Microwave Preparation , Spectral Studies and Antimicrobial Activities Evaluation of Mn ( II ) , Ni ( II ) , Hg ( II ) , Co ( II ) and Cu ( II ) Complexes with Schiff Base Ligand Rehab

New Schiff base and their Mn,Co,Ni, Cu and Hg complexes formed by the condensation of O-phathaldehyde and ethylene diamine (2:1) to give ligand (L 1 ) in the first step ,then the ligand (L 1 ) with 2aminophenol (1:2) to give ligand (L 2 ) were prepared by classic addition through microwave method . These compounds (Ligands and complexes) have been diagnosed electronic spectra, FT-IR, 1 H-& 13 C-NMR (only ligand), magnetic susceptibility, elemental microanalysis and molar conductance measurements. Analytical values displayed that all the complexes appeared (metal: ligand) (1:1) ratio with the six chelation. All the compounds appear a high activity versus four types of bacteria such as; (Escherichia coli), (Staphylococcus aureus),(Bacillus btilis), (Staphylococcus aureus) and (Pseudomonas aeruginosin).


Introduction
In every day of life, the improved pharmaceuticals in coordination chemistry have a large interdisciplinary relation for transition metal ion that are used to control the harmful effects of fungi and bacteria [1][2][3][4][5][6][7][8].The studies about behavior ligands in the chelation with transition metal ions by using the microwave as assisted were considered as one of the important properties in green chemistry [9].The application of microwave-supported preparation continues to develop in organometallic [10], coordination [11] and organic chemistry pace [12].The reactions in Microwave-irradiated show using shorter reaction times, less amount of solvent or solvent-free conditions present low cost, good yield, minimum pollution, simplicity in handling and processing [13].By microwave approaches, there is little literature on the preparation of metal complexes [14,15] Materials: All the used chemicals O-phathaldehyde, ethylene diamine, 2-amino phenol, glacial acetic acid, HBr ,CaCl 2 and reagents and solvents such as ethanol, methanol in addition to various metal chlorides were obtained from Sigma-Aldrich.

Instrumentation
Electronic spectra were recorded using UV-Vis.spectrophotometer type CECIL, England, by using quartz cell has path length (1cm) in range (200-1000)nm in DMSO at room temperature.Melting point was measured by "Gallenkamp Melting point Apparatus".Elemental microanalysis C.H.N. was carried out using Euro Vector EA 3000 A Elemental Analysis (Italy).FT-IR measurements were calculated on Shimadzu-8300, Spectrophotometer in the range of (4000-400cm -1 ) as KBr disc.In DMSO by using a Bruker 300 MHZ (Switzerland) were obtained on ( 1 H and 13 C-) NMR spectra, Chemical shift was obtained in δ(ppm) unit downfield internal reference (TMS), Conductivity measurements were obtained from WTW conductivity meter by using ethanol as a solvent of 10 -3 M concentration at room temperature.Magnetic susceptibility measurements were obtained at room temperature on the solid state applying Faraday's Method using Bruker BM6 instrument.Metal analyses of complexes were determined by using a Shimadzu PR-5.GRAPHIC PRINTER atomic absorption spectrophotometer.

Conventional technique for the preparation of the ligand [5]
(L 1 ) was synthesized by the condensation of (1:2) molar ratio of ethylenediamine (0.060g, 0.001mmole) and O-paraldehyde (0.268g, 0.002 moles) with 3droup glacial acetic acid dissolved in(15mL) ethanol.The product mixture was refluxed for 4 h on a water bath and then left to cool overnight.The colored solid result of the ligand was filtered, washed with hot ethanol many times and dried at room temperature in air and finally desiccated under low pressure in desiccators.m.p. 171°C.Yield: 67 %.

Synthesis of [L 2 ]:
The [L 2 ] has prepared according to the method synthesis of [L 1 ] scheme( 2) by(2:1)( 2-aminophenol :L 1 :) molar ratio (0.380g) was mixed in a grinder completely.The mixture in the microwave oven was then irradiated by taking (3-4 mL) of absolute ethanol as a solvent.The reaction was finished in a shortened time (4-5 min) with more yields than were got in the conventional procedure.Then the results were recrystallized from ethanol and lastly dried in desiccators over anhydrous CaCl 2 under low pressure.

Conventional technique for the synthesis of metal complexes
All the complexes were synthesized by blending 10 mL of a methanolic solution of (10 mM) salt {(1.98 g MnCl 2 .4H 2 O , 2.38 g CoCl 2 .6H 2 O, 2.37 g NiCl 2 .6H 2 O, 1.72g CuCl 2 .2H 2 O, and 2.71 g HgCl 2 )} with 10 mL a methanolic solution of (10 mM) the Schiff base (L 2 ) in{ (metal: ligand) (1:1) }ratio, then refluxed mixture for 1 h on a water bath.The precipitated complexes were filtered, washed several times with ethanol and dried under low pressure in a desiccator over CaCl 2 .Also by using an electric oven they were further dried the results were at 55-70 °C.

Microwave technique for the synthesis of metal complexes
The metal salts and the ligand and were mixed in a grinder in a {(metal: ligand) (1:1)} ratio.In the irradiated oven, the mixture was irradiated by taking 3-4 mL ethanol solvent.The mixing was finished in a shortened time (2-3 min) with more yields than were get in the classic method.Then the results were recrystallized from 2ml of {ethanol, methanol, and distilled water} and finally dried in desiccators over anhydrous CaCl 2 under low pressure.

Antimicrobial activity
The antimicrobial activity(in vitro)of the realized ligand and their metal chelates were examined against the four types of bacteria as (Escherichia coli and Staphylococcus aureus, Pseudomonas aeruginosin) by the disc diffusion method using nutrient agar as the medium using a micropipette in ethanol and the plate was incubated at 37 °C 24 h.After incubation, we measured the samples that considered as the inhibitory power of the specified test bacterial [4].

Results and Discussion
As an outcome of the irradiated -supported preparation, the time of reaction showed that it was diminished from more hours to little minutes also got good yields of the results were received looked at those fulfilled by the customary preparation method.In the microwave method, rotation of mixture platform tray makes reaction mixture more homogeneity.The repetition of the preparation process to make sure the results [3] .All the metal complexes are characterized by the following data.Based on the elemental analysis the composition of metal complexes and percentage of various elements help to formulate the complexes.They were solid, colored and disintegrated on warming at rising of the temperatures and were less or more solvent in basic organic solvents.The data of a comparison of the two preparation techniques showed that reactions which were completed 5.2-6.8min by the microwave methods but were demanded 4.6-7.20 h by the conventional method and the yields were got better 61.8-75.8% to 76.2-85.4%. .

Molar conductivity
All the complexes had stoichiometry for (ligand: metal) was (1:1).The watched molar conductance of metal chelates at room temperature in ethanol, were shown in Table 5.They were consistent with the non-electrolytic nature of all the complexes [2,3].The IR data support these assignments IR spectrum of the ligand displayed the generality characteristic frequencies due to(C=N) azomethine and (C-O) groups and showed in the formed ligand, NH 2, and C=O bonds were disappeared.The free ligand spectrum, Figure ( 1) displayed band at (3441) cm -1 is attributed to the deformation and stretching of the phenolic OH.These bands were disappeared in the spectra of the complexes [7].The two bands at (1678, 1620) cm -1 attributed to the two azomethine groups of the ligand, after complexation, these bands were shifted to lower frequencies in the region (1668-1661) cm -1 and (1617-1614) cm -1 , elucidating the bonding of nitrogen atoms of (C=N) imine groups to the metal ions.This can be illustrated by the granting of electrons from nitrogen to the vacuous d-orbital of the metal atom [8].The phenolic C-O stretching vibration that showed at (1211) cm -1 in the ligand, this band was shifted towards higher frequencies about (22-16) cm -1 in the complexes, Figure (2).This suggests deprotonation of the phenolic OH group after its coordination with the metal ion [9].This shift confirms the participation of oxygen in the C-O-M bond.In the low-frequency region, the band of weak intensity observed for the complexes in the region (567-555) cm -1 is attributed to M-O and in the region (474-438) cm -1 is attributed to M-N.The IR data of both the Schiff base and their metal complexes showed that the Schiff base was the type of hexadentate ligand through chelated to the metal ion [10].

Antimicrobial activities
The antimicrobial activities in vitro of the prepared ligand and their corresponding metal complexes against bacteria such as Escherichia coli and Staphylococcus aureus , Pseudomonas aeruginosin were established in Table (5).All compounds are checked and displayed better antimicrobial activity versus the microorganism [17].On comparing it was shown that the activity of the complexes had moderate as compared to the standard but all the complexes were more active than their single ligand.The greater inhibition zone of the complexes than the free ligand can be expounded based on the chelation theory and the Overtone concept.The interfere of the partial sharing of the positive charge of the metal ion and the ligand orbital with donor groups are due to reduce the polarity of the metal ion in upon chelation.Furthermore, this enhances the blocking of the metal binding sites and the penetration of the complexes into lipid membranes in the enzymes of microorganisms that the delocalization of the π-electrons increases up to the full coordination ring [18].

Conclusion
One of a green chemical path is the microwave technique.The prepared compounds were diagnosed by spectral analyses and different chemical-physic.In route of the microwave helped syntheses, it was spotted that the time of reaction was decreased from many hours to few minutes and the results were obtained in good yield as a comparison to those of the conventional method.The metal ions bound with the diagnosed hexadentate ligand type N 4 O 2 in six donor sites are present four N-azomethine and two O-phenylic.

1 Microwave technique for the synthesis of the Schiff bases Synthesis of
the results were recrystallized from ethanol and finally dried in desiccators over anhydrous CaCl 2 under low pressure.(yield: 80 %).
(4) signals in the integral intensities of the 1 HNMR spectrum of ligand Figure (3) were found to agree with the number of the following signals: DMSO at δ H 2.479, CH 2 at δ H 5.38; C 6 H 5 as multiple at δ H 7.31~8.28;HCOcarbonylgroupatδ H 10.38 .The peaks observed at δ H 8.78 and δ H 8.85 are attributable to the HC=N amine group present in the ligand [5].CH 2 at 56.70, 61.84; =C-N at 101.41, C 6 H 5 as multiple at 128.50~141.13.The peaks observed at 160.05 and 192.87are attributable to the C=N imine group, and C=O carbonyl group C=N imine group, respectively[6].The characteristics frequencies of the free and mixed ligand complexes of the metals are given in Table(4).