Synthesis, Characterization, and Thermal Analysis of a New Acidicazo Ligand's Metal Complexes

: The researchers wanted to make a new azo imidazole as a follow-up to their previous work. The ligand 4-[(2-Amino-4-phenylazo)-methyl]-cyclohexane carboxylic acid as a derivative of trans-4-(aminomethyl) cyclohexane carboxylic acid diazonium salt, and synthesis a series of its chelate complexes with metalions, characterized these compounds using a variety technique, including elemental analysis, FTIR, LC-Mass, 1 H-NMRand UV-Vis spectral process as well TGA, conductivity and magnetic quantifications. Analytical data showed that the Co (II) complex out to 1:1 metal-ligand ratio with square planner and tetrahedral geometry, respectively while 1:2 metal-ligand ratio in the Cu(II), Cr(III), Mn(II), Zn(II), Ru(III)and Rh(III)complexes with octahedral geometry except Mn complex has tetrahedral geometry. The Ligand functions as a neutral tridentate ligand in all complex investigations, coordinating Cr(III), Zn(II), Ru(III), and Rh(III) ions via the N atom of amine and azo groups, as well as the O phenolic OH group. When coordinated with the Cu(II), Co(II), and Mn(II) ions via the two N atoms of the amine and azo groups, this Ligand functions as a neutral bidentate.


Introduction:
Azo dyes are one of the most diverse, useful, and important classes of organic compounds and a great importance in a different fields of chemical analysis due to their containment more than one effective group able to form coordination complexes with a various metal ions , which are characterized by their colors , In general, azo dyes have great coloring qualities and produce vibrant hues ranging from yellows through oranges, reds, and blues, as well as high molar absorption and stability, making them suitable for a variety of applications in science and technology. They also play a significant role in food and analytical chemistry. [1][2][3] Azo dyes are utilized in a variety of applications, including textile dyeing, biomedical research, and advanced chemical synthesis. Antibacterial, antifungal, antibiotic, antiviral, and cytotoxic properties are among the many biological actions of these colors. [4][5][6][7] Azo-dyes are chemical compounds comprising one or more aromatic or heterocyclic moieties with at least one conjugated chromophoricazobond (-N=N-). As a result, they constitute the most important group of disperse dyes, as they are characterized by the presence of an azo moiety (N=N) in their structure. 4 They've found a wide range of uses, primarily in the dyestuffs sector, but also in cosmetics, and medicines industries. [3][4][5] As reagents for extracting and determining the trace amount of metal ions in various materials, azo dyes have gotten a lot of interest. Azo dye complexes have received a lot of attention because of their intriguing features and potential applications as catalysts, antimicrobials, colorants, corrosion inhibitors, and anticancer agents. 8 The aim of this work is to synthesize a novel azo ligand from an aliphatic amine with spectroscopic analysis of its composition as well as to synthesize Cu(II), Cr(III), Mn(II), Zn(II), Ru(III), and Rh(III)complexes with spectroscopic analysis 1. Materials and equipment: All chemicals and reagents were purchased commercially (Sigma-Aldrich, Merck, and others) and utilized without further purification. The Single-V Euro vector model EA/3000. 3.O-single, was used to conduct elemental analyses (C, H, and N Metal ions were estimated as metal oxides using a gravimetric method. The complexes' molar conductance was measured using a temperature of 25 °C and a concentration of 1103 M, the conductometer WTW was used. Dimethyl form amide was used to dissolve all of the complexes (DMF On a mass spectrometry (MS) QP50A: DI Analysis ShimadzuQP-2010-Plus (E170Ev) spectrometer, mass spectra for substances were recorded The UV-Vis spectrophotometer UV-1800 Shimadzu was used to study the spectra in the ultraviolet-visible (UV-Vis) range A Brucker300 MHz was used to record the proton nuclear magnetic resonance ( 1 H-NMR) spectrum for ligand in DMSO-d6. The IR Prestige-21 was used to study the Fourier transform infrared (FTIR) spectra, and the Perkin-Elmer Pyris Diamond TGA and DSC were used to conduct thermo gravimetric investigations.

Synthesis of azo dye ligand: 4-[(2-Amino-4phenylazo)-methyl]-cyclohexane carboxylic acid
Tranexamic acid (0.1577 g,1mmole) melted in a mixture (5ml ethanol, 3ml HCl conc.), and diazotized at 5°C with 10% solution of NaNO 2 . For 3-aminophenol, a diazotized solution was added with stirring to a cooled ethanolic solution at (0.109g, 1mmole). Then after mixing directly, a dusky colored mix andazo ligand precipitation was seen. This deposit was filtered, washed a number of ounces for a (1:1) (C 2 H 5 OH: H 2 O) mixture, and then dried. Scheme 1 depicts the reaction. The mixture was heated to 65°C for 2 hours, then cooled in an ice bath till precipitation occurred, before being left overnight. The reactions are depicted in Scheme 1. The solid complexes were separated and rinsed with distilled water and a small amount of heated ethanol to eliminate any unreacted components. Finally, vacuum desiccators were used to dry the complexes. The analytical and physical properties of the ligand and its metal complexes are summarized in Table 1. Results and Discussion: 1. Physical and chemical properties of azo dye ligand This amorphous appearance, which takes the shape of a fine brown powder, distinguishes the azo dye ligand (HL). This synthesisligand is water and DMSO soluble, however it is only sparsely soluble in ethanol. In the presence of air, the metallic ion and azoligand complexes remained stable.

1 H-NMR spectra
The ligand 1 H-NMR spectra revealed a peak at δ (1.38) ppm, which was attributed to chemical shifts of N=N-CH 2 . The chemical shift of (CH 2 -CH 2 ) protons on the Tranexamic acid was assigned to the peaks at δ (1.9) ppm. The multiple signals noted at δ (2.69) ppm for ligand, these were referred to CH 2 -COO proton in cyclohexane ring. The NH 2 group which appear as singlet at 4. 61ppm.The different peaks at (6.82-7.56) ppm are attributed to the aromatic protons of benzene groups. The proton (OH) of the carboxyl group COOH is responsible for the singlet signal at (11.49) ppm. 9,10 3. Electronic spectra measurements Table 2 and of the ligand H 2 L andits complexes. The n⟶π* transition of the (N=N) azo group in the free ligand produced a peak with a high intensity band with absorption maxima at (302 nm, 33112.5 cm −1 ) and two peaks at 330 and 426 ascribed to the n⟶π* transition of the (N=N) azo group in the free ligand. 11 These peaks were shifted in all metal complex spectra, indicating that the azo group was involved in coordination. 4 Spin transitions at 360, 465, and 651 nm were seen in the electronic spectrum of Cr(III) complex due to 4 A 2 g → 4 T 1 g (P) (ν 3 ), 4 A 2 g → 4 T 1 g (F) (ν 2 ), and 4 A 2 g → 4 T 2 g (F) (ν 1 ), respectively, indicating an octahedral geometry of the complex.The magnetic moment of the complex was weighed at room temperature to be 3.61 B.M., which is close to the spin alone value, implying an octahedral geometry around the chromium ion. 12 The spectrum of [Mn(L) 2 ] complex exhibited bands at;21505, 25000 and 34722cm −1 attribute to 6 A 1 → 4 T 1(G) and 6 A 1 → 4 T 2(G) transitions beside ligand field band, respectively. 13,14 The spectrum of Co(II) complex contained four bands at 324, 480, 614, and 677nm attributed to L.F, C-T , 4 A 2(F) → 4 T 1(P) and 4 A 2(F) → 4 T 2(F) transitions, respectively assigned to tetrahedral Co(II) ion, which is indicative of a tetrahedral geometry.The metal ion is in a tetrahedral environment, as evidenced by this. Due to Jahn-Teller distortion, square planar Cu(II) complexes have a strong absorption band between 600 and 700 nm. The Cu(II) complex's spectrum exhibits a maximum at 635 nm, showing this. 13 Because d-d transitions are not feasible, electronic spectra did not provide any useful information, and the magnetic susceptibility of the Zn(II) complex showed that it contains diamagnetic moments. In fact, this conclusion is in good agreement with prior work on octahedral geometry. 15 respectively, whilst the band at 34843 cm -1 is a charge transfer transition, the octahedral geometry of the Rh(III) complex can be ascribed. 17 Ruthenium(III) complex (displayed three bands at 331, 400 and 480 nm. The second band is due to LMCT transition and the third is assigned to 2 T 2 g→ 2 A 2 g 18 transition. UV-vis analysis also indicated the development of metal (II)/(III) azodye complexes. In DMSO solution, electronic spectra of the produced azo-dye ligand and its metal complexes in the wavelength range 200-1100 nm (1 × 10−3 M). 10,19 .

Liquid chromatography-mass spectrometry (LC-MS) measurements
The electron impact of fragmentation was used to obtain the mass spectra of the novel ligand and metal complexes. High-resolution MS was used to examine the free azo ligand and its complexes, as well as massive fragments associated with breakdown products. Fig.1 depicts the ligand H 2 L electron impact mass spectrum. This ligand molecular weight has been determined to be 277g/mol. A peak at 276 m/z was attributed to [M]+ and related to a novel azo moiety C 14 H 19 N 3 O 3 in the spectra. Different fragments could be responsible for the peaks at 137, 84, and 55 m/z. Their intensity shows the pieces' stability. 20 Fig.2 depicts the mass spectrum of the Cr(III) complex. A peak at 618 m/z was found in the spectra, which corresponded to the complexmoiety [C 28 H 34 N 6 O 6 Cr] -. Other distinctive peaks at 276, 173 and 156 m/z could be attributed to different components. Fig.3 depicts the mass spectrum of the Mn(II) complex. The compound moiety C 28 H 36 N 6 MnO 6 was identified by a peak at 605 m/z in the spectra. Other distinctive peaks at 260, 195, and 156 m/z could be attributed to different fragments. Fig.4 depicts the mass spectrum of the Rh(III) complex. The complexmoiety [C 28 H 34 N 6 RhO 6 ]had a peak at 653 m/z, which corresponded to this moiety. Other fragments could be responsible for the unusual peaks at 224, 154, 148, and 127 m/z. Schemes 2-5 discuss suggested fragmentation paths and fragment structural assignments.   Table 3.Spectrum of the ligand exhibited bands at 3429 and 3275 cm -1 which were assigned to stretching vibration of υ(NH 2 ), at the spectra of allproduced compounds these bands have been removed to lower frequency implying the coordination with metal ion. 10,20 The (N=N)stretching vibration was given to the band found at 1454 cm −1 21-23 in the unbound azo ligand (H 2 L). This band was discovered in the compounds' spectra around 1454-1456 cm −1 . The azo group of the azo ligand shifting confirmed that the azo group was involved in chelation. [22][23][24] In addition, earlier study has shown that in the presence of transition metals, the azo-dye nitrogen is always more likely to favor complexation. 25,26 It was difficult to confirm that the Co(II)complex was engaged in chelate formation due to the presence of coordinated water molecules. The existence of OH bands in the IR spectra of Co(II) complex in the 3423 cm1 region was attributed to the presence of coordinated water molecules in the coordination sphere. Stretching vibrations in the range (869, 696 cm −1 ) were also discovered to match to υ(M-OH 2 ). This is a strong evidence that water molecules are involved in the coordination for the unbound ligand, the IR spectra revealed a large stretching vibration band at 3462 cm −1 , which could correlate to the phenolic group's OH. 27 23,29,30 Finally, the azo-dye ligand connected to the metal ions through three sites: the nitrogen site of the azo group, the main amine, and the oxygen site by deprotonation of the amine and phenolic groups, as determined by the IR spectra of all produced compounds. 23,30,31 Therefore, the ligand behaved as a N,N,O tridentate ligand in the Cr(III), Zn(II), Ru(III) and Rh(III) complexes and N,N bidentate ligand in the Cu(II), Co(II) and Mn(II) complexes.The spectrum of the ligand shows sharp absorption band at 1639 cm -1 due to ν(C=O) of carboxylic group. In the produced complexes spectra, it is noticed with a slight modification in form and moved to higher frequencies 1676-1670 cm -1 . 32,33 These variances point to hydrogen bonding between the carboxylic group's C=O and the orthogonal OH group. The azo group was shifted toward lower frequencies in their complexes spectra, and the primary amine group appeared within the (3436-3325) cm -1 region, as well as the disappearance of the resorcinol hydroxyl group. These findings can be explained by the participation of NH 2 &azo-nitrogen in coordination with metallic ions, as seen in complexes spectra. [34][35][36] Table  4 shows the findings of the study.Co(II), Cr(III), and Ru(III) decompose in two stages with an unbroken residue, while the ligand decomposes in three stages with an unbroken residue. 39,40 The Mn(II) and Rh(III) complexes disintegrate in one stage with an unbroken residue. This is in line with the calculated values and the formula recommended. [41][42][43] Open Access Baghdad Science Journal

Conclusion:
Many researchers have been interested in preparing these types of compounds and studying their properties and effectiveness, especially the difference between the aromatic rings attached to the nitrogen atoms of azo group ,that may be acidic group or basic or both ,and the distribution of the compensated groups at different sites in the aromatic ring relative to the group of azo, for example, hydroxyl group if attached at the ortho site that make up more importance due to share coordinated with metal ions to form Five chelatingring called This type ofcompounds are orthohydroxyl azo. In this study we are synthesis of new azo ligand, this type of reagent was selected to contain multiple consistency sites and seven new chelates complexes with some metallic ions, and to characterization the ligand and Its complexes by using different techniques. All of the synthesized azo compounds were validated by fourier transform infrared (FT-IR), 1 H-NMR spectrum characterisation, and C.H.N. elemental analysis in this research, which concentrated on the creation of new azo.