Synthesis of divalent complexes of Ni(II), Cu(II), and Zn(II) from azodicarbonamide in a mixture of methanol and aqueous solvents: spectral characterizations and antimicrobial studies. (2023)

Autor(en): Ayman AO Younes [1]; Abdel Majid A. Adam [2]; Moamen S. Refat (correspondence to autor) [2,*]; Asthma S. Al-Wasidi [3]; Abdulrahman A. Almehizia [4]; Mohamed A. Al-Omar [4]; Ahmed M. Naglah (corrective autor) [4,*]; Abdulrahman M. Al-Obaid [5]; Hamad M. Alkahtani [5]; Ahmad J. Obaidullah [5]; Mohamed Y. El-Sayed [6]; Kareem A. Asla [7]

1 Introduction

Azodicarbonamide (ADCA; Figure 1) is a yellow powder that is widely used in industry as a blowing agent [1,2,3] in the manufacture of various products; it is non-toxic, odorless and environmentally friendly when decomposed. Among the gases resulting from the decomposition of ADCA are 65% N[sub.2] gas, 24% CO, 5% CO[sub.2] and 5% ammonia [4,5,6]. The structure of azodicarbonamide is as follows [7]:

The current method of decomposing ADCA is as follows: hydrazodicarbonamide (biurea) is synthesized from hydrazine hydrate and urea by an acid condensation reaction [8] and ADCA is produced by the biurea oxidation method. In biurea oxidation, there are several ways to produce azodicarbonamide and they include chlorate method, chlorine method, hydrogen peroxide method and dichromate oxidant structure [8,9]. Due to its benefits including improving products containing gluten and its low cost, azodicarbonamide is used as a dough conditioner [10,11,12]. Azodicarbonamide doesn't usually interact directly with flour, but when wheat is mixed with water to form a dough, it can generate reactive oxygen. The sulfhydryl group (-sh) of wheat protein amino acids is oxidized by reactive oxygen, which forms disulfide bridges (-s-s) that link the protein chains to form a mesh structure. It is known that the addition of initiators, especially zinc and calcium salts, can reduce the temperature at which azodicarbonamide decomposes, according to several researchers [13,14] when azodicarbonamide interacts with calcium- or zinc-based salts. , the resulting azodicarboxylic acid salts, which serve as a catalyst for temperature decomposition. Also, the Lewis acid-base reaction, where the activating addition metal acts as an electron-accepting Lewis acid, is the triggering mechanism of the azodicarbonamide decomposition process, and the azodicarbonamide acts as a base, I mean it's an electron. donor pair. It has also been hypothesized that metals with filled pre-external d-electron orbitals could form complexes with azodicarbonamide molecules as ligands [15]. Breaking of the -c-n= bond is facilitated by complex synthesis, resulting in a lack of electron density around the n-c bond of the azo group.

2. Materials and Methods

2.1. teams

Azodicarbonamide and its metal complexes have been characterized using various techniques. The CNH elemental analysis was repeated three times using a LECO analyzer (model Micro TruSpec) to ensure the reproducibility of the results. The FT-IR spectra of the complexes were measured on a Perkin-Elmer FTIR 1000 spectrophotometer using a KBr disc. Measurement of the UV-Vis spectra for the compounds was performed in DMF solutions in a UNICAM UV-300 spectrophotometer (cuvette thickness 1 cm). Thermal analysis (TG and DTG) was performed at 25-950 °C with a heating rate of 10 °C min[sup.1] using a Perkin Elmer TGA thermal analyzer. Magnetic susceptibility measurement was performed at 25°C using Balance, Sherwood Scientific, Cambridge Science Park Cambridge, England.

2.2. Synthesis of azodicarbonamide systems

All chemicals used in this study were ultrafine and required no further purification. Azodicarbonamide purchased from (Fluka Chemical Co. 99.9%), Cu(NO[sub.3])[sub.2] 6H[sub.2]O, ZnCl[sub.2] and NiCl[sub.2] x H [ sub.2]O (99.9%, Aldrich Chemical Co., USA). NiCl[2]6H[2]O, Cu(NO[sub.3])[sub.2]6H[2]O and ZnCl[2] (1mmol) were added to azodicarbonamide (2mmol) in a mixture of 50% (v/v) methanol and water to make 40 mL of three azodicarbonamide systems. Colored precipitates were prepared by refluxing the reaction mixtures at appropriate temperatures for about 3 to 5 hours. The precipitates were filtered and washed with MeOH and water, after which they were dried over CaCl 2 in a desiccator. About 73-79% of the crops were produced.

23. Antimicrobial test

The diffusion method [16,17] was used to determine the zone of inhibition of azodicarbonamide and its complexes against G (+ve) bacteria (Bacillus subtilis and Aspergillus oryazae) and fungi (Penicillium sp.). Dimethyl sulfoxide was used as the control solvent. Two different concentrations, 3 mg/ml and 6 mg/ml were used on agar plates incubated at 37 ± 0.5°C for 24 h.

3. Outcome and Discussion

3.1. Elementary and conductance and magnet torque data

A new series of azodicarbonamide complexes was prepared by refluxing azodicarbonamide with alcoholic solutions of Ni(II), Cu(II), and Zn(II). The compounds obtained are air-stable and soluble in the organic solvents dimethyl sulfoxide and dimethylformamide. Molar conductivity measurements of ADCA and its complexes were performed in a DMSO solution and revealed the neutral and non-electrolytic nature of the compounds prepared. The stoichiometry of the compounds was confirmed by the elemental analysis results, which agreed well with the calculated values. The electronic spectra as well as the characteristic infrared bands were considered as further evidence for the proposed geometry of the compounds. Information from the microanalytical examination of the complexes revealed a 1:2 stoichiometry (metal:ligand) with molecular formulas [Ni(ADCA)[sub.2](Cl)[sub.2]] 1.5H[sub.2] O ( 1 ), [Cu(ADCA)[sub.2](NO[sub.3])[sub.2]]H[sub.2]O (2), and [Zn(ADCA)[sub. 2] (Cl)[sub.2]]H[sub.2]O (3), where ADCA is C[sub.2]H[sub.4]N[sub.4]O[sub.2] ( Figure 2) . Physical Data: Conductivity, magnetic and elemental analysis results are listed in Table 1.

3.2. magnetic properties

All of the complexes considered were considered paramagnetic based on the magnetic moment measurements in Table 1, except for the diamagnetic zinc(II) complex, which exhibited a six-coordinate geometry, since the measurement temperature affects the exact value of the magnetic moment field and size the spin-orbit coupling. All observations were made at room temperature. At room temperature, the magnetic moment of the solid nickel(II) complex was 3.46 B.M, which is within the range of experimental data (3.32 B.M) and indicates two unpaired electrons of Ni(II) in an octahedron. The atmosphere. The Cu(II) complex showed a u[sub.eff] value of 1.93 B.M, which agrees with the experimental range (1.96 B.M) and indicates one unpaired electron per Cu(II) ion. suggesting that these complexes reside within are consistent with a spinless, distorted octahedral geometry.

3.3. IR spectra of azodicarbonamide and its complexes

Comparison of the IR spectra of the complexes with those of the azodicarbonamide determines the type and location of coordination that may be involved in chelate formation. The most important theoretically important experimental and calculated IR spectral bands of azodicarbonamide and its metal complexes are given in Table 2 and shown in Figure S1a–d with their preliminary assignments. The bands at 1727 cm[sup.1] in the IR map represent an overlap of the C=O and NÀC stretching modes, which are most intensely active in the infrared. The azodicarbonamide bands observed in the IR spectrum at 1116 cm[sup.1] are assigned to the same vibration, that is, a superposition of the NH[sub.2] stretching bands and the C=O and NÀC stretching modes. The bands at 1330 cm[sup.1] in the IR spectrum and at 1332 cm[sup.1] are attributed to an overlapping of the stretching bands NH[2], the N-C stretching vibration and the N-C = Ó bending vibration. In the IR spectrum of the azodicarbonamide (Figure 3a), the strong characteristic band at 1728 cm[sup.1] can be observed, which is attributed to the stretching vibration of C=O [18]. Azodicarbonamide has two likely sites for coordination with metals containing azo and C=O groups [19]. The observed wavenumber changes and the broadening of the azodicarbonamide spectrum were considered to be the result of intermolecular hydrogen bonding [20]. However, these intermolecular hydrogen bonds are broken by coordination with metals. The strong carbonyl stretching peak at 1728 cm[sup.1] in azodicarbonamide shifts to 1621, 1556, and 1679 cm[sup.1], indicating an interaction of carbonyl and copper(II) and zinc(II) ions indicates nickel(II) ion within the coordination compound. The coordination of azodicarbonamide with metal ions was further confirmed by the appearance of new bands between 551–585 and 407–465 cm[sup.-1] denoted by metallic nitrogen (M-N) and metallic oxygen (M-O) propagating the vibrations individually . These bands were not present in the free ligand spectra, confirming the involvement of O and N in coordination with transition metal ions [21,22]. Therefore, IR spectra show that the azodicarbonamide ligand is bidentate and coordinates to the metal through the nitrogen atom of the azo group and the oxygen atom of the carbonyl groups [19].

3.4. thermal studies

Using thermogravimetric analysis, azodicarbonamide and its metal complexes are studied at 25–1000 °C in a nitrogen environment (Table 3 and Figure 3). The DTG curves show rate of weight loss versus temperature scale, while the TGA curves show percent weight loss as a function of temperature. Decomposition of azodicarbonamide between 165 and 195 °C liberates gas to form a residue. The gas consists of N2 gases, CO and a third substance which is ammonia or HNCO acid depending on the temperature. The residue is a combination of biurea, HNCO and H[sub.3]N[sub.3]C[sub.2]O[sub.2] while the sublimate consists of HNCO, cyamlide and urea [ 23, 24 , 25,26,27]. Two main reactions, (i) and (ii), appear to occur simultaneously in the first decomposition mode, in which azodicarbonamide decomposes to produce biurea. HNCO and N[sub.2] in the second decomposition mode to produce ammonia, N[sub.2], HNCO and H[sub.3]N[sub.3]C[2]O[sub.2] . The first decomposition mode occurs twice as often as the second at 171.5 °C, while the secondary reactions of isocyanic acid appear to produce cyanuric acid, cyamellide, carbon monoxide, and urea. The originally formed biurea decomposes at higher temperatures into urazole and ammonia [27,28]. The sequence for the thermal degradation of azodicarbonamide is given (Scheme S1).

O[Ni(C[sub.2]H[sub.4]N[sub.4]O[sub.2])[sub.2](Cl)[sub.2]] 1.5H[sub.2 O The ]O thermogram shows three main stages of decomposition. In the first step, T [max] = 265 °C and the residue is 0.5 HCNO + 2 Cl [sup.] + N [sub. 2] + 1.5H [sub. 2] O with percent weight loss of 39.12 (calculated 38.95%). In the second step, T[sub.max] = 353.51 °C and the residue is C[sub.2]N[sub.2]O[sub.2] + 0.5HCN with a percent weight loss of 25.75 (calculated 25.66%). In the last step, the final residue is 1.5NH[sub.3] + 0.5HCN + N[sub.2] + NiO with a weight loss of 36.13% (35.05% calculated). O [Cu(C[sub.2]H[sub.4]N[sub.4]O[sub.2])[sub.2](NO[sub.3])[sub.2]] HO [ sub.2] The thermogram shows three degradation stages in the temperature range of 45–1000 °C. In the first stage, T[sub.max] = 45°C with a weight loss of 8.981% (9.541% calculated), which corresponds to the loss of H[sub.2]O + HNCO. In the second stage, T[sub.max] = 250 °C and is accompanied by a weight loss of 41.065% (41.675% calculated), corresponding to the loss of HNCO + C[sub.2]H[sub.3 ] N[ sub.3] O[sub.2] + N[sub.2] + 0.5NH[sub.3]. Thus, the final thermal decomposition product obtained is 0.5NH[sub.3] + 2NO[sub.3] + CuO + 0.5C. For [Zn(C[sub.2]H[sub.4]N[sub.4]O[sub.2])[sub.2](Cl)[sub.2]]H[sub.2 ] Or Thermogram, the decomposition takes place in four stages. In the first stage, T[sub.max] = 158 °C, with a weight loss of 8.371% (8.02% calculated), corresponding to the loss of H[sub.2]O + N[sub. two]. In the second stage T[max] = 197 °C, corresponding to NH[sub.3] + HCN losses with weight losses of 14.034% (calculated 15.55%). In the third step T[max] = 538 °C, corresponding to the loss of Cl[sup.] + HCN for a weight loss of 28.19% (calculated 25.13%). Finally, C[2]H[sub.3]N[sub.3]O[2] + ZnO + 2C is obtained through the final decomposition step.

3.5. Electronic spectral measurements

Absorption spectra of the azodicarbonamide ligand and its metal complexes in DMF were recorded in the wavelength range from 200 to 800 nm. As can be seen in Tables 4 and 4, ADCA has three strong absorption bands at 241, 331 and 433 nm corresponding to p&agr; p* and no? p* electronic transitions [29]. The electronic spectrum of the Ni(II) complex showed three absorption bands at 717, 564 and 520 nm, which correspond to spin-allowed transitions [sup.3]A[sub.2g] (F) → [sup.3]T[sub. 2g] (F), [sup.3]A[sub.2g] (F) → [sup.3]T[sub.1g] (F) and [sup.3]A[sub.2g] (F) → [sup.3]T[2g] (P), as is characteristic of the distorted octahedral geometry of the Ni(II) ion [30,31]. The spectrum of the Cu(II) complex shows two bands in the ultraviolet and visible region at about 521 and 400 nm, corresponding to [sup.2]E[sub.g] → [sup.2]T[sub.2g] and Intraligand transitions [31]. The zinc(II) complex shows an absorption band at 386 nm ascribed to the LMCT transition and six-coordinate geometry, and this is supported by its diamagnetic nature and the absence of the d–d band due to its full d[10]. Electronic configuration.

3.6. Optical Band Gap Energy

Tuac's equations [32,33] were used to predict the optical gap, right? = (h? - Ex.)n where h? = the energy of the photon, h = Planck's constant, n = ½ or 2 for direct and indirect transitions, a = the absorption coefficient, A = an energy-independent constant.

Figure 5 shows the graph of (ah?)[sup.2] and (ah?)[sup.1/2] versus (hv). A band gap is obtained by extrapolating the linear component of the curve to (ah?)[sup.1/2] = 0. The following equation was used to calculate the absorption coefficient (a): a = 1/dln( 1 / T), where d = cuvette optical path length and T = estimated transmission. In the solvent DMF, the band gaps for azodicarbonamide and its Ni(II), Cu(II), and Zn(II) complexes were 3.79, 1.91, 2.50, and 1.96 eV, respectively, and are given in Table 4 and 6 listed. To provide insight into the data presented in Table 4, complexation minimizes the E[sub.g] values ​​in place of the azodicarbonamide linker. This decrease in E[sub.g] values ​​is due to the transfer of electrons from the ligand to the metal ion [34]. It is speculated that the presence of Ni or Cu ions in a given complex increases the electronic mobility of the ligand by accommodating them in its vacant layer. This leads to an expansion of the localized levels in the resulting complex and as a result the gap is narrower and widely used in optical, electronic and energy conversion devices [35]. In fact, a small energy difference facilitates the transition of electrons between HOMO and LUMO, so that the molecule becomes more electrically conductive [36]. The low E[sub.g] values ​​for the investigated compounds are in good agreement with the reported values ​​and consequently can be used as highly efficient semiconductors and photovoltaic materials [34,37,38,39].

According to the Urbach formula: a(h?) = ao exp(h?/Eu) with a[sub.o] = constant, E[sub.u] = the Urbach energy, which is interpreted as the amplitude of the localized states .

The absorption coefficient a depends exponentially on the photon energy when hv = E[sub.g]. From the diagram of lna versus h? (Figure 5) the Urbach energy (E[sub.u]) can be calculated and must be equal to the reciprocal of the slope of the straight line of the linear part of the curve. The estimated values ​​of E[sub.u] are 22.94, 9.377, 4.29 and 19.53 meV, corresponding to azodicarbonamide and its Ni(II), Cu(II) and Zn(II) complexes, respectively. Low E[sub.u] values ​​indicate minor defects in the complex structure.

3.7. Mass spectrum of azodicarbonamide and its metal complex

The expected formulas in Figure 2 were confirmed by the following mass spectroscopic fragmentations of azodicarbonamide and its Ni(II), Cu(II), and Zn(II) complexes (Figure S2). The mass spectrum of azodicarbonamide with a molecular ion peak at m/z = 116.9 corresponds to C[2]H[4]N[4]O[2]. Meanwhile, another peak at m/z = 100.2 belongs to [C[sub.2]H[sub.2]N[sub.2]O[sub.2]][sup.] of the nitroacetonitrile ion. For the guanidine structure, the hydroxide ion, [CH[sub.6]N[sub.3]O][sup.], belongs to the peak at m/z = 76.1. The last peak at m/z = 59.2 belongs to the diazenyl methoxide ion [CH[sub.3]N[2]O][sup.]. In addition, the last peak at m/z = 44 belongs to the aminomethanone ion [CH[sub.2]NO][sup.]. In addition, the last peak at m/z = 30.4 belongs to the diazenion [N[sub.2]H[sub.3]][sup.+] [40] (Scheme S2). The mass spectrum of the Ni(II) complex (Figure S2) shows that the parent ion peak at m/z = 279 belongs to [C[sub.4]H[sub.5]N[sub.7]NiO[ sub .5 ]][sup.+]. The other fragments of the complex give peaks with different intensities at different values ​​such as 243 [C[sub.4]H[sub.3]N[sub.5]NiO[sub.4]][sup.+] , 226 [C [sub.4]N[sub.4]NiO[sub.4]][sup.+] and 164 [C[sub.2]N[sub.2]NiO[sub.2]] [ sup.+] . The fragmentation pattern of the mass spectrum of the Ni(II) complex (Scheme S3) is consistent with the expected structure. The mass spectrum of the Cu(II) C[sub.4]H[sub.10]CuN[sub.10]H[sub.11] complex (Figure S2) shows the corresponding molecular ion peak at m/z = 375 to [C [sub.4]H[sub.7]CuN[sub.9]O[sub.9]][sup.+]. The other fragments of the complex show the peaks at different values; for example, [C[sub.3]H[sub.7]CuN[sub.7]O[sub.3]][sup.+] has a peak at 251, [H[sub.6]CuN[sub. 6]O[sub.2]][sup.] peaks at 211, [C[sub.2]H[sub.3]CuN[sub.5]O[sub.2]][sup.+]- Peaks at 191 and [C[sub.2]H[sub.3]N[sub.5]O][sup.+] peaks at 122. The fragmentation pattern in Scheme S4 ​​is consistent. according to the proposed structure of the Cu(II) complex. The mass spectra of the Zn(II) complex (Figure S2) show that the molecular ion peaks at m/z = 386.6 correspond to [C[sub.4]H[sub.10]N[sub.8] O[sub .5] Cl[sub.2]Zn][sup.+]. The other fragments of the complex show that the peaks at m/z = 358.46, 340.46, 323.46, 253, 210.46 and 183.46 [C[sub.4]H[sub.10]Cl [sub.2]N[sub] correspond to .6]O[sub.5]Zn][sup.+], [C[sub.4]H[sub.8]Cl[sub.2]N[sub. 6 ]O[sub.4]Zn ] [sup.+], [C[sub.4]H[sub.5]Cl[sub.2]N[sub.5]O[sub.4]Zn][ sup.+], [C[sub. 4]H[sub.5]N[5]O[sub.4]Zn][sup.+], [C[sub.3]H[sub.4]N[sub.4]O[sub .3 ]Zn][+] or [C[sub.2]H[sub.3]N[sub.3]O[sub.3]Zn][sup .+]. The fragmentation pattern in Scheme S5 is consistent with the proposed structure of the Zn(II) complex.

3.8. Biological Activity: Antibacterial proof

The data listed in Tables 5 and 6 represent the antibacterial and antifungal properties of azodicarbonamide ligand and its metal complexes. As information about the data, the following observations can be concluded: azodicarbonamide and its Zn(II) complex show no antimicrobial activity, and the Ni(II) complex shows significant antifungal activity against Aspergillus oryzae and Penicillium sp. with inhibition zones of 1.3 and 0.3 cm. However, it has no antibacterial effect. The Cu(II) complex has acceptable antifungal activity against Aspergillus oryzae with a zone of inhibition of 0.6 cm.

3.9. Computer studies

Theoretical studies were performed using DMOL[sup.3] in the Materials Studio package[41,42,43,44]. DFT seminuclear pseudopod (dspp) calculations were performed using the dual base sets as well as the polarization function (DNP) [45]. The RPBE function is based on the generalized gradient approximation (GGA) as the best correlation function [46,47]. The structures of the ADCA complexes (Scheme 1, Scheme 2, Scheme 3, Scheme 4, Scheme 5, Scheme 6, Scheme 7, Scheme 8, Scheme 9, Scheme 10, Scheme 11 and Scheme 12) together with the numbering represent optimized molecular structures of azodicarbonamide ligand atoms and their metal complexes. The following can be concluded from the data for the bond length and the bond angles of the azodicarbonamide compounds listed in Table 6, Table 7, Table 8 and Table 9:

1. The bond lengths of the azodicarbonamide unit show a significant change after complexation. Remarkable changes were observed for C(4)-N(1), C(3)-N(2), N(1)-N(2), C(4)-O(5), and O(6). - C(3) bond lengths that increase or decrease depending on the coordination with metal ions [48].

2. The bond angles in the Ni complex are quite close to its octahedral geometry, predicting sp[sup.3]d[sup.2] or d[sup.2]sp[sup.3] hybridization [49] ]. The Cu complex shows a distorted Oh geometry. However, the bond angles in the Zn complex predict the hexagonal environment around the Zn metal ion.

3. The distances of the C(4)-O(5) and C(3)-O(6) bonds of the carbonyl group in azodicarbonamide are easy due to the formation of a strong M-O bond that makes the C-O bond stronger lengthens weakly [50].

4. The bond distances of Ni-O and Cu-O in the Ni and Cu complexes are shorter than that of Zn-O in the Zn complex, reflecting the greater strength of the Ni-N and Cu-N bonds. The Ni-N and Cu-N bond distances in the Ni and Cu complexes are shorter than the Zn-N distances in the Zn complex, reflecting the greater strength of the Ni-N and Cu-N bonds.

5. The data recorded in Table 10 reveal some quantum chemical parameters, including the energies of the frontier orbitals (E[sub.HOMO], E[sub.LUMO]), the energy gap (E[sub.H]-E[sub.L] ), electronegativity (?), chemical potential (µ), global hardness (?), global softness (S) and global electrophilic index (?) calculated from the following equations [51 , 52.53] .

Δ(electronegativity) = -1/2(E[sub..LUMO]+E[sub.HOMO]) μ(potential)=-α=1/2(E[sub..LUMO]+E[sub .HOMO]) Δ(hardness) = 1/2(E[sub..LUMO] - E[sub.HOMO]) S(softness) = 1/2? Δ(electrophilicity) = µ 2/2?

1. The s = 1/? The energy gap calculated for azodicarbonamide is 1.775 eV larger than that of the corresponding metal complexes. In addition, the value of ΔE[sub.H-L] for the Ni complex is the smallest - ΔE[sub.H-L] = 0.957 eV - which agrees with the experimental data.

2. The energetic parameters (total energy, binding energy, and dipole moment) were calculated and listed in Table 11. The higher negative values ​​of the binding and total energies for the azodicarbonamide complexes indicate the greater stability of the metal compounds prepared compared to that of the azodicarbonamide molecule.

4. Conclusion

Physicochemical studies of new azodicarbonamide complexes obtained from the reflux of the ligand with solutions of alcoholic salts of Ni(II), Cu(II), and Zn(II) were presented. Elemental, IR, molar conductivity, magnetic, UV-Vis, bulk, and thermal analyzes were performed to confirm the molecular structures of the studied compounds. The vibrational spectra show the neutral bidentate behavior of the ADCA ligand. The ligand under study coordinates to metal ions through the oxygen of the (C=O)[azo] groups and the nitrogen of the (N=N)[azo] groups. Molar conductivity measurements demonstrate the electrodeless nature of all compounds with 1:2 stoichiometry. Magnetic measurements and electronic spectra predict the paramagnetic and octahedral geometry of the copper and nickel complexes, but the zinc complex is diamagnetic and has a hexacoordinate geometry. The energy gap between HOMO and LUMO for the studied metal complexes is smaller than that of the synthesized ADCA ligand, indicating the easiness of electron transfer. Ni(II) and Cu(II) complexes can be used as fungicides. However, azodicarbonamide and its zinc complex lack biological activity.

author contributions

Conceptualização, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; metodología, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; Software, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; validação, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; formal analysieren, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; investigação, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; recursos, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; curadoria de dados, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; redação – preparação do borrador original, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; redação—revisão e edição, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; visualização, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; supervisión, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; administração de projetos, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. y K.A.A.; aquisição de fundos, A.A.O.Y., A.M.A.A., M.S.R., A.S.A.-W., A.A.A., M.A.A.-O., A.M.N., A.M.A.-O., H.M.A., A.J.O., M.Y.E.-S. e K.A.A. Todos os autores leram e aceitaram a versão publicada do manuscrito.

Data Availability Statement

Data available on the journal website.

conflicts of interest

The authors declare no conflict of interest.

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expression of gratitude

The authors thank the Dean of Scientific Research, King Saud University for funding through the Vice-Chancellor of Scientific Research Chairs; (Chair of Drug Research and Development). The authors thank Princess Nourah Bint Abdulrahman University, Riyadh, Saudi Arabia for funding this work through Researcher Support Project number (PNURSP2023R35).

additional materials

The following support information can be downloaded from: https://www.mdpi.com/article/10.3390/cryst13030367/s1, Figure S1: a. FTIR spectrum of pure azodicarbonamide. B. FTIR spectrum of the Ni(II) complex. C. FTIR spectrum of the Cu(II) complex. D. FTIR spectrum of the Zn(II) complex, Figure S2: a. Mass spectra of the azodicarbonamide ligand [40]. B. Mass spectra of the Ni(II) complex. C. Mass spectra of the Cu(II) complex. D. Mass spectra of Zn(II) complex, Scheme S1: azodicarbonamide decomposition reaction, Scheme S2: fragmentation pattern of azodicarbonamide ligand, Scheme S3: fragmentation pattern of Ni(II) complex, Scheme S4: fragmentation pattern of Ni(II ) complex Cu(II) complex, Scheme S5: Fragmentation pattern of the Zn(II) complex.

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Figures, schemes and tables

Figure 1: The molecular formula of ADCA. [Download the PDF to view the image]

Figure 2: The proposed structures of the synthesized complexes. [Download the PDF to view the image]

Figure 3: TG and DTG thermograms of (a) azodicarbonamide complexes (b) Ni(II), (c) Cu(II), and (d) Zn(II). [Download the PDF to view the image]

Figure 4: UV-Vis spectra of azodicarbonamide and its metal complexes. [Download the PDF to view the image]

Figure 5: Graph of ah?[sup.0.5] vs. photon energy (E) of (a) azodicarbonamide and its complex (b) Ni(II), (c) Cu(II) and (d) Zn(II)) . [Download the PDF to view the image]

Figure 6: The antifungal inhibition zones of Ni(II) complex (a), Cu(II) complex (b) and Zn(II) complex (c) against Aspergillus oryzae. [Download the PDF to view the image]

Scheme 1: DFT-optimized geometry of the azodicarbonamide ligand. [Download the PDF to view the image]

Scheme 2: DFT-optimized geometry of HOMO azodicarbonamide. [Download the PDF to view the image]

Scheme 3: DFT-optimized geometry of azodicarbonamide LUMO. [Download the PDF to view the image]

Scheme 4: DFT-optimized geometry of the Ni complex. [Download the PDF to view the image]

Scheme 5: DFT-optimized geometry of the Ni HOMO complex. [Download the PDF to view the image]

Scheme 6: Optimized LUMO-DFT geometry of the Ni complex. [Download the PDF to view the image]

Scheme 7: DFT-optimized geometry of the Zn complex. [Download the PDF to view the image]

Scheme 8: DFT-optimized geometry of the Zn HOMO complex. [Download the PDF to view the image]

Scheme 9: Optimized LUMO-DFT geometry of the Zn complex. [Download the PDF to view the image]

Scheme 10: DFT-optimized geometry of the Cu complex. [Download the PDF to view the image]

Scheme 11: DFT-optimized geometry of the Cu-HOMO complex. [Download the PDF to view the image]

Scheme 12: Optimized LUMO-DFT geometry of the Cu complex. [Download the PDF to view the image]

Table 1: Microanalytical and physical data of azodicarbonamide and its complexes.

Table 2: Vibrational assignments of important IR bands of the azodicarbonamide ligand and its metal complexes.

Table 3: Maximum temperature, T[sub.max] (°C) and weight loss values ​​of the decomposition steps of the azodicarbonamide metal complexes.

Table 4: Absorption data and band assignments of the azodicarbonamide ligand and its complexes.

Table 5: Inhibition diameters (cm) of azodicarbonamide ligand and its metal complexes.

Table 6: Selected bond lengths (Å) and bond angles (°) of the ligand (ligand) using the DFT method of DMOL calculations [sup.3].

Table 7: Selected bond lengths (Å) and bond angles (°) of the ligand (Cu complex) using the DFT method from DMOL calculations [sup.3].

Table 8: Selected bond lengths (Å) and bond angles (°) of Ni complex ligand using DFT method of DMOL calculations [sup.3].

Table 9: Selected bond lengths (Å) and bond angles (°) of the ligand (Zn complex) using the DFT method from DMOL calculations [sup.3].

Table 10: Some quantum chemical parameters of azodicarbonamide and its complexes.

Table 11: Various theoretical molecular parameters of azodicarbonamide and its complexes.

author links):

[1] Department of Chemistry, Faculty of Science, University of Bisha, Bisha 61922, Saudi Arabia

[2] Department of Chemistry, Faculty of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi-Arabien

[3] Department of Chemistry, Faculty of Science, Princess Nourah Bint Abdulrahman University, Riad 11671, Saudi-Arabien

[4] Chair of Drug Exploration and Development (DEDC), Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Saud University, Riad 11451, Saudi-Arabien

[5] Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Saud University, Riad 11451, Saudi-Arabien

[6] Department of Chemistry, Faculty of Science, Jouf University, Sakaka 2014, Saudi-Arabien

[7] Department of Chemistry, Faculty of Science, Zagazig University, Zagazig, 44519, Ägypten

University of Leeds, Leeds, UK

Author's Note(s):

[*] Correspondence: moamen@tu.edu.sa (MSR); anaglah@ksu.edu.sa (A.M.N.)

DOI: 10.3390/cristal13030367