Analytical grade chemical reagents were used. All chemicals used in this study are of the highest purity from commercial suppliers such as Merck; BDH and Aldrich they include 1,4-Naphthoquinone, Acetamide and Formamide, CoCl₂∙6H₂O, NiCl₂∙6H₂O and CuCl₂∙2H₂O. The organic solvents such as absolute ethanol and methanol, DMF and DMSO are purchased from Alpha Easer.

Melting point apparatus (Gallen Kamp, Germany) was used to investigate the melting points. Elemental microanalysis of the separated solid chelates for C, H and N were performed in the Micro analytical Center, Cairo University, using CHNS-932(LECO) Vario Elemental analyzers. Infrared spectra were recorded on Perkin-Elmer FT-IR type 1650 spectrophotometer in wave number region 4000 - 40 cm⁻¹. The spectra were recorded as KBr pellets. The ¹H NMR spectra were recorded using 300 MHz Varian-Oxford Mercury. The deuterated solvent used was dimethylsulphoxide (DMSO-d₆) and the spectra extended from 0 - 15 ppm. DTA-TG apparatus. The electron impact (EI) mass spectra (MS) at 70 eV of the tested compounds has been done using MS-5988 GS-MS Hewlett-Packard instrument. TGA was carried out in dynamic nitrogen atmosphere (10 mL∙min⁻¹) with a heating rate of 10˚C∙min⁻¹ using DTG-50 H Shimadzu simultaneous. The molar conductance of solid chelates in DMF was measured using WPA CM35 Conductivity meter fitted with platinized platinum electrodes. The antibacterial and antifungal activities were evaluated at the Microbiological laboratory, Micro analytical center, Cairo University, Egypt.

Modified Kirby-Bauer disc diffusion method [9], has been used to determine the antimicrobial activity of the tested samples [10]. Examined 100 μl of the tested bacteria or fungi and found it was developed in 10 ml of fresh media until they reached a count of approximately 10⁸ cells/ml for bacteria and 105 cells/ml for fungi. 100 μl of microbial suspension was spread onto agar plates corresponding to the broth in which they were maintained. Isolated colonies of each organism that might be playing a pathogenic role should be selected from primary agar plates and tested for susceptibility by disc diffusion method of the many media available, NCCLS recommends Mueller-Hinton agar due to it results in good batch-to-batch reproducibility. Disc diffusion method for filamentous fungi tested by using approved standard method (M38-A) developed. For evaluating the susceptibilities of filamentous fungi to antifungal agent. Disc diffusion method for yeast developed by National Committee for Clinical Laboratory Standards using approved standard method (M44-P). Plates inoculated with filamentous fungi as Asprgillus flavus at 25˚C for 48 hours; Gram (+) bacteria as Staphylococcus aureus; Gram (−) bacteria as Escherichia coli, they were incubated at 35˚C - 37˚C for 24 - 28 hours and yeast as Candida albicans incubated at 30˚C for 24 - 28 hours, then the diameters of the inhibition zones were measured in millimeters with slipping calipers of the National Committee for clinical Laboratory Standards [11], have been used standard discs of tetracycline (antibacterial agent), and amphotericin B (antifungal agent) served as positive controls for antimicrobial activity but filter discs impregnated with 10 μl of solvent (distilled water, chloroform, DMSO) were used as a negative control. The agar used is Mueller-Hinton agar that is rigorously tested for composition and pH. Further the depth of the agar in the plate is a factor to be considered in the disc diffusion method. This method is well documented and standard zones of inhibition have been determined for susceptible and resistant values. Blank paper discs (Schleicher and Schuell, Spain) with a diameter of 8.0 mm were impregnated with 10 μl of tested concentration of the stock solutions. When a filter paper disc impregnated with a tested chemical is placed on agar, the chemical will diffuse from the disc into the agar. This diffusion will place the chemical in the agar only around the disc. The solubility of the chemical and its molecular size will determine the size of the area of chemical infiltration around the disc. If an organism is placed on the agar, it will not grow in the area around the disc if it is susceptible to the chemical. This area of no growth around the disc is known as zone of inhibition or clear zone. For the disc diffusion, the zone diameters were measured [12], found that, agar based methods such test and disc diffusion can be good alternatives because they are simpler and faster than broth-based methods.

The results of elemental analyses and physical properties of the free ligands and its metal chelates shown in Table 1 are in good agreement with those required by proposed formulae. The isolated solid complexes are stable at room temperature, partly soluble in organic solvents (L¹ - L²), but completely soluble in DMF and DMSO. Based on the above mentioned results, it can propose the general structural formulae of the complexes (M:L) ratio 1:1 is represented in Figure 1 and Figure 2.

The metal chelates were dissolved in DMF at 25˚C ± 2˚C and the molar conductivities of 5 × 10⁻⁴ M of their solutions were measured by recommended procedure [13]. The obtained molar conductance values are listed in Table 1. The molar conductivity value of Co(II), Ni(II) and Cu(II) chelates of free ligands (L¹ - L²) are found to be 5.20 up to 7.76 Ω⁻¹∙mol⁻¹∙cm². The chelates are nonionic in nature and they are considered as non-electrolytes.

The main FT-IR bands of 2-acetyl-3-amino-1,4-naphthoquinone (L¹) and (L²) and their corresponding metal chelates are presented in Table 2.

The vibration spectra of prepared ligand L¹ exhibit a very broad band at 3433 cm⁻¹ and at 3413 cm⁻¹ assigned to the υ (NH₂) stretching vibration of (C2-NH₂) of the naphthoquinone. The stretching band at 1624 cm⁻¹ and at 1690 cm⁻¹ can be assigned to the ʋ (C=O). The stretching band at 1577 cm⁻¹ and at 1536 cm⁻¹ can be assigned to the υ (C-N). The vibration spectra of the prepared complexes of L¹ exhibits a broad bands around 3548, 3542 and 3553 cm⁻¹ due to the υ (OH)

stretching, similarly L² exhibits a broad bands around 3537, 3543 and 3539 cm⁻¹ due to the υ (OH) stretching. The lower shift of υ (NH₂) band in at 3392, 3378 and 3355 cm⁻¹ for L¹ and 3400, 3370 and 3362 cm⁻¹ for L² - Co(II) Ni(II) and Cu(II) complexes support the contribution of N-atom of NH₂ group in complex formation. On complexation L¹ show lower shift at 1618, 1609 and 1616 cm⁻¹ for Co(II), Ni(II) and Cu(II) ions respectively due to stretching vibration of ʋ (C=O), which supports the involvement of oxygen atom of (C=O) group in chelation. In a similar fashion on complexation L² show lower shift at 1674, 1680 and 1673 cm⁻¹ for Co(II), Ni(II) and Cu(II) ions respectively due to stretching vibration of υ (C=O), which supports the involvement of oxygen atom of (C=O) group in chelation. Also on complexation of L¹ and L² with Co(II), Ni(II) and Cu(II) ions respectively, a red shift has been observed in υ (C-N) stretching vibration at 1586, 1584 and 1588 cm⁻¹ and at 1587, 1583 and 1591 cm⁻¹ respectively which may be due to increase of bond order of carbon to the nitrogen link following the coordination of the imine nitrogen atom to metal ions. The stretching bands of the coordinated water molecules υ (H₂O) was observed at 808, 868 and 896 cm⁻¹ for Co(II), Ni(II) and Cu(II) - L¹ complexes and at 987, 972 and 924 cm⁻¹ for Co(II), Ni(II) and Cu(II) - L² complexes. The new bands observed at 582, 578 and 586 cm⁻¹ of L¹ complexes assigned to υ (M-O) and at 472, 469 and 467 cm⁻¹ assigned to υ (M-N). Also new band are observed at 572, 577 and 583 cm⁻¹ in all complexes of L² under study assigned to υ (M-O) and at 469, 466 and 468 cm⁻¹ assigned to υ (M-N).

The TGA thermal analyses data of the synthesized metal chelates are tabulated in Table 4.

The biological activity of Ligand (2-Acetyl-3-Amino-1,4-Naphthoquinone) L¹ and its metal complexes Figure 4 shows higher results than that of the free ligand. But all of them are lower than standard. Therefore, the biological activity of the complexes follow the order Co(II) > Cu(II) > Ni(II) against Staphylococcus aureus, Bacillus subtilis and Escherichia coli organisms. But with Candida albicans the biological activity follows the order Co(II) > Ni(II) > Cu(II).

The biological activity of Ligand (2-formyl-3-amino-1,4-naphthoqunone) L² and its metal complexes Figure 5 shows higher results than that of the free ligand. But all of them are lower than standard. Therefore, the biological activity of the complexes follow the order Co(II) > Cu(II) > Ni(II) against Bacillus subtilis and Escherichia coli organisms for (L²) and complexes Meanwhile, the biological activity of the complexes follow the order Cu(II) > Co(II) > Ni(II) against Staphylococcus aureus. But with candida albicans the biological activity follows the order Ni(II) > Co(II) > Cu(II).

The importance of this, lies in the fact that these complexes could be applied fairly in the treatment of some common diseases caused by E. coli e.g. Septicemia, Gastroenteritis, Urinary tract infections and hospital acquired infections according to [16]. However, the complexes were specialized in inhibiting Gram-positive and Gram-negative bacterial strains. The importance of this unique property of the investigated complexes lies in the fact that, it could be applied safely in the treatment of infections caused by any of these particular strains. Generally, the activity of the free ligand was increased upon complexation with metal ions; the enhancement in activity can be explained on the basis of chelation theory, reported by [17] [18]. Chelation reduces the polarity of the metal ion considerably, mainly because of the partial sharing of its positive charge with donor groups and the possible p electron delocalization over the whole chelate ring. Chelation not only reduces the polarity of metal ion, but also increases the lipophilic character of the chelate. As a result of this, the interaction between the metal ion and the cell walls is favored, resulting in interference with normal cell processes.