Micronutrients, It is realized that, productivity of crops is being adversely affected due to deficiencies of micronutrients [1]. Microelements are generally offered to plants by adding them to medium or spraying then on leaves. When they are applied as inorganic salts to the growing medium, they transform to insoluble forms, so their absorption by the plants decrease. Moreover, leaf fertilizers in form of inorganic mineral structure hardly diffuse from the leaf surface into the plant because of their high weight molecular structure [2]. In order to eliminate these negative effects leaf fertilizers with organic structure as synthetic chelates were developed [3,4,5] . It has been suggested that microelements as inorganic or organic complexes should be applied to the leaves instead of adding them to the growing medium in order to solve microelement requirements of the plants. Chelates obtained by the reaction of metallic salts with their synthetic or natural organic complexes save metal cations from undesirable reactions such as precipitation; they play a significant role in increasing solubility and availability of micronutrients [6,7]. For this reason, synthetic precursors which have the ability of making strong chelate is almost used in plant growing medium. From another point of view, these chelators are not phytotoxic to plants. They are able to make complexes especially with heavy metals and prevent them to uptake by plants in higher ratio [8]. The work in this research was directed to synthesis; spectral characterization of metal amino acid complexes derived from hydrolyzate of soya protein isolate and study their applications as foliar fertilizers. This process is considered as a low cost and a plant growth promoter novel technology.

Materials and method
All chemicals used were of analytical reagent grade (AR) and of the highest purity available. C, H, N and Cl analyses were determined at the Analytical Unit of Cairo University, Egypt. A standard method was used to determine metal(II) ion. All metal complexes were dried under vacuum over P2O5. The IR spectra were measured as KBr and CeBr pellets using a Perkin-Elmer 683 spectrophotometer (4000-400 cm -1 ). Electronic spectra were recorded on a Perkin-Elmer 550 spectrophotometer. The conductance of 10 -3 M solutions of the complexes in DMF was measured at 25°C with a Bibby conductimeter type MCl. Mass spectra were recorded using JEULJMS-AX-500 mass spectrometer provided with data system. Magnetic susceptibilities were measured at 25°C by the Gouy method using mercuric tetrathiocyanato cobalt(II) as the magnetic susceptibility standard. Diamagnetic corrections were estimated from Pascal's constant. The magnetic moments were calculated from the equation:
The solid ESR spectra of the complexes were recorded with ELEXSYS E 500 Bruker spectrometer at room temperature. Diphenyl picrylhydrazide was used as a standard (DPPH) material. T. L. C was used to confirm the purity of prepared complexes.

Biological activity
Evaluation of the growth promotion and productivity ability of the organically chelated metal nutrients on cucmber plant was conducted at Department of Technical Support in Delta Aagro Chemical Company. The evaluation process was carried out in a green house with 400 m 2 area and a number of 10 lines containing 196 plants. Cucmber plant was divided into six groups: The first one "T0" was sprayed only with water; and this group was considered the untreated control; the second group "T1" was treated with 3% micronutrient solution (equivalent to 60 ppm of each micronutrient), "T2" group was sprayed with 3 % amino acid solution, Groups four, five and six "T3, T4 and T5" were treated with 2%, 2.5% and 3%T3 J u n e 1 6 , 2 0 1 4 of the amino acid micronutrient chelate solutions (equivalent to 40 ppm, 50ppm and 60ppm of each micronutrient) respectively. The solutions were applied in the form foliar sprays at two growth stages: on 15 th and 30 th days after transplantation. The growth characters like plant height, stem diameter, leaves area, number of flowers, number of branches per plants and total yield per plant was determined after last harvest.

RESULTS AND DISCUSSION
Acid hydrolysis of soy isolate protein produced L-amino acids which reacted with metal (II) ions (M (II)) to yield metal chelates. In order to study the structure of chelates and mode of coordination, M(II) chelates of some L-amino acids were prepared individually. These chelates were characterized by elemental and spectral analyses (IR, U.V-VIS, mass spectra and ESR), electrical conductances, magnetic measurements and thermal analyses (DTA and TGA). The prepared Metal(II) chelates were found to be stable at room temperature and non hydroscopic. The analytical and physical data ( Table 2) and spectral data (Table 3)

Mass spectra
The mass spectra of Ni(II) complex (5)

Thermal Analyses (DTA and TGA)
Since The IR spectra indicate the presence of water molecules, thermal analyses, were carried out to ascertain their nature. The DTA and TGA curves in the temperature 25-600 C range for complexes (1) (3) and (13) show that, these complexes are thermally stable up to 60 C. The results show also that, the complexes lose hydrated water molecules in the 60-90 C range; this process is accompanied by an endothermic peak. The coordinated water molecules were eliminated at relativity higher temperature than those of the hydrated water molecules 120-180 C, (Table 5), which are accompanied by an endothermic peak. These results are compatible with TGA data [9,24,33]. The removal of an CH3COOH molecule accompanied by endothermic peaks for complexes (3) and (13) respectively in the (265-310)C and (120-198)C ranges. Loss of an HCL molecule accompanied by an exothermic peak was observed for complex (1) at the temperature range 259-310C, DTA results are compatible with the TGA data. The complexes show an endothermic peak within 198-260 C range with no weight loss (TGA), due to melting points of the complexes. The complexes show exothermic peaks within 259-550 C range, (Table 5), corresponding to oxidative thermal decomposition, which proceeds slowly with a final residue, leaving metal oxides [24]. The observations were confirmed by TGA weight losses. The thermal decomposition of complex (2) can be represented as follow: J u n e 1 6 , 2 0 1 4

Biological activity
The synthesized metal chelates were evaluated as plant growth promoter. Results indicated that the growth criteria like plant height and number of branches per plant were improved by increasing dose of the organically chelated amino acid metal nutrient to a concentration of 2.5%. At this concentration the plants recorded the maximum height (110 cm), while plant recorded lower height (97.7 cm) when the micronutrient chelate was foliarly applied the plant at 2.0 % concentration. Treating plants with micronutrient solution 3% produced plants with 86.4 cm while amino acid solution 3% produced plants with 89.2 cm height. The least plant height (78.3) cm was recorded upon treating the plant with the control. The number of branches per plant was maximum (9.1) using 2.5% amino acid chelate as a foliar spray. It was followed by 2% foliar spray of amino acid chelate with 8.1 branches per plant. Whereas foliar spray of unchelated metal nutrient solution at 3% produced 5.4 branches per plant and the amino acid solution at concentration 3% showed 6.2 branches per plant. The least number of branches per plant (2.9) was recorded using the control. (Table 6). Growth characters like stem diameter of plants and leave area of plants were increased significantly with application of increased