1. Introduction

2. Experimental

3. Results and discussion

3.1. Sample Characterization

3.1.1. Structural determination of the ligand, MHB

Mass spectrum: The purity and predicted molecular weight of the compound have been emphasized throughout the mass spectrum (Figure 1). The molecular ion peak for the MHB was at m/e = 288.35 [(C₁₅H₁₂O₆), calculated m/e = 288.35].

IR spectrum: The spectrum data (Figure, 2, Table 2) exhibited υ(C-O)_phenolic, ν(OH)_phenolic, δ(OH)_phenolic and υ(C=O)_caroxylic at 1281, 3150, 1200 and 1648 cm^-1, respectively [27]. It is believed that the presence of phenolic OH at the lower site (3150 cm^-1) indicates that intermolecular H-bonding (O–H.O-H) between related molecules. The widening form of υOH_phenolic provides support for this suggestion, whereas the band resulting from intramolecular hydrogen bonds is sharp. The significant reduction in frequency reveals how strong the link is. The broad band at 2395-2650 cm^-1 confirms the presence of the intermolecular hydrogen bond among MHB molecules.

Figure 1. Mass spectrum of MHB.

Figure 1. Mass spectrum of MHB.

Absorption of the (C=O)_carboxyl is lower than typical position (1700-1730 cm^-1) due to the presence of MHB as dimer (intermolecular hydrogen bonding) and internal conjugation (the lone pair on the carboxyl’s OH is in delocalization with C=O). Four bands associated to aromatic (C=C) vibrations were also found at 1609, 1585, 1489, and 1435 cm^-1. Moreover, Figure 2 shows the locations of additional bands corresponding to the phenyl rings at 791 cm^-1 (out of plane deformation), υCH_aromatic (near 3033 cm^-1) and methylene (-CH₂-) groups (υCH_asym= 2905, υCH_sym = 2836 and δCH_rocking = 754 cm^-1).

Table 2. Significant IR and XRD data of the zinc(II) complex and free ligand.

Table 2. Significant IR and XRD data of the zinc(II) complex and free ligand.

Compound	Wavenumbers of infrared data (cm-1)						XRD data
	phenolic (OH) str.	phenolic (OH) bend.	phenolic (C-O) str.	Carboxylic (OH) (H-bond) str.	(C=O) L: Carboxylic complex: carboxylate str.	(Zn-O) str.	Angle (d Value)	θ°	β (rad)	D (nm)
MHB	≈3150	1200	1281	2395-3650	1648	-	13.206° (6.69913 Å), 15.324° (5.77747 Å), 16.239°(5.45398 Å), 19.169° (4.62643 Å), 19.797° (4.48108 Å), 22.694° (3.91519 Å), 23.424° (3.79470 Å), 26.521° (3.35814 Å), 29.789° (2.99686 Å), 30.990° (2.88335 Å), 34.075° (2.62905 Å), 35.858° (2.50227 Å), 38.488° (2.33714 Å), 40.300° (2.23612 Å), 42.072° (2.14595 Å)	23.47	0.011	14.4
Zn-MHB	-	-	1248	-	1554	618, 624	7.387° (11.95800 Å)	7.39	0.056	2.6

NMR spectrum: According to a prior report [1], the ¹H NMR spectra of MHB revealed signals at 3.8 (CH₂, d), 11.2 (COOH, s, broad), 11.6 (phenolic OH, s, broad) and 6.7 - 7.9 (aromatic protons, m). The correct locations of–OH groups and –COOH, where the labile protons can be replaced by deuterium, were demonstrated by disappearing signals of -COOH and -OH following addition of D₂O. In accordance with IR findings, the spectral widening of the phenolic OH and COOH signals provided support the formation of hydrogen bonds between these groups.

3.1.2. Structural determination of the complex, Zn-MHB

Along with their diamagnetism and white color, the Zn^II (d¹⁰ configuration) could be regarded as a limit for the spectroscopic description of Zn derivatives due to their diamagnetism and white color. Conversely, the lack of ligand field stabilization might provide extremely flexible coordination geometry that is exclusively controlled by the ligands’ charge and steric hindrance. [28,29].

IR spectrum: A comparison of the IR spectrum of the complex with this of MHB (Fig, 2, Table 2) signified that MHB acts as a tetradentate ligand chelating two zinc ions via the deprotonated phenolic (-OH) and carboxyl (COOH) groups. The following evidences support this suggestion: (1) The negative shift of υ(C-O) band (MHB:1281 → Zn-MHB: 1248 cm^-1). (2) Disappearance of υ and δ(OH)_phenolic in the ligand upon complexation. (3) The carbonyl group (C=O) of the carboxyl (L: 1648 cm^-1, Table 2) disappears and the carbonyl of the carboxylate appears instead at 1554 cm^-1. (4) Obscure of broad band assigned to the intermolecular H-bond of COOH in ligand (2395-2650 cm^-1) points to breakage of this bond by coordination with zinc. The persistence of two additional bands in the range 600-620 cm^-1, centered at 618 and 624 due to (Zn-O) [30], is further evidence for the coordination of phenolic and carboxylic oxygen. On the other hand, the coordinated ethanol and water in the complex are indicated by the stretching vibrations observed within 3450 - 3550 cm^-1 (υOH_ethanol, υOH_water) and two somewhat weaker bands assigned to rocking (OH_water, 870 cm^-1) and wagging (OH_water, 614 cm^-1) vibrations.

Figure 2. FT-IR spectra of MHB ligand and Zn-MHB complex.

Figure 2. FT-IR spectra of MHB ligand and Zn-MHB complex.

UV-Vis spectrum: The electronic spectrum of the MHB and Zn-MHB were scanned and shown in Figure 3. MHB gave five peaks centered at 361, 351, 341, 319, 280 associated with n→π* (C=O)_carboxyl, n→π* phenolic OH, π→π* (C=O), π→π* phenolic and π→π* (phenyl) transitions, respectively. The π→π* and n→π* transitions were suggested for phenolic OH considering it is in delocalization with the carboxyl group’s C=O. As well known, Zn(II) complexes does not display d–d transitions due to their fully filled d¹⁰ configuration, however they frequently show charge transfer spectra. The same MHB peak locations with a slight shift were visible in the Zn-MHB electronic spectrum, along with peak of absorption at 420 nm due to L to M charge transfer (LMCT). The existence of the latter new CT band is consistent with complex having a tetrahedral structure [31] and confirmed coordination of MHB with Zn(II) ion.

Thermogravimetric analysis: The thermogram of the Zn-MHB has been studied. The TG curves up to 800 °C (Figure 4) revealed several weight loss steps. The first one (40-110 °C) is caused by the elimination of crystalline water molecules (found/calculated = 6.6/6.2)%, the second weight loss stage (110-280 °C) arise from removal of coordinated two water molecules (found/calculated = 6.7/6.2)% whereas the third weight loss step (280-400 °C) comes from elimination of coordinated ethanol (found/calculated = 14.4/15.9)%. The other four peaks are the result of the Zn(II) complex decomposition, which produces metal oxides in the last stage.

In light of the results mentioned above, the logical structure of the Zn(II) chelate is displayed in Scheme 1. A tetrahedral confirmation for Zn-MHB is supported by the fact that Zn(II) ion is a late transition metal with full d valence electrons, meaning that a sTable 18-electron complex may be produced through 4-coordination number.

Scheme 1. Schematic diagram of Zn-MHB complex formation.

Scheme 1. Schematic diagram of Zn-MHB complex formation.

3.1.3. Powder XRD studies

X-ray diffraction pattern are recorded for MHB and Zn(II) complex. The patterns of the samples are presented in the Figure 5 and the diffraction data include the inter-planar distances d (Å) and crystallite size are given in Table 2. The findings show that the MHB is crystalline, i.e., it has a single geometric shape with a distinct repeating pattern of its constituent molecules. The purity, single phase nature and crystallinity of the MHB particles are really indicated by the well-defined, sharp peaks in the XRD patterns [32]. The fact that Zn-MHB’s diffraction patterns differ significantly from those of the ligand indicates that the chelation

process was successful. The XRD pattern of Zn-MHB indicated an amorphous character, suggesting that the constituent particles are arranged randomly. Specific melting temperature of MHB proved that MHB is crystalline material. In X-ray diffraction and crystallography, the Scherrer equation [33] is a formula used to estimate the smallest size or diameter of a nanogranule; it is not relevant in limits larger than 200 nm. The Debye– Scherrer equation is

D =kλ/β cosθ;

where: λ = wavelength of X-ray radiation (Cu Kα=1.54 Å), β = the line broadening at full width at half maximum height (FWHM) in radians, k=constant taken as 0.94, θ = diffraction angle in degree and D = average crystallite size (Å),. The MHB and Zn-MHB crystallite sizes were found to be 14.4 and 2.5 nm, respectively.

3.1.4. Optical properties

Transmittance spectrum measurements have been used to study the compounds’ optical characteristics. Figure 6a shows the transmittance that was obtained. The energy gap (E_g) is the amount of energy required to move an electron from the valence band to the conduction band. Both the resultant electron in the conduction band and the electron hole in the valence band are free to migrate inside the crystal lattice and carry out electrical current conductivity. Small band gaps (0.1 to <⁚ 4 electron volts, eV) are found in semiconductors, big band gaps (> 4 eV) are found in insulators, and Conductors have very small band gaps or none at all because the valence and conduction bands overlap to produce a continuous band. Since the band gap value determines the material’s optical characteristics, or its capacity to absorb light or photon energy, it was necessary to measure it. The values of the indirect optical band gap were computed and are displayed in Figure 6b. The MHB and Zn-MHB were discovered to have E_g values of 3.23 and 3.16 eV, respectively. The result indicates that the conduction of ligand and complex resemble ZnO (E_g=3.37), GaN (E_g=3.4) and ZnSe (E_g=2.7) [34]. As reported in literature [35], it could be explain the slightly higher E_g values of MHB in comparison to its analogous Zn(II) complex. Through the acceptance of ligand electrons in its shell, zinc tends to increase ligand mobilization. It can be found that after chelation; the localized levels’ width is increased, resulting in a reduced band gap. It is noteworthy to emphasize that a small band gap facilitates electronic transitions between the HOMO-LUMO energy states, increasing the molecule’s electro-conductivity [36]. The MHB and Zn(II) complex both have band gap values lie in the range of semiconductors and could be employed in applications of optoelectronic [37].

The refractive index, which controls the speed of light in media other than a vacuum, is an essential property for optical applications. The smaller the refractive index (n), the higher the light travels within the substance. The evaluation of optical materials’ refractive indices is crucial for their application in optic devices, such as switches and modulators. Furthermore, one important physical characteristic that is commonly used in chemistry to assess purity is the refractive index. The subsequent relationship has been used to estimate the reflectance:

R + T + A= 1

The refractive index values (n) of the compounds may be approximately expressed by the relation [38,39],

r is the usual reflectance in this case. The changes in n values with λ,nm of the incident light are shown in Figure 6c. Because of certain interactions between photons and electrons, it is seen that the refractive index changes as the incident light beam’s wavelength varies [40]. Additionally, this figure shows how complexation affects the refractive index of the free ligand where the chelation leads to a difference in the n values. It is evident from the data in Figure 6c that the refractive index rises gradually until it remains almost constant.

The optical conductivity (σ_opt) depends on the values of n and frequency/wavelength of incident light and is given from [41]

σ_opt = nkν = nck/λ

k= αλ/4π

Where ν, λ, k, c, n, α and A stand for the frequency, wavelength, extinction coefficient, light velocity, refractive index, absorption coefficient and absorption, respectively. Figure 6d displays the variation of σ_opt as a function of photon energy (hv). The diagram illustrates precisely how, for two compounds, the ligand’s conductivity is nearly constant and the complex’s σ_opt value increases with photon energy or light frequency in the range of 1 to 3. After this, the ligand conductivity increases in comparison to the complex, which seems to change depending on the incident light frequency.

How far light can go through a compound is determined by its penetration depth. This depth—also known as skin depth—is reached when the material’s internal radiation intensity drops to roughly 37% of its initial level. The relationship has been used to determine the light penetration depth (W) through the ligand and zinc complex is:

W = λ/4πk

where the wavelength and extinction coefficient are denoted by k and λ, respectively. As a result, depending on the characteristics of the material and the radiation’s wavelength, electromagnetic radiation may either go away instantly or penetrate a substance very deeply. Actually, depth can provide the details with greater significance and insight. Figure 6e displays the fluctuation of W vs photon energy. Until the photon energy is 3.3, the penetration distance of the ligand is higher than that of the complex after which the opposite happens.

Figure 6. Variation of optical parameters for ligand and complex (a) transmittance, T, (b) band gap energy, E_g, (c) refractive index, n (d) optical conductivity, σ_opt and (e) penetration depth, W. .

Figure 6. Variation of optical parameters for ligand and complex (a) transmittance, T, (b) band gap energy, E_g, (c) refractive index, n (d) optical conductivity, σ_opt and (e) penetration depth, W. .

3.1.5. Morphological Studies on the MHB and Zn-MHB

Transmission electron microscopy (TEM) analysis [42] was carried out to study the morphological properties and the TEM images at the same magnification are shown in Figure 7. The TEM micrographs of both MHB and Zn-MHB exhibited regular spherical structures. While some of the Zn-MHB particles are heterogeneously dispersed and aggregated, the MHB particles appear to be mono-crystalline, non-aggregated, and evenly distributed. The obtained outcome is in good agreement with the XRD findings. The nanostructure of the

complex in comparison to the ligand was further verified by the TEM pictures, where MHB and Zn-MHB give average particle sizes of 116 and 95 nm, respectively. In fact, the chelation-induced change of ligand particles into zero dimensional (0-D) nanoparticles might be regarded as a successful outcome. Nano scale of the Zn-MHB points to the possibility of utilizing the produced Zn(II) complex in nanotechnology, in the field of medicine, environmental remediation and as quantum dots especially its band gap (E_g) locates in semiconductor rang.

Figure 7. TEM images of MHB and Zn-MHB.

Figure 7. TEM images of MHB and Zn-MHB.

3.1.6. Antibacterial investigation

Antimicrobial evaluation of MHB was carried out while its corresponding Zn(II) complex was not due to its insolubility as mentioned in experimental section. Screening of antimicrobial activity of synthesized MHB exhibits no activity against enterococcus faecalis, high activity against salmonella typhimurium and moderate activity towards other examined bacteria (Figure 8). While the MHB did not exhibit greater activity than the reference, it exhibited beneficial activity against the tested strains of several bacteria, especially salmonella. Salmonella infections in animals used for food production are a severe public health problem since animal foods are thought to be a major source of human illness. Eggs and meat from chickens and other food animals are the most frequently found causes of infection. Salmonellosis outbreaks in humans have also been linked to milk and dairy products. Infected water may also contaminate fruits and vegetables, which could also be a source of infection. Within 24 hours of infection, s. typhimurium-caused salmonellosis in people and food animals is characterized by severe intestinal inflammation, fever and diarrhea. Because salmonella can use a variety of virulence factors to overcome colonization resistance and cause intestinal inflammation, it is dangerous [43]. According to what was said, the increased efficacy of MHB against Salmonella typhimurium in comparison to gentamycin may be regarded as a distinguishing characteristic. The ability of MHB to permeate lipid membranes and blocked the metal binding sites in microbial enzymes serves as an example of how effective it is against bacteria. [44,45]. This behavior led to destroy the enzymes and hence impedes the formation of proteins necessary for further growth of the organisms [46].

3.1.7. Cytotoxic assay

Exposure to excess doses of chemical compounds or drugs may cause many health problems such as skin rashes, burns, damage to the kidneys and lungs, impact on the central nervous system, cancer, and many more. To get a preliminary indication of the cytotoxic of MHB in normal cells, MHB was evaluated against normal mammalian cell lines including African Green Monkey Kidney (VERO) and Human normal melanocytes of skin (HFB4). The cell viability values are exhibited in Figure 9. The concentration needed to destroy 50% of healthy cells (CC₅₀) was estimated. Human normal melanocytes had a CC₅₀ of 119.45 ± 6.31 µg/ ml, however mammalian cells from African green monkey kidney showed lesser sensitivity (153.85 ± 10.47 µg/ml). In general, the MHB was practically devoid of significant cytotoxic activity in normal mammalian cell [47]. Of course this result was speculated as MHB mimic hydroxybenzoic acid to a large extent and hydroxybenzoic acid is a natural substance employed in a variety of medicinal formulations as well as food and cosmetic additives [48,49].

4. Conclusions

References

1. L. Kahl, Ber 31 (1898.) 143.
2. Takashi, H.; Takaaki, H.; Hyozo, S.; Alan, P.M.; Kaipenchery, A.K.; Simon, G.B.; Kata, M.M.; Tatjana, S.; Nazar, S.A.E.; Hong-Sik, H.; Galina, G.T.; Richard, A.B. Molecular design of lipophilic disalicylic acid compounds with varying spacers for selective lead(II) extraction, Talanta 52 (2000) 385-396. [CrossRef]
3. Clemmensen, E.; Heitman, A.H.C. Methylenedisalicylic acid and its reaction with bromine and iodine, J. Am. Chem. Soc. 33 (1911) 733-745. [CrossRef]
4. Frederick, J., Rauner. Def. Pub! U.S. Pat. 878,020; Chem. Abstr. 1970, 73, 125729.
5. Patel R. P.; Karampurwala A. M.;Shah J. R.; Physicochemical studies on square planar Co²⁺, Ni²⁺ and Cu²⁺ chelate polymers, Macromol. Mater. Eng. 87 (1980) 87 – 94.
6. Kaltenberg, J.; Plum, J.L.; Ober-Blobaum, J.L.; Honscheid, A.; Rink, L.; Haase, H. Zinc signals promote IL-2-dependent proliferation of T cells. Eur. J. Immunol. 40 (2010) 1496 - 1503. [CrossRef]
7. Kim, A.M.; Bernhardt, M.L.; Kong, B,Y.; Ahn, R.W.; Vogt, S.; Woodruf, T.K.; O’Halloran, T.V.; Zinc sparks are triggered by fertilization and facilitate cell cycle resumption in mammalian eggs. ACS Chem. Biol. 6 (2011) 716 - 723. [CrossRef]
8. Xu Y, Luo F, Zheng JM, Syntheses, structures, and magnetic properties of a series of het-erotri-, tetra- and pentanuclear Ln^III–Co^II compounds. Polymers 11 (2019) 196. [CrossRef]
9. Chen DM, Zhang NN, Liu CS, Jiang ZH, Wang XD, Du MA. Mixed-cluster approach for building a highly porous cobalt(II) isonicotinic acid framework: gas sorption properties and computational analyses. Inorg. Chem. 56 (2017) 2379–2382. [CrossRef]
10. Li W.D., Guo X.Z., Zhang ZY, Chen, S.S. Metal(II) coordination polymers derived from mixed 4-imidazole ligands and carboxylates: syntheses, topological structures, and properties. Polymers 10 (2018) 622. [CrossRef]
11. Zhang CH, Chen YG, Tang G, Liu SX Polynuclear complexes of main group and transition metals with polyaminopolycarboxylate and polyoxometalate. Dalton Trans 41(2012) 9971. [CrossRef]
12. Gao F., Chunji N, Jiazuan. Study on mixed ligand complexes of rare earth with nitrilotriacetic acid and amino acid. Chinese Journal of Applied Chemistry 3 (1990) 10 -13.
13. Trevin, S., Bedioui, F., Gomez, M. G., Charreton, C. B. Electro polymerized nickel Micro cyclic complex - base films design and elctro-catalytic application. J. Mater. Chem. 7 (1997) 923-928. [CrossRef]
14. Ahmed, A.H; Sherif, E. M; Methylenedisalicylic acid as a bio corrosion inhibitor for aluminum in concentrated sodium chloride solutions, ACS Omega. 7 (2022) 19193 - 19203. [CrossRef]
15. Perez-Cano HJ, Robles-Contreras A. Basic aspects of the mechanisms of bacterial resistance. Rev Med MD 4 (2013)186-191.
16. [16] Kantouch, A.; Atef El-Sayed, A.; Salama, M.; Abou El-Kheir, A.; Mowafi, S. Disalicylic acid and some of its derivatives as antibacterial agents for viscose fabric, Int. J. Biol. Macromol. 62 (2013) 603-607. [CrossRef]
17. Yishan F.; Jianxin F.; Chunjing T.; Pengfei L.; Bo C.; Mechanical properties and antibacterial activities of novel starch-based composite films incorporated with disalicylic acid, Int. J. Biol. Macromol. 155 (2020)1350-1358. [CrossRef]
18. [18] Ghezzi, L. Spepi, A. Agnolucci, M. Cristani, C. Giovannetti, M. Tiné, M.R. Duce, C. Kinetics of release and antibacterial activity of disalicylic acid loaded into halloysite nanotubes, Appl. Clay Sci. 160 (2018) 88-94. [CrossRef]
19. Cushman, M.; Kanamathareddy, S. Synthesis of the covalent hydrate of the incorrectly assumed structure of aurintricarboxylic acid (ATA). Tetrahedron 46 (1990) 1491–1498 and references therein. [CrossRef]
20. Thabet, M.S.; Ahmed, A.H. Ship-in-a-bottle synthesis and physicochemical studies on zeolite encapsulated Mn(II), Mn(III)-semicarbazone complexes: Application in the heterogeneous hydroxylation of benzene. J. Porous Mater. 20 (2013) 319-330. [CrossRef]
21. Mott, N. F.; Davis E. A. Electronic Processes in Non-Crystalline Materials”, 2nd, Clarendon Press, oxford, 1979.
22. Ahmed, A.H.; Hassan,A.M.; Gumaa,H.A.; Mohamed,B.H.; Eraky,A.M. Physicochemical studies on some selected oxaloyldihydrazones and their novel palladium(II) complexes along with using oxaloyldihydrazones as corrosion resistants. Inorg.Nano-Met.Chem. 47(2017)1652−1663. [CrossRef]
23. Ahmed, A.H.; Hassan, A.M.; Gumaa, H.A.; Mohamed, B.H.; Eraky, A.M.; Omran, A.A. Copper(II)-oxaloyldihydrazone complexes: Physico-chemicalstudies; energy band gap and inhibition evaluation of free oxaloyldihydrazones toward the corrosion of copper metal in acidic medium. Arab. J. Chem. 12 (2019) 4287−4302. [CrossRef]
24. Hindler, J.A.; Howard, B.J.; Keiser, J.F. Antimicrobial agents and Susceptibility testing. In: Howard BJ(Editor), Clinical and pathogenic Microbiology. Mosby-Year Book Inc., St. Louis, MO, USA, 1994.
25. Abo-Ashour MF, Eldehna WM, Nocentini A, Bonardi A, Bua S, Ibrahim HS, Elaasser MM, Kryštof V, Jorda R, Gratteri P, Abou-Seri SM, Supuran CT. 3-Hydrazinoisatin-based benzenesulfonamides as novel carbonic anhydrase inhibitors endowed with anticancer activity: Synthesis, in vitro biological evaluation and in silico insights. Eur J Med Chem.; 184 (2019) 111768. [CrossRef]
26. Gomha, S.M.; Riyadh, S.M.; Mahmmoud, E.A. and Elaasser, M.M. Synthesis and Anticancer Activities of Thiazoles, 1,3-Thiazines, and Thiazolidine Using Chitosan-Grafted-Poly(vinylpyridine) as Basic Catalyst. Heterocycles; 91 (2015) 1227-1243. [CrossRef]
27. [27]. Ali A.M.; Ahmed, A.H.; Mohamed, T.A.; Mohamed B.H.; Chelates and corrosion inhibition of newly synthesized Schiff bases derived from o- tolidine” Transit. Met. Chem. 32 (2007) 461 - 467. [CrossRef]
28. Pettinari C.; Lorenzotti A.; Pellei M.; Santini C. Zinc(II), cadmium(II) and mercury(II) derivatives of bis(4-halopyrazol-1-yl)alkanes: synthesis, spectroscopic characterization and behaviour in solution. Polyhedron 16 (1997) 3435-3445. [CrossRef]
29. Adhikari S.; Bhattacharjee T.; Butcher R.J.; Porchia M.; De Franco M.; Marzano C.; Gandin V.; Tisato F. Synthesis and characterization of mixed-ligand Zn(II) and Cu(II) complexes including polyamines and dicyano-dithiolate(2-): In vitro cytotoxic activity of Cu(II) compounds. Inorg. Chim. Acta 498 (2019) 119098. [CrossRef]
30. Lal, R.A.; Basumatary, D.; Arjun, K.D.;, Kumar, A.; Synthesis and spectral characterization of zinc(II), copper(II), nickel(II) and manganese(II) complexes derived from bis(2-hydroxy-1-naphthaldehyde) malonoyldihydrazone, Transit. Met. Chem. 32 (2007) 481–493. [CrossRef]
31. Temel, H., Çakir, Ü.; Otludil, B.; Uğraş, H.İ. Synthesis, spectral and biological studies of Mnn(II), NiII), Cu(II), and Zn(II) complexes with a tetradentate Schiff base ligand. complexation studies and the determination of stability constants (Ke). Synth. React. Inorg. Met-org Chem. 31 (2001) 1323-1337 and references therein. [CrossRef]
32. Joseyphus, R. S.; Nair, M.S.; Synthesis, characterization and biological studies of some Co(II), Ni(II) and Cu(II) complexes derived from indole-3-carboxaldehyde and glycylglycine, as Schiff base ligand, Arab. J. Chem. 3 (2010) 195–204. [CrossRef]
33. Patterson, A., The Scherrer formula for X-ray particle size determination. Phys. Rev. 56 (1939) 978–982. [CrossRef]
34. Streetman, Ben G., Solid State electronic Devices, 5^th Ed., New Jersey: Prentice, 2000.
35. Karipcin, F.; Dede, B.; Caglar, Y.; Hur, D.; Ilican, S.; Caglar, M.; Sahin, Y.; A new dioxime ligand and its trinuclear copper(II) complex: Synthesis, characterization and optical properties, Opt. Commun. 272 (2007) 131–137. [CrossRef]
36. Sengupta, S.K.; Pandey, O.P.; Srivastava, B.K.; Sharma, V. Trends in Structural Mechanics: Theory, Practice, Transit. Met. Chem. 23 (1998) 349-353.
37. Turan, N. Gündüz, B. Körkoca, H. Adigüzel, R. Çolak, N. Buldurun, K. Study of structure and spectral characteristics of the zinc(II) and copper(II) complexes with 5,5-dimethyl-2-(2-(3-nitrophenyl)hydrazono)cyclohexane-1,3-dione and their effects on optical properties and the developing of the energy band gap and investigation of antibacterial activity, J. Mex. Chem. Soc. 58(1) (2014) 65-75.
38. Gittleman, J. I. Sichel, E.K. Arie, Y. Composite semiconductors: Selective absorbers of solar energy, Sol. Energy Mater. 1 (1979) 93-104. [CrossRef]
39. Belmokhtar, A.; Yahiaoui, A.; Hachemaoui, A.I.; Abdelghani, B.; Sahli, N.; Belbachir, M., ANovelPoly{(2,5-diylfuran)(benzylidene)}:Anew Synthetic Approach and Electronic Properties, ISRN Physical Chemistry 2012 (2011)7 781879.
40. Yakuphanoglu, F.; Erten, H., Refractive index dispersion and analysis of the optical constants of an ionomer thin film, Optica. Applicata. 4 (2005) 969-976.
41. Paul, T.C. ; Podder, J.; Synthesis and characterization of Zn- incorporated TiO2 thin flms: impact of crystallite size on X-ray line broadening and bandgap tuning, Appl. Phys. A 125 (2019) 818. [CrossRef]
42. Basma H. Amin, Hanaa Y. Ahmed, , Eman M. El Gazzar, , and Monda M. M. Badawy, Enhancement the Mycosynthesis of Selenium Nanoparticles by Using Gamma Radiation Dose-Response: An International Journal 4 ( 2021) 1–8. [CrossRef]
43. Fabrega A., Vila J. Salmonella enterica serovar typhimurium skills to succeed in the host: virulence and regulation. Clin. Microbiol. Rev. 26 (2013) 308–341. [CrossRef]
44. Ahmed, A.H. N,N`-bis[2-hydroxynaphthylidene]/[2-methoxybenzylidene]amino]oxamides and their divalent manganese complexes: Isolation, spectral characterization, morphology, antibacterial and cytotoxicity against leukemia cells. Open Chem. 18 (2020) 426–437. [CrossRef]
45. Ahmed, A.H.; Hassan, A.M.; Gumaa, H.A.; Mohamed, B.H.; Eraky, A.M. Nickel(II)-oxaloyldihydrazone complexes: Characterization, indirect band gap energy and antimicrobial evaluation. Cogent Chem. 2 (2016) 1142820. [CrossRef]
46. Kavitha, P. Reddy, K.L. Synthesis, spectral characterization, morphology, biological activity and DNA cleavage studies of metal complexes with chromone Schiff base, Arab. J. Chem. 9 (2016) 596-605. [CrossRef]
47. Mohareb1, R.M. EL-Sharkawy, K.A. Al Farouk, F.O. Synthesis, cytotoxicity against cancer and normal cell lines of novel hydrazide–hydrazine derivatives bearing 5H-chromen-5-one, Med. Chem. Res. 28 (2019)1885–1900. [CrossRef]
48. G J Baxter, A B Graham, J R Lawrence, D Wiles, J R Paterson, Salicylic acid acid in soups prepared from organically and non-organically grown vegetables, Eur. J. Nutr. (2001). [CrossRef]
49. William P. Coleman III MD, Harold J. Brody MD, Advances in chemical peeling, Dermatol. Clin. 15 (1997) 19-26. [CrossRef]