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This study reviews on the Macrocyclic ligands that are polydentate ligands that contain donor atoms either incorporated or linked to the cyclic backbone and have been shown to have biological importance in a variety of investigations. Using the template technique, tetraaza macrocyclic complexes of transition metals Ni(II), Cu(II), Fe(III), and Mn(II) were produced in methanolic conditions. These complexes lacked hygroscopicity and were composed entirely of crystalline solids. The structures of these complexes were determined using the analytical methods UV-Vis and IR Spectroscopy. Antibacterial activity of macrocyclic complexes (1-6) was evaluated against Gram-negative (Escherichia coli and Vibrio cholerae) and Gram-positive microorganisms (Bacillus subtilis and Staphylococcus aureus). We observed in this work that these manufactured complexes had only a weak antibacterial activity, with the exception of macrocyclic complex (6), which exhibited moderate antibacterial activity.

The Objective of this paper is to study on the characterization of transition metal complexes and their antibacterial properties.

They are extremely useful as pigments and colourants due to their vivid hues and chemical inertness [S. Karaboceket al, 2006; K. Shankar et al, 2009]. There is a lot of interest in bioinorganic chemistry at the moment. The importance of macrocycles in biology has led to a new trend in the study of their complexation chemistry with a wide range of metal ions [D. Singh et al, 2010; S. Chandra et al, 2006]. Metalloporphyrin and metallocorrin structural features in macrocyclic complexes are analogous to those in synthetic models [E. Kubaszewski and T Malinski, 1992; R. Vaumet et al., 1982]. For the synthesis of more complex compounds with potential medical applications, new avenues of research such as those undertaken by J. Eilmes and colleagues (in 1985 and 1997) to achieve peripheral substitution that provides points of attachment for further structural modification are now open to us. When it comes to figuring out how macrocycles work in the body, studying synthetic model molecules like these can be helpful [S. Cunha et al., 2005].
As a result of macrocyclic complexes & many pharmacological and coordination features [E.V. Caemelbecke et al, 2005; E. Kimura, 1993], researchers have focused their efforts on them. antibiotics are utilised in both humans and animals as a significant therapeutic chemical to treat infections. [D. Guillemot, 1999; T. Rosuet al, 2006]. According to recent investigations, frequent use of antibiotics results in a growing therapeutic issue [R. Corrêaet al, 1998; G. Turhan- Zitouniet al, 2001]. Antibiotic resistance inhibitors in the form of macrocyclic complexes can assist to minimise this. While macrocyclic compounds and their antibacterial properties are of great relevance, this paper was taken into consideration. The basic objective of this research is to analyze the characterization of Transition Metal Complex.

All chemicals used in this study were of AnalaR Grade. Six macrocyclic complexes were synthesized and characterized. Synthesis of Macrocyclic Complexes All Complexes were produced utilising template approach by condensation of acefone/diacetyl in the presence of corresponding metals salts. To a methanolic solvent (=50), o-phenylenediamine/3, 5 diamino benzoic acid with acetone/diacetyl followed by metal salt in ratio 2:2:1 were added in round bottom flask. Shake thoroughly and refluxing was carried out for 6-8 hours. The change in colour was appeared. The circular bottom flask was placed aside for its chilling. The filtering and washing were carried out by methanol and dried in vacuum. The coloured compounds were obtained and taken for further investigations.

Table 1 Analysis of Macrocyclic Complexes

Macrocyclic Complexes (Molecular Formula)	Color	Yield (%)	Elemental Analysis
			C%		H%		N%		M%
			Cal.	Found	Cal.	Found	Cal	Found	Cal	Found
MC-I/C22H26N4Nicl2O8	Purple	45	43.72	42	4.3	4	9.27	9.1	13	12
MC-II/C24H25N4CuCl2O12	Blue	40	41.4	41.2	3.54	3.5	8.05	8	11.1	11
MC-III/C20H22N4 CuCl2O8	Blue	44	41.37	40.2	3.78	3.75	9.35	9	9.35	9
MC-IV/C24H25N4FeCl2O4	Green	50	52.42	51.5	4.46	4.4	10.8	9.5	10.8	10.35
MC-V/C42H30N4FeCl2O4	Pale Green	42	70.98	70.8	4.22	4	9.02	7.75	9.02	8.9
MC-VI/C22H21N4NiCl2O8	Violet	40	56.96	56	4.52	4.5	9.7	12.02	9.7	9.3

 Characterization

nElements (C, H, and N) and colours and yields were analysed for all the complexes. A spectrophotometer was used for the UV-Vis measurements (Systronics UV-Vis spectrophotometer 117). There were 50 scans on the Nicolet Aligent 1100 FT-Ir spectrometer, and the results were published in infrared spectra. In IR spectra, a decrease in _C=N to 7–10 cm^–1 relative to the free ligand was seen for all complexes containing azomethine nitrogen coordination.

Biological Activity

A variety of bacteria cultures, including Escherichia coli and Vibrio cholerae, Staphylococcus aureus and Bacillus subtilis, were used to test the antibacterial activity of the target compounds that were produced in this study. In this study, Escherichia coli and Vibrio cholerae, Staphylococcus aureus and Bacillus subtillus were isolated from the MTCC (Microbial Type Culture Collection),and used as test isolates. The preliminary antibacterial activity was determined using the Agar-diffusion technique, which was previously described. A sterile disc of 5 mm diameter made of filter paper (Whatsmann no. 1) and impregnated with test macrocyclic complexes (10 mg/ml of DMSO) was used in this approach, and it was incubated at 37^oC for 12 hours. After 12 hours, the inhibition zones around the dried impregnated discs were assessed using a scanning electron microscope. The Antibacterial activity was classed as extremely active (>14 mm), moderately active (10-14 mm), somewhat active (6-10 mm), and inactive (less than 5 mm). Less than 5 mm was considered inactive. By employing a micro broth dilution procedure, it was possible to calculate the minimum inhibitory concentration (MIC) of the substances. A standard culture of test bacteria was injected with varying doses of the chemicals using the broth dilution microbiological technique (MIC method). In the wake of an overnight incubation at 37 degrees Celsius, the minimal inhibitory concentration (MIC) of the compounds was calculated by monitoring the lowest concentration of the compounds that would suppress observable growth of the test bacteria. The optical density (OD) at 600 nm was used to measure growth, which was calculated photo metrically.

The present studies described the six macrocyclic complexes (I-VI) of different metals synthesis and their antibacterial activities. These complexes were crystalline solids and non-hygroscopic. The formulae for these macroxyclic complexes were assigned on the basis of analytical data and enable us to predict the possible structure of the synthesized complexes.

Table 2 UV-Vis Spectral data of Macrocyclic Complexes (nm)

Molecular Formula	max (nm)l
C22H25N4NiCl2O8	548.4
C24H25N4CuCl2O12	402
C20H22N4CuCl2O8	374
C24H25N4FeCl2O4	520
C42H30N4FeCl2O4	425
C22H21N4NiCl2O8	389

Table 2 shows the electronic absorption spectrum data of the complexes in dimethyl sulfoxide (DMSO) at ambient temperature for the different compounds. When complexes are dissolved in DMSO, their electronic spectra exhibit bands in the visible–ultraviolet range. In the azomethine (-C=N) group of compounds, the absorption bands below 400 nm are almost similar and can be ascribed to π-π* transitions occurring in the C=N group. The Ni(II) complexes have a square-planar geometry around the central metal ions, whereas the Cu(II) complexes have an octahedral geometry around the core metal ions [S. Chandra and L.K. Gupta 2004; S. Chandra and S.D Sharma 2002]. The absorption bands found in the 350-550 nm region are most likely due to transitions of the n- π** of the imine group [E. Konig, 1971], with the transitions of the n- π * of the imine group being the most likely explanation. [B.N. Figgis and M.A. Hitchman, 2000; A.A.A. Emara and M.I.A. Omima, 2007] The electronic spectra of nickel(II) and its complexes exhibit an absorption band at 380-550 nm that has been attributed to the 2Eg 2T2g transition, which is characteristic of tetragonally elongated octahedral or square planar Ni(II) and Co(II) complexes have been demonstrated to have electronic absorption bands in the visible range that are dependent on the presence of a solvent.

Fig. 1 Proposed Structures of Dicataionic form of Macrocyclic Complexes, where 1-6 are macrocyclic complexes I-VI

These results are consistent with documented red shifts in the low energy d-d band of Ni (II) and Co(II) complexes in DMSO, which can be explained in part by the presence of a weak ligand field. The infrared spectra of KBr pellets were acquired on a Nicolet Nexus Aligent 1100 FT-IR spectrometer using 50 scans and were reported in centimetres per metre per second (cm^-1n ). For all complexes coordination of azomethine nitrogen was supported by lowering of_C=N to 7-10 cm^-1 as compared to free ligand in IR spectra. Results of IR-spectroscopy were summarized in the table below:

Table 3 Infrared Spectral Data of Macrocyclic Complexes (cm^-1)

Molecular Formula	(NH)n	(ClOn4)
C22H26N4NiCl2O8	3240s	1097(s,b) 623m
C24H25N4CuCl2O12	3220s	1092 (s,b) 620m
C20H22N4CuCl2O8	3210m	1090  (s,b) 618m
C24H25N4FeCl2O4	3200s	1100 (s,b) 620sn
C42H30N4FeCl2O4	3210s	110 (s,b) 620sn
C22H21N4NiCl2O8	3230s	1080 (s,b) 620sn

Where s=strong, vs=very strong, b=broad, m= medium.

A band at 623 cm–1 in the infrared spectrum of Complex I indicated the presence of a noncoordinated perchlorate ion with a wavelength of about 1097 cm–1. It was discovered that complex II exhibited IR bands near 1092 cm-1, which, together with a band at 620 cm-1, indicated the presence of noncoordinated perchlorate ion, while complex III exhibited IR bands near 1090 cm-1, which, together with a band at 618 cm-1, indicated the presence of noncoordinated perchlorate ion. A series of very strong IR bands about 1100 cm-1, as well as a band at 620 cm-1, were seen in Complex IV, indicating the existence of non-coordinated perchlorate ion (Table 3). There were two extremely strong IR bands in Complex V, one around 1100 cm-1 and the other at 620 cm–1, which indicated that the perchlorate ion was present but not coordinated. Complicated VI had IR bands at 1080 cm-1 and a band near 600 cm-1, both of which indicated the existence of non-coordinated perchlorate ion in the sample. The macrocyclic complexes that have been proposed are (1) 1,4,8,11 dibenzotetraaza-tetradeca 7,14-Diene; (2) 1,4,8,11 dibenzotetraaza-tetradeca 7,14-Diene; and (3) 1,4,8,11 dibenzotetraaza-tetradeca 7,14-Diene. (2) 1,5,9,13-tetraaza dibenzoichexadeca 8,16 Cu(II) Macrocyclic complex, (3) 1,4,7,10-tetraaza dibenzododeca 6,12 diene Cu(II) Macrocyclic complex, (4) 1,5,9,13-tetraaza dibenzoichexadeca 8,16 diene Fe(III) Macrocyclic complex, (5) 1,5,8,12 tetraazad Iron III macrocyclic compound, (6) 1, 5, 8, 12, tetraazadibenzoic acid 6,7,13,14 tetramethyltetradeca 7,14-diene is a tetramethyltetradeca 7,14-diene with the formula 6,7,13,14 tetramethyltetradeca Ni(II) Macrocyclic Complex was discovered, and the related molecular structures were shown in figure 1.

The research described above was a previous examination of the antibacterial activity of macrocyclic complexes. It also demonstrates that the complexes have the power of generating novel antimicrobial metabolites when exposed to bacteria. The development of new chemical classes of antibiotics is the outcome of macrocyclic complexes demonstrating antibacterial activity; these complexes have the potential to be used as selective agents for the maintenance of human or animal health in the future, as well as biochemical tools for the study of infectious disease.

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