Synthesis, Characterization and Biological Evaluation of Cr(III), Fe(III), Co(II), Ni(II), Zn(II) and Cd(II) Complexes Using an Azo Dye as Ligand

Azo ligand 11-(4-methoxyphenyl azo)-6-oxo-5,6-dihydro-benzo[4,5] imidazo[1,2-c] quinazoline-9-carboixylic acid was derived from 4-methoxyaniline and 6-oxo-5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazoline-9-carboxylic acid. The presence of azo dye was identified by elemental analysis and spectroscopic methods (FT-IR and UV-Vis). The compounds formed have been identified by using atomic absorption in flame, FT.IR, UV-Vis spectrometry magnetic susceptibility and conductivity. In order to evaluate the antibacterial efficiency of ligand and its complexes used in this study three species of bacteria were also examined. Ligand and its complexes showed good bacterial efficiencies. From the obtained data, an octahedral geometry was proposed for all prepared complexes.


1.Introduction
Azo dyes which contain O, N-donor atoms react as chelating agents for many elements and present bioactive properties [1,2]. Because of their low price and color fastness, the produced azo dyes have been investigated for industrial applications mainly, such as clothes, leather, plastics, food, cosmetics and toys [3,4]. Azo compounds have been widely used as analytical reagents in spectrophotometric and extraction-photometric analysis for metals determination [5]. Metal chelates for heterocyclic azo compounds which were more interesting in inorganic and organometallic chemistry, and also have been granted for application in bioactive systems, catalysis and materials science [6]. These metal chelates were used for industrial applications, synthesis, leather dyeing, vinyl polymers, for pharmaceuticals, inhibition of DNA, RNA, protein synthesis, nitrogen fixation [7,8].

2.3.Azo ligand preparation
4-methoxyaniline (0.307gm, 1mmole) melted in a mixture of 10mL ethanol including 2mL conc. HCl and 10mL distilled water and diazotized at 5 o C with 10% solution of NaNO2. The diazotized solution was gradually added under stirring into a cooling ethyl alcohol solution at 0.697 gm,1mmole of 6-oxo-5,6-dihydro-benzo[4,5]imidazo[1,2-c]quinazoline-9-carboxylic acid. After that, 25 mL of NaOH 1M solution was added into the dark color mix, and the deposition of azo ligand was also observed. This precipitate was filtrated, several times washed with ethyl alcohol, then allowed to dry. The interaction are presented in Figure 1.

Study of biological properties
Three bacterial species have been used during this study: Escherichia Coli (E.Coli) as Gram Negative Bacteria, Staphylococcus Aureus (Staph. Aurous) as Gram Positive Bacteria, and Morganella Marganii in Nutrient Agar medium. DMSO was used as solvent and also as control, focus from compounds has been 10 -3 M, using disc sensitivity evaluation. That path includes exposition from zone for inhibition towards spread from micro-organism at agar dish. Dishes have been brood into 24 h at 37 o C.

3.Results and discussions
Azo ligand (L) was characterized using FTIR and UV-Vis spectra. The solid compounds were generated through reaction from ethyl alcohol solution from ligand for aqueous solution from metal ions at (1:2) and (1:3) ratio. Metal compounds from complexes have been into good correspondence for calculated values (Table 1) considering physical characteristics. Molar conductance for the compounds at a concentration 10 -3 M on ethyl alcohol consist electrolytic style [9], the data being presented in Table 2. Table 1. Physical characteristics of the ligand as well its complexes

Electronic spectra
The UV-Vis spectrum of azo ligand (L) and their compounds are presented in Table 2. UV-Vis spectroscopy into ligand (L) presents three peaks. The first and second appear for 247 and 287 nm due to (-*) electronic transitions, while the third peak is present at 370 nm as consequence to (n-*) electronic transitions [10]. The spectrum of Cr III displays peaks for 251, 328 and 383 nm whom was qualified into ligand field and charge transfer. Other two peaks can be observed at 460 and 584 nm due to the continuity electronic transitions type 4 A2g → 4 T1g(P) 4 A2g → 4 T1g(F) continuity. The magnetic moment of the complex was found at 3.86 B.M, which was much closer to the octahedral perimeter [11]. Fe III spectrum displays peaks at 271, 329 and 391 nm due to ligand field and charge transfer. Other peak shows at 438 nm due to the electronic transition type 6 A1g → 4 T1g(G). The magnetic moment of the complex was found at 5.90 B.M which was much close to the octahedral perimeter [12]. The spectrum for Co II complex displays peaks in 283, 333 and 380 nm 236 nm whom were qualified into ligand field and charge transfer. Else two peaks at 440 and 561 nm whom were referred into electronic transition type 4 T1g(F) → 4 T1g(P) and 4 T1g(F) → 4 A2g(F), also the value for magnetic moment on 4.62 B.M may be considered as an extra confirmation to octahedral geometry [13]. Electronic spectrum for NiII complex showed peaks in 276 and 352 nm consequent into ligand field. Peak in 397 whom was appointed into charge transfer and electronic transition style 3 A2g → 3 T1g(P) and peak in 437 nm whom was into 3 A2g → 3 T1g(F) continuity. The magnetic moment for complex has been discovered in 2.91 B.M whom was much close to the octahedral perimeter [14]. Electronic spectral from ZnII and CdII complexes do offer charge transfer, and magnetic susceptibility seemed the complex has diamagnetic moments, result to (d-d) transition are not likely hence electronic spectrum did not confer any productive datum, on fact outcome is a good agreement for former work from geometry of octahedral [15].

Fourier transformed infrared spectra
Pertinent vibration bands for free ligands as well their compounds have been registered into KBr at area 4000-400 cm -1 . Assignments into distinctive bands for FT IR spectra to free azo ligand (L) and compounds are abbreviated in Table 3. Table 3. Fundamental frequencies to the ligand and its compounds (cm -1 ) Table 4. Diameters (mm) to suppression of compounds by bacteria The IR spectrum for the azo ligand offer bands in 3364 and 1682 cm -1 , whom were qualified into stretching vibration for ν (OH) carboxyl and ν (C=O). Since no significant change in these bands was observed, we can conclude that is no coordination through these group [16,17]. The band on 1622 cm -1 has been attributed to ν (C=N) stretching frequency [18], ion complexation a shifting for alteration into form was noticed for this band, whereas growing into density was observed, specificaly being an outcome from coordination for metal ion. IR spectra band for ligand at 1483 cm -1 is consequently due to stretching vibration for ν (N=N) [19]. For complexation process a shifting of this band was noticed, whereas growing into density was observed, which can be an outcome of metal ion coordination. The new bands that were registered at 487-430 cm -1 are temporarily attributed to ν (M-N) (Metal-Ligand) stretching bands [20][21][22]. The presence of coordination water [23] in the spectra of Co II , Ni II , Zn II and Cd II complexes have been observed at (453-433)cm1.
Finally, the antibacterial activities of the ligand and their compounds have as well been examined using the bacteria species chosen for this study. In Table 4 are shown the suppression capability of various bacteria pattern for the generated compounds during this study.

Conclusions
Complexes can be a synthetic challenge to improve the properties of metal complexes and have been shown to exhibit a broad range of possible geometry for synthesized complexes. The studies revealed octahedral and six coordinated metal complexes formation. Azo dye prepared was identified